Brainstem: Pons

Question 1

Definition and size

Answer 1

Middle part of brain stem
1 inch long
Lying between medulla and midbrain

Question 2

Parts

Answer 2

2 parts
1. Ventral: (basis pontis)
2. Dorsal (tegmentum)

Question 3

External features (surfaces)

Answer 3

1. Ventrellar (basilar) surface
2. Dorsal (tegmental) surface

Question 4

Ventral surface contents

Answer 4

1. Basilar groove
2. Transverse pontine fibers
3. Exit of middle 4 cranial nerves

Question 5

Basilar groove

Answer 5

Median shallow groove lodging basilar artery

Question 6

Transverse pontine fibers

Answer 6

Thick ridges which collect on each side forming middle cerebellar peduncle (MCP) which connects pons to cerebellum

Question 7

Exit of middle 4 cranial nerves

Answer 7

1. Trigeminal (5th cranial) nerve
2. Abducent (6th cranial) nerve
3. Facial (7th cranial) nerve
4. Vesticulocochlear (8th cranial) nerve

Question 8

Trigeminal (5th cranial) nerve

Answer 8

Emerges by large lateral sensory and small medial motor roots from lateral part of front pons close to its upper border

Question 9

Abducent nerve

Answer 9

Emerges from sulcus between pyramid and pons

Question 10

Facial and vesitebulocochlear nerve

Answer 10

Emerge from cerebellopontine angle

Question 11

Dorsal surface

Answer 11

Forms upper 1/2 of 4th ventricle floor separated from back of open medulla by medullary stria and bounded lateral by SCP

Question 12

Dorsal surface contents

Answer 12

1. Medial eminence and facial colliculus
2. Sulcus limitans
3. Upper vestibular area

Question 13

Medial eminence and facial colliculus

Answer 13

At medial eminence lower end produced by abducent nucleus and encircling facial nerve fibers

Question 14

Sulcus limitans

Answer 14

Lateral to medial eminence, its lower part lies lateral to facial colliculus and is called superior fovea

Question 15

Upper vestibular area

Answer 15

Overlies superior and lateral vestibular nuclei

Question 16

Arterial supply

Answer 16

1. Anterior part (basis pontis)
2. Posterior part (tegmentum)

Question 17

Basis pontine

Answer 17

Pontine branches of basilar artery

Question 18

Tegmentum

Answer 18

1. Lower pons: posterior inferior cerebellar artery (vertebral artery)
2. Upper pons: superior cerebellar artery (basilar artery)