Nuclei of the Brainstem

Question 1

Somatomotor (SM/ GSM/ GSE) nuclei

Answer 1

• Located in dorsomedial column
• Multipolar neurons
• Responsible for innervation of Striated muscles derived from somites. —-> muscles of eye and tongue
• CN: 3,4,6(lat. rectus),12 (C1-C6 motor neurons of Accessory n)

Question 2

Branchiomotor (SVM/ SVE)

Answer 2

• Nuclei from Venterolateral column
• Trigeminal motor nucleus (5)
• Facial motor nucleus (7)
• Ambigous nucleus (CN: 9,10,11)

5: mimical m and muscles of mastication.
7: mimical m, stapedius and ant belly of digastric.
9: to stylopharyngeal m.
10: Laryngeal/pharyngeal m’s.
11: soft palate and pharyngeal area.

Question 3

Genaral visceromotor (GVM/GVE)

Answer 3

• Parasympathetic/secretomotor.
• Innervation of viscera (smooth muscle and glands)
• CN’s : 3,7,9,10

Question 4

Explain the two steps in which innervation of viscera always occurs

Answer 4

1) CN nuclei sends preganglionic parasympathetic fibers to an autonomic ganglia, where they synapse with the MULTIPOLAR neurons in the ganglia.
2) postganglionic fibers sent fron ganglia to target cell.

Exception: adrenal medulla receives pregang. fibers from spinal cord instead —–> thus adrenal medulla is aclassified as a “modified sympathetic ganglion”

Question 5

General viscerosensory (GVS/ GVA)

Answer 5

• From eg. Baroreceptors and chemoreceptors( afferent input from carotid body and sinus, as well as abdominal and thoracis viscera)
• Nucleus : Lateral Ala Cinerea (solitary?)
• Multiunipolar relay neurons.

Question 6

Special viscerosensory (SVS/ SVA)

Answer 6

• For taste (special senses)
• Solitarty tract nucleus.
• Relay neurons receiving afferent input from taste buds in tongue and accessory taste buds on epiglottis.
• CN’s : 7: (anterior 2/3s of tounge)
  9: Post 1/3d of tongue (Valate pappilae).
  10: Accessory taste buds on epiglottis

Question 7

General somato sensory GSS (GSA)

Answer 7

-relay neurins receive fibers from somatic receptors:
-mechano, noci, and thermoreceptors from skin, joints,
and muscles of the head. —-> 3 sensory types.
- Principle sensory / pontine trigeminal nucleus:
Epicritic sensibility :fine touch, vibration.
-Mesencephalic trigeminal nucleus:Proprioceptive sensibility: inf. of positioning of joints and muscles —> afferent input from Golgi tendons and muscle spindles.

-Spinal trigeminal nucleus: Protopathic sensibility: pain, crude touch, temp
OBS. Spinal receives protopathic afferents from CN: 7,9 and 10 as well.

Question 8

Special Somato-Sensory (SSS/SSA)

Answer 8

Relay neurons in the most lateral column in brainstem receives fibers carrying vestibular and auditory signals

• Hearing and balance.
• Chochlear nucleus (dorsal and ventral)
• Vestibular nucleus (sup. med. inf and lat)
• CN 8