Medial cutaneous nerve of the arm

The medial cutaneous nerve of the arm, also known as the lesser internal cutaneous nerve of arm, is a branch of the medial cord of the brachial plexus and supplies the skin of the medial side of the arm as far distal as the medial epicondyle.

Gross anatomy

Origin

The medial cutaneous nerve of the arm arises from the medial cord of the brachial plexus and receives fibers form the eighth cervical and first thoracic nerve roots.

Course

The medial cutaneous nerve of the arm is the smallest and most medial of the branches of the brachial plexus. Originally posterior to the axillary vein, it then comes to lie on the medial side of the vein. In the arm it descends along the medial side of the brachial vein to the mid-portion of the arm where it pierces the deep fascia of the arm to give off its terminal cutaneous branches.

Branches and supply

• skin of the medial side of the arm as far distal as the medial epicondyle of the humerus and olecranon of ulna

Relations

• courses along the medial side of the axillary and brachial veins
• shortly after branching from the brachial plexus the medial cutaneous nerve of the arm communicates with the intercostobrachial nerve, the lateral cutaneous branch of the second intercostal nerve which supplies the skin of the axilla.

Variant anatomy

The medial cutaneous nerve of the arm is not always protected under the axillary vein and is consequently sometimes subject to injury during the dissection of axillary lymph nodes.