Session 4: Functional Neuroanatomy: Topography of the Brain and Brainstem

Question 1

# Define & appropriately use the descriptive anatomical terms: afferent, efferent, somatic and visceral/autonomic in relation to the organisation and parts of the peripheral nervous system LO
(Sem 2 self study)

Q.1. In the spinal cord, the general rule is that dorsal components tend to be concerned with?, and ventral with?
2. How does this contrast with the CNS?

Answer 1

A. 1. afferent (sensory) functions
efferent (motor) functions
2. In the medulla it is as if the two dorsal (sensory) components have been dragged laterally so that sensory components are no longer dorsal but lateral, and motor components now not so much anterior as medial. Higher in the brain stem the pattern becomes less and less obvious, and it has all but disappeared in the diencephalon.

Question 2

Q. Knowing the info above which part of the PNS are the autonomic nerves located?

Answer 2

A. Dorsal part of the spinal cord if motor / efferent

Question 3

Q. Define afferent

Answer 3

A. Towards -> towards the spinal cord from a stimulus

Question 4

Q. Define efferent

Answer 4

A. Away -> from the spinal cord to the effector

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Question 5

Q. Define somatic​

Answer 5

A. Voluntary motor control

Question 6

Q. Define visceral/autonomic

Answer 6

A. Involuntary motor actions/ control

Question 7

Understand the concept of sensory input from viscera and somatic structures to the CNS and motor output from the CNS to visceral and somatic structures by way of the peripheral nervous system LO

Answer 7

Question 8

Understand the functional organisation of the nervous system into central and peripheral nervous systems LO

Q. What is the CNS and PNS composed of?

Answer 8

A. CNS: Cerebral hemispheres, brainstem & cerebellum & Spinal cord
PNS: Dorsal and ventral roots, Spinal nerves & Peripheral nerves

Question 9

Define and appropriately use the descriptive anatomical terms: superior, inferior, ipsilateral, contralateral, proximal, distal, anterior, posterior, deep, superficial, medial, lateral, dorsal, ventral, rostral and caudal LO

Q. Label the diagrams stating which surfaces are the dorsal and ventral surfaces and why

Answer 9

Question 10

Q. Label the brain with the correct axis

Answer 10

Question 11

Answer 11

Question 12

Q. At what location does the axis change?

Answer 12

A. In the medulla, pons and midbrain the ventral aspect of the neural tube is anterior, and the dorsal aspect is posterior, much as in the spinal cord. Above the midbrain, the axis bends forwards so that in the diencephalon, the ventral aspect is inferior and the dorsal surface superior.

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Question 13

Q. What is the meaning of rostral?

Answer 13

A. situated or occurring near the front end of the body (particularly nose region)

Question 14

Q. What makes up the brainstem and what are their functions?

Answer 14

A. Midbrain (mesencephalon)
• Eye movements and reflex responses
Pons
• Feeding
• Sleep
Medulla medulla for medusa vision motor
• Cardiovascular and respiratory centres
• Contains a major motor pathway to sound and vision (medullary pyramids)

Question 15

Q. What does decussation mean?

Answer 15

A. Fibres cross from one hemisphere to the other side of the hemisphere

Question 16

Q. Define Sulci, gyri and fissures

Answer 16

A. Sulcus: a ‘groove or furrow’ in the brain separating adjacent gyri

Gyrus: A ‘ridge or fold’ in the brain

Fissure: A large ‘crack’ or ‘split’ between adjacent large areas of the brain

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Question 17

Label the frontal, temporal, parietal, occipital lobes and cerebellum (lateral aspects of cerebral hemisphere)

Answer 17

Image drawn wrong as lateral sulcus divides both the frontal lobe and parietal lobe above from the temporal lobe below.

Question 18

The principal external features of the cortex and the primary functional sites for motor, sensory, language, hearing, olfaction and vision. LO

Q. State the function of each of the lobes

Answer 18

A. Frontal lobe: Higher cognition, motor function, speech
Parietal lobe: Sensation, spatial awareness
Temporal lobe: Memory, smell, hearing, olfaction
Occipital lobe: Vision
Cerebellum: Co-ordination and motor learning

Question 19

Q. State where the Visual, auditory, olfactory centres are located

Answer 19

A. • The visual cortex is in the occipital lobe (posterior)
• The auditory cortex is on the superior surface of the temporal lobe.
• The olfactory cortex is on the under surface of the temporal lobe, principally the uncus.

