Skull, Cranial Anatomy Flashcards
(113 cards)
1
Q
What are the 8 bones of the neural skull (neurocranium)?
A
2 parietal 2 temporal 1 frontal 1 occipital 1 sphenoid 1 ethmoid
2
Q
What re the 14 facial bones?
A
2 maxillae 2 palatine 2 nasal 2 inferior conchae 2 zygomatic bones 2 lacrimal bones 1 vomer 1 mandible
3
Q
What is the lambdoid suture?
A
The separation between the parietal/occipital and temporal/occipital bones
4
Q
What is the sagittal suture?
A
The separation between the two parietal bones
5
Q
What does the the anterior cranial fossa contain?
A
Inferior/anterior frontal lobes
6
Q
What does the middle cranial fossa contain?
A
Temporal lobes and serves to anchor the tentorial fold of the dura mater. It also contains the sella turcica (Turkish saddle) for the pituitary gland and many passages for nerves and vessels.
7
Q
What does the posterior cranial fossa contain?
A
Cerrebellum
Pons
Medulla oblongata
Foramen magnum
8
Q
What contains the cristae galli?
A
Ethmoid
9
Q
Where are the clinoid process and the sella turcica located?
A
On the sphenoid bone
10
Q
Where is the internal occipital ridge life?
A
In the occipital bone
11
Q
What bone contains the petrous ridge?
A
Temporal bone
12
Q
What are the sites of vulnerability that may be filed and compress the brain?
A
- Epidural space
- Subdural space
- Arachnoid granulations
13
Q
Where does the middle meaning artery enter the skull?
A
The foramen spinosum
14
Q
Where is the weakest point on the side of the skull
A
Pterion
15
Q
What are the consequences of an epidural hematoma?
A
- Depression of ant. Choroidal artery
- Compression of post. Cerebral artery
- Medial displacement of middle cerebral vessel and Sylvia point
- Compression of 3rd nerve leading to homolateral pupil dilation, ptosis, and 3rd nerve muscle palsy
- Herniation of cerebellum tonsil, depression of post. Inf. Cerebellar artery
16
Q
On which tract can an epidural hematoma impinge?
A
Cortico-spinal tract
17
Q
Difference between subdural and epidural hematoma?
A
Subdural is venous and epidural come from artery supply
18
Q
What are some things that can cause subdural hematoma?
A
Symptom of shaken baby syndrome
Roller coaster syndrome
(Hard shaking )
19
Q
What are the consequences of a stage 1 concussion?
A
Irregular protein and neurofibillary tangles
Headaches, depression, etc.
20
Q
What are the consequences of a stage 2 concussion?
A
More tangles (brain damage)
When in frontal cortex, associated with headaches, depression, mood swings, explosive tendencies, etc
21
Q
What are the consequences of a stage 3 concussion?
A
More tangles than stage 2.
Damage to frontal cortex, associated with problems in judgement, planning etc…
22
Q
What are the consequences of a stage 4 concussion?
A
End stage Disease with paranoia, dementhia, aggressive tendencies, etc.
23
Q
How does CSF exit the 4th ventricle?
A
Foramen of Luschka
Foramen of Magendie
24
Q
What does the anterior fontanelle separate?
A
The single frontal and the two parietal bones
25
What does the sphenoidal fontanelle separate?
The area between the sphenoid, parietal, temporal, and frontal bones
26
What does the mastoid fontanelle separate?
The area between the temporal, occipital and parietal bones
27
Is pulsation of a fontanelle normal?
Yes
28
What can indicate pathology on a fontanelle?
Deformations such as a bulge or depression
29
What replaces the fontanelles and by when?
By 18 to 24 months the fontanelles are replaced through intramembranous ossification
30
What are the sutures of the neurocranium formed by?
The closures of the fontanelles
31
What can premature closure of fontanelles lead to?
Cranio-facial abnormalities such as Crouzon syndrome
32
When is the growth of the facial skull usually complete?
