4.1 Cranial Nerves

Question 1

Neurone structure?

Answer 1

Dendrite Cell body (perikaryon Axon (Myelin sheath - Schwann cells in PNS, oligodendrocytes in CNS) Axon terminals

Question 2

What is a nerve

Answer 2

Collection of single axons of neurones bound together by 3 layers of CT.

Question 3

What are the layers of CT in PNS and CNS

Answer 3

PNS Endoneurium Perineurium Epineurium CNS Pia mater Arachnoid mater Pia mater

Question 4

How are nerves classified?

Answer 4

By function: Afferent (motor) Efferent (sensory) Mixed Autonomic Cranial or spinal (location of cell body) Cranial = in brain Spinal = in spinal cord

Question 5

What are the 5 segments of the developing brain?

Answer 5

Forebrain (Prosencephalon) - telencephalon, diencephalon Midbrain (Mesencaphalon) Hindbrain (Rhombencephalon) - metencephalon, myelencephalon

Question 6

Significance of cranial foramina?

Answer 6

Nerves and Vessels pass through. Reduce mass of cranium. Make skull base physically weak. Nerve compression in foramina. Route for infection and metastases.

Question 7

Label

Answer 7

Cribriform plate

Optic canal

Superior orbital fissure

Foramen Rotundum

Foramen Ovale

Internal Acoustic meatus

Jugular foramun

Hypoglossal Canal

Foramen magnum

Question 8

State which nerve emerges from each foramen.

Answer 8

Cribriform plate: CNI

Optic canal: CNII

SOF: CNIII, CNIV, CNV1, CNVI

Foramen Roturndum: CNV2

Formaen Ovale: CNV3

Internal Acoustic Meatus: CNVII, CNVIII

Jugular Foramen: CNIX, CNX, CNXI

Hypoglossal Canal: CNXII

Question 9

Give the Name and function of each CN

Answer 9

I - Olfactory - Sensory

II - Optic - Sensory

III - Occulomotor - Motor

IV - Trochlear - Motor

V - Trigeminal - Both

VI - Abducens - Motor

VII - Facial - Both

VIII - Vestibulocochlear - Sensory

IX - Glossopharyngeal - Both

X - Vagus - Both

XI - Spinal Accessory - Motor

XII - Hypoglossal - Most