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Question 20

Q. On the diagram label the central sulcus and the lateral sulcus and state what lobes they separate

Answer 20

Lateral sulcus: Frontal lobe & parietal lobe above from the temporal lobe below
Central sulcus: parietal lobe from the frontal lobe and the primary motor cortex from the primary somatosensory cortex

Question 21

Q. What fissure is this image highlighting?

Answer 21

Median saggital fissure

Question 22

Q. The large fissure between the parietal and temporal lobes is the ?

Answer 22

A. lateral fissure

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Question 23

Q. The median sagittal fissure separates the right and left hemispheres. It contains the?

Answer 23

A. falx cerebri

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Question 24

Q. What are Commissures? Give an e.g.

Answer 24

A. Numerous bundles of fibres (white matter) connect the two sides: these are the commissures, and the largest, deep in the sagittal fissure, is the corpus callosum.

Question 25

Q. What is anterior and posterior to the central sulcus and what are their functions?​

Answer 25

A. Precentral gyrus: the main motor area concerned with the initiation of voluntary movement
Postcentral gyrus: the main sensory area

Question 26

Q. The inferior aspect of the cerebral hemisphere

1. What is the optic chiasm:
2. What is the uncus:
3. What is the Medullary pyramids:

Answer 26

A. 1. A site where fibres in the visual system cross over desiccation

2. Part of the temporal lobe that can herniate, compressing the midbrain (inc in ICP)
3. Location of descending motor fibres (each has around 1 million axons!)

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Question 27

Label the optic chiasm, uncus & medullary pyramids on the diagram

Answer 27

Question 28

Answer 28

Question 29

Q. The medial aspect of the cerebral hemisphere

1. What is the Corpus callosum?
2. What is the Thalamus ?
3. What is the Hypothalamus ?

Answer 29

A.1. Fibres connecting the two cerebral hemispheres

2. Sensory relay station projecting to sensory cortex
3. Essential centre for homeostasis

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Question 30

Q. On the diagram showing the medial surface label the white & grey matter, corpus callosum, thalamus, hypothalamus.

Answer 30

Question 31

Q. The hypothalamus forms the floor of the third ventricle. Its most obvious features when inspecting the brain from below are the pituitary stalk and the mammillary bodies (mammilla = little mamma or breast). The hypothalamus contains the centres regulating appetite (arcuate nuclei) and much autonomic activity (e.g. temperature regulation) as well as controlling the activity of the pituitary gland.
– The posterior pituitary is a component part of the hypothalamus with direct neural connections from the ? nuclei of the hypothalamus. Hormones released by the posterior pituitary (oxytocin, vasopressin) are manufactured in the cell bodies of neurons in these nuclei, and travel down axons to the posterior pituitary where they are released into the bloodstream.
– The anterior pituitary is a separate gland that migrates from the roof of the? The hypothalamus controls it by releasing hormones into the hypophyseal portal system of veins, through which they are transported to the anterior pituitary to act upon its component cells.

Answer 31

A. supraoptic and paraventricular, primitive pharynx Rathkes pouch

Question 32

Difference & similarities in PNS & CNS

Answer 32

Question 33

Q. What CN does the hindbrain contain?

Answer 33

A. V–XII (facial sensation, and movements of the upper end of the gut tube for ingestion & phonation)

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Question 34

Q. What CN does the Midbrain contain? It has centres for what reflexes?

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Answer 34

A. III and IV and the centres for eye reflexes (e.g. pupillary light reflex) and auditory reflexes.

Question 35

Q. Forebrain this gives rise to the?

Answer 35

A. Diencephalon (thalamic structures), and the right and left telencephalic derivatives – the cerebral hemispheres (frontal, parietal, occipital and temporal lobes)

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Question 36

Q. Diencephalic derivatives are concerned with

Answer 36

A. motor and sensory coordination, regulation and control, and include the optic vesicles, which give rise to the optic nerves and retinas.

