Brachial plexus

Medial cutaneous nerve of the forearm

cutaneous innervation to skin over biceps brachii muscle then down arm to supply skin of anterior/medial surface of forearm

Posterior cord

- occurs posterior to the second part of the axillary artery - originates as the union of all 3 posterior divisions - contains contributions from all roots of the brachial plexus (C5-T1) - nerves associated with the posterior cord supply posterior compartments - five nerves originate from the posterior cord of the brachial plexus: 1. Upper subscapular 2. Thoracodorsal 3. Lower subscapular 4. Axillary Nerve 5. Radial Nerve

Axillary nerve

1. Motor to deltoid m. and teres minor m. 2. Sensory to skin of upper lateral arm 3. originates from the posterior cord and passes inferiorly and laterally along the posterior wall to exit the axilla through the quadrangular space 4. passes posteriorly around the surgical neck of the humerus and innervates both the deltoid and teres minor muscles and skin of upper lateral arm 5. accompanied by the posterior circumflex humeral artery

Suprascapular artery

1. a branch of the thyrocervical trunk in the neck 2. participates in shoulder anastomosis 3. accompanied by suprascapular nerve in lateral parts of neck and posterior scapular region

Medial cutaneous nerve of the arm

1. cutaneous innervation of the medial distal 3rd of the arm (T1) 2. communicates with intercostobrachial nerve of T2

Medial Cord

1. is medial to the second part of the axillary artery and is the continuation of the anterior division of the inferior trunk 2. It is positioned medial to the second part of the axillary artery

Medial pectoral nerve

1. lateral to the lateral pectoral nerve 2. innervates Pectoralis Major and Minor muscles 3. most proximal branch of the medial cord

1. Each of the 3 trunks of the brachial plexus divides into an anterior and posterior divisions 2. The 3 posterior divisions combine to form parts of the brachial plexus that give rise to nerves associated with the posterior compartments of the upper limb 3. The 3 anterior divisions form parts of the brachial plexus that ultimately give rise to peripheral nerves associated with the anterior compartments of the upper limb

How do the divisions of the brachial plexus correspond to the innervation of anterior and posterior of arm?

Aa = axillary artery Lc = lateral cord P = posterior cord An = axillary nerve R = radial nerve Pc = posterior cutaneous nerve of arm TM = teres major TB = triceps brachii LD = latissimus dorsi muscle S = Subscapularis muscle Tn = thoracodorsal nerve LS = lower subscapular nerve U = upper subscapular nerve M = medial cord

Identify the labelled structures

Suprascapular nerve

Motor to supraspinatus muscle and infraspinatus muscle that branches off of superior trunk

D = dorsal scapular nerve Rm = rhomboid minor RM = rhomboid major L = levator scapulae

identify the labelled structures

L = lateral pectoral nerve M = medial pectoral nerve

identify the labelled structures

L = long thoracic nerve S = serratus anterior muscle

identify the labelled structures

ulnar nerve

1. Motor to 1.5 muscles of anterior forearm 2. Motor to most intrinsic muscles of the hand 3. Sensory to medial 1/3rd of palm and dorsal hand and medial 1.5 fingers (palmar and dorsal sides) 4. large terminal branch of the medial cord 5. passes through the arm and forearm into the hand where it innervates all intrinsic muscles of the hand (except for the three thenar muscles and the two lateral lumbrical muscles) 6. On passing through the forearm, branches of this nerve innervate the flexor carpi ulnaris muscle and the medial half of the flexor digitorum profundus muscle

Dorsal scapular nerve (C5)

1. Motor to levator scapulae muscle, rhomboid major muscle, and rhomboid minor muscle 2. passes posteriorly, often piercing the middle scalene muscle in the neck, and continues deep to levator scapulae and the rhomboid muscles

