Topography of the brain

Question 1

Which structures comprise the brainstem?

Answer 1

Midbrain, pons and medulla.

Question 2

Where is the diencephalon in relation to the brainstem?

Answer 2

Diencephalon lies above the midbrain and is not part of the brainstem.

Question 3

Which CN’s emerge from the brainstem?

Answer 3

All except 1 and 2. CNIV comes from the posterior aspect, CNIII and 5-12 come from the anterior aspect. These innervate the head and neck.

Question 4

What are the main functions of the brainstem?

Answer 4

• Pathway for fibre tracts running between higher and lower centres
• Brainstem centres produce the rigidly programmed automated behaviours that are essential for survival

Question 5

Which cavity is posterior to the medulla oblongata and pons?

Answer 5

The cavity of the 4th ventricle. In life this is closed off as the cerebellum sits behind it.

Question 6

Which structure continues from the lower part of the medulla?

Answer 6

Medulla continues as the spinal cord after the foramen magnum.

Question 7

Name the structure that connects the medulla to the cerebellum.

Answer 7

Inferior cerebellar peduncle.

Question 8

Which CN’s emerge from the surface of the medulla?

Answer 8

CNIX, CNX, CNXI and CNXII.

Question 9

What are the pyramidal tracts?

Answer 9

These are ventral (motor) tracts that decussate (cross over) at the level of the medulla.

Question 10

Which nuclei are present in the grey matter of the medulla?

Answer 10

• CN nuclei
• Olivary nuclei
• Nuclei of the reticular formation
• Sensory nuclei (gracile and cuneate which are for fine touch and proprioception)

Question 11

Which CN’s emerge from the surface of the pons?

Answer 11

CNV, CNVI, CNVII and CNVIII.

Question 12

Which structure connects the pons to the cerebellum?

Answer 12

Middle cerebellar peduncle.

Question 13

What type of fibres run in the medial lemniscus?

Answer 13

Sensory fibres - cuneate and gracile

Question 14

What are the pontine nuclei?

Answer 14

Nuclei in the pons involved in motor activity. Important in learning motor skills.

Question 15

Which embryological structure does the midbrain develop from?

Answer 15

Mesencephalon

Question 16

What forms the central cavity of the midbrain?

Answer 16

Cerebral aqueduct

Question 17

Which peduncles emerge from the midbrain?

Answer 17

Superior cerebellar peduncle posteriorly and cerebral peduncle anteriorly.

Question 18

Which CN’s emerge from the midbrain?

Answer 18

CNIII and CNIV (only one to emerge posteriorly).

Question 19

What are the corpora quadrigemina?

Answer 19

The 2 superior and 2 inferior colliculi located on the dorsal aspect of the midbrain. These are reflex centres involved in vision and hearing.

Question 20

Which subcortical centres for the extrapyramidal motor system are located in the midbrain?

Answer 20

• Red nucleus

- Substantia nigra

Question 21

What does the inferior olivary nucleus control?

Answer 21

Motor control

Question 22

What is the function of the nuclei in the reticular formation?

Answer 22

Maintaining behavioural arousal and consciousness.

Question 23

Where does motor and sensory information cross?

Answer 23

• Motor: in the medulla at the pyramids

- Sensory: lower down in the spinal cord

Question 24

Which structure separates the R and L hemispheres of the cerebellum?

Answer 24

Vermis

Question 25

What are the names of the lobes in each hemisphere of the cerebellum?

Answer 25

Anterior, posterior and flocculonodular lobes.

Question 26

What are the grooves of the cerebellum called?

Answer 26

Sulci are the depressions and folia are the elevations.

Question 27

Describe the white matter of the cerebeuulum.

Answer 27

- Arbor vitae: tree-like inside of the cerebellum | - Cerebellar peduncles: connect cerebellum to the rest off the brain

Question 28

What are the functions of the cerebellum?

Answer 28

1) Posture maintenance 2) Fine tuning motor activity Cerebellum takes information from: pyramidal tracts (motor), ipsilateral proprioceptors and vestibular nuclei (balance and posture) --> calculates the best ways to coordinate these inputs and sends this information to the cerebrum via the superior cerebellar peduncle. In the cerebellum, R half controls R side and L half controls L side (opposite to cerebrum).

Question 29

What is ataxia?

Answer 29

A disorder affecting co-ordination, balance and speech - usually caused by damage to the cerebellum.

Question 30

What can be done to test for ataxia?

Answer 30

1) Finger-nose test 2) Heel-knee test 3) Walking in a straight line

Question 31

Which substance affects the cerebellum?

Answer 31

Alcohol

Question 32

Which structures form the diencephalon?

Answer 32

- Thalamus (80%) - Hypothalamus and pituitary stalk - Epithalamus (pineal gland) --> All are mainly grey matter

Question 33

Where is the diencephalon?

Answer 33

Deep within the cerebral hemispheres, around the 3rd ventricle.

Question 34

What is the function of the thalamus?

Answer 34

A sensory relay station containing anterior, medial and lateral (LGB for visual pathway is here) groups of nuclei.

Question 35

Name the structure that separates the thalamus from the hypothalamus?

Answer 35

Hypothalamic sulcus.

Question 36

What is the function of the hypothalamus?

Answer 36

Main visceral control centre and essential for overall homeostasis.

Question 37

Which arteries supply the brain?

Answer 37

- 2 x ICA enter via the foramen lacerum - 2 x vertebral arteries enter via the foramen magnum These enter the circle of Willis which supplies the cerebrum.

Question 38

Which arteries supply the brainstem and cerebellum?

Answer 38

Vertebral arteries join together to form the basilar artery. Vertebro-basillar system supplies the brainstem and cerebellum.

Question 39

Which level does the basilar artery divide?

Answer 39

The basilar artery ends at the midbrain where it splits into the 2 x PCA's.

Question 40

What does the CoW protect against?

Answer 40

Protective feature against vaso-occlusion of large arteries, but the branches supplying the cerebral hemispheres are effectively end arteries.

Question 41

Which part of the cerebrum does the ACA supply?

Answer 41

Medial aspect of the cerebral hemispheres, excluding the occipital lobe.

Question 42

Which part of the cerebrum does the MCA supply?

Answer 42

Lateral aspect of the cerebral hemispheres.

Question 43

Which part of the cerebrum does the PCA supply?

Answer 43

Inferior aspect of the cerebral hemispheres and occipital lobe.

Question 44

Where do the venous sinuses of the brain lie?

Answer 44

Between 2 layers of dura matter.

Question 45

Which veins do the dural venous sinuses ultimately drain to?

Answer 45

IJV's