TBL 34 Flashcards
(92 cards)
1
Q
What is the floor of the cranial cavity?
The _____-shaped floor is formed by _______.
A
cranial base is the floor of the cranial cavity
from anterior to posterior, the bowl-shaped floor is formed by three cranial fossae.
2
Q
What forms the anterior cranial fossa (3)?
A
anterior cranial fossa is formed by the frontal bone
anterolaterally, cribriform plate of the ethmoid bone in the midline, and the lesser wings of the sphenoid bone posteriorly.
3
Q
What forms the posterior edges of the lesser wings? Also (Answer) terminates MEDIALLY as _______.
A
the sphenoidal crests are the posterior edges of the lesser wings and terminate medially as the anterior clinoid processes.
4
Q
Where are the frontal lobes of the cerebral hemispheres lodged?
A
the frontal lobes of the cerebral hemispheres are
lodged in the anterior cranial fossa.
5
Q
On the skull, identify the cribriform plate of the ethmoid bone and the frontal bone in the
anterior cranial fossa. Find the lesser wings of the sphenoid bone, the sphenoidal crests,
and the anterior clinoid processes.
A
Bone (In Lab)
6
Q
the middle cranial fossa is composed of (4)- centrally/laterally.
A
the middle cranial fossa is composed centrally by
the body of the sphenoid bone and laterally by the greater wings of the sphenoid bone plus the
squamous and petrous parts of the temporal bone.
7
Q
What area of skull accommodates the pituitary gland?
A
the hypophyseal fossa in the body
of the sphenoid bone accommodates the pituitary gland.
8
Q
Discuss the dorsum sellae.
A
the dorsum sellae denotes the square posterior wall of the body of the sphenoid bone from which the posterior clinoid processes project superiorly.
9
Q
Where are the superior orbital fissures located and what’s their function?
A
superior orbital fissures are located beneath the sphenoidal crests and provide conduits between the middle cranial fossa and orbit.
10
Q
the trigeminal ganglion resides in the (structures) and CN V1 traverses the (structure) into the (structure).
A
the trigeminal ganglion resides in the middle cranial fossa
and CN V1 traverses the superior orbital fissure into the orbit.
11
Q
What’s the origin of the frontal nerve and nasociliary nerve?
A
CN V1 generates the frontal nerve
the nasociliary nerve is another orbital branch of the ophthalmic nerve.
12
Q
TEMPORAL lobes of the cerebral hemispheres
are lodged in the (structure).
A
temporal lobes of the cerebral hemispheres
are lodged in the middle cranial fossae.
13
Q
On the skull, locate the superior orbital fissures, body of the sphenoid bone, hypophyseal
fossa and dorsum sellae in the middle cranial fossa.
A
Bone (In lab)
14
Q
What form the posterior cranial fossa (2)?
A
the posterior cranial fossa is formed mostly by the
occipital bone and the petrous temporal bone contributes to its anterolateral sides.
15
Q
Identify the jugular foramen and foramen magnum and clivus.
Where is the clivus located?
A
jugular foramen and locate the foramen magnum and the clivus between the foramen magnum and the dorsum sella.
16
Q
Where does CN XII exit, innervation, serves to transport (fibers)?
A
CN XII exits the posterior cranial fossa via the hypoglossal canal
it innervates the skeletal muscles of the tongue and transports somatic motor fibers of C1 to the
thyrohyoid and geniohyoid muscles.
17
Q
medulla oblongata and pons of the brainstem
reside (structure).
the midbrain of the brainstem extends from the (structure) into the (structure).
A
medulla oblongata and pons of the brainstem
reside on the clivus
the midbrain of the brainstem extends from the posterior
cranial fossa into the middle fossa.
18
Q
(2-Structures) reside in the posterior cranial fossa.
A
occipital lobes of the cerebral hemispheres and the cerebellum reside in the posterior cranial fossa.
19
Q
On the skull, find the squamous and petrous parts of the temporal bone, the occipital bone,
foramen magnum, clivus, hypoglossal canal and jugular foramen in the posterior cranial
fossa.
A
Bone (In lab)
20
Q
Discuss relation of cranial and spinal meninges.
A
the brain is covered by cranial meninges that are continuous with the spinal meninges of the spinal cord at the foramen magnum.
21
Q
Discuss how and why the arachnoid is in its relation against the dura?
Discuss the tissue of the pia relation to brain.
A
the arachnoid is held against the dura by CSF in the subarachnoid space
the pia, several layers of fibroblasts linked by tight junctions and separated by loose connective tissue, adheres to the surface of the brain.
