Cranial Cavity--Sievert Flashcards
(133 cards)
1
Q
What are the 2 main divisions of the skull?
A
- Neurocranium–the area that surrounds the brain
2. Viscerocranium–bones of the face
2
Q
How is the neurocranium mainly formed? Which bones are components?
A
mainly large flat bones
formed mainly intramembranously
3
Q
What are the 3 embryological derivatives of the skull?
A
Neural crest–Ectoderm
Paraxial Mesoderm–Somites
Lateral Plate Mesoderm
4
Q
Where does the division b/w the neural crest & the somites occur?
A
this happens at the precordal plate at the rostral end of the notochord.
5
Q
T/F Sometimes there is overlap that occurs in which some paraxial mesoderm is anterior to the prechordal plate.
A
False. If you are anterior to the prechordal plate–>neural crest cells.
6
Q
What is the embryological derivative of the sphenoid bone?
A
most of it is neural crest
a small posterior portion of it is paraxial mesoderm
7
Q
There is a chunk of neural crest tissue @ the rostral end of the notocord. What does it give rise to? What is the clinical significance of this?
A
Facial Structures of the skull
Heart Structures
**if you see congenital facial deformities in a child, look for heart problems–>probably present b/c they originate from the same tissue.
8
Q
Which embryonic derivative does the laryngeal cartilage come from?
A
lateral plate mesoderm.
9
Q
What are the 2 types of bone formation?
A
Endochondral Ossification
Intramembranous Ossification
10
Q
What are the 2 components of the neurocranium?
A
The membranous & cartilaginous parts.
11
Q
What makes up the membranous part? Why is it called this?
A
The frontal bone, parietal bones, part of the temporal bones, part of the occipital bone.
Called this b/c they are formed via intramembranous ossification.
Note: these are mainly flat bones.
12
Q
The occipital bone is formed via intramembranous ossification & some __________.
A
endochondral ossification.
13
Q
The Cartilaginous portion of the neurocranium is called what? It is formed via which type of ossification? This mainly applies to bones in the _______.
A
Called chondrocranium
Formed via endochondral ossification.
Mainly in bones in the base of the skull.
14
Q
Which bones are a part of the chondrocranium–cartilaginous portion of the neurocranium?
A
Sphenoid Bone
Ethmoid Bone
Part of Temporal Bone
Part of Occipital Bone
15
Q
T/F All of the components of the neurocranium are from the embryological derivative paraxial mesoderm.
A
FALSE. They come from different embryological derivatives…these are separate concepts. Think about fcn of housing brain when you think about the neurocranium.
So the sphenoid bone is derived from both neural crest & paraxial mesoderm & is a part of the cartilaginous portion of the neurocranium.
16
Q
What are the exceptions to the general statement that the large flat bones of the neurocranium are membranous?
A
The temporal bone & occipital bone are partially formed via endochondral ossification.
17
Q
T/F Due to their different ossification processes, the temporal bone & occipital bones are a part of both the neurocranium & viscerocranium.
A
False. They are entirely a part of the neurocranium. They are just partially a part of the membranus & cartilaginous portions of the neurocranium. Once again–>concepts of ossification, neuro v. viscerocranium, & embryological derivatives. A LOT of overlap.
18
Q
T/F Bones of the floor of the cranial cavity form via endochondral ossification.
A
True. This includes the sphenoid, ethmoid, & part of the temporal bone.
19
Q
Viscerocranium develops primarily from _____ and comes from ______.
-Some parts of the viscerocranium develop from ___________.
A
membrane
comes from neural crest
**cartilaginous models.
20
Q
Which parts of the viscerocranium develop from a cartilage model?
A
middle ear ossicles, laryngeal cartilages and hyoid bone.
21
Q
When you see craniofacial defects what should you think?
A
think neural crest problem
look for other defects, including @ the heart.
22
Q
Why do newborns have a small face?
A
lack of teeth–>small jaw
no paranasal sinuses
facial bones underdeveloped
23
Q
Which fontanels do you see in a newborn?
A
6 Anterior Posterior Sphenoid-Lateral (2) Mastoid-Lateral (2)
24
Q
What happens @ fontanels in a newborn?
