nervous system, meninges, ventricles, and CSF Flashcards
how is the nervous system split
central nervous system and peripheral nervous system
central nervous system (CNS)
encased in bones of the skull and vertebral column
-highly protected
-consists of the brain (cerebrum, cerebellum, brainstem and subcortical structures) and spinal cord
-control center, integration, and processing
what is the protection for the CNS
scalp and skin, skull and vertebral column, CSF, and meninges
peripheral nervous system (PNS)
spinal nerves and cranial nerves (31 and 12)
-carrying information to and from CNS
-somatic and autonomic division
cerebrum
contains :
-gyri, sulci, fissures
-6 lobes all with their own functions
-cortical regions
frontal lobe
higher mental processes
parietal lobe
processes sensory information
occipital lobe
processes visual information
temporal lobe
processes auditory information
insula lobe
involved in consciousness
limbic lobe
processes memory and emotion
parts of the brainstem
peduncles, midbrain, pons, medulla, and cranial nerves entering and exiting
spinal cord
within CNS, well protected
-vertebrae
-meninges
spinal nerve
within PNS, emerges between two adjacent vertebrae
-efferent/descending
-afferent/ascending
what information is carried by efferent/descending spinal nerves
motor information to muscles or glands
what information is carried by afferent/ascending spinal nerves
sensory information from receptor organs
3 layers of meninges
dura mater, arachnoid mater, pia mater
dura mater
outermost layer
-meningeal layer and endosteal layer (adheres to inside of skull)
arachnoid mater
lies on the inner surface of the dura
-web like
-subarachnoid space is below this
-contains cisterns
-arachnoid trabeculae
cisterns
large pockets
-enlargement of the space
arachnoid trabeculae
collagenous strands that connect the arachnoid and the pia for susspension
pia mater
closely adhere to the CNS tissue
falx cerebri
dura mater that separates hemispheres
-protects the brain from it not being squishes
venous sinus
spaces where the endosteal and meningeal layers of the dura separate
-cavities
superior sagittal sinus
runs through the hemispheres
inferior sagittal sinus
collects used blood and fluids
dural septa
two layer folds separating the cranium into compartments
-i.e. falx cerebri
tentorium cerebelli
separates the cerebellum from the cerebral hemispheres
infratentorial vs. supratentorial
contains cerebellum and brainstem vs. contains cerebrum
tentorial notch
opening where the brainstem passes into the cerebrum
epidural hematoma
occurs if the meningeal arteries are torn
-bleeding between the periosteum (endosteal layer of dura) and skull bones
-adhering to bone (lemon)
subdural hematoma
from dural venous sinus or vein attachment at the sinus
-blood is beneath the dura
-following shape of space (banana)
subarachnoid hemorrhage (subarachnoid hematoma)
bleeding between the brain and the arachnoid (under arachnoid)
-bleeding from veins
cerebrospinal fluid (CSF)
provides a fluid cushion, surrounding the brain and spinal cord
-circulates within the ventricles
functions of CSF
buoyancy and chemical homeostasis
-draining unwanted substance away from the CNS
-supplying some nutrients
-excretion of waste products as CSF leaves
-transporting hormones
flow of CSF
from lateral ventricles through foramina of monro, third ventricles, through cerebral aqueduct to 4th ventricle of pons and medulla. exits through two foramina of luschka and foramen of magendie to enter cisterna magna
-circulates through subarachnoid space and as pressure increaased it will be sucked in by arachnoid villa and will enter the superior sagittal sinus to get to the jugular vein to leave
parts of the lateral ventricle
anterior horn (forward position), posterior horn (near occipital lobe), inferior horn (down to temporal lobe), collateral trigone (meeting of three horns)
venous drainage
superior sagittal sinus is the large on top, straight sinus, transverse sinus then the sigmoid sinus down to jugular vein
meningitis
infection of the meninges
-bacterial or viral
-can cause ossification of the labyrinth
-spreads from meninges to the cochlea via the cochlear aqueduct
hydrocephalus
excess fluid around the brain
-a disruption of CSF circulation
-pressure rises and ventricles expand
communicating vs. non-communicating hydrocephalus
lateral ventricles are connected to the subarachnoid space vs. blockage could be due to something within the ventricles (cannot get through the flowing pathway)
normal pressure hydrocephalus (NHP)
slowly developing from gradual blockage of CSF
-CSF builds up and ventricles enlarge, compression of tissue
there is more CSF in the____________ than the ventricles
subarachnoid space
-around 90 mL in the space and around 25-60 mL in ventricles
CSF is constantly produced by the ….
choroid plexus within ventricles
how is hydrocephalus often treated
use of a shunt