Median nerve

1. Motor to most muscles of anterior forearm 2. Motor to some intrinsic muscles of hand 3. Sensory to lateral 2/3rd of palm and palmar side of lateral 3.5 fingers and their nail beds 4. passes through the arm and forearm into the hand where it innervates the three thenar muscles and the two lateral lumbrical muscles 5. On passing through the forearm, branches of the this nerve innervate all the muscles of the anterior forearm except flexor carpi ulnaris muscle and the medial half of the flexor digitorum profundus muscle, which are innervated by the ulnar nerve

Musculocutaneous nerve

1. Nerve pierces coracobrachialis muscle of arm 2. innervates all 3 flexor muscles in anterior arm: coracobrachialis, biceps brachii, and brachialis 3. terminates as lateral cutaneous nerve of the forearm 4. Sensory to lateral forearm

Radial nerve

1. is the largest terminal branch of posterior cord 2. Motor to muscles of the posterior arm and posterior forearm 3. Sensory to skin of posterior arm, posterior forearm, dorsolateral hand and dorsal side of proximal part of lateral 3.5 digits. 4. passes out of the axilla and into the posterior compartment of the arm by passing through the triangular interval 5. accompanied through the triangular interval by the deep brachial (profunda brachii) artery, which originates from the brachial artery in the anterior compartment of the arm

lateral pectoral nerve

1. motor to pectoralis major 2. most proximal of branches from the lateral cord 3. passes anteriorly, together with the thoraco-acromial artery, to penetrate the clavipectoral fascia 4. medial to the medial pectoral nerve

Long thoracic nerve (C5-C7)

1. motor to serratus anterior 2. passes vertically down the neck, through the axillary inlet, then down the medial wall of the axilla to supply the serratus anterior muscle 3. lies on the superficial aspect of the serratus anterior muscle

Thoracodorsal Nerve

1. passes vertically along the posterior axillary wall 2. penetrates and innervates the latissimus dorsi muscle.

Lateral Cord

1. results from the union of the anterior divisions of the superior and middle trunks 2. it is positioned lateral to the second part of the axillary artery.

Brachial plexus

1. somatic network of nerves formed by the union of the ventral rami of spinal nerves C5-C8 and T1 2. plexus originates in the neck, and passes laterally and inferiorly over rib I, then enters the axilla 3. parts of the brachial plexus from medial to lateral: roots, trunks, divisions, cords, branches

Mun = musculocutaneous nerve Lc = lateral cord Aa = axillary artery Mc = medial cord U = ulnar nerve MM = medial part of median nerve Mn = medial nerve LM = lateral part of the median nerve

identify the labelled structures

S = Superior Trunk C5 and C6 M = Middle Trunk C7 only I = inferior trunk C8 and T1

identify the labelled structures

S = supraspinatus I = infraspinatus both innervated by suprascapular nerve which branches off of superior trunk

identify the labelled structures and what they are innervated by

Upper (Superior) Subscapular Nerve

is short and passes into and supplies the subscapularis muscle

Lower (Inferior) Subscapular Nerve

passes inferiorly along the posterior axillary wall and innervates the subscapularis and teres major muscles

Cords of the brachial plexus are named for their relationships to the second part of the axillary artery.

how are cords of the brachial plexus named?

Nerve to subclavius

identify the highlighted structure

A = axillary nerve Pc = posterior cord Pch = Posterior circumflex humeral artery

identify the labelled structures

P = posterior cord A = axillary nerve R = radial nerve

identify the labelled structures

musculocutaneous nerve, the lateral root of the median nerve, the median nerve, the medial root of the median nerve, and the ulnar nerve form an "M" over the third part of the axillary artery

what forms the M of the brachial plexus?

Cords, most of the side branches, and terminal branches - Branches of the infraclavicular part of plexus arise from the cords and are approachable through the axilla

what is included in the infraclavicular part of the brachial plexus?

Ventral rami of spinal nerves (roots), trunks, and divisions - Four branches of the supraclavicular part of the plexus arise from the roots and trunks and are approachable through the neck

what is included in the supraclavicular part of the brachial plexus?

radial nerve

what is the structure labelled R?