NEURO: Structure of the Nervous System

Question 1

The human nervous system is comprised of the

Answer 1

central nervous system (CNS)

Peripheral nervous system (PNS) - Somatic
nervous system and Autonomic nervous system

Question 2

What are the major regions of the brain?

Answer 2

1. FOREBRAIN
   - TELENCEPHALON (OR CEREBRUM)
   - DIENCEPHALON
2. BRAINSTEM
   - PONS
   - MEDULLA OBLONGATA
   - MIDBRAIN
3. CEREBELLUM

Question 3

What are the three orientations for brain scans?

Answer 3

• sagittal
• coronal
• transverse/horizontal

Question 4

What are the axes of the brain

Answer 4

ANTERIOR-POSTERIOR

• ANTERIOR = FRONT
• POSTERIOR = BEHIND

ROSTRAL-CAUDAL

• ROSTRAL = “NOSE”
• CAUDAL = “TAIL”

DORSAL-VENTRAL

• DORSAL = TOP
• VENTRAL = BOTTOM

SUPERIOR-INFERIOR

• SUPERIOR = ABOVE
• INFERIOR = BELOW

Question 5

With afferent sensory fibres, what type of information is being carried where?

Answer 5

Sensory information is being carried from the periphery to the brain.

Question 6

With efferent motor fibres, what type of information is being carried where?

Answer 6

Motor instructions are being carried from the brain to the periphery.

Question 7

List the names of the 12 cranial nerves.

Answer 7

1. Olfactory Nerve
2. Optic Nerve
3. Oculomotor Nerve
4. Trochlear Nerve
5. Trigeminal Nerve
6. Abducens Nerve
7. Facial Nerve
8. Vestibulocochlear Nerve
9. Glossopharyngeal Nerve
10. Vagus Nerve
11. Accessory Nerve
12. Hypoglossal Nerve

Question 8

Describe the olfactory nerve (CN I).

Answer 8

It is purely sensory - olfaction (smell).

In our noses, there is olfactory epithelium, which transmits information to the olfactory bulb.
The olfactory bulb then transmits the smell information to 3 different places:
1. olfactory cortex: where we have the conscious perception of the smell
2. hippocampus: where we have odour memory, and it decides if an action is to be induced because of the smell
3. hypothalamus amygdala: where we store the motivational

Question 9

Describe the optic nerve (CN II).

Answer 9

It is purely sensory - vision.

It takes information from our rods and cones at the back of our retinas to the visual cortex in our occipital lobes (in the brain). It does this via retinal ganglion cells, with the information travelling through the lateral geniculate nucleus in the thalamus.

Question 10

Describe the oculomotor nerve (CN III).

Answer 10

It is both motor and parasympathetic.

For the motor part, it controls some of our eyeball and eyelid movement (CN III + IV + VI).

For the parasympathetic part, it’s concerned with pupillary constriction and accommodation.

Question 11

Describe the trochlear nerve (CN IV).

Answer 11

It conveys motor information.

It is involved in eyeball movement (CN III + IV + VI).

Question 12

Describe the abducens nerve (CN VI).

Answer 12

It conveys motor information.

It is involved in eyeball movement (CN III + IV + VI).

Question 13

What is the function of the palpebrae muscles?

Answer 13

They are controlled by CN II, and they’re used for eyelid opening.

Question 14

Describe the trigeminal nerve (CN V).

Answer 14

It is involved in receiving signals from our facial skin regions. It has three divisions:

• opthalmic (sensory)
• maxillary (sensory)
• mandibular (sensory)

Question 15

Describe the facial nerve (CN VII).

Answer 15

It conveys sensory, motor and parasympathetic information.

For the sensory part, it helps with taste on the anterior two-thirds of the tongue.

For the motor part, it controls the muscles of facial expression. It also controls the stapedius muscle, a muscle in our ear which blocks it when we need to dull down information that is either harmful or useless.

For the parasympathetic part, it controls the salivary glands, the lacrimal glands, the glands of the nose and palate.

Question 16

Describe the vestibulocochlear nerve (CN VIII).

Answer 16

It conveys sensory information - hearing and balance.

With hearing, the cochlea cells project to the medial geniculate nucleus (in the thalamus), then to the auditory cortex (in the temporal lobe).

With balance, the vestibular hair cells project to the ventral posterolateral nucleus (in the thalamus), then to the vestibular cortex (in the temporal lobe).

Question 17

Describe the glossopharyngeal nerve (CN IX).

Answer 17

It has sensory, motor and parasympathetic functions.

It has a variety of sensory functions. It plays a sensory role with the pharynx, the auditory tube, the middle ear, the posterior third of the tongue, and detects blood pressure changes in the aorta.

With its motor functions, it controls swallowing.

With its parasympathetic functions, it stimulates the salivary glands.

Question 18

Describe the vagus nerve (CN X).

Answer 18

It has sensory, motor and parasympathetic functions.

With the sensory, its involved with the sensation of pain and associated viscera.

With the motor, it controls the muscles used for speech and swallowing.

With the parasympathetic, it controls the smooth muscle in the lungs, heart and abdominal organs.

Question 19

Describe the accessory nerve (CN XI).

Answer 19

It conveys motor information from our brain to the periphery; it does it cranialy and via the spine.

Cranialy, it controls the muscles of the pharynx, larynxa and soft palate.

Via the spine, it controls the head and neck muscles.

Question 20

Describe the hypoglossal nerve (CN XII).

Answer 20

It conveys motor information.

It controls tongue movement for swallowing and speech.

Question 21

Describe the meninges.

Answer 21

The brain doesn’t come into contact with the skull. There are three membranes surrounding the brain called the meninges.

They are the:

• dura mater: tough, in-elastic
• arachnoid membrane: adheres the two layers together
• pia mater: a thin membrane that adheres closely to the brain

The subarachnoid space is filled with cerebrospinal fluid (CSF).

Question 22

How is the CSF (cerebrospinal fluid) made?

Answer 22

The CSF is made in the choroid plexus.

CSF flows from the cerebrum ventricles down to the brainstem and spinal cord.
CSF enters the subarachnoid space via apertures near the cerebellum.
CSF is absorbed by blood vessels in the arachnoid space.

Question 23

What are the functions of the CSF?

Answer 23

• it protects the brain from physical and chemical injury
• it regulates intracranial pressure
• it is essential in exchanging nutrients and waste products between the blood and the CNS

Question 24

How does the Circle of Willis come about?

Answer 24

There are two pairs of arteries that supply blood to the brain: the vertebral arteries and the carotid arteries.
Branches from these arteries supply blood throughout the brain.

They also form an interconnected structure called the Circle of Willis.

Question 25

Which artery supplies the lateral surface of the cerebrum?

Answer 25

Most of the lateral surface of the cerebrum is supplied by the middle cerebral artery.

Question 26

What artery supplies the medial wall of the cerebral hemisphere?

Answer 26

Most of the medial wall of the cerebral hemisphere is supplied by the anterior cerebral artery.

Question 27

What are the major regions of the brain?

Answer 27

1. FOREBRAIN
2. BRAINSTEM
3. CEREBELLUM
   -TELENCEPHALON (OR CEREBRUM)
   -DIENCEPHALON
4. FOREBRAIN
5. BRAINSTEM
6. CEREBELLUM
   MIDBRAIN
   PONS
   MEDULLA OBLONGATA