WK 6 Spinal Tracks, blood supply to brain

Question 1

What is the internal capsule and where is it found?

Answer 1

An area of white mater where there are fibres running down to the midbrain Found between the lentiform nucleus and the thalamus

Question 2

What is the ‘regular’ white mater in the brain called?

Answer 2

Corona radiata

Question 3

What structure connects the two hemispheres of the brain?

Answer 3

The corpus callosum

Question 4

What is the corticospinal tract?

Answer 4

White mater motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk

Question 5

The motor neuron fibres in the corticospinal tract cross sides when they reach what?

Answer 5

The motor decussation at the bottom of the medulla

Question 6

What cranial nerves supply muscles and what muscles are these?

Answer 6

CN III (oculomotor) = extra-ocular muscles CNIV (trochlear) = superior oblique muscle of the eye CN V (trigeminal) = muscles of mastication + others CN VI (abducens) = lateral rectus of the eye (turns the eye out) CN VII (facial) = muscles of facial expression CN IX (glossopharyngeal) = stylopharyngeus CN X (vagus) = muscles of larynx and pharynx CN XI (accessory) = muscles of larynx and pharynx, sternocleidomastoid and trapezius muscle CN XII (hypoglossal) = muscles of the tongue

Question 7

What cranial nerve cell bodies sit in the midline in the brainstem?

Answer 7

-trochlear nucleus -oculomotor nucleus -abducens nucleus -hypoglossal nucleus

Question 8

What nucleus’ for cranial nerves sit ‘out to the side’ in the brainstem? Why?

Answer 8

Trigeminal motor nucleus Facial nucleus Nucleus ambiguus Because formed from pharyngeal arches

Question 9

What are the corticonuclear tracts?

Answer 9

Tracts from the cortex to the cranial nerve nuclei

Question 10

What kind of input do cranial nerves have? What cell bodies are the exception to this?

Answer 10

Bi-lateral input (from both sides of brain) Exceptions = hypoglossal (unilateral input) and facial nerve (only bi-lateral input to the upper facial muscles)

Question 11

The 1st pharyngeal arch gives rise to what muscles?

Answer 11

Muscles of mastication

Question 12

The 2nd pharyngeal arch gives rise to what muscles?

Answer 12

Muscles of facial expression

Question 13

The 3rd pharyngeal arch gives rise to what muscles?

Answer 13

Small muscle in the pharynx (stylopharyngeus)

Question 14

The back pharyngeal arches (4 onwards) give rise to what muscles?

Answer 14

Muscles of larynx and pharynx

Question 15

What blood vessels supply the internal capsule artery?

Answer 15

Lenticulostriate arteries (that come off from middle cerebral artery)

Question 16

Why is it common for the internal capsule to be damaged in a stroke?

Answer 16

Because it is easy for the lenticulostriate arteries that supply the internal capsule to be blocked as they are small

Question 17

The brain is composed of 2 hemispheres, connected by what?

Answer 17

Corpus callosum

Question 18

The hemispheres of the brain are separated by what?

Answer 18

Deep longitudinal fissure

Question 19

The brain is covered by small grooves called what and what binds these grooves together?

Answer 19

Called sucli and bound together by gyri (ridges)

Question 20

What is the postcenral gyus also termed? What does the term postcentral gyrus mean?

Answer 20

Primary somato-aesthtic cortex (primary sensory cortex)

The gyrus found after the central sulcus of the brain

Question 21

What does the postcentral gyrus do?

Answer 21

Sensory info/stimuli are interpreted and put into context

Question 22

What is the pre-central gryus? What is it responsible for?

Answer 22

The primary motor cortex - coordinated motor response

Question 23

The primary motor cortex contains what kinds of cells?

Answer 23

Giant pyramidal ceels (cells of Betz)

Question 24

What is the term used to decribe that particular parts of the brain correspond/are devoted to particular parts of the body?

Answer 24

Somatotopic localisation

Question 25

Where is somatotopic localisation found?

Answer 25

In both the primary and sensory motor cortex

Question 26

Where is the motor speech area found in the brain? What is the motor speech area also termed?

Answer 26

On the frontal lobe in the left side only

Bronca’s area

Question 28

Where is the visual cortex found?

Answer 28

On the medial side of the occipital lobe

Question 29

Where is the motor speech are found in the brain?

Answer 29

Frontal lobe on the left side only

Question 30

What is the importance/function of the motor speech area?

Answer 30

Is used to put words together - need it to make words intelligible

Question 31

Where is the auditory cortex found?

Answer 31

At the transverese temporal gyri

Question 32

If a patient came in with a paralysed face, upper limb and trunk but spared lower limb, what would be the likely cause?

Why is the lower limb spared?

Answer 32

A stroke affecting the middle cerebral artery

Because the part of the motor nucelus that is dedicated to the lower limb is supplies by the anterior cerebral artery which will be unaffected

Question 33

Describe/draw the bloody supply to the brain.

Answer 33

Circle of Willus - see notes

Question 34

The circle of Willus probably does what?

Answer 34

Equalises pressures in arteries (but also means if one part blaocked then can bypas it)