When all teeth have emerged.
33
What are the 3 foramina on the face that the trigeminal nerve exits from?
V1: supra-orbital
V2: infra-orbital
V3: mental foramina
34
What bone can be mistaken for a fracture in posterior view?
The Wormian bone
35
What forms the anterior fossa??
Frontal, ethmoid and the body and lesser wings of the sphenoid bone
36
Where does the butterfly shaped middle fossa of the skull extend to?
From the crest of the sphenoid bone anteriorly, the greater wings of the sphenoid, and the squamous parts of the temporal bones laterally, and the petrous portion of the temporal bones posteriorly.
37
What are the boundaries of the posterior fossa?
Anterior midline by the dorsum sellae of the sphenoid bone and laterally by the petrous ridge and mastoid region of the temporal bone.
The base is largely composed of the occipital bone and contains the foramen magnum for the exit of the spinal cord.
38
What are the points of attachment for the dura mater?
The crista galli
Clinoid processes
Petrous portions of the temporal bone
Internal occipital ridge
39
The pterion defines the union of what 4 bones ?
The parietal, frontal ,greater wing of the sphenoid and the squamous part of the temporal bone
40
Why is the pterion a clinically important landmark?
Because it overlies the anterior branch of the middle meningeal artery on the internal aspect of the skull
41
What part of the temporal bone is thin and relatively easy to fracture?
The squamous part
42
What restrains the movement of the brain?
The dural folds
43
What are the two most important dural folds that restrain brain movement?
Falx cerebri (between the two cerebral hemispheres)
The tentorium cerebelli
44
Where does the falx cerebro extend from?
The falx begins at the crista galli and extends as a crescent-shaped fold to it termination on the internal occipital ridge
45
Where does the tentorium cerebelli span from?
Emerges as a dural fold from the clinoid processes of the sphenoid and each petrous ridge of the temporal bone to meet the falx cerebri
Note: a midline hiatus allows for the passage of the brain stem
46
What separates the cerebrum above from the cerebellum?
Tentorium cerebelli
47
What covers the pituitary fossa?
A small fold, the dosum sellae (compared to tentorium and falx)
48
Where is the epidural space and what can lead to this space being filled?
Between the periosteal layer of the dura mater and the skull
Fractures of the skull, specially in the area of the meningeal vessels, can lead to this becoming a real space filled with blood
49
Where is the sub-dural space located and what can lead to this space being filled?
Between the arachnoid and dura mater
The major veins of the sub-arachnoid space must traverse this space to access the superior sagittal sinus and are vulnerable to tearing. This sinus is one of many venous channels that are located between 2 layer of dura.
50
Where are the veins that traverse the sub-arachnoid space heading?
Superior sagittal sinus
51
Where is the squamous portion of the temporal bone most vulnerable at?
At and around the pterion
52
Where do the meninges received their blood supply from?
The meningeal blood vessels which receive blood from the external carotid artery and enter the skull through the foramen spinosum (middle meningeal artery)
53
If one or both lamina o the skull are fractured such that the dura is torn in the region of the meningeal artery, what can happen?
The vessel will rupture and arterial blood will accumulate in the epidural space resulting in an epidural hematoma.
54
Why does arterial blood form a localized swelling that displaces the brain?
Because the outer layer of the dura is tightly adherent to the bone
55
How is the extend of hemadural trauma genereally judged?
```
By levels of consciousness:
Alert
Stupor
Partial coma
Deep Coma
```
56
What is the fatality of a hematoma is not rapidly treated?
Up to 50% fatal
57
What is commonly seen in a person who suffered from a hematoma?
A lucid interval after the injury followed by a rapid deterioration
58
What characteristic does a epidural hematoma show on a CT scan?
A lenticular shape
59
When displacement of the temporal lobe of the brain is severe enough in an epidural hematoma, what can occur?
