Chapter 13B Study Guide

What is the phrase to remember the Cranial Nerves in order?

Oh once one takes the anatomy final, very good vacations are heavenly.

What is the phrase to remember about primary functions of cranial nerves as sensory, motor, or both.

Some say marry money, but my brother says big brains matter most.

What is the first cranial nerve?

Olfactory

What is the second cranial nerve?

Optic

What is the third cranial nerve?

Oculomotor

What is the fourth cranial nerve?

Trochlear

What is the fifth cranial nerve?

Trigeminal

What is the sixth cranial nerve?

Abducens

What is the seventh cranial nerve?

Facial

What is the 8th cranial nerve?

Vestibulocochlear

What is the ninth cranial nerve?

Glossopharyngeal

What is the tenth cranial nerve?

Vagus

What is the eleventh cranial nerve?

Accessory

What is the twelfth cranial nerve?

Hypoglossal

A nerve is defined as:
A. Bundle of neuron cell bodies in CNS
B. Bundle of axon fibers in PNS
C. Single axon in CNS
D. Cluster of dendrites

Bundle of axon fibers in PNS

Layers of connective tissue around a nerve:

Endoneurium → around individual axons , Perineurium → around a fascicle, Epineurium → around entire nerve

Sensory (afferent) nerves carry impulses:
A. From CNS to muscles
B. From receptors to CNS
C. Only within spinal cord
D. Only to glands

From receptors to CNS

Motor (efferent) nerves carry impulses:
A. From receptors to CNS
B. From CNS to muscles/glands
C. From sensory neurons to interneurons
D. Only to spinal cord

From CNS to muscles/glands

A ganglion is:
A. Cluster of neuron cell bodies in CNS
B. Cluster of neuron cell bodies in PNS
C. Bundle of axons
D. Spinal cord enlargement

Cluster of neuron cell bodies in PNS

Typical ganglion location:
A. Inside brain
B. Along cranial nerves or next to spinal cord
C. In muscles
D. In skin

Along cranial nerves or next to spinal cord

Step 1 of nerve regeneration:
A. Schwann cells form regeneration tube
B. Axon distal to injury degenerates (Wallerian degeneration)
C. Axon reconnects with muscle
D. Synapse strengthens

Axon distal to injury degenerates (Wallerian degeneration)

Step 2 of nerve regeneration:
A. Schwann cells & macrophages clear debris
B. Axon grows along tube
C. Action potentials regenerate
D. Cortical plasticity occurs

Schwann cells & macrophages clear debris

Step 3 of nerve regeneration:
A. Axon grows toward target
B. Schwann cells form a regeneration tube
C. Axon degenerates
D. CNS repair occu

Schwann cells form a regeneration tube

Step 4 of nerve regeneration:
A. Axon grows along tube toward target cell
B. Schwann cells die
C. Muscle atrophy begins
D. Synaptic plasticity

Axon grows along tube toward target cell

Step 5 of nerve regeneration:
A. Axon dies
B. Axon re-establishes synaptic contact with muscle or receptor
C. CNS neurons regenerate
D. Sensory fibers degenerate

Axon re-establishes synaptic contact with muscle or receptor

Nerve regeneration occurs:
A. Only in CNS
B. Only in PNS
C. Equally in CNS & PNS
D. Rarely in PNS

Only in PNS

How many pairs of cranial nerves exist?
A. 10
B. 12
C. 31
D. 14

12

Olfactory nerve (I) function:
A. Vision
B. Smell
C. Taste
D. Eye movement

Smell

Optic nerve (II) function:
A. Smell
B. Vision
C. Swallowing
D. Facial expression

Vision

Oculomotor nerve (III) controls:
A. Superior oblique only
B. Most eye muscles, eyelid, pupil constriction, lens focusing
C. Facial muscles
D. Tongue muscles

Most eye muscles, eyelid, pupil constriction, lens focusing

Trochlear nerve (IV) controls:
A. Lateral rectus muscle
B. Superior oblique muscle
C. All eye muscles
D. Eyelid only

Superior oblique muscle

Trigeminal nerve (V) function:
A. Face sensation & mastication muscles
B. Only eye movement
C. Tongue muscles
D. Hearing

Face sensation & mastication muscles

Abducens nerve (VI) controls:
A. Superior oblique
B. Lateral rectus muscle of eye
C. Facial muscles
D. Taste

Lateral rectus muscle of eye

Facial nerve (VII) controls:
A. Facial muscles, taste anterior 2/3 tongue, lacrimal & salivary glands
B. Eye muscles only
C. Tongue posterior 1/3 only
D. Pharyngeal muscles only

