MA - Neuroanatomy III

Question 1

Each segment of the spinal cord gives rise to a pair of spinal nerves that consist of (3):

Answer 1

1. Axons of motor neurons that innervate a group of muscles
2. Axons of sensory neurons that innervate a defined area of skin
3. Axons of sympathetic neurons to structures in the body wall that control body temp (blood vessels, sweat glands etc.

Question 2

What are 3 features of cranial nerves?

Answer 2

• The peripheral nerves in the head and neck
• Emerge from the brainstem (except I & II)
• They can be purely sensory (including special), purely motor, or mixed

Question 3

Where do cranial nerves arise from? (2)

Answer 3

• From the brain (I & II) -
• From the brainstem (III – XII)

Question 4

Which cranial nerves are part of the midbrain, pons and medulla?

Answer 4

III and IV - midbrain
V - VIII - pons
IX - XII - medulla

Question 5

What are the names of the 12 cranial nerves?

Answer 5

I – Olfactory
II – Optic
III – Oculomotor
IV – Trochlear
V – Trigeminal
VI – Abducens
VII – Facial
VIII – Vestibulocochlear
IX – Glossopharyngeal
X – Vagus
XI – (Spinal) Accessory
XII - Hypoglossal

Question 6

What are the 3 purely sensory cranial nerves?

Answer 6

1) Olfactory (I) - smell
2) Optic (II) - sight
3) Vestibulochochlear (VIII) - hearing and balance

Question 7

What are the 5 purely motor cranial nerves?

Answer 7

1) Oculomotor (III) - Eye movements
2) Trochlear (IV) - Eye movements
3) Abducens (VI) - Eye movements
4) Accessory (XI) - Neck muscles
5) Hypoglossal (XII) - Tongue

Question 8

What are the 4 mixed motor and sensory cranial nerves?

Answer 8

1) Trigeminal (V)
2) Facial (VII)
3) Glossopharyngeal (IX)
4) Vagus (X)

Question 9

Nerve-carrying parasympathetic fibres (4)

Answer 9

CRANIOSACRAL

III - Oculomotor
VII - Facial
IX - Glossopharyngeal
X - Vagus

Question 10

What is the limbic system?

Answer 10

The ‘Emotional’ or ‘Feeling’ brain. (The ‘reacting’ Brain)

• Under control of the ‘thinking’ brain

Relates to brain structures that deal with emotion, memory, and basic drives

• Species preservation, self-preservation

Question 11

What are the 3 major parts of the limbic system?

Answer 11

• Hypothalamus (output)
• Amygdala (input)
• Hippocampus (input)

Question 12

What is hypothalamus action in the limbic system? (3)

Answer 12

• Primary output node of the limbic system, with connections to the frontal lobes and brainstem.
• Receives input from hippocampus and amygdala
• Suprachiasmatic nucleus – circadian rhythms

Question 13

What are 4 features of the amygdala?

Answer 13

• Located within the temporal lobe; comprised of a group of nuclei
• Emotional centre of the brain; Fear centre of the brain
• Controls aggression (‘fight’) and (‘fear’)
• Responsible for arousal, fear, excitement, anxiety, violence

Question 14

What are the actions of the amygdala in the limbic system? (3)

Answer 14

• Has reciprocal connections with many brain regions (hippocampus, brain stem, diencephalon, olfactory cortex, etc)
• Various (sensory) stimuli and autonomic input converge in amygdala
• Generates ‘learned’ emotional responses

Question 15

What are 3 features of the hippocampus?

Answer 15

• Located within the temporal lobe
• Involved in spatial memory
• Memory processing (storage – short & long; consolidation, encoding, retrieving)

Question 16

What structures are involved in hippocampul formation? (3)

Answer 16

• Hippocampus (CA1 – CA4)
• Dentate gyrus
• Parahippocampal gyrus (Subiculum & entorhinal cortex)

Question 17

What is a trisnynaptic circuit?

Answer 17

3 interconnected afferent pathways, taking information into the hippocampus for processing – memory retrieval

Question 18

What 3 cells are involved in hippocampul formation?

Answer 18

• Granule cells in DG
• Pyramidal cells in CA3
• Pyramidal cells in CA1

Question 19

Describe the 3 synapses involved?

Answer 19

(synapse 1)
Entorhinal Cortex → DG via the perforant path

(synapse 2)
DG → CA3 via mossy fibres

(synapse 3)
CA3 → CA1 via Schaffer collaterals