The lobe ca herniate over the tentorium onto the brain stem compressing cranial nerve III (oculomotor)
This results in:
Oculomotor palsies
Papillary dilation
Ptosis (drooping eyelid)
Disruption of the cortico-spinal tract leading to motor deficits
60
Where is the subdural space a real space?
At the point where the subarachnoid veins enter the superior sagittal sinus
61
How does a subdural hematoma occur?
Trauma that causes a shear force that damages a vein as it traverses the sub-dural space. Venous blood will accumulate in the subdural space
62
How does a subdural hematoma look on a CT and how deadly is it?
Bright in the CT
Roughly 60% fatal (especially those in a coma). Extend of damage is determined by venous pressure.
63
How can a hematoma present on a patient?
Symptoms can be intermittent and include:
Headaches
Lethargy
Slurred speech
64
What is a contusion?
A tear in the fabric of the brain that damages blood vessels, glial cells, and neurons and usually leads to motor and sensory deficits
E.g. Trauma-induced Parkinson's disease
65
What can lead to Parkinson's disease?
Contusions
E.g. Muhammad Ali
66
Is the brain sensitive to pain or pressure?
No?
67
What does dilation of blood vessels and irritation of the dura mater cause?
Debilitating headaches
68
What nerves innervate the dura mater in the cranium?
V, IX and X
69
What is chronic traumatic encephalopathy (CTM)?
Accumulation of "minor concussions" which have a cumulative effect that lead to significant impairment. This can only be diagnosed post-mortem by the presence of neurofibrillary tangles.
70
Why does a loss of consciousness after a head injury require a neurological examination?
Because more severe types of concussions are accompanied by an extended period of unconsciousness with damage extending into the realm of hematomas.
71
What is a serious consequence of head trauma that may skip over the Glasgow scale?
Leakage of CSF
72
What are some high risk for bleeding signs where Ct is recommended?
1- a Glasgow score less than 15 2hours after injury
2- skull depression
3- basal skull fracture [blood behind the eardrum]
4- "raccoon eyes"
5- CSF leaking from nose or ears
6- Battle's sign (bruising behind the ear)
73
What are the criteria in the Glasgow scale?
1. Eye opening
(spontaneous 4, to loud voices 3, to pain 2, none 1)
2. Verbal response
(Oriented 5, confused and disoriented 4, inappropriate words 3, incomprehensible words 2, none 1)
```
Moto response
(Obeys commands 6, localizes pain 5, withdraws from pain 4, abnormal flexión posturing 3, extensor posturing 2, none 1)
```
74
What are the 4 ventricles?
2 lateral, and a singled 3rd and 4th
75
Where do the anterior and posterior horns of the lateral ventricles extend to?
Anterior: into the frontal cerebral hemispheres
Posterior: extend into the temporal lobes
76
What connected the 3rd and fourth ventricle?
Iter (aka aqueduct of Sylvius)
77
Where is CSF produced?
In the choroid plexuses
78
Where does the CSF produced in the lateral ventricles pass through to reach the 3rd ventricle?
2 foramina of Monroe
79
How does the CSF circulate through the subarachnoid space?
Pulsation of the cerebral blood vessels
80
What are the arachnoid granulations
One way valves where excess CSF exits into the superior sagittal sinus from the subarachnoid space.
81
Why do the arachnoid granulations have poor design?
They shut down when venous pressure exceeds that in the subarachnoid space. This can cause the ventricles to expand
82
How much CSF does the sub-arachnoid space hold?
150ml whereas 300 ml of CSF is produced each day (min)
83
What can blockage of the iter result in?
Hydrocephalus due to blockage of CSF and build up in the lateral and third ventricles
84
What does expansion of the ventricles compress in hydrocephalus?
The thalamus, basal ganglia, and the internal capsul
85
What are the symptoms of hydrocephalus and its treatment?
Symptoms: progressing headache, nausea, loss of balance, difficulty walking, etc
Treatment: inserting a shunt that passes the CSF from the ventricles to the venous system
86
Any head trauma that results in the leakage of a clear fluid from the nose or ears is?