A
these are areas where flat bones of the skull meet & eventually form sutures
these allow for overlap during the birthing process
25
Premature suture closure causes what condition?
craniosynostosis
26
What happens if you have incomplete closure of the anterior neuropore?
the skull bones will fail to grow together
| **can result in cranioschisis
27
What is a cranioschisis a variant of?
spina bifida
| main difference is that it occurs at the rostral end of the neural tube
28
What exactly occurs in cranioschisis?
neural tube fails to close
brain tissue exposed to amniotic fluid & degenerates
can result in anencephaly
fetus usu not viable
29
What are 2 variants of cranioschisis? What are the differences b/w them?
Meningocele: meninges are bulging out
Meningoencephalocele: meninges & brain vesicles are bulging out
30
What are the 5 brain vesicles?
```
Telencephalon
Diencephalon
Midbrain
Pons
Medulla
```
31
Describe the epidural space in the cranial cavity.
Trick Q! There is NO true epidural space in the cranial cavity. This only starts @ the spinal cord after the foramen magnum. There is a "potential epidural space" in the cranial cavity. The dura is fused tightly to the bones of the cranium & there are even some CT spicules connecting everything.
32
T/F The dura mater forms the periosteum of the interior cranial cavity.
True
33
Where are the meningeal arteries that supply the cranial cavity found?
They are found b/w the skull & dura mater. This is in the potential epidural space. You can even see the impression of these arteries in the skull.
34
Describe the layers of the dura mater.
There are 2 layers.
Periosteal layer--located closest to the bone
Meningeal layer--located closest to the arachnoid mater
**they can't be separated.
35
What is it called when the 2 layers of the dura mater are naturally separate?
called dural sinus
36
Once again, what is it called when there is a rupture of a meningeal artery?
epidural hematoma
37
What are the different branches of meningeal arteries found in the cranial cavity? Which is most susceptible to injury?
Middle meningeal--most susceptible to injury b/c of the thinness of the surrounding bones
Anterior meningeal
Posterior meningeal
38
The middle meningeal artery is a branch of what artery? Which hole in the skull does it enter thru?
branch of maxillary artery
| goes thru foramen spinosum.
39
What is an epidural hematoma?
This is a condition in which a meningeal artery (usu middle) ruptures & creates a high pressure bleed in the epidural space. It creates a space where there wasn't one by separating the dura mater from the bone. Causes compression of the brain & increase in intracranial pressure.
40
Can an epidural hematoma be deadly?
Absolutely, 15-20% of ppl who have it die.
41
Why is an epidural hematoma deadly?
b/c it is known as a space occupying lesion. It pushes on the structures of the brain...the first of which to go are the cardiovascular & resp centers. Deadly.
42
How do you treat an epidural hematoma?
you drill holes into the skull to decrease the intracranial pressure. you take measures to stop the bleed.
43
What is the hallmark of an epidural hematoma?
a lucid interval
pts will go in & out of consciousness
sometimes pt will regain consciousness & then die suddenly-->called Talk & Die Syndrome
44
Where is the arachnoid mater located in the cranial cavity? What is found underneath it?
It is located right underneath the dura mater. It is usu sitting tightly up against it. Underneath this is the subarachnoid space.
45
What do you find in the subarachnoid space?
you find CSF
| you also find cerebral arteries & veins
46
T/F You find meningeal arteries on top of the arachnoid mater once you peel back the dura mater.
FALSE You find some cerebral veins. No meningeal arteries b/c those are on top of the dura mater.
47
Why do you sometimes see cerebral veins on top of the arachnoid mater?
b/c the cerebral veins in the subarachnoid space pierce thru the arachnoid mater to empty out to a dural sinus at some point.
48
What is one of the main sinuses for cerebral veins to empty into?
parasagittal sinus
49
What would be the relationship b/w the arachnoid mater & the brain if the CSF was gone from the subarachnoid space?
It would collapse against the brain
50
What do you see running thru the sulci in a gross brain?
you see the cerebral vessels in the subarachnoid space.
51
If a cerebral vein is ruptured in a dural sinus, what can you get?
a subdural hematoma
| **this is low pressure, but can be dangerous over time as pressure builds up
52
What are arachnoid villi or granulations? What is their fcn?
These are funky looking portions of arachnoid mater that also pierce their way thru the dura mater to get to the dural sinus. They act as a one-way valve that releases CSF fluid into the dural sinus
53
Where is CSF produced? How frequently is it produced? What is one of the most important fcns of CSF?
