Basic Structures and Vocab

Question 1

Describe white matter and it’s three derivatives. (8)

Answer 1

White matter is the axons and their supporting cells in the CNS only. It is white due to the fatty myelin.
Funiculus (funiculi) are multidirectional segments of white matter containing multiple pathways.
Tracts are unidirectional white matter pathways connecting two two regions of grey matter. They exist within a funiculus.
Fasciculus (fasciculi) are subdivisions of tracts.

Question 2

Describe grey matter and it’s two derivatives. (6)

Answer 2

Grey matter is made up of cell bodies and dendrites, is heavily vascular and is CNS only. It does contain axons to communicate with the white matter.
Cell columns are grey matter in organised laminae (Rexed Laminae) similar to white matter tracts.
Nuclei are a population of neurones in the CNS that supply motor innervation to a muscle. Functionally related cell bodies.

Question 3

Describe the PNS equivalents of grey and white matter. (2)

Answer 3

A ganglion is equivalent to the grey matter in the PNS, it is collections of cell bodies.
A peripheral nerve is equivalent to white matter because it is axons.

Question 4

Describe the differences between:
Association fibres 
Commissural fibres
Projection fibres. 
(3)

Answer 4

Association - connect cortical regions within the same hemisphere.
Commissural - connect left and right hemispheres or cord halves.
Projection - connect cerebral hemispheres with cord / brainstem or vice verse.

Question 5

Describe the functions of the different parts of the brainstem. (6)

Answer 5

Midbrain - eye movements, reflex responses to sound and vision
Pons - feeding and sleep
Medulla - cardiovascular and respiratory centres, major motor pathways in medullary pyramids.

Question 6

Describe these important landmarks:
Central sulcus (2)
Precentral gyrus (1)
Postcentral gyrus (1)
Lateral / Sylvia’s fissure (1)
Parieto-occipital fissure (2)
Calcarine sulcus (2)
Parahippocampal gyrus (2)
Cingulate gyrus (3)

Answer 6

Central sulcus - sits in the coronal plane, dividing frontal and parietal lobes.
Precentral gyrus - contains primary motor cortex according to the motor homunculus.
Postcentral gyrus - contains primary sensory cortex according to the sensory homunculus.
Lateral / Sylvia’s fissure - separates temporal from frontal / parietal lobes
Parieto-occipital fissure - separates parietal and occipital lobes in the longitudinal fissure
Calcarine sulcus - transverse through the occipital lobe from parieto-occipital sulcus, within the longitudinal fissure.
Parahippocampal gyrus - a gyrus within the uncut of the temporal lobe important for memory encoding.
Cingulate gyrus - a gyrus in the longitudinal fissure that is supero-anterior to the corpus callosum that is important for emotion and memory

Question 7

Describe the functions of these midline structures: 
Corpus callosum
Thalamus
Fornix
Hypothalamus
Tectum
Cerebellar tonsil

Answer 7

Corpus callosum - connects the two hemispheres
Thalamus - sensory relay station between second and third order sensory neurones
Fornix - outflow of the hippocampus
Hypothalamus - homeostasis
Tectum - dorsal midbrain structure used in reflexes to auditory and visual stimuli.
Cerebellar tonsil - bit of the cerebellum that can herniate and compress the midbrain

Question 8

Describe the ventricular system of the brain. (7)

Answer 8

The two lateral ventricles exist superior-lateral, and contain most of the choroid plexus which produces CSF, draining through the interventricular foramen into the third ventricle, and then through the cerebral aqueduct into the diamond shaped fourth ventricle.
The fourth ventricle drains through 4 holes: the central canal through the spinal cord, two lateral Luschka holes and one midline Magendie hole, which drain CSF into the subarachnoid space.

Question 9

Describe CT scan weighting and how to assess perfusion of brain tumours on a CT. (4)

Answer 9

T1 - fat is bright, fluid is low
T2 - fat and fluid are bright, tendons etc are low - T2 = H2O.
Gadolinium is used to assess perfusion of tumours because it can’t cross BBB, so if the tumour is bright on T1 + Gd, it’s outside the BBB, so meningeal.

Question 10

Define dysphagia

Answer 10

Difficulty swallowing

Question 11

Define quadriplegia

Answer 11

Partial or total loss of feeling and motor control in all 4 limbs and the torso.

Question 12

Define paraplegia.

Answer 12

Partial or total loss of feeling and motor control in the lower limbs.

Question 13

Define ataxia

Answer 13

Lack of voluntary muscle movements due to cerebellar lesion

Question 14

Define dyslexia

Answer 14

A common learning difficulty causing problems with reading and writing

Question 15

Define aphasia

Answer 15

An impairment in language, affecting either the production or comprehension on language.

Question 16

Describe hypertonia

Answer 16

Increased muscle tone due to damage to UMN leading to increased excitability of LMNs because UMN inhibition has been lost.

Question 17

Describe spasticity

Answer 17

A type of hypertonia caused by lesions in the pyramidal tract where the predominant muscle group has the most power and the limb exists in that state - more resistance in one direction than in the other.

Question 18

Describe rigidity

Answer 18

A type of hypertonia caused by extrapyramidal lesions. Same resistance in all directions.

Question 19

Describe the differences between pyramidal tract lesions and extrapyramidal lesions. (3)

Answer 19

Whether the lesion occurs in the medullary pyramids or not.
Pyramindal = stroke, motor neurone disease, spinal cord compression
Extrapyramidal = Parkinson’s disease

Question 20

Describe paresis

Answer 20

Partial paralysis caused by nerve damage or disease

Question 21

Describe akinesia

Answer 21

Difficulty performing movements despite having the motor capacity to do it, relating to cerebral lesions

Question 22

Describe hemiplagia

Answer 22

Paralysis of one side of the body

Question 23

Describe apraxia

Answer 23

Damage to the posterior motor cortex leading to difficulty planning motor control.

Question 24

Describe dysarthria

Answer 24

Difficulty speaking

Question 25

Describe dysdiadochokinesis

Answer 25

Impaired ability to perform rapidly alternating movements, relating often to cerebellar lesions

Question 26

Describe agnosia

Answer 26

Inability to recognise sensory information

Question 27

Describe bradykinesia

Answer 27

Slow movements often associated with Parkinson’s disease

Question 28

Describe arreflexia or hyporeflexia

Answer 28

Below normal levels of reflexes.

Question 29

Describe chorea

Answer 29

Dance-like, Jerry involuntary movements especially affecting the arms, hips and face. Associated with Huntington’s Disease

Question 30

Describe dysphonia

Answer 30

Difficulty in speaking due to physical disorder of the mouth or vocal cords