22
Q
Origin of middle meningeal artery and where does it enter (how)?
A
middle meningeal artery arises from the maxillary artery
in the infratemporal fossa and enters the middle cranial fossa via the foramen spinosum.
23
Q
Discuss what forms the foramen spinosum and grooves.
A
locate the foramen spinosum and grooves created by the middle meningeal artery and its anterior and posterior branches.
24
Q
veins accompanying the middle meningeal arterial branches traverse the (structure) and empty into the (structure).
A
veins accompanying the middle meningeal arterial branches traverse the foramen spinosum and empty into the pterygoid venous plexus.
25
What fibers convey somatic sensations from the cranial dura?
CNs V1, V2 and V3 and peripheral fibers from the
| DRG at C2 and C3 convey somatic sensations from the cranial dura.
26
dural pain is referred to the (regions) supplied by nerves (provide examples).
dural pain is referred to the cutaneous or mucosal regions supplied by the nerves (e.g., the scalp or skin of the face or neck, or the nasal or oral mucosae).
27
discuss the periosteal layer of the cranial dura and what forms the dural inholdings and dural venous sinuses?
the periosteal layer of the cranial dura adheres
to the inner surface of the cranium and the meningeal layer separates from the periosteal layer to form dural infoldings and dural venous sinuses.
28
superior cerebral veins on the surface of the brain drain into the (structure).
superior cerebral veins on the surface of the brain drain into the superior sagittal sinus.
29
superior sagittal sinus resides in the (structure)
the dural venous sinuses are lined by _____.
superior sagittal sinus resides in the cerebral falx
the dural venous sinuses are lined by endothelium.
30
Describe the cerebral falx and spatial relation function.
cerebral falx is a vertical infolding of the meningeal
| dura that partially separates the bilateral cerebral hemispheres.
31
(Portion) of the cerebral falx attaches to the cerebellar tentorium- describe cerebellar tentorium.
its (Portion of the cerebral falx) bony attachment enables the cerebellar tentorium to
posteroinferior portion of the cerebral falx attaches to the cerebellar tentorium, a horizontal dural infolding.
its bony attachment enables the cerebellar tentorium to cover the posterior cranial fossa
32
the tentorium separates (structures)
the tentorium separates the occipital lobes of the cerebral hemispheres from the cerebellum.
33
observe the tentorial notch in the cerebellar tentorium
Informational
34
the midbrain of the brainstem traverses the (structure) as it passes from (structure) into the (structure)
the midbrain of the brainstem traverses the tentorial
| notch as it passes from the posterior cranial fossa into the middle cranial fossa.
35
like the superior sagittal sinus, the inferior sagittal sinus
resides in the (structure) and its (fxn) to then form (structure).
like the superior sagittal sinus, the inferior sagittal sinus
resides in the cerebral falx.
it unites with the great cerebral vein, which drains the deep cerebral veins, to form the straight sinus.
36
the confluence of sinuses drains into the (structure) that course along the (spatial relation and structure) to join the (structure) at the (spatial relation and structure).
the confluence of sinuses drains into the right and left
transverse sinuses that course along the posterolateral attached margins of the cerebellar tentorium to join the sigmoid sinuses at the posterior aspect of the petrous temporal bones.
37
the sigmoid sinuses course within (structures) and join the (structures) at the (structure).
the sigmoid sinuses course within deep grooves in
| the temporal and occipital bones and join the IJVs at the jugular foramina
38
Describe the cavernous sinuses (lined by and location).
the cavernous sinuses are plexuses of endothelium-lined dural venous channels on the lateral sides of the body of the sphenoid bone.
39
(structures) are the primary tributaries of the cavernous sinuses that drain via the (structure) into the (structures)
the superior ophthalmic veins are the primary tributaries of the cavernous sinuses that drain via the inferior petrosal sinuses into the sigmoid sinuses.
40
the inferior petrosal sinuses also drain into the (structure) that traverses the (structure) to join the (structure).
Discuss the relation to metastasis and distant/near tumors. (provide examples)
the inferior petrosal sinuses also drain into the basilar plexus that traverses the foramen magnum to join the internal vertebral venous plexus of the spinal cord.
metastasis from distant tumors (e.g., prostate or cervical cancer) to the brain occurs via this venous pathway.
41
TINY EMISSARY veins pierce the floor of the middle cranial fossa (fxn).
tiny emissary veins pierce the floor of the middle cranial fossa to allow additional drainage of the cavernous sinuses into the pterygoid venous plexus.
42
On the skull, locate the grooves for the middle meningeal artery, the transverse sinuses,
and the sigmoid sinuses.
