Central Nervous System

Question 1

What is the CNS composed of?

Answer 1

Brain:
Forebrain - cerebral hemisphere + diencephalon
Midbrain 
Hindbrain - Pons, Medulla + Cerebellum
Spinal Chord

Question 2

Name the lobes in the brain

Answer 2

Frontal
Parietal
Temporal
Occipital
Limbic 
Insular Cortex

Question 3

Frontal lobe function

Answer 3

Regulate and incite motor function, language, cognitive functions(attention/memory)

Question 4

Parietal Lobe function

Answer 4

Sensation, sensory aspects of language, spatial orientation and self-perception

Question 5

Temporal lobe function

Answer 5

Processing auditory information

Question 6

Occipital lobe function

Answer 6

Processing visual information

Question 7

Limbic lobe function (and parts of brain it includes)

Answer 7

Includes amygdala, hippocampus, mamilliary body and cingulate gyrus

Concerned with learning, memory, emotion, motivation and reward

Question 8

Insular cortex position and function

Answer 8

Lies deep within lateral fissure

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

Question 9

Describe the layers of the meninges

Answer 9

Skin
Bone
Dura - thick composed of periosteal and meningeal (durable + dense) layers
Arachnoid - thin, transparent fibrous membrane
Pia mater - thin, translucent and mesh-like

Question 10

Cerebrospinal fluid

Production, location, amount, removal, comparison to plasma

Answer 10

Produced in choroid plexus of lateral, 3rd and 4th ventricles
Occupies ventricular system and sub-arachnoid space
125ml volume and 500ml produced each day
Reabsorbed via arachnoid villi into superior Sagitta sinus l
Lower pH, less glucose, protein and potassium than plasma

Question 11

Describe compositions of spinal chord with regards to nerves

Answer 11

8pairs of cervical nerves
12pairs of thoracic nerves
5pairs of Lumbar nerves
5pairs of Sacral nerves
1 pair of Coccygeal nerves

Nerves emerge through intervertebral foramina
Relationship between nerves and foramina changes:
Cervical nerves 1-7 emerge above vertebrae
Cervical nerves 8- Coccygeal nerves 1 emerge below vertebrae

Question 12

Which parts of the spinal chord are enlarged and why?

Answer 12

Cervical chord enlargement - due to innervation of upper limbs

Lumbar chord enlargement - due to innervation of lower limbs

Question 13

What is the major pathway for voluntary movement and what is it composed of?

Answer 13

Corticospinal tract:

Composed of upper motor neurons in primary motor cortex and lower motor neurons in brainstem and spinal chord

Question 14

What are the major pathways for sensation?

Answer 14

Dorsal Column Pathway - fine touch, vibration and proprioception from the skin and joints

Spinothalamic Pathway - pain, temperature and crude touch from the skin

Question 15

Difference between Descending and Ascending Tracts

Answer 15

Descending tracts are motor containing lateral corticospinal and ventral corticospinal tracts
Ascending tracts are sensory containing dorsal column, later and ventral spinothalamic tracts

Question 16

Where are the upper and lower motor neurones located?

Answer 16

Upper motor neurons - primary motor cortex

Lower motor neurons - brain stem (head and neck muscles) or spinal chord (trunk and limb muscles)

Question 17

Name and describe brainstem motor tracts

Answer 17

Vestibulospinal - provides info about head movement and position and mediate a postural adjustments
Tectospinal - orientation of head/neck during eye movement
Reticulospinal - control of breathing and emotional motor function
Rubrospinal - innervates lower motor neurons of the upper limb

Question 18

Name the two principal ascending pathways

Answer 18

Dorsal column pathway and Spinothalamic pathway

Question 19

What is the function of Dorsal column pathway?

Answer 19

Mechanical:
Fine discriminative touch 
Pressure
Vibration
Proprioception

Question 20

What is the function of Spinothalamic pathway?

Answer 20

Mechanical, Chemical & Thermal:
Crude touch
Pain
Temperature

Question 21

Describe the Dorsal Column Pathway route

Answer 21

Fibres enter via dorsal horn and enter the ascending dorsal column pathways
Info conveyed from lower limbs and body (below T6) travel ipsilaterally along gracile tract
Info conveyed from upper limbs and body (above T6) gravel ipsilaterally along the cuneate tract

Question 22

3 neurones in Sensory pathways

Answer 22

First one has cell body in dorsal root ganglion
Second one has cell body in medulla (gracile/cuneate nucleus)
Third neurone is found in the thalamus

Question 23

What determines the difference between using the dorsal column pathway and the Spinothalamic pathway?

Answer 23

The second order neurone’s location of their cell bodies

Question 24

Location of 3rd order neurons

Answer 24

From thalamus project to the Somatosensory Cortex

Question 25

Somatosensory homunculus

Answer 25

Size of somatotopic areas is proportional to density of sensory receptors in that body region

Question 26

Describe the Spinothalamic pathway

Answer 26

Pain and temperature sensations ascend within the lateral Spinothalamic tract
Crude touch ascends within the anterior Spinothalamic tract
Primary neurone comes in through the dorsal horn it synapses onto the second order neurone which crosses over onto the opposite side of the body and travels up the contralateral side synapsing on to the third order neurone in the thalamus

Question 27

Neurone synapses in dorsal horn (in relation to Spinothalamic tract)

Answer 27

Primary afferent axons terminate upon entering the spinal chord and second order neurons decussate immediately in the spinal chord and form the Spinothalamic tract which then terminates in the thalamus