DHUBS 2 - WEEK 9 - EXAM

Question 1

What is a ganglion and where is ganglia located?

Answer 1

A ganglion is a collection of neuronal cell bodies located outside of the central nervous system.

Question 2

What are the 3 layers of connective tissue surrounding a nerve?

Answer 2

Epineurium:
Contains the major blood vessels

Perineurium:
Contains bundles of axons known as fascicles.

Endoneurium:
Connective tissue surrounding axons.

Question 3

What are the different types of peripheral nerves?
What are their general functions?

Answer 3

Spinal nerves formed by anterior and posterior nerve roots exiting the spine.

Spinal nerves supply:
- Somatic efferent fibres to the skeletal muscles of the trunk and limbs

• Somatic afferent fibres to the skin, muscles and joints.
• Visceral efferent autonomic fibres, and
  some spinal nerves contain visceral afferent fibres as well.

Question 4

Name the 12 cranial nerves and their functions.

Answer 4

Cranial Nerve I:
Olfactory nerve
Function: Smell

Cranial Nerve II:
Optic nerve
Function: Vision

Cranial Nerve III:
Oculomotor nerve
Function: Innervates 4 eye muscles for eye movement
- elevates the eyelid
- Constricts pupils

Cranial Nerve IV:
Trochlear nerve
Function: Innervates 1 eye muscle - Superior oblique.

Cranial Nerve V:
Trigeminal nerve
Functions:
- Sensation to face and meninges.
- Muscles of mastication.

Cranial Nerve VI:
Abducens nerve
Function:
1 eye muscle - Lateral rectus.

Cranial Nerve VII:
Facial nerve
Function:
Muscles of facial expression.
Taste to the anterior 2/3 of the tongue.

Cranial Nerve VIII:
Vestibulocochlear nerve.
Function:
- Cochlear apparatus of the inner ear (hearing)
- Vestibular apparatus of the inner ear (balance)

Cranial Nerve IX:
Glossopharyngeal nerve.
Function:
- Taste to remainder of tongue.
- Sensation to the pharynx, middle ear and some of outer ear.
- Some pharyngeal muscles.
- Parasympathetic supply to parotid gland.
- Chemoreceptors and baroreceptors of carotid body.

Cranial Nerve X:
Vagus nerve
Functions:
- Taste to remainder of oral cavity.
- Sensation to some of outer ear, pharynx and posterior fossa meninges.
- Laryngeal and most pharyngeal muscles.
- Parasympathetic supply to most internal organs.
- Chemoreceptors and baroreceptors of aortic arch.

Cranial Nerve XI:
Accessory Nerve:
Functions:
- Cranial portion: some pharyngeal muscles.
- Spinal portion: Upper trapezius and sternocleidomastoid (SCM) muscles.

Cranial Nerve XII:
Hypoglossal nerve
Functions:
Muscles of the tongue.

Question 5

Understand the general role of the subtypes of motor and sensory nerves in the
cranial nerves.

Answer 5

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Sensory types can be:
- Somatic sensory – sensation from the body like the spinal nerves.
- Special sensory – senses like vision, hearing, balance and taste.
- Visceral sensory – sensation from the internal organs.

Motor types can be:
- Somatic motor - to regular skeletal muscle.
- Branchial arch motor – skeletal muscle that arises from the branchial arches.
- Visceromotor – parasympathetic supply to much of the body.