{"id":20333,"date":"2026-04-09T09:02:45","date_gmt":"2026-04-09T09:02:45","guid":{"rendered":"https:\/\/hlsllc.org\/tos\/?page_id=20333"},"modified":"2026-04-13T22:57:54","modified_gmt":"2026-04-13T22:57:54","slug":"anatomy-of-the-thoracic-outlet","status":"publish","type":"page","link":"https:\/\/hlsllc.org\/tos\/anatomy-of-the-thoracic-outlet\/","title":{"rendered":"Anatomy of the thoracic outlet"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"20333\" class=\"elementor elementor-20333\" data-elementor-post-type=\"page\">\n\t\t\t\t<div class=\"elementor-element elementor-element-decacca e-con-full e-flex e-con e-parent\" data-id=\"decacca\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0c41db1 elementor-widget elementor-widget-heading\" data-id=\"0c41db1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Anatomy of the thoracic outlet\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-6c292a4 e-con-full e-flex e-con e-parent\" data-id=\"6c292a4\" data-element_type=\"container\" data-e-type=\"container\" id=\"top\">\n\t\t<div class=\"elementor-element elementor-element-26eac5d e-con-full e-flex e-con e-child\" data-id=\"26eac5d\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-49ec476 elementor-widget elementor-widget-text-editor\" data-id=\"49ec476\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\">\n\n<p class=\"fusion-title-heading title-heading-left\">\nTable of Contents\n<\/p>\n\n<\/div>\n\n<div class=\"awb-toc-el\">\n\n<div class=\"awb-toc-el__content\">\n\n<ul class=\"awb-toc-el__list\">\n\n<li>\n<a href=\"#toc_Anatomy_of_the_thoracic_outlet_explains_thoracic_outlet\">\nAnatomy of the thoracic outlet explains thoracic outlet syndrome\n<\/a>\n<\/li>\n\n<li>\n<a href=\"#toc_Anatomy_of_the_spine\">Anatomy of the spine<\/a>\n<\/li>\n\n<li>\n<a href=\"#toc_Anatomy_of_a_nerve\">Anatomy of a nerve<\/a>\n<\/li>\n\n<li>\n<a href=\"#toc_Anatomy_of_the_brachial_plexus\">Anatomy of the brachial plexus<\/a>\n\n<ul>\n\n<li>\n<a href=\"#toc_Segmental_anatomy_of_the_brachial_plexus\">\nSegmental anatomy of the brachial plexus\n<\/a>\n\n<ul>\n\n<li><a href=\"#toggle_86003677425164f4c\">Nerve Roots<\/a><\/li>\n<li><a href=\"#toggle_277ab4171e2e6a980\">Trunks<\/a><\/li>\n<li><a href=\"#toggle_1ffe096d61f28aafd\">Divisions<\/a><\/li>\n<li><a href=\"#toggle_73207b8c688414210\">Cords<\/a><\/li>\n<li><a href=\"#toggle_aaa841cce13790e88\">Terminal Branches<\/a><\/li>\n\n<\/ul>\n\n<\/li>\n\n<\/ul>\n<\/li>\n\n<li>\n<a href=\"#toc_Anatomy_of_the_thoracic_outlet\">\nAnatomy of the thoracic outlet\n<\/a>\n\n<ul>\n\n<li>\n<a href=\"#toc_Tunnels_of_the_Thoracic_Outlet\">\nTunnels of the Thoracic Outlet\n<\/a>\n<\/li>\n\n<li>\n<a href=\"#toc_Scalene_triangle\">Scalene triangle<\/a>\n<\/li>\n\n<li>\n<a href=\"#toc_Costoclavicular_Interval\">\nCostoclavicular Interval\n<\/a>\n<\/li>\n\n<li>\n<a href=\"#toc_Retropectoralis_Space\">\nRetropectoralis Space\n<\/a>\n<\/li>\n\n<\/ul>\n\n<\/li>\n\n<\/ul>\n\n<\/div>\n<\/div> \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f168226 e-con-full e-flex e-con e-child\" data-id=\"f168226\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-26b38d5 e-con-full e-flex e-con e-parent\" data-id=\"26b38d5\" data-element_type=\"container\" data-e-type=\"container\" id=\"to\">\n\t\t<div class=\"elementor-element elementor-element-8ebfb28 e-con-full e-flex e-con e-child\" data-id=\"8ebfb28\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2137768 elementor-widget elementor-widget-heading\" data-id=\"2137768\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Anatomy_of_the_thoracic_outlet_explains_thoracic_outlet\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Anatomy of the thoracic outlet explains thoracic outlet syndrome\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-47d2a24 elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"47d2a24\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3d88582 elementor-widget elementor-widget-text-editor\" data-id=\"3d88582\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><p>Abnormal anatomy of the thoracic outlet causes compression or tension of the vital structures in the thoracic outlet. As a result, patients experience the symptoms of thoracic outlet syndrome. While the anatomy of the thoracic outlet is complex, understanding the anatomy of the thoracic outlet enables understanding of TOS. We can strive to understand the structures that cause compression as well as the structures that become compressed.<\/p><p>Understanding of the anatomy of the thoracic outlet is challenging. We have created videos to help with this challenge, which you can find on our\u00a0<a href=\"https:\/\/www.tosmri.com\/thoracic-outlet-syndrome-education\/thoracic-outlet-syndrome-educational-videos\/\">TOS Video page<\/a>, or on\u00a0<a href=\"https:\/\/www.toseducation.org\/\" target=\"_blank\" rel=\"noopener\">TOS education.org<\/a>.<\/p><p><a id=\"anatomy-top\" class=\"_mPS2id-t mPS2id-target mPS2id-target-first\"><\/a>We can categorize the essential anatomy of the thoracic outlet into these categories:<\/p><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2ddd23b elementor-icon-list--layout-traditional elementor-list-item-link-full_width elementor-widget elementor-widget-icon-list\" data-id=\"2ddd23b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Anatomy of the spine<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Anatomy of a nerve<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Anatomy of the brachial plexus<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Anatomy of the thoracic outlet<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-152fab1 elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"152fab1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e2c3981 elementor-widget elementor-widget-heading\" data-id=\"e2c3981\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Anatomy_of_the_spine\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Anatomy of the spine\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a6605ac elementor-widget elementor-widget-text-editor\" data-id=\"a6605ac\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><p>Understanding of the anatomy of the thoracic outlet begins with understanding the anatomy of the spine. The spine supports our body weight while allowing flexibility in multiple directions. The brachial plexus nerves arise from the spinal cord, pass through the central canal of the spine, and then exit the spine at multiple levels through neural foramina to enter each thoracic outlet.<\/p><p>The\u00a0<em>vertebral body<\/em>\u00a0is the basic building block of the spine. Vertebral bodies (also known as\u00a0<em>vertebrae<\/em>)\u00a0are stacked one upon the other from the skull to the pelvis. The vertebral bodies support our body weight.