Structure of the Nervous System

Question 1

What is the human nervous system and its subtypes?

Answer 1

The human nervous system is comprised of the central nervous system and the peripheral nervous system
The CNS is the brain and spinal cord
The PNS is all other parts of the nervous system
The PNS can be subdivided into the somatic and the autonomic nervous systems
The somatic nervous system provides innervation to the skin, joints and skeletal muscle and controls voluntary movement and locomotion
The autonomic nervous system provides innervation to the cardiovascular system, internal organs and smooth muscle to control blood pressure heart rate, digestion etc.

Question 2

What are the major brain regions?

Answer 2

Forebrain:
	- Telencephalon (or cerebrum)
	- Diencephalon
Brainstem:
	- Midbrain
	- Pons
	- Medulla oblongata
Cerebellum

Question 3

What are the axes of the brain?

Answer 3

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 4

What are the planes of the brain?

Answer 4

Coronal:
- Divide the brain into a front (anterior) and a back (posterior) section
Horizontal:
- Divide the brain into an upper (superior) and a lower (inferior) section
Sagittal:
- Divide the brain into two hemispheres
- Further characterised as midsagittal (midline) or parasagittal (more lateral)

Question 5

What are the 12 cranial nerves?

Answer 5

The cranial nerves describe the twelve pairs of nerves arising from the brainstem that perform a diverse range of functions
Cranial nerves one and two are part of 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 Heaven

Question 6

What does the 1st cranial nerve do?

Answer 6

Cranial nerve I (olfactory)
Special sensory (one of the 5 special senses)- sensation of smell
In our noses we have an olfactory epithelium which contains olfactory receptor cells which transmits olfactory information to various brain structures namely the hippocampus the frontal cortex and the amygdala
The olfactory nerve function is to mediate this transmission of information to the olfactory bulb where it is subsequently conveyed to other brain regions

Question 7

What does the 2nd cranial do?

Answer 7

Special sensory- sensation of vision
Transmitting information from rods and cones in our retina via the lateral geniculate nucleus, located in the thalamus to the visual cortex located in the occipital lobe

Question 8

What does the 3rd cranial nerve do?

Answer 8

Cranial nerve III (oculomotor)
Somatic motor- eye and eyelid movement
Visceral (autonomic) motor- parasympathetic control of pupil size

Question 9

What does the 4th cranial nerve do?

Answer 9

Cranial nerve IV (trochlear)
Somatic motor-eye movement
If you look at the image below you can see which nerve is responsible for which movement

Question 10

What does the 6th cranial nerve do?

Answer 10

Cranial nerve VI (abducens)

Somatic motor- eye movement

Question 11

What does the 7th cranial nerve do?

Answer 11

Cranial nerve VII (facial)
Somatic sensory- movement of muscles of facial expressions
Special sensory- sensation of taste in anterior tongue (discussed in a later lecture)

Question 12

What does the 8th cranial nerve do?

Answer 12

Cranial nerve VIII (vestibulocochlear)
Auditory-vestibular (vestibulocochlear) nerve
Special sensory- hearing and balance

Question 13

What does the 9th cranial nerve do?

Answer 13

Cranial nerve IX (glossopharyngeal)
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 14

What does the 10th cranial nerve do?

Answer 14

Cranial nerve X (vagus)
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 15

What does the 11th cranial nerve do?

Answer 15

Cranial nerve XI (spinal accessory)

Somatic motor- movement of muscles in the throat and neck

Question 16

What does the 12th cranial nerve do?

Answer 16

Cranial nerve XII (hypoglossal)

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

Question 17

What are the meninges and their function?

Answer 17

The meninges describe the three membranous layers that cover the brain (and the spinal cord)
From superficial to deep, the meninges comprise:
- Dura mater- forms a touch inelastic layer, tightly to the brain
- Arachnoid mater- lies closely against the dura mater, separated by the subdural space
- Pia mater- comprised of a thin membrane that lies closely to the brain, separated from the arachnoid mater by the subarachnoid space, a fluid filled space (CSF)
Meninges function:
Primary function is in the protection of the brain and spinal cord
Roles in passage of cerebrospinal fluid (CSF) in relation to the ventricular system
Support of cerebral and spinal blood vessels- vasculature system

Question 18

What is the ventricular system of the brain?

Answer 18

The ventricular system comprises a series of interconnected, cerebrospinal fluid (CSF)- filled spaces that lie at the core of the forebrain and brain stem
The ventricular system comprises:
- Lateral ventricles
- Third ventricle
- Fourth ventricle
Within each of these ventricles is a special tissue called the choroid plexus which is responsible for producing the cerebrospinal fluid (CSF) that fills these ventricular spaces

Question 19

What are the functions of the ventricular system?

Answer 19

Ventricular system functions:

- Protection of the brain (e.g. cushion for physical shock)
- Transport (e.g. nutrients, waste products)
- Other functions include regulation of buoyancy- reduces the net weight and therefore pressure put on the base of the brain

Question 20

What is the vasculature of the brain like?

Answer 20

Two pairs of arteries supply blood to the brain; the internal carotid arteries and the vertebral arteries
Anterior circulation is derives 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 21

What are the different vertebral arteries?

Answer 21

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-known as posterior communicating arteries- that connect to the internal carotid arteries

Question 22

What are the internal carotid arteries?

Answer 22

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, the anterior communicating artery, form the circle of Willis at the base of the brain

Question 23

What is the vasculature system function?

Answer 23

Delivery of oxygen
Removal of carbon dioxide
Transport (e.g. nutrients, waste products)

Question 24

What does the 5th cranial nerve do?

Answer 24

Cranial nerve V (trigeminal)
Somatic sensory- sensation of touch to the face
Somatic motor- movement of muscles of mastication (chewing