LESSON 11_BRAINSTEM Flashcards
(66 cards)
1
Q
Brainstem comprises of (top to bottom):
* ____
* ____
* ____
____ - demarcates the separation between the medulla and SC at the ____
A
Brainstem comprises of (top to bottom):
* midbrain
* pons
* medulla
Foramen magnum - demarcates the separation between the medulla and SC at the cervicomedullary junction
2
Q
Boundaries of the Brainstem
- rostral: ____
- caudally: ____ at the level of the ____ and ____
A
- rostral: midbrain-diencephalic junction
- caudally: cervicomedullary junction at the level of the foramen magnum and pyramidal decussation
3
Q
functions of the brainstem
A
- acts as a conduit for ascending and descending tracts to the high centers in the forebrain
- contains reflex centers associated with cardiovascular and respiratory functions and consciousness
- contains nuclei of CN III-XII
4
Q
attached to the dorsal surface of the pons and upper medulla
A
cerebellum
5
Q
only in the midbrain; has the superior and inferior colliculi
A
tectum (roof)
6
Q
tegmentum (covering)
* at the midbrain, is ventral to the ____
* at the pons and medulla, is ventral to the ____
makes up the main bulk of ____ and ____
A
tegmentum (covering)
* at the midbrain, is ventral to the cerebral aqueduct
* at the pons and medulla, is ventral to the 4th ventricle
makes up the main bulk of brainstem nuclei and reticular formation
7
Q
The ____ is most ventral portion of the brainstem with a large collection of fibers making up the ____ and ____ tracts.
A
basis
corticospinal; corticobulbar
8
Q
Surface Anatomy
Ventral Surface of the Brainstem
* ____
* ____ - where the ____ exits ventrally
Dorsal Surface of the Brainstem
* ____ - superior and inferior colliculi
A
Ventral Surface of the Brainstem
* cerebral peduncles
* interpeduncular fossa - where the oculomotor nerve exits ventrally
Dorsal Surface of the Brainstem
* tectum - superior and inferior colliculi
9
Q
Surface Anatomy
Pons
* ventral surface - ____; ____
* limited dorsally by the ____
* dorsolaterally, attached to the ____ by the ____
A
Pons
* ventral surface - transverse fibers; convex
* limited dorsally by the 4th ventricle
* dorsolaterally, attached to the cerebellum by the superior, middle, and inferior cerebellar peduncles
10
Q
Surface Anatomy
Medulla
* ventral surface - ____ and ____ (____) located lateral to the ____
* dorsal surface (____ medulla) - ____
A
Medulla
* ventral surface - pyramids and olives (inferior olivary nuclei) located lateral to the pyramids
* dorsal surface (caudal medulla) - posterior columns tracts and their nuclei
11
Q
forms the floor of the 4th ventricle
A
pons (rostral) to rostral medulla (caudal)
12
Q
bumps on the floor of the 4th ventricle; found in the pons
A
facial colliculi
13
Q
The ____ and ____ are formed by the CN XII nucleus and the dorsal motor nucleus of CN X (medulla).
A
The hypoglossal trigone and vagal trigone are formed by the CN XII nucleus and the dorsal motor nucleus of CN X (medulla).
14
Q
joins the 4th ventricle superiorly; runs through the midbrain
A
cerebral aqueduct of Sylvius
15
Q
where the 4th ventricle drains into caudally
A
two lateral foramina of Luschka and one medial foramen of Magendie
16
Q
The sensory and motor nuclei are demarcated by the ____, which is still along the ____ wall of the 4th ventricle.
* motor nuclei located ____
* sensory nuclei located ____
A
The sensory and motor nuclei are demarcated by the sulcus limitans, which is still along the lateral wall of the 4th ventricle.
* motor nuclei located ventromedially
* sensory nuclei located dorsolaterally
motor nuclei, ventromedially
17
Q
The tectum is located ____ to the cerebral aqueduct.
