174 Neuroanatomy: Draw It to Know It
Know-It Points
Spinal & Cranial Nerve Origins
■ Th e trilaminar developing embryo contains
ectoderm, mesoderm, and endoderm.
■ Th e neural crests are neural tube derivatives that give
rise to, amongst other things, the peripheral nervous
system.
■ Sclerotome diff erentiates into bone; dermatome
derives the dermis; the myotomal masses derive
skeletal muscle.
■ An artery and nerve pair corresponds to each
somite segment, and wherever the products of
that somite go, the nerve and artery pair follows.
■ Th e sulcus limitans separates the basal and alar plates.
■ Th e basal plates, which produce the ventral roots,
house motor cell columns.
■ Th e alar plates, which receive the dorsal roots, house
s e n s o r y c e l l c o l u m n s.Spinal & Cranial Nuclear Classifi cation
■ In the spinal cord:
- Th e general somatic aff erent column lies in the
posterior horn. - Th e general somatic eff erent column lies in the
anterior horn. - Th e general visceral aff erent column lies in the
posterior intermediate horn. - Th e general visceral eff erent column lies in the
anterior intermediate horn.
■ In the brainstem:- Th e general somatic eff erent column lies medial to
the general visceral eff erent column. - Th e general visceral aff erent column lies medial to the
general somatic aff erent column. - Within the upper medulla, the special somatic
aff erent column spans the width of the alar plate. - Th e special visceral cell columns hug the sulcus
l i m i t a n s.
Cranial Nerve Nuclei
■ Th e somatomotor set is nearly exclusively general
somatic eff erent, but it also includes a single general
visceral eff erent nucleus.
■ Th e solely special sensory set is exclusively special
somatic aff erent.
■ Th e pharyngeal arch derivatives contain all of the cell
column types except for the general somatic eff erent
and special somatic aff erent cell columns.
■ Th e somatomotor set lies in midline and comprises
cranial nerves 3, 4, 6, 12, and 11.
■ Th e solely special sensory set comprises cranial nerves
1, 2, and 8.
■ Th e pharyngeal arch set comprises cranial nerves 5, 7,
9, and 10.