Very serious bruh
87
How is pneumocephalus caused?
A fracture of the frontal sinus that allows the CSF to escape though the nose
88
What is a symptom of pneumocephalus?
Severe headaches
89
What veins of the superficial temporal veins have direct connections to the venous sinuses?
Emissary veins
90
What are the four distinct but inter-connected venous systems of the head?
1. Superficial temporal veins
2. Diploic veins
3. Venous sinuses
4. Major veins of the subarachnoid space
91
Where are the diploic veins?
Ramify between the 2 laminate of the skull
92
Where are the venous sinuses?
Within the dura mater to drain the brain (they form channels)
93
What are the major veins of the subarachnoid space direct connections to?
Capillary networks in the Pía mater that receive blood from the brain
94
Where do the superior cerebral veins drain into?
Where do the inferior cerebral veins drain into?
1. The superior sagittal sinus
| 2. The inferior sagittal sinus and then the great vein (of Galen) and the straight sinus)
95
Where do the blood from both systems merge? (Sup and inf. Sagittal sinuses)
At the confluens of the sinuses in the occipital region
96
Where does the blood go after meeting in the confluens?
The blood courses through the transverse and sigmoid sinus on each side to exit the skull in the internal jugular vein
97
The direction of blood vein in the head is dependent o what??
The venous pressure because the systems are all interconnected. It is influenced by posture and by the pressure in the CSF
98
What is the most clinically significant sinus because of its location?
The cavernous sinus
99
How can infections of the face move into the cavernous sinus where they are difficult to treat?
Through the interconnection of the facial, angular, ophthalmic veins with the cavernous sinus
100
What are the characteristics of a pulsating exophthalmos?
1. The eyeball protrudes and retracts with the heartbeat
2. A pulse in the orbit can be detected and blocked by carotid compression
3. The flowing of blood (Bruit) can be detected with a stethoscope
101
How can a pulsating exophthalmos occur?
By wearing of the wall of the internal carotid artery. This can lead to the formation of an aneurism within the cavernous sinus. If the aneurysm bursts, then the blood pressure in the sinus will be that of the arterial system. This causes a swelling of the ophthalmic veins in the orbit.
102
By what sinus does the carotid artery pass on the way to the brain?
The cavernous sinus
103
What can cause interference to the cavernous sinus and the course of neighboring nerves because of its location?
Pituitary tumor because the sinus is located on either side of the pituitary gland
104
What is a leading cause of hypertension?
Hemorrhagic stroke
105
What are the two types of hemorrhagic strokes?
Intracerebral (within the brain)
| Subarachnoid
106
How does a hemorrhagic stroke occur?
From a weakened vessel that ruptures and bleeds into the surrounding brain. This typically occurs at either an aneurism or an arteriosvenous malformation (AVM)
107
What artery is directly continuous with the middle cerebral artery (MCA)
The internal carotid artery
108
What are the branches of the MCA that supply the region of the internal capsul and thalamus?
Striate arteries
109
What are the common sites for aneurysm in the Circe of Willis?
1. Anterior communicating artery (30-35%)
2. Bifurcation of the internal carotid and posterior communicating artery (30-35%)
3. Bifurcation of Middle cerebral artery (20%)
4. Basilar artery bifurcation (5%)
5. Remaining posterior circulation arteries (5%)
110
What are the symptoms of an aneurysm the circle of Willis?
Tend to be asymptomatic
When they rupture they cause blinding headaches and can be fatal
111
An embolism that dislodges from a thrombosis in the carotid artery will pass upwards to block what arteries?
The striate arteries
112
The ischemia from the blockage of the striate arteries causes what?
Will damage the axons passing through the internal capsul thus causing a paralysis and loss of sensation on the opposite side of the body.
113
What is thalamic pain syndrome (Dejerine-Roussy syndome) that can occur after ischemia from a striate artery blockage?
Extreme pain with no peripheral source
