Nervous System II Flashcards
Describe the flow of CSF in the ventricles
2 lateral ventricles (temporal horn –> frontal horn) –> (through inter-ventricular foramina) midline 3rd ventricle –> 4th ventricle (via cerebral aqueduct) –> sub-arachnoid space of cranial cavity median aperture and 2 lateral apertures
What produces CSF?
choroid plexus
Olfactory Nerve
CN I; Sensory; carries olfactory information from olfactory epithelium through the foramina of cribiform plate
Optic Nerve
CN II; Sensory; Carries visual information from the retina through the optic canal
Vestibulocochlear Nerve
CN VIII; Sensory; Carries balance and hearing from inner ear (cochlea and vestibular apparatus) through the internal auditory meatus
occulomotor nerve
CN III; motor; innervates 4 of the 6 extrinsic muscles of the eye, and intrinsic muscles (iris and ciliary body/lens)
trochlear nerve
CN IV; motor; innervates superior oblique (down and out muscle)
Abducens Nerve
CN IV; motor; innervates lateral rectus (abducts the eye)
Spinal Accessory Nerve
CN XI; motor; innervates the sternocleidomastiod (rotates the head) & trapezius muscles (shrugs the shoulders); exits cranium via jugular foramen
Hypoglossal nerve
CN XII; motor; innervates the intrinsic and extrinsic muscles of tongue. Exits via hypoglossal canal
3 branches of trigeminal nerve
V1 - Ophthalmic
V2 - Maxillary
V3 - Mandibular
Ophthalmic nerve
V1 branch of trigeminal nerve V; somatosensory from cornea, nose and forehead; superior orbital fissure
Maxillary nerve
V2 branch of trigeminal nerve; somatosensory from maxilla, upper lip & teeth, hard palate; foramen rotundum
Mandibular Nerve
V3 branch of trigeminal nerve ; tomato-sensory mandible, lower lip & teeth, anterior 2/3 tongue; motor to muscles of mastication
Facial Nerve
CN VII; Internal Aug Meatus;
Sensory - Taste: ant 2/3 of tongue
motor - muscles of facial expression
motor (visceral) - all glands (salivary) of face/oral cavity except parotid gland
Where does CSF drain into after the 4th ventricle?
into the sub-arachnoid space of cranial cavity
how much CSF is produced per day by the choroid plexus?
500ml
where is the choroid plexus located?
It is a vascularized tissue found within all 4 cerebral ventricles
What is the choroid plexus made up of ?
specialized epithelial cells which determine which solutes enter the CSF and which don’t
what occurs when production of CSF is greater than absorption
hydrocephalus
what are the functions of CSF?
- provides protection
- maintains constancy of environment for brain tissue (provides nutrients and ions)
- removes cellular waste products
What is the total volume of the subarachnoid space?
150ml
How is CSF drained from the subarachnoid space?
It is drained into venous sinuses by arachnoid villi
What are arachnoid villi?
tufts of arachnoid that extend through dura (meningeal layer) into venous sinus
Where are arachnoid villi most numerous?
superior sagittal sinus; are seen as arachnoid granulations
What is the function of the arachnoid granulations?
functions to transport CSF from villi and granulations into venous blood.
what 2 sets of arteries supply the brain?
- internal carotids
2. vertebrals
what would result from occlusion in the middle cerebral artery?
Since this artery supplies the motor and pre-motor areas in the frontal lobe, a large area of the parietal lobe and the superior surface and anterior pole of the temporal lobe, occlusion may result in sensory and motor deficits of the contralateral body( trunk upper limbs, head and face & language deficits.
occlusion of the anterior cerebral artery would result in what?
sensory and motor deficits of the contralateral body (lower limbs). This is because this artery supplies the medial and superior surfaces of frontal & parietal lobes
What parts of the brain does the anterior cerebral artery supply?
medial and superior surfaces of the frontal and parietal lobes
what parts of the brain does the middle cerebral artery supply?
lateral cortical and subcortical areas. Superior surface and anterior pole of temporal lobe
what areas does the posterior cerebral artery supply?
occipital lobe and inferior surface of temporal lobe
what do the vertebral arteries (before they form the basilar) supply?
cervical spinal cord and the cerebellum
What is a stroke?
occurs when blood supply to the brain is interrupted
What are the 2 types of strokes?
- Ischemic stroke - occlusion of vessels
- Hemorrhagic stroke - more commonly involves smaller vessels under chronic hypertension; also subarachnoid hemorrhage (due to aneurysms)
what is a sinus?
channel carrying venous blood and convey that blood from the brain to the internal jugular veins; under low pressure
what does the internal jugular vein do?
Drains the blood from the brain and returns it to the heart
What cranial nerves are sensory (3) ?
- olfactory - olfactory information from olfactory epithelium through foramina of cribiform plate
- optic - carries visual information from retina through optic canal
- vestibulocochlear - balance and hearing from inner ear
What cranial nerves serve motor functions?
3 extraoccular muscles:
- occulomotor (III) - 4/6 extrinsic muscles of the eye, and intrinsic muscles (iris and ciliary body/lens)
- trochlear (IV) - superior oblique (down and out muscle)
- abducens (VI) - lateral rectus (abducts eye)
- spinal accessory (XI) - trapezius and sternocleidomastoid
- Hypoglossal (XII) - intrinsic and extrinsic muscles of tongue
What cranial nerves are mixed?
- trigeminal
- facial
- glossopharyngeal
- vagus
glossopharyngeal nerve
CNIX; jugular foramen
sensory: taste: post 1/3 of tongue
motor - assist in swalling
motor (visceral) - parotid
Vagus
CN X; Vagus; jugular foramen
sensory: taste: epiglottis; visceral sensory from reap.tract and viscera
motor - swallowing (vomiting)
motor (visceral) - respiratory tract, heart, and esophagus, stomach, intestines