Bone (In lab)
43
How can facial infections spread to the cavernous sinus or to the pterygoid venous plexus?
facial vein can travel up to the inferior or superior ophthalmic vein--> cavernous sinus. Deep Facial vein branch from the facial vein---> pterygoid plexus.
Because of these connections, an infection of the face may spread to the cavernous sinus and pterygoid venous plexus.
44
How does thrombophlebitis of the cavernous sinus typically occur?
In persons with thrombophlebitis of the facial vein, pieces of an infected thrombus may extend into the cavernous sinus, producing thrombophlebitis of the cavernous sinus.
45
Why can a fracture of the pterion be life threatening?
Fracture of the pterion can be life threatening because
it overlies the frontal branches of the middle meningeal
vessels, which lie in grooves on the internal aspect of the lateral wall of the calvaria.
A hard blow to the side of the head may fracture the thin bones forming the pterion producing a rupture of the frontal branch of the middle meningeal artery or vein crossing the pterion. The resulting hematoma exerts pressure on the underlying cerebral cortex.
An untreated middle meningeal vessel
hemorrhage may cause death in a few hours.
46
How do the sources and locations of extravasated blood differ with an epidural hematoma, a dural border hematoma, and a subarachnoid hemorrhage?
Note: blood extravasation - the leakage of blood from a vessel into tissues surrounding it; can occur in injuries or burns or allergic reactions. extravasation - the process of exuding or passing out of a vessel into surrounding tissues; said of blood or lymph or urine.
Extradural (epidural) hemorrhage is arterial in origin.
Blood from torn branches of a middle meningeal
artery collects between the external periosteal layer of
the dura and the calvaria. The extravasated blood strips the dura from the cranium.
A dural border hematoma is commonly called a subdural
hematoma; however, this term is a misnomer
because there is no naturally occurring space at the dura– arachnoid junction. Hematomas at this junction are usually caused by extravasated blood that splits open the dural border cell layer. The blood does not collect
within a preexisting space, but rather creates a space at the dura–arachnoid junction . Dural border hemorrhage
is typically venous in origin and commonly results from tearing a superior cerebral vein as it enters the superior sagittal sinus.
Subarachnoid hemorrhage is an extravasation of blood,
usually arterial, into the subarachnoid space.
Most subarachnoid hemorrhages result from rupture of a
saccular aneurysm (sac-like dilation on the side of an artery), such as an aneurysm of the internal carotid artery
47
the forebrain, midbrain, and hindbrain create three (things) and where?
the forebrain, midbrain, and hindbrain create three
| dilations in the cephalic end of the neural tube.
48
the forebrain consists of (2) and discuss.
the forebrain consists of the telencephalon that forms the cerebral hemispheres and the diencephalon that forms the optic vesicles, hypothalamus, infundibular stalk, and pars nervosa.
49
the straight sinus runs along the (structure and area) to the (structure) and joins the (structure).
the straight sinus runs along the midline attachment of the cerebral falx to the cerebellar tentorium and joins the confluence of sinuses.
the superior sagittal sinus also empties into the confluence of sinuses.
50
Discuss the draining of the confluence of sinuses.
the confluence of sinuses drains into the right and left
transverse sinuses that course along the posterolateral attached margins of the cerebellar tentorium to join the sigmoid sinuses at the posterior aspect of the petrous temporal bones.
51
Discuss the course of the sigmoid sinuses and (structure) it joins and where.
the sigmoid sinuses course within deep grooves in
| the temporal and occipital bones and join the IJVs at the jugular foramina
52
Describe the cavernous sinuses (type of tissue and location).
the cavernous sinuses are plexuses of endothelium-lined dural venous channels on the lateral sides of the body of the sphenoid bone.
53
What are the primary tributaries of the cavernous sinuses and what do (answer) drain into?
the superior ophthalmic veins are the primary tributaries of the cavernous sinuses that drain via the inferior petrosal sinuses into the sigmoid sinuses.
54
Discuss the inferior petrosal sinuses (drain location and join a structure).
the inferior petrosal sinuses also drain into the basilar plexus that traverses the foramen magnum to join the internal vertebral venous plexus of the spinal cord.
55
metastasis from distant tumors (e.g., prostate or cervical cancer) to the brain occurs via _____.
metastasis from distant tumors (e.g., prostate or cervical cancer) to the brain occurs via this venous pathway.
56
a
tiny emissary veins (unlabeled) pierce the floor of the middle cranial fossa to allow
additional drainage of the cavernous sinuses into the pterygoid venous plexus.
57
On the skull, locate the grooves for the middle meningeal artery, the transverse sinuses,
and the sigmoid sinuses.