<\/p><p>Between each vertebral body lies an\u00a0<em>intervertebral disc<\/em>. Each disc is firmly attached to the vertebral body above it and to the body below it. The disc has a fibrous outer layer that stabilizes each vertebral body to the next. The center of each disc contains a jelly-like substance that absorbs impacts from walking, jumping and other movement. The flexible discs allow movement in multiple directions:<\/p><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2e1e07f elementor-icon-list--layout-traditional elementor-list-item-link-full_width elementor-widget elementor-widget-icon-list\" data-id=\"2e1e07f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Flexion and extension: Forward and backward bending<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Lateral bending: Side to side bending<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\"> Rotation: Side to side twisting<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2c4d939 elementor-widget elementor-widget-image\" data-id=\"2c4d939\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"600\" height=\"400\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Spine-AP-Lateral-Labeled-1.jpg\" class=\"attachment-large size-large wp-image-20356\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ca496f0 elementor-widget elementor-widget-heading\" data-id=\"ca496f0\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">The spine comprises five anatomic regions, from top to bottom:\n\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7687a44 elementor-icon-list--layout-traditional elementor-list-item-link-full_width elementor-widget elementor-widget-icon-list\" data-id=\"7687a44\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Cervical spine: The neck<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Thoracic spine: The mid-back; twelve paired ribs arise from the thoracic spine, forming the rib cage<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Lumbar spine: The low back<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Sacral spine: The base of the spine; joins the pelvis to the spine<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Coccyx: The tailbone; in humans, the coccyx represents a vestigial tail<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4355f13 elementor-widget elementor-widget-image\" data-id=\"4355f13\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"600\" height=\"625\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Spine-Regions-Labeled.jpg\" class=\"attachment-large size-large wp-image-20363\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-926fa6f elementor-widget elementor-widget-heading\" data-id=\"926fa6f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Each region of the spine has a different number of vertebral bodies:\n\n\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-88a1cd4 elementor-icon-list--layout-traditional elementor-list-item-link-full_width elementor-widget elementor-widget-icon-list\" data-id=\"88a1cd4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Cervical spine-seven segments, numbered C1 (\u2018Cervical\u2019 1) through C7<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Thoracic spine-twelve segments, numbered T1 (\u2018Thoracic\u2019 1) through T12; each body has a rib on each side<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Lumbar spine-five segments, numbered L1 (\u2018Lumbar\u2019 1) through L5<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Sacral spine-five segments, numbered S1 (\u2018Sacral\u2019 1) through S5; these segments are fused together into one bone in adults, which articulates with the pelvis on each side.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Coccyx-three to five segments, with variable degrees of fusion in the adult; usually referred to as a single unit rather than separate vertebrae.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0b3b4ba elementor-widget elementor-widget-text-editor\" data-id=\"0b3b4ba\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A bony arch arises from the back of each vertebral body. These arches line up to form a flexible bony tunnel, the\u00a0<em>spinal canal<\/em>. The spinal canal runs from the base of the skull to the pelvis, and it contains and protects the spinal cord. At each spinal level, a nerve leaves the spinal cord on each side. Each nerve exits the spinal canal through a tunnel between the bony arches to reach the body or extremities. This tunnel is called a\u00a0<i>neural foramen<\/i>.<\/p><p>On the back and sides of each arch we see a number of bony levers, which allow for attachments of the numerous muscles that stabilize and move the spine.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-75469ac elementor-widget elementor-widget-image\" data-id=\"75469ac\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"800\" height=\"328\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Spine-anatomy-detail.jpg\" class=\"attachment-large size-large wp-image-20373\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-dce4db5 elementor-widget elementor-widget-text-editor\" data-id=\"dce4db5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-text fusion-text-6\"><p>A fluid filled sac (the\u00a0<i>thecal sac<\/i>) fills the skull and central spinal canal, and contains the brain and spinal cord. Similar to the bony vertebral levels, the spinal cord comprises cervical, thoracic, lumbar, sacral and coccygeal segments. Thus, cervical nerve roots exit the upper spinal cord, and the coccygeal nerve roots exit the distal spinal cord. It should be noted that the levels in the spinal cord do not align with the levels in the bony spine. Therefore, exiting nerve roots travel a variable distance in the thecal sac before exiting at their respective neural foramina.<\/p><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8b5e11a elementor-widget elementor-widget-image\" data-id=\"8b5e11a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"400\" height=\"550\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Spinal-Segments.jpg\" class=\"attachment-large size-large wp-image-20380\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-45183b7 elementor-widget elementor-widget-text-editor\" data-id=\"45183b7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-text fusion-text-6\"><div class=\"fusion-text fusion-text-7\"><p>Nerve fibers are vulnerable to\u00a0<a href=\"https:\/\/www.tosmri.com\/what-is-thoracic-outlet-syndrome\/causes-of-thoracic-outlet-syndrome\/causes-of-neurogenic-thoracic-outlet-syndrome\/\">compression or tension<\/a>\u00a0as they travel in narrow spaces throughout the body. Within the spinal canal, a bulging disc or herniated disc can press on the spinal cord. A narrowed neural foramen can compress an exiting nerve root. These are examples of\u00a0<em>nerve entrapment<\/em>, where compression or tension on a nerve causes symptoms in the territory of that nerve.