NSCI 311 L6 Flashcards L6 MT1 (V)

What are the 3 main functions of the brainstem?

1) Acts as a conduit (tracts)

2) Houses cranial nerve nuclei (III-XII, except XI)

3) Integrates vital functions

Ventral Surface Photo

Doral Surface Photo

What are the 4 longitudinal partitions of the brainstem?

Base (ventral), Tegmentum, Ventricular System, Tectum (roof)

In which longitudinal partition would you find the…

1) Corticospinal fibers?

2) Spinal lemniscus? 

3) Corticonuclear fibers?

4) Superior colliculi?

5) Medial lemniscus?

How many cranial nerve pairs are there?

12, numbered rostral → caudal

Cranial Nerve Mnemonics

Which CNs are sensory only? Motor only? Mixed?

Sensory = I, II, VIII (O.V.O → Olfactory. Vestibulochlear. Optic)

Motor = III, IV, VI, XI, XII

Mixed = V, VII, IX, X (F.G.T.V → Facial. Glossopharyngeal. Trigeminal. Vagus)

What does SSA mean?

Special somatic afferent = Vision, hearing, balance

What does GSA mean?

General somatic afferent = Somatosensation from skin +muscles (Touch, pain, temp, proprioception etc)

What does SVA mean?

Special visceral afferent = Taste & smell

What does GVA mean?

General visceral afferent = Sensations from internal organs (e.g heart pain or gut cramps)

What does GVE mean?

General visceral efferent = Parasympathetic only (“rest & digest” + “feed & breed”) signalling to smooth muscle, glands etc

What does SVE mean?

Special visceral efferent = Motor info to branchial arch muscles (face, pharynx, larynx)

What does GSE mean?

General somatic efferent = Motor info to skeletal muscles

What are branchial arches?

Paired “outpouchings” (lil bulges) of mesoderm; also called “pharyngeal arches”

Where do somatic muscles of the head + neck originate?

Cranial somites

What are the 2 plates of a dividing neural tube?

Alar and basal plates

What divides alar vs basal plates?

Sulcus limitans

Alar vs Basal plate functions?

Alar = sensory (dorsal)

Basal = motor (ventral)

What migration pattern is shown here?

Secondary migration of branchial motor & somatic sensory nuclei

How are brainstem nuclei arranged longitudinally?

Same-modality nuclei align in (rostral-caudal) columns; not all columns at every level

SVA nuclei align with which column?

With GVA (visceral sensory)

Can one CN have multiple nuclei?

Yes—typically one nucleus per modality

CN V (Trigeminal Nerve) type(s) & modalities?

Both sensory & motor;

• Somatic sensation

• Branchial motor

Parts of sensory trigeminal nerve nuclei?

3 parts:

• Mesencephalic nucleus (midbrain → pons)

• Chief nucleus (mid-pons)

• Spinal nucleus (pons → cervical spine)

What does the spinal nucleus do?

Receives pain & temperature

• Also continuous w/ the dorsal horn in the spinal cord

What does the chief sensory nucleus do?

Receives fine touch & vibration

Mesencephalic nucleus purpose?

Receives proprioception

• Only nucleus w/ cell bodies of primary sensory neurons in the CNS

CN V: Corticonuclear Fibers (UMNs) Picture

CN VII “modalities” (its sensory/motor neurons + functions)?

Both; sensory + motor

• Branchial motor

• Visceral motor

• Special sensory (taste)

• Somatic sensory

Facial motor nucleus function?

Branchial motor → muscles of facial expression

• Fibers loop around abducens nucleus

Superior salivatory nucleus function?

• Lacrimation (tear production)

• Salivation (Saliva production)

Nucleus solitarius function?

Taste sensation

CN VII: Corticonuclear Fibers (UMNs) photo

UMN (central) facial lesion causes…

Contralateral lower-face paralyis

LMN (peripheral) facial lesion causes…

Entire ipsilateral side paralysis (i.e bell’s palsy)