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15) Brainstem Topography
BALES BLUE STAFF = important
Terms in this set (78)
When viewing the brainstem from the classical standard view, what is the patient's position?
What kind of view of a section is this?
Where is the R of the brainstem in relation to the patient?
Inferior view (surface) of section
The R of the brainstem in on the R of the patient
What is the patients position in the standard view of the brainstem for MRI or CTs?
What is this section view?
When looking at a view of the R of a section, what side is the patient on?
Inferior view (surface) - underside of brain
R side of section = L side of patient
What are the first 6 cranial nerves?
1 - Olfactory
2 - Optic
3 - Oculomotor
4 - Trochlear
5 - Trigeminal
6 - Abducens
What are the cranial nerves 7 - 12?
7 - Facial
8 - Vestibulocochlear
9 - Glossopharyngeal
10 - Vagus
11 - Spinal Accesory
12 - Hypoglossal
The brainstem gives origin to which cranial nerves?
III - X and XII
(3-10 and 12)
What is the basic 3-region organization of the brainstem from dorsal to ventral?
What is the boundary between the tectum and tegmentum?
In relation to the ventricular system, where is the tectum of the brainstem found?
The tectum is DORSAL to the ventricular system
When looking at the external brainstem from a ventral view, what region of the brainstem can be seen?
(not structure, but which region out of the 3-region organization)
From a ventral view of the external brainstem, what part of the medulla can be seen?
The pyramids of the medulla
When looking at a ventral view of the external brainstem, what can be seen below the pyramids of the medulla?
Decussation of the pyramids
What does decussation mean?
CROSSING - a crossed tract of nerve fibers
What fossa sits above the pons in a ventral view of the external brainstem?
What cranial nerve exits from this fossa?
CN III (3 = Oculomotor)
What nerve exits at the pontomedullary junction
(between pons and medulla)?
(6 = Abducens)
What nerve roots exit between the pyramid and the olive?
(12 = Hypoglossal)
What structure of the midbrain can be seen from a dorsal view of the brainstem?
What are the 4 mounds of gray matter seen on the tectum?
(2 superior and 2 inferior)
The superior colliculi on the tectum are for what sense?
The inferior colliculi on the tectum are for what sense?
(eyes are superior to the ears)
The 4 colliculi collectively are called what?
What cistern surrounds the tectum?
What structure sits above the tectum in a dorsal view of the external brainstem?
RECAP: what 3 CNs come out of the brainstem from the ventral surface?
What is the ONLY CN to exit dorsally from the brainstem?
Where does it exactly exit?
CN IV (4 = trochlear)
Exits: pontomesencephalic junction
(right below the inferior colliculus)
The points at which the cerebellum attaches to the brainstem are called?
Which peduncle is the largest?
Middle cerebellar peduncle
The superior cerebellar peduncle is almost continuous with what structure above it?
This structure functions as the roof of what other structure?
This structure connects what 2 other structures?
Almost continuous with the superior medullary velum
Roof of the upper 4th ventricle
Connects the CEREBELLUM to the BRAINSTEM
AGAIN: the 4th ventricle choroid plexus is associated with what?
The INFERIOR medullary velum
The upper half of the 4th ventricle overlies what?
What about the lower half?
Upper half: pons
Lower half: open medulla
What kind of matter are the cerebellar peduncles?
What is the obex?
What happens here in terms of the ventricles?
The bottom apex of the 4th ventricle floor
(and/or the junction of the closed medulla (inferior) and the open medulla (superior))
This is where the large 4th ventricle narrows down and leads to the central canal
Just lateral to the obex of the 4th ventricle floor on either side of it are two bumps called?
Below the gracile and cuneate tubercles are two similar ridges called?
These two are found in what column of the spinal cord?
They are found above what level?
Fasciculus gracilus (medially)
Fasciculus cuneatus (laterally)
Found on the dorsal column of the spinal cord
What structure is located on the medulla in-between the medulla pyramids and the cuneate tubercles?
(on the anterior and superior surface of the medulla just below the pons)
What structure of the midbrain is superior to the pons from the ventral surface of the brainstem?
(front of the midbrain)
The trochlear n. (IV = 4) exits from what surface of the brainstem and what junction?
What does it wrap around to what surface?
Exits from the dorsal surface
(at the pontomesencephalic junction)
It wraps around the cerebral peduncle (of the midbrain) to the ventral surface
CN V (facial) exits from where?
Middle cerebellar peduncle junction
(Upper side of the pons )
CN 6 (abducens) exits from where?
(where the pons and medulla meet)
CN 7 (facial) and 8 (vestibulocochlear) exit the brainstem from where?
