The posterior cutaneous nerve of arm (internal cutaneous branch of musculospiral, posterior brachial cutaneous nerve) is a branch of the radial nerve that provides sensory innervation for much of the skin on the back of the arm. It arises in the axilla.

Posterior cutaneous nerve of arm
Cutaneous nerves of right upper extremity. ("Post. brach. cutan." visible at center left.)
Details
From	Radial nerve
Identifiers
Latin	nervus cutaneus brachii posterior
TA98	A14.2.03.050
TA2	6432
FMA	44948
Anatomical terms of neuroanatomy [edit on Wikidata]

It is of small size, and passes through the axilla to the medial side of the area supplying the skin on its dorsal surface nearly as far as the olecranon.

In its course it crosses behind and communicates with the intercostobrachial.