A
dorsal
18
Q
Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN I
A
- olfactory nerve
- sensory
- olfaction
- cerebrum (ventral surface of frontal lobes)
- cribriform plate
19
Q
Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN II
A
- optic nerve
- sensory
- vision
- cerebrum
- optic canal
20
Q
Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN III
A
- oculomotor nerve
- motor
- eye movement, pupil constriction
- midbrain - ventral near midline; exit at interpeduncular fossa between PCA and SCA
- superior orbital fissure
21
Q
Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN IV
A
- trochlear
- motor
- eye movements
- midbrain (dorsal)
- superior orbital fissure
22
Q
only cranial nerve that exits dorsally; immediately decussates once it exits
A
trochlear nerve
23
Q
Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN V
A
- trigeminal nerve
- both
- facial sensation and muscles of mastication
- pons (ventrolateral)
- V1 from superior orbital fissure, V2 from foramen rotundum, V3 from foramen ovale
V1 (opthalmic), V2 (maxillary), V3 (mandibular)
24
Q
Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN VI
A
- abducens nerve
- motor
- eye movements
- pons (pontomedullary junction; ventrally near midline)
- superior orbital fissure
25
# Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN VII
* facial nerve
* both
* muscles of facial expression; taste, lacrimation, and salivation
* pons (ventrolateral; cerebellopontine angle [CPA])
* auditory canal (stylomastoid foramen)
26
# Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN VIII
* vestibulocochlear/auditory nerve
* sensory
* hearing; equilibrium sense
* pons (ventrolateral; CPA)
* auditory canal
27
# Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN IX
* glossopharyngeal nerve
* both
* pharyngeal muscles; carotid body reflexes; salivation
* medulla - ventrolateral (CPA)
* jugular foramen
28
# Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN X
* vagus nerve
* both
* parasympathetics to most organs; laryngeal muscles (voice); pharyngeal muscles (swallowing); aortic arch reflexes
* medulla - ventrolateral
* jugular foramen
29
# Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN XI
* spinal accessory nerve
* motor
* head turning (trapezius and SCM muscles)
* medulla
* jugular foramen (enters skull via foramen magnum)
30
# Name, Sensory/Motor, Function, Emerge from, Exit Foramen
CN XII
* hypoglossal nerve
* motor
* tongue movement
* medulla (between pyramids and olives)
* hypoglossal foramen (canal)
31
# Identify where the opening of the skull is located
Anterior cranial fossa
* perforations in cribriform plate -
Middle cranial fossa
* optic canal -
* superior orbital fissure -
* foramen rotundum -
* foramen ovale -
* foramen spinosum -
* foramen lacerum -
Posterior cranial fossa
* foramen magnum -
* hypoglossal canal -
* jugular foramen -
* internal acoustic meatus -
Anterior cranial fossa
* perforations in cribriform plate - **ethmoid**
Middle cranial fossa
* optic canal - **lesser wing of the sphenoid**
* superior orbital fissure - **between lesser and greater wings of the sphenoid**
* foramen rotundum - **greater wing of the sphenoid**
* foramen ovale - **greater wing of the sphenoid**
* foramen spinosum - **greater wing of the sphenoid**
* foramen lacerum - **between petrous part of temporal and sphenoid**
Posterior cranial fossa
* foramen magnum - **occipital**
* hypoglossal canal - **occipital**
* jugular foramen - **between petrous part of temporal and condylar part of occipital**
* internal acoustic meatus - **petrous part of temporal**
32
tumor in this area will affect CN VII-XI
cerebellopontine angle (CPA)
33
internal carotid artery exits through where?
carotid foramen
34
shallow, diamond shaped depression on the dorsal surface of the pons and medulla that forms the floor of the 4th ventricle
rhomboid fossa
35
# Medullary Surface Landmarks
continuation of the posterior median sulcus of SC
protuberance of the CN XII nucleus
protuberance of the dorsal motor nucleus of the CN X ... this lies ____ to the previous one
posterior median fissure
hypoglossal trigone
vagal trigone ... lies **lateral** to the hypoglossal trigone
36
# Pontine Surface Landmarks
Subependymal bundle of CN VII ... this winds around which nucleus?