It is produced continually in the choroid plexus of the ventricles
**one of the most important fcns is buoyancy
54
Where is the pia mater found?
directly overlying the brain. Underneath the subarachnoid space. It follows all the sulci & gyri
55
What is found in the subdural sinuses? Where does it drain to?
Here you find CSF from the arachnoid villi & you find blood from the cerebral veins. It eventually drains into the internal jugular vein.
56
What are the veins called that go thru the skull & into the scalp? What is their clinical significance?
These are called emissary veins. They can spread infection from the scalp to the subdural sinus.
57
If you get an infection in one section of the scalp...which structure makes it super easy for that to spread across the scalp? And with the help of emissary veins potentially into a subdural sinus?
the loose areolar tissue that is found beneath the galea aponeurotica & above the periosteum.
58
The meningeal dura help form the dural sinus...but else do they help form?
dural reflections
59
What are the 2 examples of places where the 2 layers of the dura mater split?
```
dural sinuses
dural reflections (think meningeal dura on each side)
```
60
What is the name of the dural reflection that separates the 2 hemispheres of the brain?
the falx cerebri
61
Which one of these is more dangerous?
ASDH: Acute Subdural hematoma
CSDH: chronic subdural hematoma
The acute subdural hematoma is more dangerous.
| 50% survival rate
62
What do you need to know about acute subdural hematomas?
blood gathers quickly in the subdural space
usu occurs after traumatic brain injury
get cerebral edema usu too
need surgery to recover
63
What do you need to know about chronic subdural hematomas?
blood gathers slowly in the subdural space
usu doesn't occur after a noticeable brain injury
outcome is relatively good
requires careful observation & slow drainage
64
What is the clinical significance of dural reflections?
when you have a space occupying lesion that pushes around brain structures...they will be forced under or around these dural reflections & that can cause damage.
65
What are the 3 dural reflections that we talk about?
```
Falx Cerebri (separates the 2 hemispheres of the cortex)
Tentorium Cerebelli (separates the cerebellum from the cortex)
Falx Cerebelli (separates somewhat the 2 halves of the cerebellum)
```
66
T/F Tentorial notch of the tentorium cerebelli allows the brainstem space to come thru.
True.
67
T/F The dural reflections are closely associated with arterial blood pockets.
False. With venous sinuses.
68
Where is the straight sinus located?
it is located @ the intersection b/w the falx cerebri & the tentorium cerebelli
2 major veins drain into this
it goes toward the confluens
69
Why can prostate cancer be so dangerous?
b/c if it gets into the internal venous plexuses it can drain upwards & eventually get into the cranial cavity @ the inferior occipital sinus
70
Most of the sinuses drain to the confluens. Everything eventually drains from the internal jugular vein. What are the dural sinuses that we have talked about?
```
Superior Sagittal Sinus
Inferior Sagittal Sinus
Straight Sinus
Confluens
Transverse Sinus
Sigmoid Sinus
Cavernous Sinus
```
71
Where is the cavernous sinus located?
on either side of the sphenoid bone
72
What structure does V1 go thru? V2? V3? Which of these go thru the cavernous sinus?
V1: superior orbital fissure
V2: foramen rotundum
V3: foramen ovale
**only V1 & V2 go thru the cavernous sinus
73
Which carotid artery goes into the cranial cavity? Where does it end?
only the internal carotid artery
| ends in the circle of Willis
74
What all do you see in the cavernous sinus?
```
parotid gland
internal carotid artery
CN V1
CN V2
CN 3, 4, 6
```
75
What structure does the parotid gland sit in?
it sits in the sella turcica
76
What are some important venous plexuses/veins that drain into the cavernous sinus?
opthalmic plexus
pterygoid plexus
facial vein
77
What is the triangle of death?
it is an area of your face where you shouldn't pop pimples for risk of causing a facial infection that could make its way into the facial vein & spread into the cranial cavity via the cavernous sinus. could be deadly theoretically.
this is the area above your mouth & around your nose.
78
In the triangle of death which direction does blood flow?
it flows in a variety of directions based on the amount of blood-->no one way valves.
