82 Neuroanatomy: Draw It to Know It
Cutaneous Nerves — Upper Limb
Here, we will draw the cutaneous nerve innervation of
the upper limb. First, draw an anterior upper limb.
Show that the medial cord-derived medial cutaneous
nerves of the forearm and arm cover the medial forearm
and arm, respectively. And then show that the intercos-
tobrachial nerve covers the axilla. In our discussion of
the sensory innervation of the trunk, we discuss the T2
lateral cutaneous intercostal origins of the intercostobra-
chial nerve.
Next, show that the musculocutaneous nerve-derived
lateral cutaneous nerve of the forearm covers the anterior
lateral forearm; the radial nerve-derived lower lateral
cutaneous nerve of the arm covers the lower lateral anterior
upper arm; the axillary nerve-derived upper lateral cutane-
ous nerve of the arm covers the upper lateral anterior arm;
and the supraclavicular nerve covers the shoulder.
Next, draw the posterior upper limb. Th e posterior
upper limb sensory coverage is nearly identical to the
anterior upper limb coverage, so, fi rst, simply redraw the
anterior limb. Next, indicate that the radial nerve-derived
posterior cutaneous nerves to the forearm and arm cover
the midline forearm and arm, respectively.^1 – 4 , 8