between rostral and caudal parts of floor; fiber bundle coursing laterally ... surface landmark of ____ from ____ to ____ and is for ____
facial colliculi ... winds around the **abducens nucleus**
stria medullaris ... surface landmark of **arcuatocerebellar bundle** from **arcuate nucleus of medulla** to **cerebellum** and is for **respiration**
37
structures that form the roof of the 4th ventricle
velum, cerebellum, and choroid plexus of 4th ventricle
38
runs between the superior cerebellar peduncles ... this runs with what?
superior (anterior) medullary velum ... runs with the **inferior medullary velum**
39
# Lateral Boundaries of the 4th Ventricle
connects the cerebellum and midbrain
connects cerebellum and medulla
surface markings of gracile and cuneate nuclei
lateral angles of the 4th ventricle
brachium conjunctivum (SCP)
restiform body (ICP)
gracile and cuneate tubercles
lateral recess
40
connects the pons superiorly and SC inferiorly
Side Questions:
* ____-shaped; broad ____
* central canal of SC enters the lower half of the medulla to expand into the cavity of the ____
medulla oblongata
Side Questions:
* **cone**-shaped; broad **superiorly**
* central canal of SC enters the lower half of the medulla to expand into the cavity of the **4th ventricle**
41
corresponds to the level spinal cord; contains pyramidal decussation
cervicomedullary junction
42
# Ventral Surface of the Internal Brainstem
correspond to the anterior median fissure of the SC
swelling on either side of the median fissure
* bound laterally by the ____
* contains ____ to SC and ____ (for CN) in brainstem
posterolateral to the pyramids
* oval elevations produced by the underlying ____
anterior median fissure
**pyramids**
* bound laterally by the **ventrolateral sulcus**
* contains **anterior and lateral corticospinal tracts** to SC and **corticobulbar tracts** (for CN) in brainstem
**olives**
* oval elevations produced by the underlying **inferior olivary nuclei**
43
# Ventral Surface of the Internal Brainstem
emerges from the groove between the olives and pyramids
lies posterior to the olives
* connects the ____ and ____
emerges lateral to the olives
CNs ____ only at this level
**rootlets of the hypoglossal nerve**
**restiform body (ICP)**
* connects the **cerebellum** and **medulla**
**roots of the glossopharyngeal, vagus, and spinal accessory nerves**
CNs **IX**-**XII** only at this level
44
# Dorsal Surface of the Internal Brainstem
____ surface of ____ half of medulla forms lower part of floor of 4th ventricle
____ surface of ____ half of medulla is continuous with posterior aspect of SC and possesses a ____
On each side of ____, an elongated swelling the ____ is produced by the ____
Lateral to it is the ____ produced by the ____
**Posterior** surface of **superior** half of medulla forms lower part of floor of 4th ventricle
**Posterior** surface of **inferior** half of medulla is continuous with posterior aspect of SC and possesses a **posterior median sulcus**
On each side of **posterior median sulcus**, an elongated swelling the **gracile tubercle** is produced by the **gracile nucleus**
Lateral to it is the **cuneate tubercle** produced by the **cuneate nucleus**
45
# Level of Pyramidal Decussation
Superiorly, ____ occupy and form the ____
Inferiorly, about ____ of fibers decussate and continue down the ____ as ____
* Decussates at the ____
* ____ decussates on the other side and becomes the ____
Somatotopically organized
* ____ more lateral
* ____ more medial and decussates ____
____ leave as they descend to project to the CN nuclei
____ continue to ascend superiorly, posterior to the central gray matter
____ appear as posterior extensions of the central gray matter
____ becomes continuous with the inferior end of the nucleus of the spinal tract of trigeminal nerve (at the level of ____)
Superiorly, **corticospinal fibers** occupy and form the **pyramid**
Inferiorly, about **90%** of fibers decussate and continue down the **lateral funiculus** as **lateral corticospinal tract**
* Decussates at the **cervicomedullary junction**
* **10%** decussates on the other side and becomes the **anterior corticospinal tract**
