Medulla - Part 1

Question 1

Connects the pons superiorly with the spinal cord inferiorly

Answer 1

Medulla

Question 2

Where is the junction of medulla and spinal cord?

Answer 2

at the origin of the anterior and posterior roots of the first cervical spinal nerve, which corresponds approximately to the level of the foramen magnum.

Question 3

Blood supply of medulla

Answer 3

posterior inferior cerebellar artery (lateral part)
vertebral artery (medial)

Question 4

Continuous inferiorly with the anterior median fissure of the spinal cord

Answer 4

Anterior median fissure

Question 5

Swelling on each side of the median fissure
o Composed of bundles of nerve fibers called corticospinal fibers, which originate in large nerve cells (pyramidal/Betz cells) in the precentral gyrus of the cerebral cortex

Answer 5

Pyramids

Question 6

o Few nerve fibers that emerge from the anterior median fissure above the decussation
o Pass laterally over the surface of the medulla oblongata to enter the cerebellum

Answer 6

Anterior external arcuate fibers

Question 7

o Posterolateral to the pyramids
o Oval elevations produced by the underlying
inferior olivary nuclei

Answer 7

Olives

Question 8

Emerges in the groove between the pyramid

and the olive

Answer 8

Hypoglossal nerve

Question 9

Roots of these nerves emerge in the groove
between the olive and the inferior cerebellar
peduncle

Answer 9

Glossopharyngeal
Vagus
Accessory

Question 10

Forms the lower part of the floor of the fourth

ventricle

Answer 10

Superior half of the medulla oblongata

Question 11

Continuous with the posterior aspect of the spinal cord and possesses a posterior median sulcus

Answer 11

Inferior half

Question 12

o Elongated swelling located on each side of the
median sulcus
o Produced by the underlying gracile nucleus

Answer 12

Gracile tubercle

Question 13

o Lateral to the gracile tubercle

o Produced by the underlying cuneate nucleus

Answer 13

Cuneate tubercle

Question 14

Its extensive lateral spread resulted in an
alteration in the position of the derivatives of the
alar and basal plates of the embryo

Answer 14

Fourth ventricle

Question 15

Alar and basal plates: situated lateral and medial to the sulcus limitans respectively (vs. in
the spinal cord, wherein the alar and basal plates are situated posterior and anterior to the sulcus limitans)

Answer 15

Fourth ventricle

Question 16

Four levels of medulla

Answer 16

o Level of decussation of pyramids
o Level of decussation of lemnisci
o Level of the olives
o Level just inferior to the pons

Question 17

o Seen in a transverse section through the inferior half of the medulla oblongata
o Also known as the decussation of pyramids

Answer 17

Great motor decussation

Question 18

Part of the medulla where corticospinal fibers occupy and form the pyramid

Answer 18

Superior part of the medulla

Question 19

About three-fourths of the fibers cross the median plane continue down the spinal cord in the lateral white column as the __________

Answer 19

lateral corticospinal tract

Question 20

Continue to ascend superiorly posterior to the central gray matter

Answer 20

Fasciculus gracilis and fasciculus cuneatus

Question 21

Appear as posterior extensions of the centralgray matter

Answer 21

Nucleus gracilis and nucleus cuneatus

Question 22

Found in the posterior gray column of the spinal cord, which becomes continuous with the inferior end of the nucleus of the spinal tract of the trigeminal nerve (CN V)

Answer 22

Substantia gelatinosa

Question 23

o Seen in the transverse section through the inferior half of the medulla oblongata
o Also known as the decussation of lemnisci
o Found a short distance above the level of the decussation of the pyramids

Answer 23

Great sensory decussation

Question 24

o Where the lemnisci have been formed, which
have emerged from the anterior aspects of
nucleus gracilis and nucleus cuneatus
o First travel anteriorly and laterally around the
central gray matter
o They then curve medially toward the midline
where they decussate with the corresponding
fibers of the opposite side

