1. FUNCTIONAL COMPONENTS AND ORGANIZATION OF SPINAL CORD AND BRAINSTEM

2. Cross-section of embryo: Neural crest neuroectoderm
Neural fold
Neural crest
Notochord
Neural crest
Dorsal root ganglion
Surface ectoderm
Neural canal
Neural tube

3. Formation of basal and alar plates of neural tube
(Sensory projection neurons of gray matter)
(White matter)
Basal plate
(Motor neurons of gray matter)

4. Definitive structures from alar and basal plates in spinal cord
(from alar plate)
Spinal nerve
(from basal plate)
Sensory projection neuron =

5. Alar and basal plates in brain
Only found in medulla, pons, and midbrain
Separated by sulcus limitans
Form sensory and motor nuclei of cranial nerves III – XII
Sensory nuclei lateral
Motor nuclei medial

6. Cross-section of myelencephalon: Sensory cranial nerve nuclei lateral
Motor cranial nerve nuclei medial
Sensory
Motor
Sensory
Motor

7. SPINAL CORD DEVELOPMENT: NOLTE
GSA
GVA
GVE
GSE

8. BRAINSTEM DEVELOPMENT: NOLTE
GSA
GVA
GVE
GSE

9. COLUMNS OF NUCLEI IN BRAINSTEM: NOLTE TEXTBOOK
SSA
GSA
SVA
GVA
GVE
SVE
GSE
SVE, SVA, SSA NUCLEI DEVELOP AS COLUMNS IN BRAINSTEM

10. COLUMNS OF NUCLEI IN BRAINSTEM: GREY’S ANATOMY
SSA
GSA
SVA
GVA
GVE
SVE
GSE

11. NOLTE; NUCLEI MIGRATE BUT MAINTAIN SAME GENERAL ORGANIZATION

12. COLUMNS OF CELLS IN BRAINSTEM

13. Appendix:
Embryonic development of cranial sensory and motor cell columns in the Brainstem

14. Embryonic Development of the Medulla
Alar Plate
The myelencephalon develops into a closed medulla and an open medulla.
In the closed medulla:
Some cells in the alar plate migrate to the marginal zone to form the nuclei of gracilis and cuneatus.
In the open medulla:
The ventricle opens up and stretches the roof plate becoming very thin. The brain wall moves laterally: the alar plate is situated lateral to the basal plate.
Inf. Olivary Nu

15. Alar Plate gives rise to Sensory Relay Nu.
Alar plate is pushed lateral to basal plate, and separated by sulcus limitans.
Sulcus Limitans
GVE I O N
Basal Plate gives rise to Motor Nu.

16. ALAR PLATE gives rise to Nu. Gracilis, Nu
ALAR PLATE gives rise to Nu. Gracilis, Nu. Cuneatus, Inferior Olivary Nu. and 4 Sensory Cell Columns
GVA (General visceral afferent) –Caudal Solitary nucleus receives sensory inputs from mucous membrane of pharynx and larynx, aortic arch/body and carotid sinus/body (VII, IX, X).
SVA (Special visceral afferent) –Rostral Solitary nucleus receives taste sensation from tongues, pharynx and larynx, and epiglottis (VII, IX, X).
GSA (General somatic afferents)-Spinal Trigeminal Nucleus receives pain, temperature, and touch sensation from ipsilateral face, ear and neck areas (V, VII, IX, X)
SSA (Special somatic afferent )-Vestibulo-cochlear nuclei receive input from inner ear for vestibular and auditory nerves (VIII).

17. BASAL PLATE gives rise to 3 motor cell columns
GSE (general somatic motor)--Hypoglossal Nu. For CN XII.
SVE (special visceral [branchial] motor) – Nu. Ambiguus, for CN 9, 10, (cr.11) and innervating muscles of branchial arches. This cell column migrates to the deep lateral tegmentum.
The spinal accessory Nu./Nv (CN 11) somehow is also put into SVE.
GVE (general visceral motor)—Inferior salivatory Nu of IX and Dorsal motor nucleus of vagus, represent the preganglionic neurons of parasympathetic CN 9 and 10, respectively; they innervate the postganglionic neurons for the parotid gland (IX), GI and pulmonary viscera (X), respectively. The GVE to the heart, however, is incorporated into the SVE (nucleus ambiguus).

18. Review: Connecting Cranial Nerve Functional Components to Central Nuclei
Basal Plate (Motor Nu)
Alar Plate (Sensory Relay Nu)
CN# GSE GVE SVE GSA GVA SVA SSA
Forebrain
Mesencephalic Nu V
Midbrain
Chief Sensory Nu V
Pons ++
Inf. Salivatory
Medulla
Cr+ Sp++
Sup. Salivatory
D- Motor Vagus
Spinal Trigeminal Nu V
Solitary Nu
Ambiguus Nu