Somatotopically organized
* **LE** more lateral
* **neck and UE** more medial and decussates **first**
**Corticobulbar fibers** leave as they descend to project to the CN nuclei
**Fasciculus gracilis and cuneatus** continue to ascend superiorly, posterior to the central gray matter
**Nucleus gracilis and cuneatus** appear as posterior extensions of the central gray matter
**Substantia gelatinosa** becomes continuous with the inferior end of the nucleus of the spinal tract of trigeminal nerve (at the level of **C3**)
46
# Level of Lemniscal Decussation
Level of ____
At the ____ half of medulla, above the ____
Crossing of second order neuron of the ____
Decussation of lemnisci occurs anterior to the ____, posterior to the ____
Axons of neurons in the dorsal column lemnisci (____ and ____) travel ventromedially as ____ and cross to the opposite side (sensory decussation) to form the ____
____ first travel anteriorly and laterally around the ____ then curve medially toward the midline where they decussate (tracts = ____, nucleus = ____)
Level of **sensory decussation**
At the **inferior** half of medulla, above the **pyramidal decussation**
Crossing of second order neuron of the **DCML**
Decussation of lemnisci occurs anterior to the **central gray matter**, posterior to the **pyramids**
Axons of neurons in the dorsal column lemnisci (**nucleus gracilis** and **nucleus cuneatus**) travel ventromedially as **internal arcuate fibers** and cross to the opposite side (sensory decussation) to form the **medial lemniscus**
**Internal arcuate fibers** first travel anteriorly and laterally around the **central gray matter** then curve medially toward the midline where they decussate (tracts = **outer**, nucleus = **central**)
47
# Level of Lemniscal Decussation
has a dorsolateral position in the medulla; lies lateral to the internal arcuate fibers
Side Questions:
* ____ lies lateral to this
* continuous caudally with the ____ and rostrally with the ____ in the pons
* extend throughout the medulla to the level of ____ of SC
* responsible for ____ of the ____
spinal trigeminal nucleus
Side Questions:
* **spinal tract of trigeminal nerve** lies lateral to this
* continuous caudally with the **substantia gelatinosa** and rostrally with the **main sensory nucleus of the trigeminal nerve** in the pons
* extend throughout the medulla to the level of **C3** of SC
* responsible for **exteroreceptive sensations (pain, light touch, and temperature)** of the **ipsilateral side of the face**
48
# Level of Lemniscal Decussation
tracts that lie lateral to the lemnisci decussation
tracts at the anterolateral region
* lateral spinothalamic tract
* anterior spinothalamic tract
* spinotectal tract = spinal lemniscus
~~
* spinocerebellar tract
* vestibulospinal tract
* rubrospinal tract
49
lies posterolateral to the pyramids and anterior to the ICP
Side Questions
* these are oval elevations of what?
* forms the inferior part of the floor of what?
olives
Side Questions
* inferior olivary nuclei
* 4th ventricle
50
stuff at the level of the olives
* nuclei of CN VIII-XII
* spinal trigeminal nucleus
* spinal trigeminal tract
51
gray matter shaped like a crumpled paper bag with the mouth directed medially
Side Questions
* responsible for the ____
* nuclei: ____ (principal nucleus); ____ and ____
* cells of the principal nucleus send fibers across the midline to enter the cerebellum through the ____
* afferent fibers: ____, ____, and ____
* associated with ____
olivary nuclear complex
Side Questions
* responsible for the **olives**
* nuclei: **inferior olivary nucleus** (principal nucleus); **medial accessory olivary nucleus** and **dorsal accessory olivary nucleus**
* cells of the principal nucleus send fibers across the midline to enter the cerebellum through the **ICP**
* afferent fibers: **spino-olivary tracts, cerebellum, and cerebral cortex**
* associated with **voluntary muscle movement**
52
parts of the vestibular nuclear complex ... seen at the level of the olives: ____ and ____
cochlear nuclei:
* ____ → anterolateral aspect of the inferior cerebellar peduncle
* ____ → posterior aspect of peduncle lateral to the floor of the 4th ventricle
