Anatomy sheet 6

Question 1

**Brainstem is a very important structure
Why?

Answer 1

1)all ascending and descending tracts(fibers) passes through it.
2)a lot of tracts nuclei located there.
3)tracts crossing over in the brainstem.(pic2)
4)CN3-CN12 nuclei are located there.
5)Collection of nuclei called reticular formation are located there which responsible of consciousness and arousal.
6)Reflex centers (Cardiovascular and respiratory centers, Coughing, sneezing, swallowing centers) are located there.
7)Center Coordination of other function

Question 2

Brainstem is location in?

Answer 2

inferior to it is spinal cord
posterior cerebullum
above is diencephalon and cerebrum

Question 3

parts of brainstem:

Answer 3

a)medulla oblongata (caudally) b)pons c)midbrain(rostrally)

Question 4

1)midbrain»superior:

Answer 4

-optic chiasma and optic tracts (separate btw dicephalom and mid brain)makes the
superior border

Question 5

Midbrain anteriorly

Answer 5

→cerebral peduncles
Note: cerebral peduncles=basis pedunculi=crus cerebri
=cerebral peduncles are projection fibers
(Cerebrospinal tract):
Cerebral cortex →corona radiata→internal capsule→ascends toward brain stem(most anteriorly)through
Cerebral peduncles(crus cerebri)→pyramids

Question 6

Interpeduncular fossa

Answer 6

located btw these two peduncles

Question 7

2)Pons:ventrally

Answer 7

-Bulgy part anteriorly
-basilar pons (the bulgy part)
-basilar sulcus btw basilar pons, and basilar artery passes here.
-Bulbopontine sulcus: (bulbo = medulla oblongata pontine=pons)
→located btw pons and medulla oblongata.

Question 8

Medulla oblongata,ventrally

Answer 8

-four columns anteriorly (2medially/2 laterally) and sulci in-between in the midline (Called ventral median fissure).
-pyramids; medial columns (projection descending-fibers)
→there no fibers crossing over here and above
→crossing over point of the fibers is inferior to the Pyramids.
→crossing over point called; Decussation of pyramids.
-Olives;lateral columns (complex of gray matter nuclei and one of these nuclei is large and it’s called inferior olivary nucleus(bulgy).
-pre-olivary sulcus : it’s a sulcus before the olive(medial to the olive)
-post-olivary sulcus : it’s a sulcus after the olive (lateral to the olive)
-inferior cerebellar peduncles :connection btw cerebellum and brainstem.

Question 9

1)CN3 →
2)CN 4 →trochlear nerve
3)CN 5 →
4)CN6/7/8 →
5)CN9/10/11 →
6)CN12 →

Answer 9

exits from interpeduncular fossa.

exits from posterior aspect of midbrain.
inferior of Corpora quadrigemini
=the only cranial nerve that exits from posterior and it’s wraps anteriorly.

exits from the pons laterally.

exits from bulbopontine sulcus,CN6 most medial while CN8 most lateral

exits from post-olivary sulcus.

exits from pre-olivary sulcus

Question 10

brainstem (dorsally),superiorly

Answer 10

thalamus+epithalamus (habenular gland &pineal gland)

Question 11

Midbrain:(dorsally):

Answer 11

→ Corpora quadrigemini: 4 swellings
2 superior and 2 inferior colliculi.
=trochlear nerve(CN4) exits from here.
●Cerebellar peduncles -Lateral walls of 4th ventricle

Question 11

Midbrain:(dorsally):

Answer 11

→ Corpora quadrigemini: 4 swellings
2 superior and 2 inferior colliculi.
=trochlear nerve(CN4) exits from here.
●Cerebellar peduncles -Lateral walls of 4th ventricle

Question 12

2)pons and medulla,(dorsally):

Answer 12

forms the floor of the 4th ventricle (Rhomboid fossa).

Question 13

3)medulla oblongata is subdivided into:(dorsally):

Answer 13

a) opened part (4th ventricle)
b) closed part (centra canal)
→central canal is inf. to the 4th ventricle

Question 14

medulla oblongata ,There’re 4 columns on the closed part called tubercles mention it?

Answer 14

medial →gracile:

1) gracile nuclei(tubercle) →upper dilated
2)gracile fasciculus→lower narrow
#Lateral →cuneate:
1) cuneate nuclei(tubercle) →upper dilated
2)cuneate fasciculus→lower narrow

⁂gracile/cuneate fasciculus =1st order neurons (ascending tracts) →communicate with 2nd order neurons in the gracile/cuneate nucleus →to the thalamus

Question 15

*Rhomboid fossa subdivided into:

Answer 15

1)pontine part
2) medullary part (open medulla)

Question 16

*Structures of the rhomboid located in the pontine(pons) fossa ,(medial→lateral):

Answer 16

1)posterior median sulcus (centrally located)
2)medial (not median) eminence (pons)
→on both sides of the post.median sulcus
→sulcus limitans is lateral to median eminence.
→Facial colliculus→caudal bulgy part of the medial eminence, forms the nuclei of the facial N
→vestibular الدهليزي area →most lateral part (vestibular nuclei and vestibular nerve)

→Striae medullaris →axons connects both cerebellum sides. (it’s located btw pons and medulla)

Question 17

Striae medullaris →

Answer 17

axons connects both cerebellum sides.
(it’s located btw pons and medulla)

Question 18

*Rhomboid fossa : medullary part

Answer 18

→Trigons:
-vagal trigone (nuclei for Vagus nerve)
-hypoglossal trigone (Nuclei for hypoglossal nerve)

Question 19

*The entrance and exit points of rhomboid fossa:

Answer 19

1)Isthmus
→it’s the most superior part of the 4th ventricle
→btw 3rd and 4th ventricles (entrance of the cerebral aqueduct)
2)Obex
→it’s the most inferior part of the 4th ventricle (connects it to central canal)
→narrowing point of the central canal

Question 20

*brainstem structure ant.→post.

Answer 20

1)basis peduncularis+ basis pontis+ pyramids are the most anterior parts of the brainstem, where projection fibers descends (so less gray matter and nuclei)
2)Tegmentum→majority of structures are
here (gray matter/nuclei/centers/tracts)
3)tectum→ Corpora quadrigeminy in the midbrain& is posterior to cerebral aqueduct

Question 21

=How can we differentiate btw medulla and SC?

Answer 21

Gray matter in the SC is H shaped while it’s
Arranged as an islets in the medulla.

Question 22

Functional distribution of the brainstem nuclei?
Midline (Middle →lateral) هاد البودي من العقل للجسم

Answer 22

1)GSE (general somatic efferent)
2)SVE (special visceral efferent)
3)GVE (general visceral efferent)

Question 23

1)GSE (general somatic efferent)

Answer 23

III, IV, VI, XII,→motor nuclei that goes to skeletal muscles

Question 24

2)SVE (special visceral efferent)

Answer 24

V, VII, IX, X, XI
going to the skeletal muscles of pharyngeal apparatus, the origin of the muscles in the pharyngeal apparatus is the neural crest ectoderm

Question 25

3)GVE (general visceral efferent)

Answer 25

III, VII, IX, X,→preganglionic parasympathetic

Question 26

Sulcus limitans (Medline→lateral) هاد الفساد
هون العكس بالترتيب

Answer 26

1)GVA(General visceral A) – n. of tractus solitarius.
→parasympathetic afferents

2)SVA (Special visceral a) – n. of tractus solitarius
→taste and smell

3)GSA (General somatic a) – V sensory nuclei
→skin

4)SSA(special somatic A) – vestibular & cochlearالدهليزي والقوقعة
→hearing and balance