Topography of the Brain

Question 1

Where does neural tube develop from?

Answer 1

Dorsal surface ectoderm

Question 2

What do the cranial end of tube form?

Answer 2

Vesicles which develop into different parts of the brain

Question 3

What are the parts of brain in foetal development?

Answer 3

Forebrain, Midbrain and Hindbrain
Forebrain - diencephalon and cerebral hemispheres
Hindbrain - pons and medulla

Question 4

What is included in the brainstem?

Answer 4

Midbrain, pons, medulla
Cranial nerves III - XII, tracts of spinal cords and vital centres (resp.)

Question 5

What is the functions of the brainstem?

Answer 5

Pathway for fibre tracts running between higher and lower centres
10 of 12 CN so innervation of head and neck
Produce rigidly programmed automatic behaviours essential for survival

Question 6

Describe the medulla oblongata

Answer 6

Cavity is the 4th ventricle
Continues as spinal cord at foramen magnum of cranium
Lower part of medulla looks like spinal cord in structure

Question 7

What are some surface features of the medulla?

Answer 7

Pyramids and their decussation (crossing over)
Olives laterally
Connected to cerebellum by inferior cerebellar peduncle
Cranial nerves IX, X, XI, XII from surface

Question 8

Describe the caudal and cranial end of the medulla

Answer 8

Caudal - closed around IV ventricle
Cranial - opens with IV ventricle posteriorly

Question 9

Describe the pons

Answer 9

IV ventricle is posterior to it
Has middle cerebellar peduncle
Has cranial nerves V, VI, VII and VIII from its surface

Question 10

Describe the midbrain

Answer 10

Develops from mesencephalon
Central cavity - cerebral aqueduct

Question 11

What are the surface features of the midbrain?

Answer 11

Superior cerebral peduncle
Corpora Quadrigemina (superior and inferior colliculi)
Origin of oculomotor and trochlear nerve

Question 12

What is the only nerve to originate posteriorly?

Answer 12

IV - trochlear nerve

Question 13

What are the right and left hemispheres separated by?

Answer 13

Vermis

Question 14

Describe the cerebellum

Answer 14

Has anterior, posterior and flocculonodular lobe
Surface has sulci and folia
Three cerebellar peduncles connect it to brainstem

Question 15

What is included in the white and grey matter of the cerebellum?

Answer 15

Grey - cortex on surface and deep nucleii
White - arbor vitae and cerebellar peduncles

Question 16

What is the clinical significance of the cerebellum tonsil?

Answer 16

Is beside posterior lobe and if swelling then can get hernia of lobe as sitting above the foramen magnum

Question 17

What are the functions of the cerebellum?

Answer 17

Posture maintenance
Fine tuning of motor activity

Question 18

Describe how the cerebellum functions

Answer 18

Information from pyramidal tracts (motor), ipsilateral proprioceptors from periphery and info from vestibular nucleii for balance and posture
Cerebellum calculates the best way to coordinate action
Which sends blueprint back to cerebral cortex via superior cerebral peduncle

Question 19

What is abnormality of the cerebellum function?

Answer 19

Ataxia
Can do finer nose test, knee heel test and walking in straight line to check

Question 19

Describe the diencephalon

Answer 19

Deep within cerebral hemispheres, around the 3rd ventricle
Develops from diencephalic vesicle
Paired structure - thalamus and hypothalamus. All mainly grey matter

Question 20

What is the function of the thalamus?

Answer 20

For triage for sensory overload
All synapse at the thalamus

Question 21

Describe the thalamus

Answer 21

Mainly contains group of nuclei - anterior, medial and lateral group
Lateral group involved in processing sensory information
It is a sensory relay station

Question 22

Describe the hypothalamus

Answer 22

Lies below the thalamus separated from it by hypothalamic sulcus
Small in size
Is main visceral control centre and essential for homeostasis

Question 23

What is the homeostatic role of the hypothalamus?

Answer 23

Autonomic control centre, body temperature regulation, regulation of food intake, water and thirst balance, sleep wake cycle, and control of endocrine system functioning

Question 24

Describe the blood supply of the brain

Answer 24

2 ICA enter the skull through the carotid canal (foramen lacerum) to supply the brain 2 vertebral arteries (branches of subclavian arteries) enter through skull at foramen magnum and form the basilar artery

Question 25

Describe the Circle of Willis

Answer 25

Branches of the ICA join with those of opposite side and with PCA to form the continuous circle at the base of brain Protective feature against vaso-occlusion of large vessels

Question 26

What arteries are in the Circle of Willis?

Answer 26

Anterior cerebral artery Anterior communicating artery ICA Posterior communicating artery Posterior cerebral artery Basilar artery

Question 27

Where is the middle cerebral?

Answer 27

Medial aspect of cerebral hemispheres excluding occipital lobe

Question 28

Where is middle cerebral?

Answer 28

Lateral aspect of cerebral hemispheres

Question 29

Where is posterior cerebral?

Answer 29

Inferior aspect of cerebral hemispheres and occipital lobe

Question 30

Describe the venous drainage of the brain

Answer 30

Superficial and deep veins of the brain drain into venous sinuses which lie between 2 layers of dura mater Sinuses join together to ultimately drain into IJV

Question 31

What are some of the sinuses draining the brain?

Answer 31

Transverse, superior sagittal, inferior sagittal, petrosal sinus, cavernous sinus

Question 32

Describe the contents of the cavernous sinus

Answer 32

Oculomotor nerve, trochlear nerve, ophthalmic nerve, maxillary nerve, abducent nerve, ICA, sinus surrounded by dura mater