Human Physiology/The Nervous System

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Lateral cord

The 

lateral cord 

gives rise to the following nerves:

• The lateral pectoral nerve, C5, C6 and C7 to the pectoralis major muscle, or musculus pectoralis major.

• The musculocutaneous nerve which innervates the biceps muscle

• The median nerve, partly. The other part comes from the medial cord. See below for details.

Posterior cord

diagram showing human dermatoms, i.e., skin regions with respect to

the routing of their nerve connection of their afferent nerves through the

spinal cord.

The 

posterior cord 

gives rise to the following

nerves:

• The upper subscapular nerve, C7 and C8, to the

subscapularis muscle, or musculus supca of the

rotator cuff.

• The lower subscapular nerve, C5 and C6, to the

teres major muscle, or the musculus teres major,

also of the rotator cuff.

• The thoracodorsal nerve, C6, C7 and C8, to the

latissimus dorsi muscle, or musculus latissimus

dorsi.

• The axillary nerve, which supplies sensation to the

shoulder and motor to the deltoid muscle or

musculus deltoideus, and the teres minor muscle,

or musculus teres minor.

• The radial nerve, or nervus radialis, which

innervates the triceps brachii muscle, the

brachioradialis muscle, or musculus

brachioradialis,, the extensor muscles of the

fingers and wrist (extensor carpi radialis muscle),

and the extensor and abductor muscles of the

thumb. See radial nerve injuries.

Medial cord

The 

medial cord 

gives rise to the following nerves:

• The median pectoral nerve, C8 and T1, to the pectoralis muscle

• The medial brachial cutaneous nerve, T1

• The medial antebrachial cutaneous nerve, C8 and T1

• The median nerve, partly. The other part comes from the lateral cord. C7, C8 and T1 nerve roots. The first branch

of the median nerve is to the pronator teres muscle, then the flexor carpi radialis, the palmaris longus and the

flexor digitorum superficialis. The median nerve provides sensation to the anterior palm, the anterior thumb,

index finger and middle finger. It is the nerve compressed in carpal tunnel syndrome.

• The ulnar nerve originates in nerve roots C7, C8 and T1. It provides sensation to the ring and pinky fingers. It

innervates the flexor carpi ulnaris muscle, the flexor digitorum profundus muscle to the ring and pinky fingers,

and the intrinsic muscles of the hand (the interosseous muscle, the lumbrical muscles and the flexor pollicus

brevis muscle). This nerve traverses a groove on the elbow called the cubital tunnel, also known as the funny

bone. Striking the nerve at this point produces an unpleasant sensation in the ring and little fingers.