Bone (In lab)
58
the forebrain, midbrain, and hindbrain create what?
the forebrain, midbrain, and hindbrain create three
| dilations in the cephalic end of the neural tube.
59
the forebrain consists of the (structure) that forms the (structures)
the diencephalon forms the (structures).
the forebrain consists of the telencephalon that forms the cerebral hemispheres
the diencephalon forms the optic vesicles, hypothalamus, infundibular stalk, and pars nervosa.
60
the primitive midbrain (aka ______ ) forms the (structure).
the hindbrain consists of the (structures).
the primitive midbrain (aka mesencephalon) forms the midbrain of the brainstem
the hindbrain consists of the metencephalon and myelencephalon.
61
the metencephalon forms the (structures)
the myelencephalon forms the (structure)
the metencephalon forms the pons of the brainstem and the cerebellum
the myelencephalon forms the medulla oblongata of the brainstem.
62
5. From Exencephaly, Anencephaly and Craniorachischisis, pp. 311 and Figure 18.37, pp. 312
(ME): How do closure defects associated with exencephaly and craniorachischisis differ?
How can these defects be prevented?
Exencephaly is characterized by the failure of the cephalic part of the neural tube to close. As a result the vault of the skull does not form, leaving the malformed brain exposed. Later this tissue degenerates, leaving a mass of necrotic tissue- anencephaly although brainstem is intact.
In some cases the closure defect of the neural tube extends caudally into the spinal cord and the abnormality is called craniorachischisis. There is anencephaly, but with a large defect involving the spinal cord.
63
the neural tube in the telencephalon forms the (structures).
the neural tube in the telencephalon forms the
| lateral (1st and 2nd) ventricles and the 3rd ventricle in the diencephalon.
64
What forms the narrow/wide cerebral aqueduct?
the neural tube in the mesencephalon forms the narrow cerebral aqueduct
65
What forms the 4th ventricle?
the neural tube in the metencephalon and myelencephalon forms the 4th ventricle.
66
the choroid plexus project into (structures and function-rate).
the choroid plexus projecting into the ventricles produces 500 ml CSF/day.
67
Discuss the course of CSF.
CSF flows inferiorly from the lateral ventricles into the 3rd ventricle and via the cerebral aqueduct into the 4th ventricle that directs CSF into the central canal of the spinal cord or into the subarachnoid space of the
cerebral hemispheres, cerebellum, and spinal cord.
68
What creates the subarachnoid cisterns?
enlargements of the subarachnoid space along the inferior surface of the brain create subarachnoid cisterns
69
Discuss the function of the subarachnoid cisterns.
the cisterns prevent compression of the cranial nerve roots and the cerebral arterial circle against the bony cranial base.
70
Define arachnoid granulations.
arachnoid granulations are protrusions of the arachnoid through the meningeal dura mainly in the lumen of the superior sagittal sinus.
71
What covers the arachnoid granulations?
How is CSF volume regulated?
the sinus endothelium covers the arachnoid granulations
CSF volume is regulated by the absorption of CSF across the endothelium into the venous blood of the sinus.
72
Describe and discuss the ependyma (tissue type and location)
ependyma (ciliated, simple cuboidal epithelium) lines the ventricular system of the brain and the central canal of the spinal cord.
73
Discuss glial cells and their proportion in numbers compared to neurons of the CNS.
glial cells (i.e., the ependyma, microglial cells, astrocytes, andvoligodendrocytes) outnumber the neurons of the CNS by 10:1.
74
Discuss the function of oligodendrocytes.
oligodendrocytes support and myelinate the axons of the CNS
75
Define the role of microglial cells.
Microglia, as their name implies, are the smallest glial cell. They act as phagocytes and remove CNS debris, protect the brain from invading microorganisms, and constitute the brain’s immune system.
76
Discuss the formation of the blood-brain barrier.
foot processes of the astrocytes cover most of the capillary endothelial basement membrane, and with tight junctions that link the contiguous endothelial cells, form the blood-brain barrier.
77
Where does obstruction usually occur during obstructive hydrocephalus and why do the calvaria expand?
Overproduction of CSF, obstruction of CSF flow, or
interference with CSF absorption results in excess
fluid in the cerebral ventricles and enlargement of the head, a condition called obstructive hydrocephalus
Although an obstruction can occur any place, the blockage usually occurs in the cerebral aqueduct or an interventricular foramen.
The excess CSF dilates the ventricles, thins the cerebral
cortex, and separates the bones of the calvaria in infants. In infants, the internal pressure results in expansion of the brain and calvaria because the sutures and fontanelles are still open.