\u00a0<a href=\"https:\/\/www.tosmri.com\/what-is-thoracic-outlet-syndrome\/types-of-thoracic-outlet-syndrome\/neurogenic-thoracic-outlet-syndrome\/\">Neurogenic thoracic outlet syndrome<\/a>\u00a0is another, more complex, form of nerve entrapment.<\/p><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f9d5123 elementor-widget elementor-widget-image\" data-id=\"f9d5123\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"447\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Spine-vertebra-anatomy-with-HNP.jpg\" class=\"attachment-large size-large wp-image-20384\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a648bac elementor-widget elementor-widget-text-editor\" data-id=\"a648bac\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-text fusion-text-6\"><div class=\"fusion-text fusion-text-7\"><div class=\"fusion-text fusion-text-8\"><p>Once a nerve exits its neural foramen, it enters the thoracic outlet. Read more about the anatomy of the\u00a0<a class=\"_ps2id __mPS2id _mPS2id-h\" href=\"https:\/\/www.tosmri.com\/what-is-thoracic-outlet-syndrome\/anatomy-of-the-thoracic-outlet\/#anatomy-thoracic-outlet\" data-ps2id-offset=\"\">thoracic outlet<\/a>.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cb42ff4 elementor-widget elementor-widget-heading\" data-id=\"cb42ff4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Back to Anatomy<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d7df978 elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"d7df978\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-471b289 e-con-full e-flex e-con e-child\" data-id=\"471b289\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f448c03 e-con-full e-flex e-con e-parent\" data-id=\"f448c03\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-725141e e-con-full e-flex e-con e-child\" data-id=\"725141e\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-bdd04b7 elementor-widget elementor-widget-heading\" data-id=\"bdd04b7\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Anatomy_of_a_nerve\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Anatomy of a nerve<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e9b3ffc elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"e9b3ffc\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-75926d9 elementor-widget elementor-widget-text-editor\" data-id=\"75926d9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><p>Nerves connect the brain and the body. At its simplest, a nerve can be thought of as a simple wire that transmits information. At a deeper level, however, nerves are complex and varied. A basic understanding of the anatomy of a nerve will help us understand the varied symptoms of TOS.<\/p><p>In general, the human nervous system is divided into the\u00a0<i>central nervous system<\/i>\u00a0and the\u00a0<i>peripheral nervous system<\/i>. The central nervous system comprises the brain, the brainstem (the lowest and most primitive part of the brain) and the spinal cord. These structures are contained within the fluid-filled thecal sac, which sits inside the skull and spinal canal. The peripheral nervous system comprises all other nerves and nervous system structures.<\/p><p>The peripheral nervous system is divided into\u00a0<a class=\"_ps2id __mPS2id _mPS2id-h\" href=\"https:\/\/www.tosmri.com\/what-is-thoracic-outlet-syndrome\/anatomy-of-the-thoracic-outlet\/#anatomy-somatic-autonomic\" data-ps2id-offset=\"\">two parallel nervous systems:<\/a>\u00a0the\u00a0<i>somatic nervous system<\/i>\u00a0and the\u00a0<i>autonomic nervous system\u00a0<\/i>. The somatic nervous system controls voluntary bodily functions, while the autonomic nervous system controls involuntary bodily functions. Voluntary functions include motor functions, such as walking, and conscious sensations, such as feeling light touch against the skin. Involuntary functions include unconscious motor functions like blood pressure regulation, and unconscious sensory regulation, such as pupils constricting in bright light.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-19f6d6d elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"19f6d6d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5452627 elementor-widget elementor-widget-text-editor\" data-id=\"5452627\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><p>The basic building block of a nerve is the nerve cell, the\u00a0<i>neuron<\/i>. A neuron is a specialized, electrically excitable cell that receives, processes, and transmits information throughout the body. Each neuron includes a cell\u00a0<i>body<\/i>\u00a0(control center),\u00a0<i>dendrites<\/i>\u00a0(which receive signals), and an\u00a0<i>axon<\/i>\u00a0(which transmits signals). The axon, or\u00a0<i>nerve fiber<\/i>, can be extremely long relative to the size of the body. There are many different types of neurons, resulting in a large variety of nerve fibers. The body of each neuron may be located in the brain, the spinal cord, or in a\u00a0<i>ganglion<\/i>. A ganglion is a cluster of neuron cell bodies arising outside the central nervous system.<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-73f15d4 elementor-widget elementor-widget-image\" data-id=\"73f15d4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"400\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Neuron-labeled-600x400-1.jpg\" class=\"attachment-large size-large wp-image-20406\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-73cd25b elementor-widget elementor-widget-text-editor\" data-id=\"73cd25b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><p>Classification of the different types of peripheral nerve fibers is based on the diameter of the nerve fiber and whether the nerve fiber is\u00a0<em>myelinated<\/em>. Larger diameter nerve fibers conduct signals at a higher velocity than smaller diameter nerve fibers. In addition, some nerve fibers are insulated with a\u00a0<em>myelin sheath<\/em>. This is a sheath of fatty tissue produced by a support cell adjacent to the nerve fiber. The myelin sheath helps to increase\u00a0<em>nerve conduction velocity<\/em>. Somatic motor fibers are usually myelinated. Certain types of somatic sensory fibers and autonomic fibers are myelinated, while others are unmyelinated. All nerve fibers in the central nervous system are myelinated.<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5392140 elementor-widget elementor-widget-image\" data-id=\"5392140\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"417\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Myelin-Sheath-600x417-1.jpg\" class=\"attachment-large size-large wp-image-20413\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-930dd02 elementor-widget elementor-widget-text-editor\" data-id=\"930dd02\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><div class=\"fusion-text fusion-text-13\"><p>Whether the nerve fibers arise in the brain, spinal cord, or peripheral ganglion, they eventually form a peripheral nerve with hundreds or thousands of other nerve fibers. Peripheral nerves almost always include a mix of motor and sensory fibers, somatic and autonomic fibers, large and small, myelinated and unmyelinated fibers. The nerve fibers cluster together in\u00a0<em>fascicles<\/em>, and multiple fascicles cluster together within a peripheral nerve.