Antebrachial – Anatomy, Function And Structure

The word ‘antebrachial’ is the anatomical word for ‘inner forearm’. The medial antebrachial cutaneous nerve provides the sensory innervation of the medial forearm skin, which is superimposed by the olecranon.

Together with the posterior and lateral antebrachials, the cutaneous nerves, it is responsible for the sensation of the skin of the forearm.

Function And Structure

Antebrachial Region

The Antebrachial Region is classed as the ‘inner forearm’.

It emerges from the medial antebrachial cutaneous nerve through the brachial plexus and the sensory cell body located between C8 and T1.

The medial antebrachial cutaneous nerve travels up the upper arm and runs along the brachial fascia to the basilic vein, approximately 10 cm proximally to the medial epicondyle.

When the nerve leaves the fascia, it splits into two large branches, front and back, and continues to the wrist. The spinal nerve (C5-T1) originating from the cervical and thoracic spine is rooted in the biceps and divides into a root-trunk division in the spinal cord that ends in a branch.

antebrachial region
Fig 1: Cutaneous innervation of the upper extremity

The medial antebrachial cutaneous nerve is one of the three non-terminal branches of the medial cord, which represents a continuation of the anterior division of the lower trunk of the brachial plexus itself.

The other two non-terminal branches are the medial brachial cutaneous nerve. The nerves which ensure the sensory innervation of the medial arm, and the medial mammary nerve which ensures the motor innervation of the pectoralis major and minor.

The medial spinal cord is located in the superficial axillary artery, the veins, the axillary fossa, the median nerve and the ulna nerve. The medial strand contributes fibres to the median nerve and continues to the ulna nerves.

It runs along the basilica until the elbow level where it divides the elbow into volar and ulnar branches, which ensure sensory innervation of the medial forearm membrane and olecranon.

It then enters the brachial fascia, which lie above the brachial biceps, and runs to the ulnar side of the brachial artery. On his way he is accompanied by the basil vein, which crosses the triceps and brachial muscles.

The volar branch of the ramus volaris (anterior branch) is the largest and runs in front of the median vena cubiti, median and basilica.

medial antebrachial cutaneous nerve
Fig 2: Idealized distribution of the cutaneous innervation of the upper arm and forearm.

It descends to the front of the ulna side of the forearm and distributes filaments through the skin of the wrist that communicate with the palmar cutaneous and ulna nerve.

The ulnar branch crosses the medial side of a basilica before a medial epicondyle at the back of the forearms and descends from the rear to the ulnar side (wrist), spreading filaments over the skin.

It communicates with the medial brachial cutaneous, dorsal antebrachial and cutaneous branches as well as the radial and dorsal branches of the ulnar nerve.

Compression of the lateral antebrachial cutaneous nerve in the biceps tendon occurs when the nerve leaves the point of the brachial fascia at the proximal elbow flexor fold.

Symptoms include pain in the anterolateral elbow, burning and dysesthesia, which radiates to the lateral forearm when the forearm protons and the elbow is extended.

Lateral antebrachial sectional neuropathy is rare and is often overlooked in the case of elbow pain in throwing athletes.

lateral antebrachial cutaneous nerve
Lateral Antebrachial Nerve Entrapment

If the patient does not respond to non-surgical treatment, the surgical decompression of the nerve can result in complete relief of symptoms and a return to full activity if under local anaesthetic.

The patient can also be treated with non-steroidal anti-inflammatory drugs, rest, activity modification, stretching, blocking or splint.

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