78
Why do glial cells form most intracranial tumors, (i.e., gliomas)?
Unlike neurons, glia retain a postnatal ability to divide and are the source of most intracranial tumors, known as gliomas.
79
How do astrocytes respond to CNS injury?
In response to CNS injury, astrocytes undergo
| mitosis and are the main source of gliotic scar tissue (gliosis), which may impede neural regeneration.
80
What is the function of the blood-brain barrier?
The BBB restricts passage of large molecules from the capillary lumen to the surrounding tissue, but it allows free passage of gases and selected molecules such as glucose. The barrier protects neurons in the CNS from toxins, drugs, and other potentially harmful substances that may be in the bloodstream.
81
Discuss the origin of the vertebral arteries and the route taken therefore.
the vertebral arteries arise from the subclavian arteries
| and ascend in the transverse foramina of the cervical vertebrae.
82
Discuss the route of the vertebral arteries.
vertebral arteries perforate the dura and arachnoid near the foramen magnum to enter the subarachnoid space of
the spinal cord and continue through the foramen magnum into the subarachnoid space of the medulla oblongata.
83
Discuss the formation of the basilar artery. The basilar artery divides into (Structure and location).
the vertebral arteries unite at the inferior border of the
pons to form the basilar artery that divides into left and right posterior cerebral arteries at the superior border of the pons.
84
Return to Figure 7.9 (B), pp. 831 and the skull to identify the carotid canal on the external
surface of the petrous temporal bone. Surmise the internal carotid artery passes through the
canal to enter the middle cranial fossa.
Bone (In lab)
85
Discuss the route out the internal carotid artery towards the ANTERIOR clinoid process.
the internal carotid artery courses anteriorly along the
| floor of the middle cranial fossa toward the anterior clinoid process.
86
discuss the route taken by the internal carotid artery in relation to the ANTERIOR clinoid process.
the internal carotid artery makes a 180⁰ turn under the anterior clinoid process and pierces the dura and arachnoid to enter the subarachnoid space (i.e., it becomes the cerebral part of the internal carotid).
87
the cerebral parts of the internal carotid arteries
| terminally bifurcates into the (structures).
the cerebral parts of the internal carotid arteries
| terminally bifurcates into the anterior and middle cerebral arteries.
88
Discuss the anterior communicating artery and the posterior communicating arteries (what they unite/join).
the anterior communicating artery unites the bilateral anterior cerebral arteries and the posterior communicating arteries join the terminal ends of the internal carotid arteries to the bilateral posterior cerebral arteries.
89
Discuss the function of the the cerebral arterial circle (of Willis).
the cerebral arterial circle (of Willis) on the inferior
surface of the midbrain creates anastomoses between branches of the basilar artery and the left and right internal carotid arteries.
90
Why are the normal anastomoses between the cerebral arteries unable to compensate for arterial obstruction by a
cerebral embolism?
Branches of the three cerebral arteries anastomose
with each other on the surface of the brain.
However, if a cerebral artery is obstructed by a cerebral
embolism (e.g., a blood clot), these microscopic anastomoses are not capable of providing enough blood for the area of cerebral cortex concerned.
91
What is the typical cause of an ischemic stroke and what is its cardinal symptom?
What is a berry aneurysm and where does it commonly occur?
How does hemorrhagic stroke differ from ischemic stroke?
An ischemic stroke denotes the sudden development
of focal neurological defi cits that are usually related to
impaired cerebral blood flow. An ischemic stroke is
generally caused by an embolism in a major cerebral artery. The cardinal feature of a stroke is the sudden
onset of neurological symptoms.
Hemorrhagic stroke follows the rupture of an artery or a
saccular aneurysm, a sac-like dilation on a weak part of the arterial wall.
The most common type of saccular aneurysm is a berry aneurysm, occurring in the vessels of or near the cerebral arterial circle and the medium arteries at the base of the brain.
92
How do the affects of interrupted blood flow to the brain differ after 30 sec, 1-2 minutes, and 5 minutes?
What are the symptoms of TIAs and why does their occurrence increase the risk of other vascular disorders?
An interruption of blood supply for 30 sec alters a person’s brain metabolism.
After 1–2 min, neural function may be lost.
after 5 min, lack of oxygen (anoxia) can result in cerebral infarction.
Transient ischemic attacks (TIAs) refer to neurologic
symptoms resulting from ischemia.
The symptoms of TIA may be ambiguous: staggering, dizziness, light-headedness, fainting, and paresthesias. Persons with TIAs are at increased risk for myocardial infarction and ischemic stroke.