Region for diencephalon:

Question 37

Q. Cerebral hemispheres are concerned with so-called ‘higher’ functions:

Answer 37

A. Intellectual, reasoning, long-term memory, conscious perception, and voluntary movement. In the cerebral hemispheres, unlike the spinal cord, grey matter is on the external surface, often called the cerebral cortex, or simply the cortex.

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Question 38

Q. It is the caudal part of the forebrain (prosencephalon) that occupies the central region of the brain. The diencephalon is comprised of the:

Answer 38

A.

• Epithalamus (pineal gland)
• Thalamus
• Subthalamus
• Metathalamus
• Hypothalamus
• Hypophysis cerebri
• Posterior pituitary (my input)

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Question 39

Q. Where is CSF produced? What happens after it is produced?

Answer 39

A. choroid plexus, a vascular plexus present in all ventricles formed where vessels of the pia mater (external) come into contact with the ependymal lining of the central canal (i.e. there is no intervening neural tissue).
Circulation of cerebrospinal fluid (Fig. 15.3)
From the lateral ventricles, cerebrospinal fluid flows through the foramina of Monro to the third ventricle. It continues through the cerebral aqueduct to the fourth ventricle where some may enter the central canal of the spinal cord, but most passes to the subarachnoid space through foramina in the roof. It flows around the brain and spinal cord and is absorbed back into the venous system at the arachnoid granulations (

Question 40

Answer 40

Question 41

Answer 41

A. Median sagittal scan through the head: 1, frontal lobe; 2, region of cribriform plate of ethmoid; 3, nose; 4, pituitary fossa; 5, arteries which happen to have been sectioned at right-angles to the plane of the section; 6, genu of corpus callosum; 7, body of corpus callosum; 8, splenium of corpus callosum; 9, diencephalon; 10, region of pineal; 11, midbrain; 12, superior and inferior colliculi (so the section is not quite in the midline); 13, pons; 14, medulla; 15, fourth ventricle; 16, cerebellum; 17, region of (median) foramen of Magendie (between fourth ventricle and cisterna magna); 18, spinal cord.

Question 42

Answer 42

A. Coronal scan through the head, pinna to pinna: 1, parietal lobe; 2, lateral ventricle; 3, thalamus, lateral to; 4, third ventricle; 5, lateral fissure; 6, temporal lobe; 7, cerebral peduncle of midbrain; 8, pons; 9, medulla; 10, region of decussation of the pyramids; 11, spinal cord; 12, internal capsule

Question 43

Q. 1. The brain stem consists of grey matter: ?

2. White matter:
3. The midbrain houses nuclei concerned with ? reflexes
4. The cerebellum is posterior to the pons and receives most of the information from the vestibular system. Cerebellar lesions have ? effects, unlike those of the rest of the brain which are usually contralateral.

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Answer 43

A. 1. Cell bodies grouped as nuclei

2. the myelinated axons of fibre tracts
3. visual and auditory
4. ipsilateral

Question 44

1. The cerebellum is an outgrowth of the dorsal pons, separated from it by the fourth ventricle. On each side, the white matter connecting the pons and cerebellum forms the superior, middle and inferior ?
2. Function of cerebellum?

Answer 44

1. cerebellar peduncles
2. Concerned with the coordination of motor activity, the regulation of muscle tone and the maintenance of equilibrium.

Question 45

Q. Cerebellar cortex
The cerebellar cortex has superficial ? matter, inside which is ? matter &, most deeply of all, the four paired cerebellar nuclei.

Answer 45

A. grey, white,

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Question 46

1. Cerebellar disease
   Disease of the cerebellum causes?
2. Tonsillar herniation

Answer 46

1. Ipsilateral symptoms, not contralateral, manifested principally as a lack of coordination called ataxia
2. A. The tonsils rest upon the dura over the edge of the foramen magnum and in cases of raised intracranial pressure they may be pushed down either through or into the foramen magnum where they compress the posterior aspect of the brain stem and the vital (e.g. respiratory) centres it contains, causing death. This is herniation of the cerebellar tonsils, or coning. It occurs if a lumbar puncture is performed on a patient with raised intracranial pressure. The sudden release of pressure (as a result of the lumbar puncture) in the lumbar region means that the brain is pushed down as described above. This is why you should always test for signs of raised intracranial pressure (e.g. look for papilloedema of the optic disc) before performing a lumbar puncture.