<\/p><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-129b6b0 elementor-widget elementor-widget-image\" data-id=\"129b6b0\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"601\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Anatomy-Spinal-Cord-Nerve-Cross-section.jpg\" class=\"attachment-large size-large wp-image-20420\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8cd2ba1 elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"8cd2ba1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9a24c32 elementor-icon-list--layout-traditional elementor-list-item-link-full_width elementor-widget elementor-widget-icon-list\" data-id=\"9a24c32\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">The somatic nervous system<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">The autonomic nervous system<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ed23b77 elementor-widget elementor-widget-text-editor\" data-id=\"ed23b77\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-text fusion-text-6\"><div class=\"fusion-text fusion-text-7\"><div class=\"fusion-text fusion-text-8\"><p>The somatic nervous system controls voluntary bodily functions, while the autonomic nervous system controls involuntary bodily functions. Voluntary functions include motor functions, such as walking, as well as conscious sensations, such as touching a hot surface or feeling touch against your skin. Involuntary functions include motor functions, such as regulating blood vessels and blood pressure, as well as unconscious sensory regulation, such as the pupils constricting in bright light.<\/p><p>Somatic motor nerves control the voluntary muscles of the body, and allow us to move our bodies at will. Bear in mind\u00a0that we have both voluntary muscles and involuntary muscles. Voluntary muscles are those we control with conscious thoughts, such as flexing one\u2019s biceps or picking up a cup of coffee. Involuntary muscles are muscles that function on a subconscious level, usually to regulate functions of the body, such as moving food through the gut, or narrowing the pupil when bright light hits it.<\/p><p>Somatic sensory nerves transmit information from different types of receptors throughout the body back to the brain. Examples of sensory nerves include a nerve that senses a pinprick, or one that senses a hot stove. At the end of each sensory nerve is a receptor that is specialized for a specific function. Receptors are specialized for heat, pain, pressure, position sense, and other stimuli.<\/p><p>Autonomic nerves function as a subconscious, primitive nervous system that controls many involuntary functions of the human body. The autonomic nerve fibers control such functions as sweating, regulation of blood pressure, dilation or contraction of the pupils, and the function of the gut. Autonomic nerve fibers include both motor and sensory nerve fibers. Autonomic motor fibers control involuntary muscles. For example, autonomic motor fibers control the muscles in the walls of our blood vessels or bowel, regulate sweating, and control the adrenal glands. We have no conscious control of these functions. Autonomic sensory fibers transmit information about heart rate, body temperature, blood oxygen, or blood pressure back to the central nervous system. We have no direct. conscious sensation of these functions<\/p><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1968615 elementor-widget elementor-widget-image\" data-id=\"1968615\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"327\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Anatomy-Spinal-Cord-Nerve-Pathways-Labeled-3-600x327-1.jpg\" class=\"attachment-large size-large wp-image-20430\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-fed35e9 elementor-widget elementor-widget-text-editor\" data-id=\"fed35e9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-text fusion-text-6\"><div class=\"fusion-text fusion-text-7\"><div class=\"fusion-text fusion-text-8\"><div class=\"fusion-text fusion-text-16\"><p>To sum things up so far, hundreds or thousands of different nerve fibers compose a typical peripheral nerve. Each of these fibers possesses different qualities, and each has a unique function. Compression or tension on the peripheral nerve may affect many different types of nerve fibers, resulting in a variety of symptoms.<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4d678f5 elementor-widget elementor-widget-heading\" data-id=\"4d678f5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Back to Anatomy<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-dc0089b e-con-full e-flex e-con e-child\" data-id=\"dc0089b\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d74bea2 e-con-full e-flex e-con e-parent\" data-id=\"d74bea2\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1220640 elementor-widget elementor-widget-heading\" data-id=\"1220640\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Do you have questions about thoracic outlet syndrome?\n\n\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-208aeee elementor-widget elementor-widget-heading\" data-id=\"208aeee\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">We can help!\n\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-05be721 elementor-widget elementor-widget-button\" data-id=\"05be721\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm\" href=\"#\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Contact us<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d9c284f e-con-full e-flex e-con e-parent\" data-id=\"d9c284f\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-9c086b9 e-con-full e-flex e-con e-child\" data-id=\"9c086b9\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-58f278d elementor-widget elementor-widget-heading\" data-id=\"58f278d\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Anatomy_of_the_brachial_plexus\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Anatomy of the brachial plexus\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0c1ff97 elementor-widget elementor-widget-text-editor\" data-id=\"0c1ff97\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><p>A plexus is a network or cluster of nerves. The\u00a0<em>brachial plexus<\/em>\u00a0is the second largest plexus in the human body. On each side, the brachial plexus passes through the thoracic outlet to reach the arm. The anatomy of the thoracic outlet determines the course of each brachial plexus. After passing through the thoracic outlet, the brachial plexus provides the nerve supply to the upper extremity, including portions of the chest wall and shoulders.