Anatomy sheet 6 Flashcards
(27 cards)
**Brainstem is a very important structure
Why?
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
Brainstem is location in?
inferior to it is spinal cord
posterior cerebullum
above is diencephalon and cerebrum
parts of brainstem:
a)medulla oblongata (caudally) b)pons c)midbrain(rostrally)
1)midbrain»superior:
-optic chiasma and optic tracts (separate btw dicephalom and mid brain)makes the
superior border
Midbrain anteriorly
→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
Interpeduncular fossa
located btw these two peduncles
2)Pons:ventrally
-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.
Medulla oblongata,ventrally
-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.
1)CN3 →
2)CN 4 →trochlear nerve
3)CN 5 →
4)CN6/7/8 →
5)CN9/10/11 →
6)CN12 →
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
brainstem (dorsally),superiorly
thalamus+epithalamus (habenular gland &pineal gland)
Midbrain:(dorsally):
→ Corpora quadrigemini: 4 swellings
2 superior and 2 inferior colliculi.
=trochlear nerve(CN4) exits from here.
●Cerebellar peduncles -Lateral walls of 4th ventricle
Midbrain:(dorsally):
→ Corpora quadrigemini: 4 swellings
2 superior and 2 inferior colliculi.
=trochlear nerve(CN4) exits from here.
●Cerebellar peduncles -Lateral walls of 4th ventricle
2)pons and medulla,(dorsally):
forms the floor of the 4th ventricle (Rhomboid fossa).
3)medulla oblongata is subdivided into:(dorsally):
a) opened part (4th ventricle)
b) closed part (centra canal)
→central canal is inf. to the 4th ventricle
medulla oblongata ,There’re 4 columns on the closed part called tubercles mention it?
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
*Rhomboid fossa subdivided into:
1)pontine part
2) medullary part (open medulla)
*Structures of the rhomboid located in the pontine(pons) fossa ,(medial→lateral):
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)
Striae medullaris →
axons connects both cerebellum sides.
(it’s located btw pons and medulla)
*Rhomboid fossa : medullary part
→Trigons:
-vagal trigone (nuclei for Vagus nerve)
-hypoglossal trigone (Nuclei for hypoglossal nerve)
*The entrance and exit points of rhomboid fossa:
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
*brainstem structure ant.→post.
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
=How can we differentiate btw medulla and SC?
Gray matter in the SC is H shaped while it’s
Arranged as an islets in the medulla.
Functional distribution of the brainstem nuclei?
Midline (Middle →lateral) هاد البودي من العقل للجسم
1)GSE (general somatic efferent)
2)SVE (special visceral efferent)
3)GVE (general visceral efferent)
1)GSE (general somatic efferent)
III, IV, VI, XII,→motor nuclei that goes to skeletal muscles
