Brain Stem: Medulla Oblongata

Question 1

Brain stem

Answer 1

Formed of: below upwards
1. Medulla oblongata
2. Pons
3. Midbrain
Above is directly continuous with diencephalon
Below is directly continuous with spinal cord

Question 2

Medulla oblongata

Answer 2

Lower most part of brain stem

Question 3

Medulla oblongata size and extent

Answer 3

3 cm long
Continuous above above with pons lower border and below with spinal cord

Question 4

Parts

Answer 4

1. Lower 1/2 (closed medulla): transversed by central canal
2. Upper 1/2 (open medulla): forms lower 1/2 of floor 4th ventricle

Question 5

External features (surfaces)

Answer 5

1. Ventro-lateral surface
2. Dorsal surface

Question 6

Ventrolateral surface contents from medial to lateral

Answer 6

1. Anterior median fissure
2. Pyramid
3. Olive
4. Inferior cerebellar peduncle (ICP)

Question 7

Anterior median fissure

Answer 7

Continuous with that of spinal cord

Question 8

Pyramid

Answer 8

Elongated elevation produced by corticospinal fibers of pyramidal tract

Question 9

Olive

Answer 9

Oval elevation produced by inferior olivary nucleus. It is separated from pyramid by anterolateral sulcus for exit of hypoglossal (12th cranial) nerve

Question 10

ICP

Answer 10

Bundle of nerve fibers connecting medulla with cerebellum. It is separated from olive by posterolateral sulcus for exit of:
1. Glossopharyngeal: 9th cranial
2. Vagus: 10th cranial
3. Cranial root of accessory nerve: 11th cranial

Question 11

Dorsal surface

Answer 11

1. Closed medulla
2. Open medulla

Question 12

Closed medulla contents from median to lateral

Answer 12

1. Posterior median sulcus
2. Gracile tract and tubercle
3. Cuneate tract and tubercle
4. Tuberculum cinereum
5. Inferior cerebellar peduncle

Question 13

Posterior median sulcus

Answer 13

Continuous with that of spinal cord

Question 14

Posterior median sulcus

Answer 14

Continuous with that of spinal cord

Question 15

Gracile tract and tubercle

Answer 15

1. Overlies gracile nucleus
2. On each side of sulcus

Question 16

Cuneate tract and tubercle

Answer 16

Overlies Cuneate nucleus

Question 17

Tuberculum cinereum

Answer 17

Overlies spinal nucleus of Trigeminal

Question 18

ICP dorsal surface

Answer 18

On either side as 2 bundles extending upwards and lateral along 4th ventricle sides till they reach lower border of pons back where they bend sharply entering cerebellum

Question 19

Open medulla site

Answer 19

Forms lower 1/2 of 4th ventricle foor. Separated from pons back by bundle of fibers (medullary stria) and bounded lateral by ICP

Question 20

Open medulla relations

Answer 20

Transversed by vertical median sulcus, lateral to it inverted v shaped depression called inferior fovea.

Question 21

Open medulla contents

Answer 21

On each side, inferior fovea divides the medullary part into 3 triangular area from medial to lateral:
1. Hypoglossal trigone
2. Vagal trigone
3. Lower vestibular area

Question 22

Hypoglossal trigone

Answer 22

Overlies hypoglossal nerve nucleus

Question 23

Vagal trigone

Answer 23

Overlies vagus nerve dorsal nucleus

Question 24

Lower vestibular area

Answer 24

Overlies inferior and medial vestibular nuclei

Question 25

Area posterma

Answer 25

Vomiting center
Protuberance at 4th ventricle inferoposterior limit

Question 26

Atrial supply

Answer 26

Branches of vertebral artery:
Anterolateral surface
1. Anterior spinal artery
2. 4th part of vertebral artery
Posterolateral surface
3. Posterior inferior cerebellar artery
Gracile and Cuneate tracts
Posterior spinal artery