|Nerve: Brachial plexus|
|The right brachial plexus with its short branches, viewed from in front.|
|Gray's||subject #210 930|
The brachial plexus is an arrangement of nerve fibres, running from the spine, specifically from above the fifth cervical vertebra to underneath the first thoracic vertebra (C5-T1). It proceeds through the neck, the axilla (armpit region) and into the arm.
The brachial plexus is responsible for cutaneous and muscular innervation of the entire upper limb, with two exceptions: the trapezius muscle innervated by the spinal accessory nerve and an area of skin near the axilla innervated by the intercostobrachialis nerve.
This function may be impaired by tumor growth of the Apical region of either Lung.
Therefore, brachial plexus lesions can lead to severe functional impairment.
One can remember the order of brachial plexus elements by way of the mnemonic, "Read The Damn Cadaver Book" - Roots, Trunks, Divisions, Cords, Branches or - Roots, Trunks, Divisions, Cords, Collateral/Pre-terminal Branches, and (Terminal) Branches.
- The five roots are the five anterior rami of the spinal nerves, after they have given off their segmental supply to the muscles of the neck.
- These roots merge to form three trunks:
- Each trunk then splits in two, to form six divisions:
- These six divisions will regroup to become the three cords. The cords are named by their position in respect to the axillary artery.
- The branches are listed below. Most branch off of the cords, but a few branch (indicated in italics) directly off of earlier structures. The five in bold are considered "terminal branches".
|roots||dorsal scapular nerve||C5||rhomboid muscles and levator scapulae||-|
|roots||long thoracic nerve||C5, C6, C7||serratus anterior||-|
|superior trunk||nerve to the subclavius||C5, C6||subclavius muscle||-|
|superior trunk||suprascapular nerve||C5, C6||supraspinatus and infraspinatus||-|
|lateral cord||lateral pectoral nerve||C5, C6, C7||pectoralis major (by communicating with the medial pectoral nerve)||-|
|lateral cord||musculocutaneous nerve||C5, C6, C7||coracobrachialis, brachialis and biceps brachii||becomes the lateral cutaneous nerve of the forearm|
|lateral cord||lateral root of the median nerve||C5, C6, C7||fibres to the median nerve||-|
|posterior cord||upper subscapular nerve||C5, C6||subscapularis (upper part)||-|
|posterior cord||thoracodorsal nerve||C6, C7, C8||latissimus dorsi||-|
|posterior cord||lower subscapular nerve||C5, C6||subscapularis (lower part) and teres major||-|
|posterior cord||axillary nerve||C5, C6||anterior branch: deltoid and a small area of overlying skin
posterior branch: teres minor and deltoid muscles
|posterior branch becomes upper lateral cutaneous nerve of the arm|
|posterior cord||radial nerve||C5, C6, C7, C8, T1||triceps brachii, supinator, anconeus, the extensor muscles of the forearm, and brachioradialis||skin of the posterior arm as the posterior cutaneous nerve of the arm|
|medial cord||medial pectoral nerve||C8, T1||pectoralis major and pectoralis minor||-|
|medial cord||medial root of the median nerve||C8, T1||fibres to the median nerve||portions of hand not served by ulnar or radial|
|medial cord||medial cutaneous nerve of the arm||C8, T1||-||front and medial skin of the arm|
|medial cord||medial cutaneous nerve of the forearm||C8, T1||-||medial skin of the forearm|
|medial cord||ulnar nerve||C8, T1||flexor carpi ulnaris, the medial 2 bellies of flexor digitorum profundus, most of the small muscles of the hand||the skin of the medial side of the hand and medial one and a half fingers on the palmar side and medial two and a half fingers on the dorsal side|