Question 47

1. Medulla
   Anterior aspect. Four swellings are visible, two on either side of the midline.
   The medial swelling on each side is the pyramid contains the?
2. Arnold, a 65 year old man, presents to his GP following an episode of sudden monocular blindness affecting the right eye. He described the visual loss like a black curtain falling over the eye, lasting 10 minutes before he regained normal vision. He reported no other signs at the time or since.
   The GP suspects a transient ischaemic attack and arranges for some initial investigations, including an ECG (i) What does the ECG show?

Answer 47

1. Descending motor corticospinal tracts to the opposite side of the body. The rootlets of XII (acessory) are attached laterally to these swellings

2.A. Regular irreggular rhythms
A FIB can lead to clot formation which can circulate and feed into the brain causing a TIA

Question 48

Q. The patient is referred to secondary care for more investigations, including an ultrasound of the neck. Following the ultrasound scan that patient has an arteriogram of the blood vessels in his neck.
(i) What does the red arrow indicate? (ii) What vessel in the neck does this relate to?

Answer 48

A.i) narrowing atherosclerosis
ii)internal no branches in the neck

Question 49

Q. Explain, with reference to your understanding of head and neck anatomy, how atherosclerotic disease within the internal carotid artery could have caused this man’s transient loss of vision

Answer 49

A. Internal carotid artery gives of the ophthalmic artery branch -> central retinal artery
Thromboembolism arising from ICA blocks Central retinal artery which is an end artery

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Question 50

Q. Arnold is rushed to the Emergency Department with a sudden onset of weakness and numbness affecting the left side of his face and left upper limb
Other than motor weakness and paraesthesia involving the left half of Arnold’s face and left arm there are no other neurological signs found. The doctor suspects a stroke.
(i) An area within which two lobes of Arnold’s
brain has been affected by the stroke, and on which side? Put you answer as
‘Right (OR) left ______ and _________ lobe’

Answer 50

A. Frontal, parietal

Question 51

Q. The precentral gyrus is split into three motor parts what are they? What is the clinical relevance?

Answer 51

Question 52

1. . Indicate on the image by shading or a large dot, which area of the brain has been affected by the stroke
2. What is the Cortical Homunculus? Where is it located and what is its function?

Answer 52

1. Face and arm area
2. Representation of the human body, based on a neurological “map” of the areas & proportions of the brain dedicated to processing motor functions, or sensory functions, for different parts of the body.

Question 53

How does the sensory one look?

Answer 53

Question 54

Q. At what part of the central nervous system do the motor fibres arising from the primary motor cortex cross to the opposite side (decussate)?

Answer 54

A. MEDULLA
(Medullary pyramids)
Decussation of pyramids

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Question 55

Q. Arnold is rushed for an urgent CT head. What is the structure labelled A?

Answer 55

A. Lateral ventricles
CSF
Black as it is fluid not dense waves pass through

Question 56

Why does the structure labelled ‘A’ and other areas seen in the CT scan appear almost black in colour?

Answer 56

Question 57

The external features of the cerebellum, understanding its principle functions in relation to motor co-ordination and balance LO

1. • The cerebellum is located at the back of the brain, inferior to what lobes?
     - How is it separated from these lobes?
2. It lies at the same level of & posterior to the which structure and how is it seperated from this structure?

Answer 57

1. • Occipital and temporal lobes, and within the posterior cranial fossa
     - Tentorium cerebelli, a tough layer of dura mater.
2. pons, from which it is separated by the fourth ventricle.

Question 58

Answer 58

Question 59

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Question 60

Answer 60

Question 61

Answer 61

Question 62

Answer 62

Question 63

1. What is the function of the vermis?
2. What is the function of the cerebellar peduncles?

Answer 63

1. To connect the two hemispheres together
2. Connect the cerebellum to the brain stem. There are six cerebellar peduncles in total, three on each side:

• Superior cerebellar peduncle is a paired structure of white matter that connects the cerebellum to the midbrain.
• Middle cerebellar peduncles connect the cerebellum to the pons and are composed entirely of centripetal fibers.
• Inferior cerebellar peduncle is a thick rope-like strand that occupies the upper part of the posterior district of the medulla oblongata.

