W8 -Structure of the Nervous System (Cranial Nerves)

Question 1

What is the hippocampus and who is a famous example?

Answer 1

The hippocampus (derived from the Greek for “seahorse”) is a region of the cerebral cortex embedded deep within
the temporal lobe.

Function:
* Learning
* Memory formation and retrieval
* Regulation of hypothalamus-pituitary-adrenal (HPA) axis

Example:
In 1985, Clive Wearing (a composer and musician) contracted a virus that
caused damage to his hippocampus:
 Anterograde amnesia (unable to create new memories)
 Retrograde amnesia (generally unable to recall past memories)

Question 2

What are the coronal sections?

Answer 2

Coronal sections can reveal important regions within the forebrain, including various sub-cortical structures (e.g. the hippocampus):

The hippocampus is located in the temporal lobe.

Question 3

What are the horizontal sections?

Answer 3

Horizontal sections can reveal important regions within the forebrain, including various sub-cortical structures (e.g. the hippocampus).

Question 4

What is the sagittal sections?

Answer 4

Sagittal sections can reveal important regions within the forebrain, including various sub-cortical structures (e.g. the hippocampus):

Separates the brain into the left and right hemisphere.

Question 5

What are cranial nerves?

Answer 5

The cranial nerves describe the twelve (I-XII) pairs of nerves arising from the brainstem that
perform a diverse range of functions. They usually carries sensory info to and from the CNS.

I. Olfactory Oh!
II. Optic Oh!
III. Oculomotor Oh!
IV. Trochlear To
V. Trigeminal Touch
VI. Abducens And
VII. Facial Feel
VIII. Auditory-vestibular
(Vestibulocochlear) Very
IX. Glossopharyngeal Good
X. Vagus Velvet
XI. Spinal accessory Such
XII. Hypoglossal

These are named from anterior to posterior.
I and II are part of the CNA
III to XII are part of the PNS

Acronym to remember:
OLd OPinioned OCtopus, TROlled TRIangle ABs From AUstralia, Got Very SPooked Here

Question 6

1) What is the olfactory nerve?

Answer 6

Special sensory – sensation of smell
In our noses, we have an olfactory epithelium containing olfactory receptor cells, which transmits information to the Hippocampus (odour memory) , frontal cortex (conscious perception of smell) , the Hypothalamus and the Amygdala (motivational and emotional aspects of smell) via the olfactory bulb.

Question 7

2) What is the Optic nerve?

Answer 7

Special sensory – sensation of vision
Transmits information from the rods and cons in the retinal ganglion cells to the lateral geniculate nucleus (thalamus) to the visual cortex (occipital lobe). This lets us interpret colour and contrast for eg.

Question 8

3) What is the oculomotor nerve?

Answer 8

• Somatic motor – eye and eyelid movement
• Visceral (autonomic) motor – parasympathetic control of pupil size

Question 9

4) What is the trochlear nerve?

Answer 9

Somatic motor – eye movement

Responsible for movement of Superior and inferior rectus moving the eye up and down. Also the Inferior oblique, moving eye outwards and the medial rectus moving the eye inwards.
Superior oblique moves the eye upwards.

Question 10

5) What is the Trigeminal nerve?

Answer 10

• Somatic sensory – sensation of touch to the face
• Somatic motor – movement of muscles of
  mastication (chewing)

Question 11

6) What is the abducens nerve?

Answer 11

• Somatic motor – eye movement
  Lateral rectus = allowing lateral movement of the eye.

Question 12

7) What is the facial nerve?

Answer 12

• Somatic motor – movement of muscles of facial expressions
• Special sensory – sensation of taste in anterior
  tongue

Question 13

8) What are the vestibulocochlear nerves

Answer 13

• Auditory-vestibular (vestibulocochlear) nerve
• Special sensory – hearing and balance

Question 14

9) What is the glossopharyngeal nerve?

Answer 14

• Special sensory – sensation of taste in posterior tongue
• Visceral sensory – detection of blood pressure changes in the aorta
• Somatic motor – movement of muscles in the throat
• Visceral motor – parasympathetic control of salivary glands

Question 15

10) What is the vagus nerve?

Answer 15

• Visceral sensory – sensation of pain associated with viscera (internal organs)
• Somatic motor – movement of muscles in the throat
• Visceral motor – parasympathetic control of heart, lungs and abdominal organs

Question 16

11) What is the spinal accessory nerve?

Answer 16

Somatic motor – movement of muscles in the
throat and neck

Question 17

12) What is the Hypoglossal?

Answer 17

Somatic motor – movement of the tongue (e.g.
swallowing and speech)

Question 18

What enables protection and support of the brain?

Answer 18

MENINGES
VASCULATURE SYSTEM
VENTRICULAR SYSTEM

Question 19

What is meninges?

Answer 19

The meninges describe the three membranous layers that cover the brain (and spinal cord).

From superficial to deep, the meninges comprise:
 Dura mater- outermost, inelastic layer surrounding the brain and spinal cord.
 Arachnoid mater - lies closely but is not attached to the Dura matter - divided by the subdural space.
 Pia mater - deepest later made of a thin membrane close to the surface of the brain. This is separated from the arachnoid matter with a subarachnoid space filled with fluid.

Function:
Cross section showing meningeal layers
* Primary function is in the protection of the
brain and spinal cord
* Passage of cerebrospinal fluid (CSF) –
ventricular system
* Support of cerebral and spinal blood vessels –
vasculature system

Question 20

How does the ventricular system of the brain work?

Answer 20

The ventricular system comprises a series of interconnected, cerebrospinal fluid (CSF)-filled spaces that lie at the core of forebrain and brain stem.
The ventricular system comprises:
Lateral ventricles - paired structures that sprouts like antlers from the third ventricle with the two cerebral hemispheres surrounding the two ventribles.
Third ventricle
Fourth ventricle - extends from the cerebral aqueducts. Characteristic diamond shape when seen within a cross section.

The choroid plexus is responsible for producing the cerebrospinal fluid (CSF) that fills these ventricular spaces

Functions:
* Protection of the brain (e.g. cushion for physical shocks)
* Transport via the cerebralspinal fluid that fills each of the ventricles. (e.g. nutrients, waste products)
* Other functions include regulation of buoyancy - cerebral spinal fluid reduces the net weight, so the pressure put on the base of the brain.

Question 21

How does the circulation to the brain work?

Answer 21

Two pairs of arteries supply blood to the brain: the internal carotid arteries and the
vertebral arteries.

• Anterior circulation is derived from the
  internal carotid arteries – supplies the
  forebrain (cerebrum and diencephalon)
• Posterior circulation is derived from the
  vertebral arteries – supplies the
  brainstem, cerebellum and upper spinal
  cord

Question 22

What are the vertebral arteries?

Answer 22

Two pairs of arteries supply blood to the brain: vertebral arteries and internal carotid arteries:

 Vertebral arteries converge near base of pons to form the basilar artery

 Basilar artery splits into the right and left
superior cerebellar arteries and the posterior
cerebral arteries at the level of the midbrain

 Posterior cerebral arteries send branches –
posterior communicating arteries – that connect
to the internal carotid arteries

Question 23

What are the internal carotid arteries?

Answer 23

Two pairs of arteries supply blood to the brain: vertebral arteries and internal carotid arteries:
 Internal carotid arteries branch to form middle
cerebral arteries and the anterior cerebral arteries
 Anterior cerebral arteries are connected by the
anterior communicating artery
 Ring of connected arteries form the circle of Willis at the base of the brain

Function:
* Delivery of oxygen (O2)
* Removal of carbon dioxide (CO2)
* Transport (e.g. nutrients, waste products)