Facial muscles, taste anterior 2/3 tongue, lacrimal & salivary glands

Vestibulocochlear nerve (VIII) senses:
A. Smell
B. Vision
C. Hearing & balance/equilibrium
D. Taste

Hearing & balance/equilibrium

Glossopharyngeal nerve (IX) functions:
A. Taste & sensory posterior 1/3 tongue, pharynx; motor for swallowing; parasympathetic to parotid gland
B. Facial muscles only
C. Eye muscles only
D. Tongue anterior 2/3 only

Taste & sensory posterior 1/3 tongue, pharynx; motor for swallowing; parasympathetic to parotid gland

Vagus nerve (X) functions:
A. Motor to pharynx/larynx; parasympathetic to thoracic & abdominal organs; sensory from viscera & taste epiglottis
B. Only motor
C. Only sensory from tongue
D. Only neck muscles

Motor to pharynx/larynx; parasympathetic to thoracic & abdominal organs; sensory from viscera & taste epiglottis

Accessory nerve (XI-11) controls:
A. Facial muscles
B. Sternocleidomastoid & trapezius muscles
C. Tongue muscles
D. Eye muscles

Sternocleidomastoid & trapezius muscles

Hypoglossal nerve (XII) controls:
A. Eye muscles
B. Tongue muscles (speech, swallowing, chewing)
C. Facial muscles
D. Neck muscles

Tongue muscles (speech, swallowing, chewing)

Spinal nerves are:
A. 12 pairs
B. 31 pairs, mixed (sensory + motor)
C. Only motor
D. Only sensory

31 pairs, mixed (sensory + motor)

Dorsal root contains:
A. Motor fibers
B. Sensory fibers; contains dorsal root ganglion
C. Autonomic only
D. Mixed fibers only

Sensory fibers; contains dorsal root ganglion

Ventral root contains:
A. Sensory fibers
B. Motor fibers
C. Both
D. Autonomic fibers only

Motor fibers

Dorsal ramus innervates:
A. Limbs
B. Posterior trunk muscles & skin
C. Anterior/lateral trunk
D. Autonomic ganglia

Posterior trunk muscles & skin

Ventral ramus innervates:
A. Limbs & anterior/lateral trunk
B. Posterior trunk
C. Spine
D. Head only

Limbs & anterior/lateral trunk

Meningeal branch innervates:
A. Vertebrae, meninges, blood vessels
B. Limbs only
C. Face only
D. Posterior trunk only

Vertebrae, meninges, blood vessels

Rami communicantes contain:
A. Somatic fibers only
B. Autonomic fibers in thoracic region
C. Cranial nerves
D. Sensory fibers only

Autonomic fibers in thoracic region

Plexus is:
A. Single nerve
B. Network of interlacing ventral rami, allows redundancy
C. Only in dorsal root
D. Bundle of sensory fibers

Network of interlacing ventral rami, allows redundancy

Major plexuses and key nerves:

• Cervical (C1–C4, some C5) → Phrenic → diaphragm, neck muscles & skin

• Brachial (C5–T1) → Axillary, Musculocutaneous, Median, Ulnar, Radial → upper limb muscles & skin

• Lumbar (L1–L4) → Femoral, Obturator → thigh muscles, abdominal wall, medial & anterior leg

• Sacral (L4–S4) → Sciatic (tibial + common fibular), Superior/Inferior Gluteal, Pudendal → buttock, lower limb, pelvis, perineum

Function of major peripheral nerves (examples):

• Phrenic → diaphragm (breathing)

• Axillary → deltoid & teres minor, shoulder skin

• Musculocutaneous → anterior arm muscles & lateral forearm skin

• Median → anterior forearm flexors, lateral palm & fingers 2–3, thumb opposition

• Ulnar → medial hand muscles & skin; flexor carpi ulnaris; clawhand if damaged

• Radial → posterior arm & forearm muscles; wrist drop if damaged

• Femoral → anterior thigh muscles & medial leg; flex hip, extend knee

• Obturator → medial thigh adductors

• Sciatic → posterior thigh, leg & foot; footdrop or paralysis if damaged

• Superior gluteal → gluteus medius & minimus, tensor fasciae latae

• Inferior gluteal → gluteus maximus

• Pudendal → perineum muscles & skin, external anal sphincter

Clinical notes:

• Dermatomes → map of skin each spinal nerve innervates; test spinal injuries

• Hilton’s law → nerve supplying a muscle that moves a joint also supplies the joint & overlying skin