Question 64

Q. The cerebellum consists of two hemispheres which are connected by the vermis, a narrow midline area. Like other structures in the central nervous system, the cerebellum consists of grey matter and white matter: where are these two forms of matter located?

Answer 64

A. Grey matter – located on the surface of the cerebellum. It is tightly folded, forming the cerebellar cortex.
White matter – located underneath the cerebellar cortex. Embedded in the white matter are the four cerebellar nuclei (the dentate, emboliform, globose, and fastigi nuclei).

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Question 65

Q. The diagram below shows how the cerebelllum can be dived into three lobes. Name the lobes by labelling the diagram.

Answer 65

Question 66

Q. The cerebellum can also be divided by function. There are three functional areas of the cerebellum – the cerebrocerebellum, the spinocerebellum and the vestibulocerebellum. State the function of each these areas (tbh you can just state the functions of the cerebellum)

Answer 66

A. Cerebrocerebellum – formed by the lateral hemispheres planning movements and motor learning. It receives inputs from the cerebral cortex and pontine nuclei, and sends outputs to the thalamus and red nucleus. This area also regulates coordination of muscle activation and is important in visually guided movements.

Spinocerebellum – comprised of the vermis and intermediate zone of the cerebellar hemispheres. It is involved in regulating body movements by allowing for error correction. It also receives proprioceptive information.

Vestibulocerebellum – the functional equivalent to the flocculonodular lobe. It is involved in controlling balance and ocular reflexes, mainly fixation on a target. It receives inputs from the vestibular system, and sends outputs back to the vestibular nuclei.

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Question 67

Understand how pathology affecting the functional areas of the brain (e.g. primary motor and sensory cortex) and cerebellum may manifest clinically. LO

Q. Dysfunction of the cerebellum can produce a wide range of symptoms and signs. The aetiology of cerebellar dysfunction is varied, with a number of possible causes. The most common are:?

Answer 67

A. stroke, physical trauma, tumours and ageing.

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Question 68

Q. The clinical picture is dependent on the functional area of the cerebellum that is affected. Damage to the cerebrocerebellum and spinocerebellum presents with problems in carrying out skilled and planned movements and in motor learning. A wide variety of manifestations are possible:

Answer 68

A. ataxia
dysarthria and scanning speech
dysmetria (past-pointing)/intention tremor
hypotonia (decreased muscle tone)
dysdiadochokinesia (difficulty in carrying our rapid, alternating movements)
inability to learn new movements
coarse nystagmus (rapid involuntary movements of the eyes)

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Question 69

Q. Damage to the vestibulocerebellum can manifest with ?

Answer 69

A. loss of balance, abnormal gait with a wide stance.

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Question 70

Q. The human cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity.
Cerebellar damage produces ?

Answer 70

disorders in fine movement, equilibrium, posture, and motor learning in humans

Question 71

Q. A 45 year old woman is referred to a neurology outpatient clinic by her GP. Subsequent investigations reveals an intracranial tumour. Her MRI image is shown on the next slide.
Within what part of the central nervous system is this tumour?

Answer 71

A. Cerebellum on the right
If higher occipital lobe

Question 72

1. In which ‘fossa’ is it located?
2. What clinical signs could the woman have potentially presented with and on which side of the body would these have been evident?

Answer 72

1. Posterior cranial fossa ((as is the occipital lobe but we are more inferior )
   Because look at the nasal septum we can see it in the CT scan so must be inferior
2. Difficult to fine tune the motor action
   IT IS IPSILATERAL so signs on the RIGHT SIDE

Question 73

Q. Damage to the cerebellum results in?

Answer 73

A. Intention tremor suggestive of cerebellum problem left arm thus left hemisphere (tour left)

Pen lid onto a pen fine tune certain motor movements (top right)

Broad base, unsteady gait feet are out wide
Ataxic gait can get ataxia in legs or arms depends on which part of the cerebellum affected (bottom left)