(lateral side where the pons and cerebellum meet)
The roots of CN XII (12 = hypoglossal) exits between what two structures?
Pyramid and the olive
Roots of CN 9 (glossopharyngeal), 10 (vagus), and more or less 11 (spinal accessory) exit where?
Dorsal to the olive
(in a line down)
In the embryo, where are the sensory fibers located?
Where do they develop from?
What soluble factor do they develop from?
In the embryo, where are the motor fibers located?
What do they develop from?
What soluble factor do they develop from?
In the upper medulla and pons, the dorsal (alar) plate splays out in what direction?
This means what will be the most lateral?
General somatic afferents (GSA) will be most lateral
Where are the general somatic afferents (GSA) located compared to the visceral afferents (GVA) within the alar plate?
GSA are DORSAL to GVA
Where is the GSE located compared to the GVE in the basal plate?
GSE is VENTRAL to the GVE
(general visceral efferents)
In the brainstem, what side is the sensory on?
What side is the motor on?
Lateral side = sensory
Medial side = Motor
Within the brainstem, where are the somatic nuclei (GSE and GSA) found?
Where are the visceral components found?
Somatic components (GSE and GSA) are at the extremes
Visceral components are INBETWEEN the somatics
GSA include what?
conscious proprioception from face and head
Special somatic afferents (SSA) include what?
Do they detect?
Vision, hearing, equilibrium
Detects LIGHT WAVES (vision)
General visceral afferents (GVA) include what?
Pain and reflexes
(from viscera, glands, and vessels)
SVA include what?
Do they detect?
Smell, taste, GI tract associated
SVE innervates striated skeletal muscle of which cranial nerves?
How do you remember this?
CN V, VII, IX, and X
(5, 7, 9, 10)
"Chew your face and swallow"
GSE innervates striated skeletal muscle of which nerves?
How do you remember this?
CN III, IV, VI, XII
(3, 4, 6,12)
"Lick your eyes"
GVE pre/post ganglionic parasympathetics are found in what four CNs?
III, VII, IX, X
(3, 7, 9, 10)
Caudal Medulla (Inferior closed medulla) section shape
Mid-Medulla (superior closed medulla) section landmark
Internal arcuate fibers
Rostal Medulla (open medulla) section landmarks
(that are not present in the superior closed medulla section)
FULL inferior olivary nucleus (vs incomplete in superior closed medulla)
As well as the big open 4th ventricle (narrow central canal in the superior closed medulla section)
Pontomedullary junction lower part section ventricle shape
(4th ventricle narrower)
Midline part of the cerebellum = ?
In the pontomedullary junction upper part section, what fibers ascend and loop over the top of what nucleus before descending?
VII fibers (7)
over the tope of the abducens nucleus
In the caudal pons section, the medial lemniscus is oriented how?
horizonatal medial lemniscus
Mid pons section ventricle shape
or vampire bat with a bit of a tail
Rostral (upper) pons section ventricle shape?
What is the pontomesencephalic junction section shape?
What major hole is at the "forehead"?
What does the forehead/face of the shape represent?
Chubby ghost (or great anus)
Hole: cerebral aqueduct
Forehead/face = midbrain
In the pontomesencephalic junction section, how is the medial lemniscus oriented?
Caudal midbrain section shape
(literally - the entire thing looks like a giant frog)
What are the eyes and mouth of the frog of the caudal midbrain section?
Eyes = inferior colliculi
Mouth = Superior Cerebellar Peduncle decussation
What section is the SCP not continuous with?
(i.e. has not decussated)
Caudal rostral midbrain section shape
(from Little Mermaid)
What nucleus is present in the rostral midbrain diencephalon junction section?
What structure is present at the top of the section that is not present in the caudal rostral midbrain section?
Red nucleus (motor)
The basilar artery forms from the vertebral arteries at about what structure of the brainstem?
(maybe a little of the pontomedullary junction)
The posterior inferior cerebellar A (PICA) branches off what artery?
Which spinal A. originates from the PICA or near the PICA?
Posterior spinal A.
The anterior inferior cerebellar A. (AICA) branches off what A?
Caudal Basilar A.
The superior cerebellar artery branches off what artery?
Rostral basilar A.
The basilar A. terminates and bifurcates into what A.?
Posterior cerebral A. (PCA)
What are the 3 territories of penetrating A. in the brainstem?
What are the respective penetrating A. branches to each territory?
1) Paramedian - paramedian brs.
2) Ventral lateral - short circumferential brs.
3) Dorsal lateral - long circumferential brs.
The basilar A. sits on what surface of the brainstem?
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