<\/p><p>Medical students spend a lot of time memorizing the detailed anatomy of the brachial plexus. Few doctors use such detailed information when diagnosing and treating patients. While it is important to understand the basic structure of the brachial plexus, it is also important to understand its relationship to the surrounding structures of the thoracic outlet.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-da4cf6d elementor-widget elementor-widget-heading\" data-id=\"da4cf6d\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Segmental_anatomy_of_the_brachial_plexus\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Segmental anatomy of the brachial plexus\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-91ee629 elementor-widget elementor-widget-text-editor\" data-id=\"91ee629\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t\n\nEach brachial plexus comprises 5 nerve roots: C5, C6, C7, C8 and T1. Once these roots leave their respective neural foramina on each side of the cervical spine, they enter the thoracic outlet. The roots from three trunks. Each of the three trunks splits into two divisions. The divisions rejoin to form cords. Finally, the cords produce five terminal nerves:\n\n<\/div>\n<div class=\"accordian fusion-accordian\">\n<div id=\"accordion-10959-1\" class=\"panel-group fusion-toggle-icon-boxed\">\n<div class=\"fusion-panel panel-default panel-86003677425164f4c fusion-toggle-has-divider\">\n<div class=\"panel-heading\">\n<h4 id=\"toggle_86003677425164f4c\" class=\"panel-title toggle fusion-responsive-typography-calculated\" data-fontsize=\"24\" data-lineheight=\"22.08px\"><\/h4>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ba99524 elementor-widget elementor-widget-n-accordion\" data-id=\"ba99524\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;default_state&quot;:&quot;all_collapsed&quot;,&quot;max_items_expended&quot;:&quot;one&quot;,&quot;n_accordion_animation_duration&quot;:{&quot;unit&quot;:&quot;ms&quot;,&quot;size&quot;:400,&quot;sizes&quot;:[]}}\" data-widget_type=\"nested-accordion.default\">\n\t\t\t\t\t\t\t<div class=\"e-n-accordion\" aria-label=\"Accordion. Open links with Enter or Space, close with Escape, and navigate with Arrow Keys\">\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1950\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"1\" tabindex=\"0\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1950\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Nerve Roots <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1950\" class=\"elementor-element elementor-element-fc824ac e-con-full e-flex e-con e-child\" data-id=\"fc824ac\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a87a473 elementor-widget elementor-widget-text-editor\" data-id=\"a87a473\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t\n\nFive nerve roots exit the spine on each side to form the brachial plexus: C5, C6, C7, C8 and T1.\n\n<\/div>\n<\/div>\n<\/div>\n<div class=\"fusion-panel panel-default panel-277ab4171e2e6a980 fusion-toggle-has-divider\">\n<div class=\"panel-heading\">\n<h4 id=\"toggle_277ab4171e2e6a980\" class=\"panel-title toggle fusion-responsive-typography-calculated\" data-fontsize=\"24\" data-lineheight=\"22.08px\"><\/h4>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1951\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"2\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1951\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Trunks <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1951\" class=\"elementor-element elementor-element-ab0231d e-con-full e-flex e-con e-child\" data-id=\"ab0231d\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0fa4d64 elementor-widget elementor-widget-text-editor\" data-id=\"0fa4d64\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The five nerve roots form three\u00a0<em>trunks:<\/em><\/p><p>C5 and C6 form the\u00a0<em>upper trunk<\/em>.<\/p><p>C7 forms the middle<em>\u00a0trunk<\/em>.<\/p><p>C8 and T1 form the\u00a0<em>lower trunk<\/em>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"toggle_1ffe096d61f28aafd\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"3\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"toggle_1ffe096d61f28aafd\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Divisions <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"toggle_1ffe096d61f28aafd\" class=\"elementor-element elementor-element-e36c90e e-con-full e-flex e-con e-child\" data-id=\"e36c90e\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2a775c5 elementor-widget elementor-widget-text-editor\" data-id=\"2a775c5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Each trunk splits into an\u00a0<em>anterior division<\/em>\u00a0and a\u00a0<em>posterior division<\/em>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"toggle_73207b8c688414210\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"4\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"toggle_73207b8c688414210\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Cords <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"toggle_73207b8c688414210\" class=\"elementor-element elementor-element-fc88a7f e-con-full e-flex e-con e-child\" data-id=\"fc88a7f\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-b3eec8d elementor-widget elementor-widget-text-editor\" data-id=\"b3eec8d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The divisions join into three\u00a0<em>cords<\/em>:<\/p><p><em>Lateral cord<\/em><\/p><p><em>Medial cord<\/em><\/p><p><em>Posterior cord<\/em><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"toggle_aaa841cce13790e88\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"5\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"toggle_aaa841cce13790e88\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Terminal Branches <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"toggle_aaa841cce13790e88\" class=\"elementor-element elementor-element-8370206 e-con-full e-flex e-con e-child\" data-id=\"8370206\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-ecb145e elementor-widget elementor-widget-text-editor\" data-id=\"ecb145e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The three cords form five terminal nerves:<\/p><p><em>Musculocutaneous nerve<\/em><\/p><p><em>Median nerve<\/em><\/p><p><em>Axillary nerve<\/em><\/p><p><em>Radial nerve<\/em><\/p><p><em>Ulnar nerve<\/em><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7b1515d elementor-widget elementor-widget-image\" data-id=\"7b1515d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"450\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Brachial-Plexus-Segments-Labeled-600x450-1.jpg\" class=\"attachment-large size-large wp-image-20497\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7f58190 elementor-widget elementor-widget-text-editor\" data-id=\"7f58190\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><p>The five terminal nerves extend down the arm. There are additional smaller nerves arising from the brachial plexus, which have been excluded for simplicity. It is worth remembering that each of the five major terminal nerves contains a mix of somatic and autonomic nerves, both motor and sensory. Given the complex branching pattern of the brachial plexus, as well as the complex mixture of nerve fibers within each branch, it should be easy to understand why compression or tension on the brachial plexus would produce complex symptoms in\u00a0<a href=\"https:\/\/www.tosmri.com\/diagnosis-of-thoracic-outlet-syndrome\/symptoms-of-thoracic-outlet-syndrome\/symptoms-of-neurogenic-thoracic-outlet-syndrome\/\">neurogenic thoracic outlet syndrome<\/a>.