Cerebral hemispheres and cells

Question 1

Which sulcus separates the parietal and temporal lobes?

Answer 1

Lateral sulcus

Question 2

What is the 5th cerebral cortex?

Answer 2

The insula cortex
Sits behind the lateral sulcus (oberculum)
Visceral sensation

Question 3

Which lobe is Broca’s area in?

Answer 3

Frontal

Question 4

What do the pre and postcentral gyri do?

Answer 4

Precentral gyrus: motor

Postcentral gyrus: sensory

Question 5

Which lobe is Wernicke’s area in?

Answer 5

Temporal

Question 6

Which lobe is the auditory cortex in?

Answer 6

Temporal

Question 7

What occurs at the angular gyrus?

Answer 7

Visual interpretation

Sits at the occipital end of lateral sulcus

Question 8

What does the uncus do?

Answer 8

Relays olfactory fibres

Question 9

What occurs at the cingulate gyrus and fornix?

Answer 9

Limbic system

Part of autonomic nervous system

Question 10

Where is the somatosensory association cortex?

Answer 10

Posterior to the postcentral gyrus

Question 11

Which parts of the body are represented in the medial side of the precentral and postcentral gyri?

Answer 11

Foot, knee and genitals (sensory)

Question 12

What is the blood supply of the medial and lateral post and precentral gyri?

Answer 12

Lateral: middle cerebral artery
Medial: anterior cerebral artery

Question 13

What are the three types of white matter?

Answer 13

Commissural fibres (corpus callosum)
Association fibres (different parts of one hemisphere)
Projection fibres (connect higher centres to spinal cord)

Question 14

What does the corpus collosum connect?

Answer 14

The right and the left hemispheres

Question 15

What is the difference between the superior and inferior longitudinal fasciculus?

Answer 15

Superior: Connects frontal lobe to occipital
Inferior: Connects anterior temporal lobe to posterior temporal lobe

Question 16

What is significant about the uncinate fasciculus?

Answer 16

Does not develop until age 30
Connects temporal (emotions) to frontal (personality)

Question 17

Where is the pineal gland?

Answer 17

Inferior and posterior to the thalamus

Superior to the superior colliculi

Question 18

What connects the two thalami within the 3rd ventrical?

Answer 18

Interthalamic adhesions

Question 19

Where does the hypothalamic sulcus run?

Answer 19

From intreventricular foramen to the entrance of the aquaduct posteriorly

Question 20

What enters the medial geniculate body?

Answer 20

Auditory pathway

Question 21

What is the difference between the VPL and the VML nuclei of the thalamus?

Answer 21

VPL contains sensory information for body and VML contains sensory information for the head and neck

Question 22

At what level does the common carotid divide into internal and external carotid arteries?

Answer 22

C4

Question 23

Which arteries does the internal carotid split into in the head?

Answer 23

Ophthalmic artery
Posterior communicating
Anterior choroidal
anterior cerebral
Middle cerebral artery

Question 24

Where does the vertebral artery run?

Answer 24

Up the transverse foramina of the cervical vertebrae usually from C6
Then enters foramen magnum and combines into basilar artery which forms posterior cerebral arteries

Question 25

What does the anterior choroidal arteries supply?

Answer 25

Choroidal plexus which makes CSF

Question 26

What are the branches of the vertebral arteries?

Answer 26

``` Anterior spinal Posterior spinal Posterior inferior cerebellar artery Basilar artery Anterior inferior cerebellar artery Pontine arteries Superior cerebellar artery Posterior cerebral arteries Meningeal branches ```

Question 27

What do the anterior, middle and posterior cerebral arteries supply?

Answer 27

Anterior: medial anterior 2/3 Posterior: inferior hemispheres and posterior 1/3 of medial Middle: outer surface There are anastomoses between these

Question 28

What is the most common location of the aneurysms in the circle of willis?

Answer 28

Between Anterior communicating and anterior cerebral arteries

Question 29

What is the blood supply of the thalamus?

Answer 29

Posterior communicating Basilar Posterior cerebral

Question 30

Which veins drain into the great vein of Galen?

Answer 30

Basal vein of Rosenthal | Internal cerebral vein

Question 31

What are the cells in grey matter?

Answer 31

``` Neuronal cell bodies Neuropil Axons and dendrites Enveloping glial cells and glial processes Capillaries ```

Question 32

What are the cells in white matter?

Answer 32

Axonal processes Supporting glial cells Blood capillaries No neuronal cell bodies

Question 33

What are the features of a typical neuron?

