Forebrain and Ventricles

Question 1

General functions of brainstem

Answer 1

Conduit - allows ascending and descending pathways to reach thalamus and cerebellum from spinal cord (relay nuclei)
Integrative - control of CVS, respiratory and consciousness (reticular formation), plus complex motor patterns such as balance
Cranial nerves - sight, hearing, equilibrium, gustation, reflex centres

Question 2

Three sections of the brainstem

Answer 2

Midbrain, pons, medulla oblongata

Question 3

Rostral to brainstem

Answer 3

Continuous with the diencephalon

Question 4

Caudal to brainstem

Answer 4

Continous with spinal cord at level of foramen magnum

Question 5

Vental to brainstem

Answer 5

Clivus of occipital bone

Question 6

Dorsal to brainstem

Answer 6

Cerebellum

Question 7

Number of cranial nerves from brainstem

Answer 7

10 out of 12

Question 8

Ventricular origins

Answer 8

Midbrain from aqueduct
Pons (and cerebellum) from mesencephalon of fourth
Medulla from myelencephalon of fourth

Question 9

Three areas always identified in cross section

Answer 9

Tectum (roof) - posterior, mainly in midbrain
Tegmentum - middle, crain nerve nuclei and tracts, reticular formation and some ascending/descending pathways
Basal - most anterior, descending fibres from cerebral cortex

Question 10

Ventral view of medulla

Answer 10

Anterior median fissure in the centre
Lateral to the anterior median tissue are the pyramids, behind which are descending motor fibres (down the pyramidal tract)
At the base of the anterior median fissure is the decussation of pyramids where descending motor fibres cross over to the other side of the body
Lateral to the pyramids is the olives
Lateral to the olives is the anterolateral sulcus
CN XII (hypoglossal nerve) emerges between the pyramids and olives
CN IX and X are found lateral to the olives in the anterolateral sulcus
CN XI is found below CN X as CN IX, X and XI all exit through the jugular foramen, whereas CN XII leaves through the foramen magnum with the spinal cord

Question 11

Dorsal view of medulla

Answer 11

Most medially is the posterior median fissure
Lateral to the posterior median fissure is the fasciculus gracilis - sensory information from lower limb (remember gracilis muscle)
Lateral to fasciculus gracilis is fasciculus cuneatus, carrying sensory information from the upper limbs
At the ventral end of the FG is the gracile tubercle, and ventral end of the FC is the cuneate tubercle. Tubercles contain cell bodies.
Opening at the ventral end of the posterior median fissure is the obex

Question 12

Caudal vs rostral medulla

Answer 12

Caudal = closed medulla, central canal, more circular
Rostral medulla = open medulla, butterfly shaped and opening into fourth ventricle. Rostral also begins the ICP (inferior cerebellar peduncle) which is the connection between medulla and cerebellum

Question 13

Junctions around the pons

Answer 13

Ventrally: Pontomesencephalic junction
Caudally: Pontomedullary junction

Question 14

Function of the pons

Answer 14

Bridge between two cerebellar hemisphere

Question 15

Basilar groove

Answer 15

Basilic artery runs down it

Down the centre line of the ventral surface

Question 16

Cranial nerves from the pons

Answer 16

Most medial: VI
More lateral: VII
Most lateral: VIII
VII and VIII emerge in the cerebellopontine angle
VII is found deeper into caudal pons behind CN VI, so damage to CN VI can have the side effect of damage to CN VII

Question 17

Divisions of the pons

Answer 17

SCP = superior cerebellar peduncle
MCP (more lateral) = middle cerebellar peduncle
ICP = inferior cerebellar peduncle

Question 18

Notable features in imagine of pons

Answer 18

Horizontal fibres - connection two halves of cerebellum

Dorsal side of caudal pons opens into 4th ventricle

Question 19

Midbrain location

Answer 19

Just above pontomesencephalic junction

Below the mammillary bodies of the hypothalamus

Question 20

Cerebral peduncles

Answer 20

Connects the midbrain to the cerebrum
Contain descending motor fibres
Curve around either side of the mammillary bodies
Also known as crus cerebri
Between the peduncles is the intrapedunclar fossa where CN III emerges

Question 21

Emergence of CN IV

Answer 21

Emerges from dorsal side, then loops around just ventral to the line of the pontomesencephalic junction
Only cranial nerve emerging from the dorsal side of the brainstem

Question 22

Dorsal view of midbrain

Answer 22

Bumps are superior and inferior colliculi
Superior deals with visual information
Inferior deals with auditory information
Colliculi form the tectum of the midbrain

Question 23

Reticulum

Answer 23

Complex, multisynaptic network of neurons in the tegmenjtum
Descending motor pathway via the reticular nuclei
Vital autonomic centres
Ascending Reticular Activating System (coma association)
Pain modulation
Sleep-wake cycle
Arousal

Question 24

Blood supply to brainstem

Answer 24

A lot

Includes SCA, PCA, AICA and PICA

Question 25

Gross anatomy of cerebellum - superior/dorsal surface

Answer 25

Anterior and posterior lobules divided by primary fissure
Split into two hemispheres
Bump on posterior side is called the vermis

Question 26

Gross anatomy of cerebellum - inferior/ventral surface

Answer 26

Similar, with tonsils near the midline and flocculonodular lobe