* medial vestibular nucleus
* inferior vestibular nucleus
* lateral vestibular nucleus
* superior vestibular nucleus
seen at the level of the olives: **medial** and **inferior**
Cochlear Nuclei
* **Anterior cochlear nucleus** → anterolateral aspect of the inferior cerebellar peduncle
* **Posterior cochlear nucleus** → posterior aspect of peduncle lateral to the floor of the 4th ventricle
53
special visceral efferent (SVE) fibers of CN IX and X
nucleus ambiguus
54
# Nucleus Ambiguus
* ____ (IX); ____ for swallowing and ____ (X)
* ____ motor neurons
* Deep within the ____
* Emerging fibers join the ____, ____ and ____
* **stylopharyngeus** (IX); **pharyngeal muscles** for swallowing and **laryngeal muscles** (X)
* **Large** motor neurons
* Deep within the **reticular formation**
* Emerging fibers join the **glossopharyngeal**, **vagus** and **cranial part of accessory nerve**
55
on the anterior surface of the pyramids; responsible for the control of breathing
Side Question:
* receives afferents from cerebral cortex and send efferents to the cerebellum through ____
arcuate nucleus
Side Question:
* receives afferents from cerebral cortex and send efferents to the cerebellum through **anterior external arcuate fibers**
56
The pyramids contain ____ and some ____ fibers.
Anterior of the medulla is separated by the ____.
The pyramids contain **corticospinal** and some **corticonuclear** fibers.
Anterior of the medulla is separated by the **anterior median fissure**.
57
Fibers emerge from the decussation of the lemnisci and send afferents to the thalamus; flattened tract on each side of the midline posterior to the pyramid
medial lemniscus
58
found in the posterolateral corner, lateral to the 4th ventricle
ICP
59
small tract on each side of midline posterior to medial lemniscus and anterior to the hypoglossal nucleus
medial longitudinal fasciculus (MLF)
60
# Medial Longitudinal Fasciculus (MLF)
* Pathway that connects the nuclei involved in eye movements (CN ____, ____ and ____) to each other and to the ____ for horizontal and conjugate eye movement
* Highly myelinated tract near midline on each side, just below ____ and ____ nuclei in the midbrain and just under the floor of the 4th ventricle in the midline of the pons
* ____ ascend in MLF to oculomotor, trochlear, and abducens nuclei mediating ____
* “____” = eyes dont move
* Pathway that connects the nuclei involved in eye movements (CN **III**, **IV** and **VI**) to each other and to the **vestibular nuclei** for horizontal and conjugate eye movement
* Highly myelinated tract near midline on each side, just below **oculomotor** and **trochlear** nuclei in the midbrain and just under the floor of the 4th ventricle in the midline of the pons
* **Medial vestibular nucleus fibers** ascend in MLF to oculomotor, trochlear, and abducens nuclei mediating **vestibulo-ocular reflex**
* “**Doll’s Eyes**” = eyes dont move
61
on the anteromedial aspect of the ICP
near the surface; between inferior olivary nucleus and nucleus of spinal tract of trigeminal nucleus
deeply placed ____ (consists of ____, ____, and ____)
diffuse mixture of nerve fibers and cells deeply placed posterior to the olivary nucleus
spinal tract and nucleus of the trigeminal nerve
anterior spinocerebellar tract
deeply placed **spinal lemniscus** (consists of **anterior spinothalamic tract**, **lateral spinothalamic tract**, and **spinotectal tract**)
reticular formation
62
runs forward and laterally and emerges between the olives and ICPs at the level just inferior to the pons
runs anteriorly and laterally; emerges between the pyramids and the olives
glossopharyngeal, vagus, and cranial part of accessory nerves
hypoglossal nerve
63
found at the level just inferior to the pons instead of the inferior vestibular nucleus
lateral vestibular nucleus
64
At the level just below the pons, the ____ are visible on the anterior and posterior surface of the ICP.
cochlear nuclei
65
at the dorsolateral border of the medulla; carries mainly inputs to cerebellum from SC ... forms a distinct bundle at the ____
inferior cerebellar peduncles
forms a distinct bundle at the **midolivary level**
66
