Medial cutaneous nerve of the arm
The medial cutaneous nerve of the arm is a branch of the medial cord of the brachial plexus.
|Medial cutaneous nerve of the arm|
|Origin:||Medial cord of the brachial plexus|
|Innervation:||Skin of the medial aspect of the upper arm - the distal third anteriorly but most of the posteromedial aspect|
|Vertebral levels:||C8 nerve root, T1 nerve root|
|Search for Medial cutaneous nerve of the arm in Gray's.|
Ventral rami of:
The nerve is one of the smallest branches of the brachial plexus, arising from the medial cord. It travels across the axilla, crossing the axillary vein and then lying medial to it. At this level it communicates with the intercostobrachial nerve. It then travels distally, medially to the brachial artery and basilic vein. At the midpoint of the upper arm it moves through the deep fascia to supply the skin of the distal third of the upper arm.
Variable depending on the site supplied by the intercostobrachial nerve, but usually an area over the anterior aspect of the distal third of the upper arm, and the majority of the posteromedial aspect. Innervation may reach as far distally as the olecranon.
It may cross the axillary vein anteriorly or posteriorly in the axilla.
The intercostobrachial nerve is intimately related to the medial cutaneous nerve of the arm. Whilst the size of either can vary markedly, there appears to be an inverse relationship between them such that a larger intercostobrachial nerve will be connected with a smaller medial cutaneous nerve and vice versa. There is often a large plexus interconnecting the two nerves in the axilla.
If the intercostobrachial nerve is supplemented by a connection from the lateral cutaneous branch of the third intercostal nerve then the medial cutaneous nerve of the arm may be absent and the brachial plexus connect directly to the intercostobrachial nerve. Even this connection may be absent occasionally.