BRACHIAL PLEXUS

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.

Contents

Function

Anatomy

Path

Diagram

Specific branches

Additional images

See also

References

External links

Function

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 funtion may be impaired by tumor growth of the Apical region of either Lung.
Therefore, brachial plexus lesions can lead to severe functional impairment.

Anatomy

Path

One can remember the order of brachial plexus elements by way of the mnemonic, "'R'ead 'T'he 'D'amn 'C'adaver 'B'ook" - 'R'oots, 'T'runks, 'D'ivisions, 'C'ords, 'B'ranches^[1] 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':

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★ "superior"^[1] or "upper" (C5-C6)

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★ "middle"^[1] (C7)

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★ "inferior"^[1] or "lower" (C8-T1)

★ Each trunk then splits in two, to form six 'divisions':

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★ anterior division^[1] of the superior, middle, and inferior trunks

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★ posterior division^[1] of the superior, middle, and inferior trunks

★ These six divisions will regroup to become the three 'cords'. The cords are named by their position in respect to the axillary artery.

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★ The ''posterior cord'' is formed from the three posterior divisions of the trunks (C5-T1)

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★ The ''lateral cord'' is the anterior divisions from the upper and middle trunks (C5-C7)

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★ The ''medial cord'' is simply a continuation of the lower trunk (C8-T1)

★ 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".

Diagram

Specific branches

'From'	'Nerve'	'Roots'	'Muscles'	'Cutaneous'
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	lower part of subscapularis 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, 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

Additional images

See also

★ Brachial plexus lesion

★ Anesthesia of the brachial plexus

References

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External links

★

★ Tutorial at anatome.ncl.ac.uk