186 Neuroanatomy: Draw It to Know It
Cranial Nerve Nuclei (Simplifi ed)
Here, we will consolidate the cranial nerve nuclei into a
simple diagram we can recall at the bedside. Note that
this compression is not a depiction of the complete cra-
nial nerve nuclei but instead provides an easy way to
remember the relative positions of the cranial nerves.
Draw another coronal brainstem. Across the top, use the
sulcus limitans to divide the brainstem into a medial,
motor division and a lateral, sensory division. Th en
divide the rostral–caudal axis of the brainstem into the
midbrain, pons, and medulla. Along the medial half of
the motor division, draw the cranial nerve nucleus of cra-
nial nerve 3 in the rostral midbrain, 4 in the caudal mid-
brain, 6 in the mid- to lower pons, 12 spanning the height
of the medulla, and 11 in the cervical spinal cord. In the
lateral motor area, draw the eff erent cranial nerve nucleus
of cranial nerve 5 in the rostral pons, 7 in the caudal
pons, and 9 and 10 spanning the height of the medulla.
Next, in the medial sensory region, draw the aff erent
cranial nerve nuclei of cranial nerves 7, 9, and 10 span-
ning the height of the medulla. Th en, draw the cranial
nerve nucleus of cranial nerve 8 from the pons into the
medulla. Next, at the lateral edge of the brainstem, show
that the aff erent nucleus of cranial nerve 5 spans from
the midbrain to the upper cervical spinal cord, and also
show that it receives additional aff erent innervation
from cranial nerves 7, 9, and 10.
Th e cranial nuclei are numbered by their rostral–
caudal positions as they exit the base of the brain. Cranial
nerve 1 lies rostral to 2, 2 to 3, 3 to 4, and so on. Th e only
exception is cranial nerve 11, which originates from
below cranial nerve 12. One way to recall this rostral–
caudal organization is to imagine that you are a primor-
dial fi sh swimming through the great sea. First, you
smell food (cranial nerve 1, the olfactory nerve); then,
you visualize it (cranial nerve 2, the optic nerve); next,
you fi x your eyes on it, for which you use your extra-
ocular eye muscles — innervated by cranial nerve 3 (the
oculomotor nerve), cranial nerve 4 (the trochlear nerve),
and cranial nerve 6 (the abducens nerve); you chew the
food using cranial nerve 5 (the trigeminal nerve) and
then taste it and smile using cranial nerve 7 (the facial
nerve). Th en, you listen for predators with cranial nerve
8 (the vestibulocochlear nerve) while you swallow the
meal with cranial nerves 9 (the glossopharyngeal nerve)
and 10 (the vagus nerve); you lick your lips with cranial
nerve 12 (the hypoglossal nerve); and toss your head
from side to side with cranial nerve 11 (the accessory
nerve).^3 , 4 , 6 – 12