Answer 33

``` Large centrally located nucleus Prominent nucleolus Nissl bodies (Free ribosomes and RER which stain dark) Single axon-pale as not much RER Multiple dendrites Mitochondria Neurotubules Secondary lysosome Golgi apparatus/stacks ```

Question 34

Why are neurotubules and neurofilaments so prevalent in dendrites?

Answer 34

Neurofilament: maintains extended form of dendrites Neurotubules: act in rapid axonal transport

Question 35

What are the two types of dendritic synapses?

Answer 35

Grey's type 1: Round vesicles with asymmetric synapse Grey's type 2: Ellipsoidal vesicles with symmetric synapse In pyramidal cells , type 1= mainly dendritic spines and smaller branches. Type 2 =perikaya and dendritic trunks

Question 36

What is the most common site of synapse?

Answer 36

Dendritic spines | Each dendrite is contacted by multiple axon terminals

Question 37

Where does collateral branching for axons occur?

Answer 37

For myelinated nerves, collateral branches occur at the node of Ranvier (Never at a point of myelination) Towards their end, axons pass out of the myelin sheath to form the pre-terminal axon

Question 38

Which cells maintain myelin sheaths?

Answer 38

CNS: oligodendrocytes | Peripheral nervous system: Schwann cells

Question 39

How do axons terminate?

Answer 39

In a synaptic filled terminal bouton

Question 40

How to tell the difference between axons and dendrites?

Answer 40

Axons: Axon hillock lacking in RER, neurotubules in clumps, myelinated, synaptic vesicles Dendrites: Larger, unmyelinated, irregular, spines on surface

Question 41

How big is a central synapse compared to a neuromuscular junction synapse?

Answer 41

90nm neuromuscular junction | 20nm synaptic cleft

Question 42

What holds pre and post synaptic junctions together?

Answer 42

Adherens junctions

Question 43

What is contained within small clear vesicles and large dense core vesicles?

Answer 43

Small, clear vesicles,: acetylcholine | Dense core vesicles: dopamine, serotonin or noradrenaline

Question 44

What is the difference between an electrical synapse and a gap junction?

Answer 44

They are the same

Question 45

What are connexons?

Answer 45

Pore like structures between 2 membranes which allow passage of ions

Question 46

What are the two types of astrocytes?

Answer 46

Fibrous (more common in white matter) Protoplasmic (more common in grey matter) or Type 1 and type 2 depending on surface antigens and embryological origin

Question 47

What are the two types of oligodendrocytes?

Answer 47

Interfasicular-aligned in rows between nerve fibres forming myelin. Each oligodendrocyte may wrap around a node of 15 axons Satellite- function not clear

Question 48

Why are glial cells important in the CNS?

Answer 48

CNS does not contain fibrous investing tissue Filling space is done by glial cells Play a role in nutritive support, soak up excess K+ ions

Question 49

What are the morphological features of astrocytes?

Answer 49

Star shaped Small nucleus and dense chromatin Contains intermediate filaments with glial fibrillary acidic protein (GFAP) Vesicles filled with glycogen Terminal expansions of cell processes form end feet which form glial limiting membrane

Question 50

What are the functions of astrocytes?

Answer 50

Endfeet stimulate endothelial cells to form tight junctions and maintain blood brain barrier Astrocytes transmit nourishment from capillaries to neuronal cell bodies and dendrites Astrocytes linked by gap junctions so form continuous transport chain. Remove K+ ions by passing them along towards blood vessels

Question 51

What is the difference between fibrous astrocytes and protoplasmic astrocytes?

Answer 51

Fibrous: more common in white matter, cyclindrical processes, weaving at right angles, provides physical support to tissue, high density of GFAP Protoplasmic: more common in grey matter, shorter, fewer glial filaments, envelop neuronal bodies and absorb K+ ions

Question 52

What are microglia?

Answer 52

Originate from mesenchymal cells Reside in CNS in resting state In tissue injury they transform into large phagocytic cells 5-15% of glial cells

Question 53

What are ependymal cells?

Answer 53

Line the ventricles and form cuboidal epithelium with cillia and microvilli Loose epithelium allowing substances to pass freely from tissue spaces into CSF No endothelium, just rests on endfeet of astrocytes

Question 54

What are the 6 layers of the cerebral cortex?

Answer 54

I. Molecular/plexiform: synaptic layer with few cells, dendrites are branches of pyramidal cells II External granular layer: stellate cells and small pyramidal cells III External pyramid layer: pyramidal cells, slender axons which run up and down towards deeper layer of the cortex IV: Internal granule layer: stellate cells V: Internal pyramidal layer: Large pyramidal neurons include giant Betz cells of primary cortex VI: multiform layer: small pyramidal cells, cells of Martinotti and stellate cells

Question 55

Describe the fibres within the layers of cerebral cortex

Answer 55

Axial and tangential Radial bundles=small + include axons both entering and leaving the cortex Tangential= originate from afferent fibres in the thalamus. Often in layers 4-5 and are known as inner and outer bands of Balliarger. Outer band visible to naked eye in layer 4 ( Stria of Gennari)