79
What separates the lateral ventricles?
the septum pellucidum
80
How do the lateral ventricles communicate w/ the 3rd ventricle?
the inter ventricular foramen of Monroe
81
How is CSF made? Where is it released?
CSF made by the choroid plexus that lines all of the ventricles
released into the subarachnoid space
82
What connects the 3rd ventricle to the 4th ventricle?
the cerebral aqueduct
83
What important space is the 4th ventricle connected to?
the subarachnoid space where CSF is released
84
If you blocked the flow of CSF at any point-->like the cerebral aqueduct or something...what would occur?
this causes increased pressure inside the brain
85
If you block reabsorption of CSF into the venous system...what occurs?
increased pressure inside & outside of the brain
86
What are 2 types of hydrocephalus?
communicating & non-communicating
87
Describe the special shape of the lateral ventricles.
They are C shaped & extend into all the different lobes of the brain.
88
Where are the 3 places that CSF can drain into the subarachnoid space?
3 foramen in the 4th ventricle
1 midline foramen-->Foramen of Magendie
2 lateral foramen-->Foramen of Luschka
89
Once the CSF is in the subarachnoid space-->how does it exit?
it can leave via reabsorption into the dural sinuses.
| this happens via arachnoid granulations
90
What is it called when you get a buildup of CSF?
hydrocephalus
* *too much production or inadequate reabsorption
* *dilation of ventricles-->increased intracranial pressure
91
Describe the journey of CSF.
```
Choroid Plexus
Lateral Ventricles
3rd Ventricle
Cerebral Aqueduct
4th Ventricle
Cisterna Magna
Subarachnoid Space
```
92
______ ml/day is produced of CSF and most of it is resorbed by the arachnoid granulations. Capacity ~____.
400-500 ml/day
| Capacity: 150 mL
93
What are the functions of CSF?
buoyancy
nutrition
waste removal
94
What are subarachnoid cisterns?
these are places of enlarged subarachnoid space
| arachnoid follows a smooth course while CNS tissue takes an abrupt turn
95
What are some important subarachnoid cisterns? Which is the most important?
Superior Cistern
Interpeduncular Cistern
Pontine Cistern
Cisterna Magna**most important
96
How can you see the cisterna magna?
you can usu see it when you take off the arch of the atlas
| this is located near the 4th ventricle
97
What do you find near the interpeduncular cistern?
the 2 big cerebral peduncles
| you also see some cranial nerves popping off, like CN3
98
What is the superior cistern located next to?
the place where the tentorium cerebelli meets the colliculi of the brainstem (midbrain)
99
How might hydrocephalus appear in an infant?
they might have a super huge head b/c of the increased pressure & b/c their sutures aren't fully closed
can result in atrophy of the brain
100
What are the 2 main sources of blood supply to the brain?
the internal carotid arteries
| vertebral arteries
101
Describe how the internal carotid arteries & vertebral arteries contribute to the blood supply of the brain.
Internal carotid artery branches off of the common carotid artery. It gives off a branch to the eye & then continues & ends @ the circle of Willis
The vertebral arteries travel thru the transverse foramina of the cervical vertebrae & go thru the foramen magnum. They combine to form the basilar artery & sit on a special occipital bone thing & continue up the bases of the cerebral hemispheres & then give off terminal branches in the circle of Willis
102
What is the name of the special part of the occipital bone that the basilar artery rests on?
clivus
| like a ski slope
103
Where is the last place of collateral flow in the brain?
the circle of Willis
| after that all terminal branches
104
Describe the Circle of Willis.
2 vertebral arteries come from the back & form one basilar artery.
This branches into 2 posterior cerebral branches that head posteriorly.
It also branches into 2 posterior communicating branches that join the middle cerebral arteries or internal carotid arteries.
The internal carotid arteries come up sorta centrally & branch into 2 middle cerebral arteries that go off to the side & 2 anterior cerebral branches that go forward. There is then one anterior communicating branch that connects the 2 anterior cerebral branches.
105
Where do the posterior cerebral arteries go?
they head back to supply the occipital lobe
106
Where do the middle cerebral arteries go?
they head underneath the temporal lobe to supply the lateral surface of the hemisphere
107
Where do the anterior cerebral arteries go?
they head up b/w the inter hemispheric fissure
108
Where does the anterior cerebral artery branch from?
can branch from the internal carotid artery or the middle cerebral artery
109
T/F If there is a blockage of an artery in the brain, the stroke symptoms will coordinate to the area of the brain that the artery supplied.
