Medulla oblongata

Question 1

What is the medulla oblongata?

Answer 1

The lowest part of the brainstem, continuous with the spinal cord.

Question 2

Where does the medulla extend from and to?

Answer 2

From the lower border of the pons to just above the first cervical nerve.

Question 3

Where is the medulla located?

Answer 3

In the anterior part of the posterior cranial fossa.

Question 4

What structure does the medulla extend down to?

Answer 4

The foramen magnum.

Question 5

What lies anterior to the medulla?

Answer 5

The clivus and meninges.

Question 6

What lies posterior to the medulla?

Answer 6

The vallecula of the cerebellum.

Question 7

What part of the brain does the medulla belong to?

Answer 7

The hindbrain.

Question 8

What space does the medulla occupy?

Answer 8

The infratentorial space.

Question 9

What are the two parts of the medulla?

Answer 9

Open (superior) part and closed (inferior) part.

Question 10

What forms the dorsal surface of the open part of the medulla?

Answer 10

The fourth ventricle.

Question 11

What happens to the fourth ventricle at the closed part of the medulla?

Answer 11

It narrows at the obex and continues as the central canal.

Question 12

What divides the medulla into right and left halves?

Answer 12

The anterior and posterior median fissures.

Question 13

What is the anterior median fissure?

Answer 13

A groove that divides the medulla in the midline.

Question 14

Where does the anterior median fissure end?

Answer 14

At the foramen caecum at the junction with the pons.

Question 15

What further divides each half of the medulla?

Answer 15

The anterolateral and posterolateral sulci.

Question 16

What is the anterior region of the medulla called?

Answer 16

The pyramid.

Question 17

What fibres make up the pyramid?

Answer 17

Corticospinal and corticobulbar fibres.

Question 18

What happens to many fibres in the lower part of the pyramid?

Answer 18

They cross at the midline to form the pyramidal decussation.

Question 19

What are the anterior external arcuate fibres?

Answer 19

Transverse fibres at the upper part of the pyramid that end in the cerebellum.

Question 20

What is the olive?

Answer 20

An oval elevation in the lateral region of the upper medulla.

Question 21

What forms the olive?

Answer 21

The inferior olivary nucleus.

Question 22

What is the circumolivary bundle?

Answer 22

A bundle of fibres curving around the lower edge of the olive.

Question 23

Where do the rootlets of the hypoglossal nerve emerge?

Answer 23

The anterolateral sulcus between the pyramid and the olive.

Question 24

Which nerves emerge from the posterolateral fissure?

Answer 24

Cranial nerves IX, X, and the cranial part of XI.

Question 25

What lies between the posterolateral sulcus and posterior median fissure?

Answer 25

The posterior region of the medulla.

Question 26

What is the V-shaped depression in the upper posterior region of the medulla?

Answer 26

The lower part of the floor of the fourth ventricle.

Question 27

What are the three longitudinal elevations below the floor of the fourth ventricle?

Answer 27

Fasciculus gracilis, fasciculus cuneatus, and inferior cerebellar peduncle.

Question 28

What forms the gracile and cuneate tubercles?

Answer 28

The nucleus gracilis and nucleus cuneatus.

Question 29

What is lateral to the cuneate nucleus?

Answer 29

The accessory cuneate nucleus.

Question 30

What fibres relay in the accessory cuneate nucleus?

Answer 30

Unconscious proprioceptive fibres of the upper limb.

Question 31

What is the function of fasciculus gracilis and fasciculus cuneatus?

Answer 31

Convey discriminative touch, pressure, vibration, position, and movement sense.

Question 32

What does fasciculus gracilis contain?

Answer 32

Fibres from the lower limb and lower trunk.

Question 33

What does fasciculus cuneatus contain?

Answer 33

Fibres from the upper limb and upper trunk.

Question 34

What is the tubercinerium?

Answer 34

An elevation lateral to the fasciculus cuneatus.

Question 35

What forms the tubercinerium?

Answer 35

The spinal nucleus of the trigeminal nerve.

