Brachial plexus

Dorsal scapular nerve

The dorsal scapular nerve most commonly arises directly from the root of C5 spinal nerve. Occasionally, it can arise from the superior trunk of the brachial plexus. The dorsal scapular nerve provides motor innervation to the levator scapulae, rhomboid major and rhomboid minor muscles.

Suprascapular nerve

The suprascapular nerve emerges from the superior trunk and carries fibers of the C5 and C6. The suprascapular nerve provides sensory innervation to the glenohumeral and acromioclavicular joints, and motor innervation to the supraspinatus and infraspinatus muscles.

Long thoracic nerve

The long thoracic nerve arises from the merger of the roots of C5, C6 and C7. This nerve provides motor innervation to the serratus anterior muscle.

Subclavian nerve

This nerve emerges from the superior trunk of the brachial plexus and contains fibers of C5 spinal nerve. The subclavian nerve provides motor innervation to the subclavius muscle.

Lateral pectoral nerves

The lateral pectoral nerves arise from the lateral cord of brachial plexus and carry fibers of C5, C6 and C7 spinal nerves. Through the anastomoses with the medial pectoral nerves, the lateral nerves participate in the innervation of the pectoralis minor muscle.

Lateral root of median nerve

This is a short branch which is one of the two roots of the median nerve. It quickly merges with the medial root, a branch of the medial cord, to form the median nerve.

Musculocutaneous nerve

The musculocutaneous nerve is a terminal branch of the lateral cord of the brachial plexus, carrying fibers of C5-C7 spinal nerves. It is a mixed nerve that provides both motor and sensory supply to the upper limb.

The motor fibers of the musculocutaneous nerve innervate the muscles of the anterior arm, namely the biceps brachii, coracobrachialis and brachialis muscle. The sensory fibers of the musculocutaneous nerve innervate the skin over the lateral surface of the forearm via the lateral cutaneous nerve of the forearm.

Medial pectoral nerves

The medial pectoral nerves arise from the medial cord of the brachial plexus, containing fibers of C8 and T1 spinal nerves. This nerve provides motor innervation to the pectoralis minor muscle and the lower sternocostal part of the pectoralis major muscle.

Medial brachial cutaneous nerve

The medial brachial cutaneous nerve, also called the medial cutaneous nerve of the arm, arises from the medial cord carrying fibers of C8 and T1 spinal nerves. This nerve provides sensory innervation to the skin of the inferior portion of the medial side of the arm.

Medial antebrachial cutaneous nerve

The medial antebrachial cutaneous nerve, also called the medial cutaneous nerve of the forearm, arises from the medial cord carrying fibers of T1 spinal nerve. This nerve provides sensory innervation to the skin of the arm overlying the biceps brachii, and the skin of the medial side of the forearm.

Medial root of median nerve

The medial root of the median nerve is the second source of the median nerve. It merges with the above mentioned lateral root to form the trunk of the median nerve.

Ulnar nerve

The ulnar nerve is a terminal branch of the medial cord of the brachial plexus that contains fibers of C8 and T1 spinal nerves. Similarly to the median nerve, the ulnar nerve is a mixed nerve that supplies motor and sensory innervation to the forearm and hand.

The ulnar nerves provides motor supply to the following:

• The remaining muscles of the forearm not supplied by the median nerve (flexor carpi ulnaris muscle, medial ½ of the flexor digitorum profundus).
• All intrinsic muscles of the hand, except for the LOAF muscles (lateral two lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis).

The ulnar nerve provides sensory supply to the following:

• Skin on the anterior and posterior aspect of the medial ½ of the palm.
• Skin on the anterior and posterior aspect of the medial 1½ fingers.

An easy way to remember the motor supply of the hand by the ulnar nerve is by using the following mnemonic.

The ulnar nerve supplies the HILA muscles of the hand:

Hypothenar muscles (opponens digiti minimi, flexor digiti minimi brevis and abductor digiti minimi)
Interossei muscles (dorsal and palmar interossei)
Medial two Lumbricals
Adductor pollicis

Subscapular nerves

There are usually two of these nerves: superior subscapular and inferior subscapular nerve. Both of these nerves arise from the posterior cord carrying the fibers of C5 spinal nerve. The superior subscapular nerve innervates the superior portion of the subscapularis muscle, whereas the inferior subscapular nerve innervates the rest of the subscapularis muscle, as well as the teres major muscle.

Thoracodorsal nerve

The thoracodorsal nerve arises from the posterior cord of the brachial plexus and carries the fibers of C7 and C8. This nerve provides motor innervation to the latissimus dorsi muscle.

Axillary nerve

The axillary nerve is one of the terminal branches of the posterior cord, carrying fibers of C5 and C7 spinal nerves. This nerve is a mixed nerve that provides both motor and sensory innervation to the shoulder region. The axillary nerve supplies the deltoid and teres muscle, as well as the skin over the deltoid muscle.

Radial nerve

The radial nerve is the second terminal branch of the posterior cord of the brachial plexus, that contains fibers of spinal nerves C5-T1. This nerve is a mixed nerve that provides motor and sensory innervation to the arm and forearm.

The radial nerve provides motor supply to the following:

• All muscles of the posterior compartment of the arm (triceps brachii muscle).
• All muscles of the posterior compartment of the forearm (brachioradialis, anconeus, supinator, extensor carpi radialis longus and brevis, extensor carpi ulnaris, extensor digitorum, extensor pollicis longus and brevis, extensor indicis, extensor digiti minimi, abductor pollicis longus).

The radial nerve provides sensory supply to the following:

• Skin on the posterior surface of the arm.
• Skin on the central, posterior surface of the forearm.
• Skin on the lateral surface of the dorsum of the hand.
• Skin on the posterior aspect of the lateral 2½ fingers.

Median nerve

The median nerve is formed by the merger of two roots that arise from the lateral and medial cord of the brachial plexus:

• The lateral root of median nerve, which is a terminal branch of the lateral cord.
• The medial root of median nerve, which is a terminal branch of the medial cord.

The median nerve courses over the entire upper limb and terminates in the hand by dividing into its terminal branches. It is a mixed nerve that provides motor and sensory innervation to several regions of the forearm and hand.

The median nerve provides motor supply to the following:

• All muscles of the anterior (flexor) compartment of the forearm except for the flexor carpi ulnaris and the medial ½ of the flexor digitorum profundus.
• All thenar muscles (abductor pollicis brevis, flexor pollicis brevis and opponens pollicis), except for the adductor pollicis.
• Two lateral lumbrical muscles.

The median nerve provides sensory supply to the following:

• Skin of the lateral ½ of the palm.
• Skin on the anterior aspect of the lateral 3½ fingers.
• Skin on the posterior aspect of the lateral 2½ fingers.

An easy way to remember the motor supply of the hand by the median nerve is by using the following mnemonic.

The median nerve supplies the LOAF muscles of the hand:

• Lateral two lumbricals
• Opponens pollicis
• Abductor pollicis brevis
• Flexor pollicis brevis