Fine repetitive movement
Disjointed and uncoordinated
Dysdiadochokinesis (bottom right)

reach with the tip of the finger for a target at arm’s length: A healthy person will move the fingertip in a rapid straight trajectory, whereas a person with cerebellar damage will reach slowly and erratically, with many mid-course corrections

Damage to the flocculonodular lobe may show up as a loss of equilibrium and in particular an altered, irregular walking gait, with a wide stance caused by difficulty in balancing.[10] Damage to the lateral zone typically causes problems in skilled voluntary and planned movements which can cause errors in the force, direction, speed and amplitude of movements. Other manifestations include hypotonia (decreased muscle tone), dysarthria (problems with speech articulation), dysmetria (problems judging distances or ranges of movement), dysdiadochokinesia (inability to perform rapid alternating movements such as walking), impaired check reflex or rebound

Question 74

Q. Thus examination involves?

Answer 74

A. neurological examination includes assessment of gait (a broad-based gait being indicative of ataxia), finger-pointing tests and assessment of posture.[3] If cerebellar dysfunction is indicated, a magnetic resonance imaging scan can be used to obtain a detailed picture of any structural alterations that may exist

Relate the topographical anatomy of the brain, brainstem and cerebellum to its appearance in cross sectional imaging i.e. CT and MRI LO

Question 75

On the CT scan label all of the structures stated in the table. Also any of the bony features that you can identify: this may be easier in the bone window image (the bone window is where the image is enhanced to make bone structures more easily identifiable)

Answer 75

Question 76

Answer 76

Question 77

Q. On the MRI images also indicate the:
• Scalp and the bone of the skull
• Location of the falx cerebri and tentorium cerebelli (both views)
o Note the relationship between the edge of the tentorium cerebelli and the uncus of the temporal lobe (on the coronal view).
• Location of dural venous sinuses- superior sagittal, straight sinus (saggital view)
• Spinal cord: and where this begins
• C1 and C2 vertebrae (sagittal view)

Answer 77

Question 78

Answer 78

Question 79

Answer 79

Question 80

Question 81

Answer 81

Question 82

State what all of these fossa accommodate

Answer 82

A. + Anterior cranial fossa - accommodates the anterior part of the frontal lobes
+ Middle cranial fossae - accommodate the temporal lobes
+ Posterior cranial fossa - accommodates the cerebellum and brain stem
+ Pituitary fossa (PF) - accommodates the pituitary gland

Question 83

Identified the gross topographical features (on external and mid sagittal views) & general organisation of the CNS in relation to the cerebrum (gyri, sulci and lobes), diencephalon, brainstem (midbrain, medulla, pons) and cerebellum, including:

The principal external features of the cortex and the primary functional sites for motor, sensory, language, hearing, olfaction and vision.
• The external features of the cerebellum
• The external features of the brainstem LO

Answer 83

Question 84

Answer 84

Question 85

Answer 85

Question 86

Q. 1. Within which of the three cranial fossae are the following parts of the brain, brainstem and cerebellum found?
- Frontal lobe
- Temporal lobe
- Occipital lobe
- Brainstem (midbrain, medulla and pons)
- Cerebellum
2. What name is given to the area of the cortex responsible for motor control of one half of the body, within which lobe is this found?
3. What name is given to the area of the cortex responsible for general sensory perception of one half of the body, within which lobe is this found?
4. A patient is diagnosed with a stroke that involves an area of the cortex in the region labelled no 6 & 7 on the plastic models
Which lobe(s) of the cortex are involved?
What functions does the part of the cortex number 6 and 7 serve?

Answer 86

A.1. - Frontal lobe – anterior
- Temporal lobe - middle
- Occipital lobe – posterior
- Brainstem (midbrain, medulla and pons) – posterior
- Cerebellum - posterior
2. Frontal lobe -> primary motor cortex
Anteirior cranial fossa
3. Parietal lobe -> primary sensory cortex
Middle cranial fossa??
4. Frontal and parietal
Frontal -> motor
Parietal -> sensory

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Question 87

Q. What will be the specific neurological consequences from involvement of this part of the brain?

Answer 87

A. Difficulty speaking
Swallowing
Intricate movements of hands

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Question 88

What is a complication of an increase in ICP

Answer 88

Cerebellar tonsil can herniate and compress the medulla

Question 89

1. What structures form the medullary pyramid? Which region of the brainstem is this found?
2. If a patient had a lesion within the structures forming the part labelled 39 what neurological consequences would become apparent and on which side of the body?

