week 2 components of intracranial vault Flashcards
1
Q
components of the intracranial vault
A
- brain 80-85%
- blood 5-10%
- CSF 10-15%
2
Q
arteries that supply blood to the brain
A
- B/L carotid arteries
- B/L vertebral arteries
3
Q
left carotid artery arises from
A
aortic arch
4
Q
right carotid artery arises from
A
innominate artery
5
Q
internal carotid artery enters where and supply what
A
- enters base of the skull
- supplies circle of Willis and eye via ophthalmic artery
- ultimately bifurcates into the anterior and middle cerebral arteries
6
Q
external carotid artery where in the skull
A
remains superficial to the skull
7
Q
flow of blood through the brain (anterior and posterior)
A
- posterior circulation – aorta > subclavian > vertebral > basilar > posterior structures and cervical spinal cord
- anterior circulation – aorta > carotid > internal carotid > circle of willis > cerebral hemispheres
8
Q
venous system drainage flow
A
- venous blood drains into the venous sinuses which lie between the layers of the dura mater and drain into the internal jugular vein
9
Q
venous system
A
- sinuses are valveless
- blood can flow back and forth
- pressure within them is negative (air embolism)
- little influence by the autonomic nervous system
10
Q
meninges 3 layers
A
- covers the brain and spinal cord
- dura mater
- arachnoid mater
- pia mater
11
Q
pia mater
A
- anchored to the brain by astrocytes which form the BBB
- allows for passage and transport of small molecules, lipophilic molecules, passive transport of glucose, active transport of amino acids
-prevents large molecules (dopamine) and charged (ionized) molecules
12
Q
arachnoid mater
A
- CSF circulates in the subarachnoid space (between arachnoid and pia mater)
- contains the blood supply to the brain
13
Q
dura mater
A
- consists of the outer ( endosteal layer) and inner (meningeal layer)
- dural sinuses are between these layers
- drains CSF
14
Q
epidural hematoma
A
- bleeding between skull and dura mater
- does not cross suture line
- arterial blood (meningeal arteries)
- fast onset of bleeding
15
Q
subdural hematoma
A
- bleeding between dura and arachnoid mater
- venous blood
- usually from tears in bridging veins
- slower onset
16
Q
subarachnoid hemorrhage
A
- SAH is a neurological emergency
- hemorrhage in the subarachnoid space (between arachnoid membrane and the pia mater)
- less common but an important cause of stroke
- usually from ruptured cerebral aneurysm
17
Q
lateral ventricles of the brain
A
2 lateral ventricles which are within the cerebral hemispheres and communicate with the 3rd ventricle through the foramen of monroe
18
Q
3rd ventricle of the brain
A
- inside the substance of the thalamus (in diencephalon), dividing it to 2 lateral parts the floor of the ventricle is the optic chiasm
19
Q
4th ventricle of the brain
A
- communicates with the 3rd ventricle via the aqueduct of sylvius
- lies anterior to the cerebellum (between pons and cerebellum)
- has a connection to the subarachnoid space through the median foramen of Magendie and 2 lateral foramen of luschka
20
Q
CSF
A
- produced by the choroid plexus
- surrounds brain and spinal cord
- 500 cc produced / 24 hrs
- total volume 150 cc
21
Q
CSF flow
A
- L & R ventricles > foramen of monro > third ventricle > aqueduct of sylvius > fourth ventricle > foramen of luschka > subarachnoid space & spinal cord
- each ventricle has a choroid plexus (site of production)
22
Q
cranial nerve 1
A
- olfactory
- sensory: nose
23
Q
cranial nerve 2
A
- optic
- sensory eye
24
Q
cranial nerve 3
A
- oculomotor
- motor: all eye muscles except those supplied by cranial nerve 4 and 6
25
cranial nerve 4
- trochlear
- motor: superior oblique muscle of eye
26
cranial nerve 5
- trigeminal
- sensory: face, sinuses, teeth
- motor: muscles of mastication
- the zygomatic branch can be damaged by mask straps
27
cranial nerve 6
- abducens
- motor: external rectus muscle of the eye
28
cranial nerve 7
- facial
- motor: muscles of the face
29
cranial nerve 8
- vestibulocochlear
- sensory: inner ear
30
cranial nerve 9
- glossopharyngeal
- motor: pharyngeal musculature
- sensory: posterior part of tongue, tonsils and pharynx
31
cranial nerve 10
- vagus nerve
- motor: heart, lungs, bronchi, GI tract
- sensory: heart, lungs, bronchi, trachea, larynx, pharynx, GI tract, external ear
32
cranial nerve 11
- accessory nerve
- motor: sternocleidomastoid and trapezius muscles
33
cranial nerve 12
- hypoglossal
- motor: muscles of the tongue
34
cranial nerve 7 (facial) specifics
- innervates muscles of facial expression (motor)
- innervates orbicularis oculi
- provides sensory and parasympathetic innervation
- frequently monitored during surgery around the face (parotidectomy, acoustic neuroma, cochlear implant)
35
cranial nerve 9 (glossopharyngeal)
- sensory innervation to the baroreceptors of the carotid sinus can cause bradycardia nd hypotension during CEA
- sensory innervation to the chemoreceptors of carotid body
- sensory innervation of the posterior oral mucosa (gag reflex)
- motor innervation of the pharynx (swallowing)
- provides parasympathetic innervation to the parotid gland
36
vagus nerve branches
SLN
RLN
37
SLN branches
- internal branch (sensory)
- external branch (motor) cricothyroid muscles
38
injury to the SLN
- external branch innervates the cricothyroid muscle which tenses the adducts the vocal cords
- injury can change voice but is not generally dangerous
39
RLN injury
- innervates all the muscles of the larynx except the cricothyroid
- unilateral injury produces abductor VC paralysis = hoarseness
- bilateral VC paralysis = partial or complete airway obstruction (resp distress, stridor)
40
vagus nerve and the heart
- convey parasympathetic innervation to the SA and AV nodes of the heart
- vagal stimulation reduces HR and is constantly active
41
vagus nerve and the lungs
- parasympathetic stimulation within pulmonary plexuses causes vasodilation and bronchoconstriction
42
vagus nerve and the GI tract
- parasympathetic innervation to majority of abdominal organs
- stimulates smooth muscles contraction and glandular secretion in these organs
- vagal stimulation during GI surgery and endoscopy = bradycardia and even asystole