Question 36

What are the two parts of the medulla based on the central canal?

Answer 36

Closed (lower) part with a central canal and open (upper) part forming the fourth ventricle.

Question 37

What separates the anterior horn from the central grey matter at the pyramidal decussation?

Answer 37

Decussating pyramidal fibres.

Question 38

What is the lateral part of the spinal nucleus of the accessory nerve?

Answer 38

The separated anterior horn.

Question 39

Where is the supraspinal nucleus located?

Answer 39

Medially within the separated anterior horn.

Question 40

What is continuous with the central grey matter in the lower medulla?

Answer 40

Nucleus gracilis and nucleus cuneatus.

Question 41

What lies lateral to the central grey matter?

Answer 41

The nucleus of the spinal tract of the trigeminal nerve.

Question 42

What forms the spinal tract of the trigeminal nerve?

Answer 42

A bundle of fibres overlying its nucleus.

Question 43

What is the most important feature of the lower medulla?

Answer 43

The decussation of pyramidal tracts.

Question 44

Where do the decussating pyramidal fibres go?

Answer 44

To the lateral corticospinal tract.

Question 45

Where are fasciculus gracilis and fasciculus cuneatus located?

Answer 45

The posterior white column.

Question 46

What replaces Clarke�s column in the medulla?

Answer 46

The accessory cuneate nucleus.

Question 47

Where is the medial lemniscus formed?

Answer 47

By internal arcuate fibres crossing in the sensory decussation.

Question 48

What is the representation pattern of the medial lemniscus?

Answer 48

Head posteriorly and feet anteriorly.

Question 49

Where are the pyramidal tracts located?

Answer 49

Anteriorly.

Question 50

What lies posterior to the medial lemniscus?

Answer 50

The medial longitudinal bundle.

Question 51

What tracts lie in the anterolateral medulla?

Answer 51

Spinocerebellar, lateral spinothalamic, and other tracts.

Question 52

Which cranial nerve nuclei are in the floor of the fourth ventricle?

Answer 52

Hypoglossal, dorsal vagus, tractus solitarius, and vestibular nuclei.

Question 53

What does the nucleus ambiguus supply?

Answer 53

Motor fibres of IX, X, and XI cranial nerves.

Question 54

What do the dorsal and ventral cochlear nuclei receive?

Answer 54

Fibres of the cochlear nerve.

Question 55

Where is the inferior olivary nucleus located?

Answer 55

At the upper medulla.

Question 56

What does the inferior olivary nucleus contribute to?

Answer 56

The olive elevation.

Question 57

What is the function of olivocerebellar fibres?

Answer 57

Terminate in the cerebellum as climbing fibres.

Question 58

What are the visceral centres of the medulla?

Answer 58

Respiratory, cardiac, and vasomotor centres.

Question 59

What supplies the medial part of the medulla?

Answer 59

The anterior spinal artery.

Question 60

What supplies the posterolateral medulla?

Answer 60

The posterior inferior cerebellar artery.

Question 61

What causes medial medullary syndrome?

Answer 61

Blockage of the anterior spinal artery.

Question 62

What are the features of medial medullary syndrome?

Answer 62

Contralateral hemiplegia, loss of vibration sense, ipsilateral tongue paralysis.

Question 63

What causes lateral medullary syndrome?

Answer 63

Blockage of the posterior inferior cerebellar artery.

Question 64

What are features of lateral medullary syndrome?

Answer 64

Ipsilateral soft palate paralysis, facial pain/temp loss, contralateral body pain/temp loss, ataxia, Horner�s syndrome.

Question 65

Why is injury to the lower medulla fatal?

Answer 65

It affects vital centres like respiratory and vasomotor centres.

Question 66

What is bulbar palsy?

Answer 66

Weakness of muscles supplied by VII�XII cranial nerves.

Question 67

What is pseudobulbar palsy?

Answer 67

Bilateral corticonuclear fibre lesion causing tongue, lips, pharynx, and palate paralysis.

Question 68

What does the medulla develop from?

Answer 68

The myelencephalic part of the rhombencephalon.