<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8cde7aa elementor-widget elementor-widget-heading\" data-id=\"8cde7aa\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#top\">Back to Anatomy<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-90d7dbe elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"90d7dbe\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-16072bc e-con-full e-flex e-con e-child\" data-id=\"16072bc\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f666075 e-con-full e-flex e-con e-parent\" data-id=\"f666075\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-08da046 e-con-full e-flex e-con e-child\" data-id=\"08da046\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a8e662f elementor-widget elementor-widget-heading\" data-id=\"a8e662f\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Anatomy_of_the_thoracic_outlet\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Anatomy of the thoracic outlet\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9cf1882 elementor-widget elementor-widget-text-editor\" data-id=\"9cf1882\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-23\"><p>Doctors have classically defined the\u00a0<i>thoracic outlet<\/i>\u00a0as the space at the top of the rib cage, where the neck joins the chest. Doctors use the term\u00a0<em>outlet<\/em>\u00a0because blood\u00a0vessels pass from the chest into the neck and shoulders through this space. At the same time, anatomists have classically defined the same space as the\u00a0<i>thoracic inlet.<\/i>\u00a0Anatomists use the term\u00a0<em>inlet<\/em>\u00a0because the esophagus and trachea pass from the neck into the chest. This point remains somewhat pedantic, and is unimportant in our discussion of anatomy. Our first media shows how the classically-defined thoracic outlet crosses the midline in front of the spine.<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2833d1d elementor-widget elementor-widget-aic-image-comparison\" data-id=\"2833d1d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"aic-image-comparison.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t        \n        <div id=\"aic-image-comparison-2833d1d\" class=\"aic-image-container\" data-offset=\"1\" data-orientation=\"horizontal\" data-before_label=\"Before\" data-after_label=\"After\" data-overlay=\"no\" data-onhover=\"yes\" data-click_to_move=\"no\">\n\t\t\t<img decoding=\"async\" class=\"aic-before-img\" alt=\"Before image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Thoracic-Outlet-Rib-Cage-Base-400x582-1.jpeg\">\n\t\t\t<img decoding=\"async\" class=\"aic-after-img\" alt=\"After image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Thoracic-Outlet-Rib-Cage-Highlight-400x582-1-1.jpeg\">\n        <\/div>\n\n        \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ae0e5e6 elementor-widget elementor-widget-text-editor\" data-id=\"ae0e5e6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-text fusion-text-24\">\n\nThe great vessels (one subclavian artery and vein on each side) exit the chest through this space. The nerve roots exit the cervical spine and form one brachial plexus on each side. After this, the vessels and brachial plexus align on each side, then pass over the first rib and enter each arm.<span class=\"Apple-converted-space\">\u00a0<\/span>\n\n<\/div>\n<div class=\"accordian fusion-accordian\">\n<div id=\"accordion-10959-1\" class=\"panel-group fusion-toggle-icon-boxed\">\n<div class=\"fusion-panel panel-default panel-86003677425164f4c fusion-toggle-has-divider\">\n<div class=\"panel-heading\">\n<h4 id=\"toggle_86003677425164f4c\" class=\"panel-title toggle fusion-responsive-typography-calculated\" data-fontsize=\"24\" data-lineheight=\"22.08px\"><\/h4>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-bf98fa6 elementor-widget elementor-widget-aic-image-comparison\" data-id=\"bf98fa6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"aic-image-comparison.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t        \n        <div id=\"aic-image-comparison-bf98fa6\" class=\"aic-image-container\" data-offset=\"1\" data-orientation=\"horizontal\" data-before_label=\"Before\" data-after_label=\"After\" data-overlay=\"no\" data-onhover=\"yes\" data-click_to_move=\"no\">\n\t\t\t<img decoding=\"async\" class=\"aic-before-img\" alt=\"Before image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Oblique-Thoracic-Outlet-Skeletal-1-400x533-1.jpeg\">\n\t\t\t<img decoding=\"async\" class=\"aic-after-img\" alt=\"After image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Oblique-Thoracic-Outlet-Soft-Tissue-1-400x533-1.jpeg\">\n        <\/div>\n\n        \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a8aeca8 elementor-widget elementor-widget-text-editor\" data-id=\"a8aeca8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tThe image below demonstrates the relationship between the bony\u00a0<a title=\"Thoracic Outlet Syndrome MRI: Diagnosis and Treatment Options\" href=\"https:\/\/www.tosmri.com\/thoracic-outlet-syndrome-mri-diagnosis-and-treatment-options\/\" data-wpil-monitor-id=\"218\">thoracic<\/a>\u00a0outlet and the soft tissues that pass through it.\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-eb6c06f elementor-widget elementor-widget-image\" data-id=\"eb6c06f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"543\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Kryski-Costoclavicular-Interval-Plexus-and-Vessels.jpg\" class=\"attachment-large size-large wp-image-20493\" alt=\"\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e8a59da elementor-widget elementor-widget-heading\" data-id=\"e8a59da\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Tunnels_of_the_Thoracic_Outlet\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Tunnels of the Thoracic Outlet\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-133413d elementor-widget elementor-widget-text-editor\" data-id=\"133413d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><p>Three vital structures (brachial plexus, subclavian artery and vein) follow a pathway through three anatomic tunnels to each arm. Narrowing of any of these tunnels may compress or stretch the nerves or vessels, causing TOS. We can better understand TOS by understanding these pathways.