True
110
What does CVA mean? What causes it?
cerebral vascular accident
| caused by an obstruction or rupture of a cerebral vessel
111
What are the 2 main categories of CVAs? What are the 3 types?
* *Ischemic
1. Thrombotic Stroke
2. Embolic Stroke
* *Cerebral Hemorrhage
3. Hemorrhagic Stroke
112
What is a thrombotic stroke?
a blood clot (thrombus) blocks blood flow to the brain
| causes ischemia
113
What is an embolic stroke?
a fatty plaque of cholesterol or a blood clot breaks away from somewhere else & flows into the brain where it blocks an artery
causes ischemia
114
What is a hemorrhagic stroke? Why is this particularly bad?
an aneurysm in the brain (break in a blood vessel)
you get an area of bleeding & the blood that is released is cytotoxic to cells...once these cells are killed they release their cell contents which are cytotoxic to other cells. Cyclical damage.
115
What is the significance of the tenurial notch in the tentorium cerebelli?
this is where the brainstem meets up with the cerebral hemispheres
116
What are the 3 cranial fossa & what sits in each of them?
Anterior Cranial Fossa: frontal lobe sits here
Middle Cranial Fossa: Temporal lobes sit here
Posterior Cranial Fossa: occipital lobe & cerebellum sits here
117
Where is the cribriform plate found? What goes thru this?
this is found in the ethmoid bone
| little tiny olfactory nerves from the olfactory bulb will pierce this & make their way into the nasal cavity
118
Where is the optic canal found? What goes thru here?
this is found in the sphenoid bone
| optic nerve
119
Where is the superior orbital fissure found? What goes thru here?
this is a tiny crack in the sphenoid bone
| V1, CN 3, 4, 6 goes thru here-->on their way to the extra ocular eye muscles
120
Where are the foramen rotundum & foramen ovale found? What do they allow the passage of?
they are both found in the sphenoid bone
| they allow V2 & V3 respectively to go thru.
121
Where is the foramen lacerum found? What goes thru here?
This is near the carotid canal. This is sorta in b/w the sphenoid, temporal, & occipital bones.
A bunch of cartilage fills in this space. An emissary vein is found here too.
122
Where is the carotid canal found? What runs thru here?
this runs thru the temporal bone. You can sorta see its opening near the foramen lacerum.
internal carotid artery is found here
123
Where is the internal acoustic meatus found? What runs thru here?
this is found in the temporal bone
CN 7 & 8 run thru this. 7 goes into the middle ear cavity & leaves via the stylomastoid foramen
8 goes into the ear & never leaves the skull.
124
What goes thru the jugular foramen? Where is this found?
it is located in b/w the temporal & occipital bones.
| this is where CN 9, 10, 11 are found
125
What is the pathway of CN 9 & 10?
they come from the medulla & pass thru the jugular foramen
126
What is the pathway of CN11?
it has its origin from some cell bodies in the upper cervical spinal cord. They pass up thru the foramen magnum & back down again thru the jugular foramen.
127
Where is the hypoglossal canal located? What pass thru there?
this opening is in the occipital bone.
| CN12 leaves the skull here.
128
The cranial nerves with the shortest/longest course are most susceptible to being damaged.
those with the longest course
129
WHere might an acoustic neuroma form? Which CNs could this potentially affect?
could form on CN8. This could end up affecting 5, 6, 7, 9, 10
130
T/F The cranial nerves exit the brainstem at a different spot than they exit the cranial cavity.
Sometimes true. Yes.
131
Which cranial nerve has the longest course & is therefore most susceptible to damage? What is its path?
Cranial Nerve 6.
passes thru a dural sleeve as it leaves the brainstem thru the pontomedullary jcn
passes thru the cavernous sinus
goes out via the superior orbital fissure
132
Aside from CN6, which other cranial nerves are particularly susceptible to damage?
CN3-5 b/c they have a long course in which they exit the brainstem in the posterior fossa & travel intradurally into the middle fossa where they leave the skull
133
T/F CN 7-12 exit the brainstem & the skull in the same place.
True. the posterior cranial fossa
| this makes them less susceptible to damage b/c they don't have as long of a course.