Answer 89

1. 39 -> medullary pyramids,location of descending motory fibres
2. The two pyramids contain the motor fibers that pass from the brain to the medulla oblongata and spinal cord. These are the corticobulbar and corticospinal fibers that make up the pyramidal tracts.

About 90% of these fibers leave the pyramids in successive bundles and decussate (cross over) in the anterior median fissure of the medulla oblongata as the pyramidal decussation or motor decussation. Having crossed over at the middle line, they pass down in the posterior part of the lateral funiculus as the lateral corticospinal tract. The other 10% of the fibers stay uncrossed in the anterior corticospinal tract. The pyramidal decussation marks the border between the spinal cord and the medulla oblongata

Left side of medullary pyramid affected
Right side of the body affected more than the left

Question 90

Q. What dense connective tissue structure (within the real skull and brain) is
found
(i) running the length of the (medial) sagittal fissure?
(ii) running between the inferior part of the occipital lobes and the cerebellum?

Answer 90

A. (i) falx cerbri
(ii) tentorium cerebelli

Question 91

Q. 1. What is epilepsy?

2. Signs and symptoms?
3. Treatment?

Answer 91

A. 1. Neurological condition where there is a tendency towards spontaneous firing of neurons (activation of action potentials) within a specific region of the cortex.
2. Both hemispheres: person loses consciousness before involuntary jerking involving all four limbs begins (a type of epilepsy known as generalised tonic-clonic epilepsy)
3. Most: oral medication
Severe epilepsy: surgical intervention may be required. One type of surgery involves severing the corpus callosum (corpus callostomy)

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Question 92

1. What benefit, would severing the corpus callosum have?
2. What affect would severing the corpus collosum have on the conscious control of muscles (motor control) on each side of the body?

Answer 92

1. Stops the epilepsy spreading from one hemisphere to the other. Does not stop seizures just less severe split brain surgery.
2. Stops the epilepsy spreading from one hemisphere to the other. Does not stop seizures just less severe split brain surgery

Question 93

Q. A 79 year old lady is brought to the Emergency Department with a suspected stroke. Examination of the patient confirms presence of abnormal neurological signs. An urgent non-contrast CT head is ordered, this is shown.

On the CT image:

(i) Label and shade the right and left cerebral hemispheres.
(ii) Label a sulcus and gyrus (any), and the frontal, temporal and occipital bones
(iii) Draw on the image where the three meningeal layers would lie, using a different coloured line for each (you will need to zoom in on the image). Note which of the layers runs into the sulci, covering every fold of the cortex.

Question 94

1. (iv) What is the structure labelled A and why does it appear darker than the surrounding brain tissue?
2. Between which layers of the meninges would cerebrospinal fluid (CSF) be found?
3. Where else, visible on this CT image would CSF be found?
4. Why might a lesion within the brainstem present with more catastrophic dysfunction of motor control (in addition to other neurological sequelae), vs a lesion of the same size that had involved part of the primary motor cortex?

Answer 94

1. Csf = fluid on a CT not dense less absorption
2. Arachnoid and pia
3. On diagram
4. Both sensory and motor pass through brainstem??

Question 95

1. Why might a lesion within the brainstem present with more catastrophic dysfunction of motor control (in addition to other neurological sequelae), vs a lesion of the same size that had involved part of the primary motor cortex?
2. A 40 year old woman is referred to a neurology outpatient clinic by her GP. Subsequent investigations reveals an intracranial tumour. Her MRI image is shown below.

(Image)
Within what structure of the central nervous system is this tumour and in which cranial fossa is it located? Relating this axial image to the plastic models will help you answer this question (clue: note that the plane of section involves the orbit and eyes)

3. What clinical signs could the woman have potentially presented with and on which side of the body would these have been evident?

Answer 95

1. Both sensory and motor pass through brainstem??
2. Hindbrain -> cerebellum
3. Right ipsilateral ataxia, cerebellum tremor, difficulty with rapid alternative movement, abnormal gait wide stance, fine motor control problems