<\/p><p>As we move from the neck to the arm, the three tunnels in this pathway have been classically defined as:<\/p><ul><li>Scalene triangle<\/li><li>Costoclavicular interval<\/li><li>Retropectoralis space<\/li><\/ul><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-33f2e17 elementor-widget elementor-widget-heading\" data-id=\"33f2e17\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Scalene_triangle\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Scalene triangle\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2e0b774 elementor-widget elementor-widget-text-editor\" data-id=\"2e0b774\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><p>After the nerve roots exit the spine, they form the brachial plexus. The subclavian artery exits the chest, after which it travels with the brachial plexus. These two structures enter the\u00a0<em>scalene triangle<\/em>. The scalene triangle is defined by the following structures:<\/p><ul><li>Anterior: Anterior scalene muscle<\/li><li>Posterior: Middle scalene muscle<\/li><li>Inferior: First rib<\/li><\/ul><p>The\u00a0subclavian vein takes a different path than the subclavian artery. The subclavian vein exits the chest and passes anterior to the anterior scalene muscle. Thus, only two of the three vital structures pass through the scalene triangle.<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0cc951c elementor-widget elementor-widget-aic-image-comparison\" data-id=\"0cc951c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"aic-image-comparison.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t        \n        <div id=\"aic-image-comparison-0cc951c\" class=\"aic-image-container\" data-offset=\"1\" data-orientation=\"horizontal\" data-before_label=\"Before\" data-after_label=\"After\" data-overlay=\"no\" data-onhover=\"yes\" data-click_to_move=\"no\">\n\t\t\t<img decoding=\"async\" class=\"aic-before-img\" alt=\"Before image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Normal-Lateral-Cropped-CCI-Labeled-600x450-1.jpeg\">\n\t\t\t<img decoding=\"async\" class=\"aic-after-img\" alt=\"After image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Normal-Lateral-Cropped-CCI-Outlined-600x450-1.jpeg\">\n        <\/div>\n\n        \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0bf64b9 elementor-widget elementor-widget-heading\" data-id=\"0bf64b9\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"oc_Costoclavicular_Interval\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Costoclavicular Interval\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d881b40 elementor-widget elementor-widget-text-editor\" data-id=\"d881b40\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><div class=\"fusion-text fusion-text-28\"><p>After the subclavian artery and brachial plexus exit the scalene triangle, they align with the subclavian vein. The three structures then enter the<em>\u00a0costoclavicular interval<\/em>. The boundaries of the costoclavicular interval\u00a0are defined by the following structures:<\/p><ul><li>Superior boundary: Clavicle<\/li><li>Inferior boundary: First rib<\/li><\/ul><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1e9112d elementor-widget elementor-widget-aic-image-comparison\" data-id=\"1e9112d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"aic-image-comparison.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t        \n        <div id=\"aic-image-comparison-1e9112d\" class=\"aic-image-container\" data-offset=\"1\" data-orientation=\"horizontal\" data-before_label=\"Before\" data-after_label=\"After\" data-overlay=\"no\" data-onhover=\"yes\" data-click_to_move=\"no\">\n\t\t\t<img decoding=\"async\" class=\"aic-before-img\" alt=\"Before image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Kryski-Retropectoralis-Space-Labeled-600x448-1.jpeg\">\n\t\t\t<img decoding=\"async\" class=\"aic-after-img\" alt=\"After image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Normal-Lateral-Cropped-CCI-Outlined-600x450-1.jpeg\">\n        <\/div>\n\n        \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-31f6373 elementor-widget elementor-widget-heading\" data-id=\"31f6373\" data-element_type=\"widget\" data-e-type=\"widget\" id=\"toc_Retropectoralis_Space\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Retropectoralis Space\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-96602e7 elementor-widget elementor-widget-text-editor\" data-id=\"96602e7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><div class=\"fusion-text fusion-text-28\"><div class=\"fusion-text fusion-text-29\"><p>The subclavian artery and vein exit the costoclavicular interval and enter the\u00a0<em>retropectoralis space<\/em>. The retropectoralis space\u00a0is defined by the following structures:<\/p><ul><li>Anterior: Pectoralis minor muscle<\/li><li>Posterior: Subscapularis muscle<\/li><li>Superior: Coracoid process of the scapula<\/li><\/ul><p>The\u00a0retropectoralis space is an inverted triangle, with the narrowest area at the bottom and the widest area at the top, just beneath the coracoid process.<\/p><\/div><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-966a1ad elementor-widget elementor-widget-aic-image-comparison\" data-id=\"966a1ad\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"aic-image-comparison.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t        \n        <div id=\"aic-image-comparison-966a1ad\" class=\"aic-image-container\" data-offset=\"1\" data-orientation=\"horizontal\" data-before_label=\"Before\" data-after_label=\"After\" data-overlay=\"no\" data-onhover=\"yes\" data-click_to_move=\"no\">\n\t\t\t<img decoding=\"async\" class=\"aic-before-img\" alt=\"Before image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Kryski-Retropectoralis-Space-Labeled-600x448-1-1.jpeg\">\n\t\t\t<img decoding=\"async\" class=\"aic-after-img\" alt=\"After image alt\" src=\"https:\/\/hlsllc.org\/tos\/wp-content\/uploads\/2026\/04\/Kryski-Retropectoralis-Space-Outlined-600x448-1-1.jpeg\">\n        <\/div>\n\n        \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-94f330b elementor-widget elementor-widget-text-editor\" data-id=\"94f330b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<div class=\"fusion-title title fusion-title-text fusion-title-size-paragraph\"><div class=\"fusion-text\"><div class=\"fusion-li-item-content\"><div class=\"fusion-text fusion-text-11\"><div class=\"fusion-text fusion-text-28\"><div class=\"fusion-text fusion-text-29\"><div class=\"fusion-text fusion-text-30\"><p>These anatomic tunnels normally conduct the three vital structures from the neck and chest to each arm. TOS occurs when narrowing of one or more of these tunnels becomes severe enough to cause symptoms. Symptoms develop when compression or stretching damages one of the three vital structures. If we hold a clear understanding of the anatomy of the thoracic outlet, we can grasp the changes in anatomy that cause TOS.