Central Nervous System

Question 1

What is the nervous system divided into?

Answer 1

CNS

PNS

Question 2

How is the brain split up?

Answer 2

Brain

Forebrain, midbrain, hindbrain

Fore: cerebral hemispheres, diencephalon (thalamus and hypothalamus)

Mid: midbrain

Hind: pons, medulla and cerebellum

Question 3

What is the limbic lobe?

Answer 3

Amygdala, hippocampus, Mamillary body and cingulate gyrus

Concerts learning, memory, emotion, motivation and reward

Question 4

What is the insular lobe?

Answer 4

Lies deep within the lateral fissure

Concerned with visceral sensations, autonomic control, interoception, auditory processing, visual-vestibular processing

Question 5

What are the layers of the meninges?

Answer 5

Dura- periosteal, meningeal

Arachnoid

Pia

Question 6

What is CSF?

Answer 6

Cerebrospinal fluid

Produced in choroid plexus of lateral, 3rd and 4th ventricles

Occupies ventricular system and sub arachnoid space

~125 ml volume, 500ml produced a day

Reabsorbed via arachnoid villi (granulations) into the superior saggital sinus

Question 7

What are the differences between plasma and CSF?

Answer 7

CSF has:

Lower pH

Less glucose

Less protein

Less potassium

Question 8

What are the segments the spinal cord is comprised of?

Answer 8

cervical (8 pairs of nerves)

Thoracic (12)

Lumbar (5)

Sacral (5)

Coccygeal (1)

These nerves emerge through in intervertebral foramina

C1-C7 emerge above their corresponding vertebra.

C8-Co1 emerge below (there is no C8 vertebra)

Question 9

What is the cervical enlargement?

Answer 9

Increased size of upper cervical part of spinal cord

Due to innervation of upper limbs

Question 10

What is the lumbar enlargement?

Answer 10

Enlarged size of the lumbar part of the spinal cord

Due to innervation of the lower limbs

Question 11

What is the major descending pathway for voluntary movements?

Answer 11

Motor

Corticospinal tract

Composed of upper motor neurones in primary motor cortex and lower motor neurones in brainstem and spinal cord

Spinal cord bit is mostly lateral and ventral

85% of fibres decussate (Cross) in the medulla (of the spine). The rest stay on the same size

Lateral are generally the limbs, ventral are generally trunk

Question 12

What are the main ascending pathways from the body to the brain?

Answer 12

Sensory

Dorsal column pathway and the spinothalamic tract

Dorsal column: fine touch, vibration and proprioception from skin and joints

Spinothalamic: pain, temperature and crude touch from the skin

Question 13

Where is the primary motor cortex?

Answer 13

In the pre central gyrus

Before the ventral sulcus

Question 14

What is the descending (motor) tract that supplies the face from the brain?

Answer 14

Corticobulbar tract

Upper motor neurones in the cortex of the brain. Lower motor neurones and nuclei in the brainstem

Responsible for movement of:

Extra ocular muscles, muscles of mastication,
Muscles of facial expession, hypoglossal muscles

Question 15

What are some extra pyramidal tracts (descending)?

Answer 15

Supply muscles that are more automated in their effects

Veatibulospinal- provides info about head movement and mediates postural adjustments

Tectospinal - orientation of head and neck during eye movements

Reticulospinal - control of breathing and emotional motor function

Rubrospinal - innervation of lower neurons of the upper limb

Question 16

Where is the primary somatosensory cortex?

Answer 16

In the post central gyrus

Begins the central sulcus

Question 17

What are the details of the (ascending) dorsal column pathway?

Answer 17

Sensory

Fibres enter the dorsal horn and enter the ascending dorsal column pathways

Information from lower limbs and body (below T6) travel ipsilaterally along the gracile tract

Information from the upper limbs and body (above T6) travel ipsilaterally along the cuneate tract

They then cross over when the reach the medulla in the brain where they synapse

Mostly chains of three neurones. Start in the dorsal root ganglion, then with a neurone in the gracile or cuneate nucleus of the medulla. Finally in the thalamus

Question 18

What are the details of the (ascending) spinothalamic pathway?

Answer 18

Sam ethers neurone structure as the dorsal column pathway (root ganglion, medulla, thalamus)

BUT whereas the dorsal pathway neurones travel ipsilaterally from the ganglion to the medulla, the spinothalamic neurones synapse at about the level they come into the spinal cord and travel contralaterally up the spinal cord until they reach the thalamus

They end in the soma sensory cortex