Answer 24

Internal arcuate fibers

Question 25

Lies lateral to the internal arcuate fibers

Answer 25

Nucleus of the spinal tract of the trigeminal nerve

Question 26

Lies lateral to the trigeminal nucleus

Answer 26

Spinal tract of the trigeminal nerve

Question 27

Composed of the lateral and anterior spinothalamic tracts and the spinotectal tract; Occupy an area lateral to the decussation of the lemnisci

Answer 27

Spinal lemniscus

Question 28

Situated in the anterolateral region of the medulla oblongata

Answer 28

Spinocerebellar, vestibulospinal and rubrospinal tracts

Question 29

largest nucleus of

this complex

Answer 29

Inferior olivary nucleus

Question 30

elevation on the surface of the medulla

Answer 30

Olive

Question 31

Gray matter is shaped like a crumpled bag with

its mouth directed medially

Answer 31

Olivary nuclear complex

Question 32

Cells of the inferior olivary nucleus send fibers ______ across the midline to enter through cerebellum through the inferior cerebellar peduncle

Answer 32

medially

Question 33

Function of the olivary nuclei

Answer 33

voluntary muscle movement

Question 34

Made up of medial vestibular nucleus, inferior
vestibular nucleus, lateral vestibular nucleus,
and superior vestibular nucleus

Answer 34

Vestibulocochlear nuclei

Question 35

situated on the anterolateral aspect of the inferior cerebellar peduncle

Answer 35

Anterior cochlear nucleus

Question 36

situated on the posterior aspect of the peduncle lateral to the floor of the fourth ventricle

Answer 36

Posterior cochlear nucleus

Question 37

o Consists of large motor neurons
o Situated deep within the reticular formation
o Emerging nerve fibers join the glossopharyngeal, vagus, and cranial part of the accessory nerve and are distributed to voluntary skeletal muscle

Answer 37

Nucleus ambigous

Question 38

o Lies beneath the floor of the fourth ventricle
o (Medial to lateral): hypoglossal nucleus, dorsal
nucleus of the vagus, nucleus of the tractor
solitaries, medial and inferior vestibular nuclei

Answer 38

Central gray matter

Question 39

o Thought to be inferiorly displaced pontine nuclei
o Situated on the anterior surface of the pyramids
o Receive nerve fibers from the cerebral cortex
o Send efferent fibers to the cerebellum through
the anterior external arcuate fibers

Answer 39

Arcuate nuclei

Question 40

o Contain the corticospinal and some corticonuclear fibers situated in the anterior part
of the medulla, separated by the anterior median fissure
o Corticospinal tract: descend to the spinal cord
o Corticonuclear tract: distributed to the motor nuclei of the cranial nerves situated within themedulla

Answer 40

Pyramids

Question 41

o Forms a flattened tract on each side of the midline posterior to the pyramid
o Emerge from the decussation of the lemnisci
o Convey sensory information to the thalamus

Answer 41

Medial lemniscus

Question 42

Forms a small tract of nerve fibers situated on each side of the midline posterior to the medial lemniscus and anterior to the hypoglossal nucleus
o Consists of ascending and descending fibers

Answer 42

Medial longitudinal fasciculus

Question 43

Situated in the posterolateral corner of the section on the lateral side of the fourth ventricle

Answer 43

Inferior cerebellar peduncle

Question 44

Situated on the anteromedial aspect of the inferior cerebellar peduncle

Answer 44

Spinal tract of trigeminal nerve and its nucleus

Question 45

Situated near the surface in the interval between the inferior olivary nucleus and the nucleus of the spinal tract of the trigeminal nerve

Answer 45

Anterior spinocerebellar tract

Question 46

o Consists of diffuse mixture of nerve fibers and small groups of nerve cells
o Deeply placed posterior to the olivary nucleus
o Also present in the pons and midbrain

Answer 46

Reticular formation