<\/p><\/div><\/div><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-749493c elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"749493c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-55d92f4 elementor-widget elementor-widget-heading\" data-id=\"55d92f4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#to\">Back to Anatomy<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-cfdf8c5 e-con-full e-flex e-con e-child\" data-id=\"cfdf8c5\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-613b891 e-con-full e-flex e-con e-parent\" data-id=\"613b891\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-5fac3c0 e-con-full e-flex e-con e-child\" data-id=\"5fac3c0\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-faface0 elementor-view-framed elementor-shape-circle elementor-position-block-start elementor-mobile-position-block-start elementor-widget elementor-widget-icon-box\" data-id=\"faface0\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-box.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-icon-box-wrapper\">\n\n\t\t\t\t\t\t<div class=\"elementor-icon-box-icon\">\n\t\t\t\t<span  class=\"elementor-icon\">\n\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-info\" viewBox=\"0 0 192 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M20 424.229h20V279.771H20c-11.046 0-20-8.954-20-20V212c0-11.046 8.954-20 20-20h112c11.046 0 20 8.954 20 20v212.229h20c11.046 0 20 8.954 20 20V492c0 11.046-8.954 20-20 20H20c-11.046 0-20-8.954-20-20v-47.771c0-11.046 8.954-20 20-20zM96 0C56.235 0 24 32.235 24 72s32.235 72 72 72 72-32.235 72-72S135.764 0 96 0z\"><\/path><\/svg>\t\t\t\t<\/span>\n\t\t\t<\/div>\n\t\t\t\n\t\t\t\t\t\t<div class=\"elementor-icon-box-content\">\n\n\t\t\t\t\t\t\t\t\t<h3 class=\"elementor-icon-box-title\">\n\t\t\t\t\t\t<span  >\n\t\t\t\t\t\t\tDiagnosis of Thoracic Outlet Syndrome\t\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/h3>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<p class=\"elementor-icon-box-description\">\n\t\t\t\t\t\tDo you have pain, numbness, tingling or weakness? Click to learn more about the diagnosis of thoracic outlet syndrome.\t\t\t\t\t<\/p>\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d831318 e-con-full e-flex e-con e-child\" data-id=\"d831318\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-32f868a elementor-view-framed elementor-shape-circle elementor-position-block-start elementor-mobile-position-block-start elementor-widget elementor-widget-icon-box\" data-id=\"32f868a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-box.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-icon-box-wrapper\">\n\n\t\t\t\t\t\t<div class=\"elementor-icon-box-icon\">\n\t\t\t\t<span  class=\"elementor-icon\">\n\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-stethoscope\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M447.1 112c-34.2.5-62.3 28.4-63 62.6-.5 24.3 12.5 45.6 32 56.8V344c0 57.3-50.2 104-112 104-60 0-109.2-44.1-111.9-99.2C265 333.8 320 269.2 320 192V36.6c0-11.4-8.1-21.3-19.3-23.5L237.8.5c-13-2.6-25.6 5.8-28.2 18.8L206.4 35c-2.6 13 5.8 25.6 18.8 28.2l30.7 6.1v121.4c0 52.9-42.2 96.7-95.1 97.2-53.4.5-96.9-42.7-96.9-96V69.4l30.7-6.1c13-2.6 21.4-15.2 18.8-28.2l-3.1-15.7C107.7 6.4 95.1-2 82.1.6L19.3 13C8.1 15.3 0 25.1 0 36.6V192c0 77.3 55.1 142 128.1 156.8C130.7 439.2 208.6 512 304 512c97 0 176-75.4 176-168V231.4c19.1-11.1 32-31.7 32-55.4 0-35.7-29.2-64.5-64.9-64zm.9 80c-8.8 0-16-7.2-16-16s7.2-16 16-16 16 7.2 16 16-7.2 16-16 16z\"><\/path><\/svg>\t\t\t\t<\/span>\n\t\t\t<\/div>\n\t\t\t\n\t\t\t\t\t\t<div class=\"elementor-icon-box-content\">\n\n\t\t\t\t\t\t\t\t\t<h3 class=\"elementor-icon-box-title\">\n\t\t\t\t\t\t<span  >\n\t\t\t\t\t\t\tNeoVista\u00ae MRI for Thoracic Outlet Syndrome\t\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/h3>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<p class=\"elementor-icon-box-description\">\n\t\t\t\t\t\tLearn how the NeoVista\u00ae MRI for TOS provides diagnostic information that is not available elsewhere.\t\t\t\t\t<\/p>\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f125f10 e-con-full e-flex e-con e-child\" data-id=\"f125f10\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-ad0411d elementor-view-framed elementor-shape-circle elementor-position-block-start elementor-mobile-position-block-start elementor-widget elementor-widget-icon-box\" data-id=\"ad0411d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-box.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-icon-box-wrapper\">\n\n\t\t\t\t\t\t<div class=\"elementor-icon-box-icon\">\n\t\t\t\t<span  class=\"elementor-icon\">\n\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-flask\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M437.2 403.5L320 215V64h8c13.3 0 24-10.7 24-24V24c0-13.3-10.7-24-24-24H120c-13.3 0-24 10.7-24 24v16c0 13.3 10.7 24 24 24h8v151L10.8 403.5C-18.5 450.6 15.3 512 70.9 512h306.2c55.7 0 89.4-61.5 60.1-108.5zM137.9 320l48.2-77.6c3.7-5.2 5.8-11.6 5.8-18.4V64h64v160c0 6.9 2.2 13.2 5.8 18.4l48.2 77.6h-172z\"><\/path><\/svg>\t\t\t\t<\/span>\n\t\t\t<\/div>\n\t\t\t\n\t\t\t\t\t\t<div class=\"elementor-icon-box-content\">\n\n\t\t\t\t\t\t\t\t\t<h3 class=\"elementor-icon-box-title\">\n\t\t\t\t\t\t<span  >\n\t\t\t\t\t\t\tTreatment of Thoracic Outlet Syndrome\t\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/h3>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<p class=\"elementor-icon-box-description\">\n\t\t\t\t\t\tBest treatment of thoracic outlet syndrome requires a dedicated team of thoracic outlet syndrome specialists.\t\t\t\t\t<\/p>\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Anatomy of the thoracic outlet Table of Contents Anatomy of the thoracic outlet explains thoracic outlet syndrome Anatomy of the spine Anatomy of a nerve Anatomy of the brachial plexus Segmental anatomy of the brachial plexus Nerve Roots Trunks Divisions Cords Terminal Branches Anatomy of the thoracic outlet Tunnels of the Thoracic Outlet Scalene triangle [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-20333","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/pages\/20333","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/comments?post=20333"}],"version-history":[{"count":39,"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/pages\/20333\/revisions"}],"predecessor-version":[{"id":21889,"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/pages\/20333\/revisions\/21889"}],"wp:attachment":[{"href":"https:\/\/hlsllc.org\/tos\/wp-json\/wp\/v2\/media?parent=20333"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}