meninges Flashcards
layers of the scap - outside to inside
skin of scalp, periosteum, bone of skull, dura mater (periosteal then meningeal), arachnoid mater, pia mater
where are blood vessels in the scalp
in the subarachnoid space
dura mater (pachymeninx)
periosteal layer meningeal layer (the two layers are separated only in certain sinuses) aracnoid mater (arachnoidea) pia mater (leptomeninx)
two dural layers
periosteal and meningeal
foramen mangum and the periosteal layer of dura (endocranium)
becomes continuous with the outer periosteum of the skull bones (pericranium)
meningeal layer of dura
form the dura covering the spinal cord within the vertebral canal
what cover the spinal cord, roots and spinal nere
dura mater and arachnoid
epidural space
“above” dura mater; between endosteum and periosteal dura
subdural space
below dura
subarachnoidal space
below arachnoid, i.e., between arachnoid and pia
subdural hematom
bleeding into the space between the dura mater and the brain itself
epidural hematoma
bleeding into the space between the dura mater and the skull
clinical signs of subdural/epidural hematoma
elevated intercranial pressure: headache, dizziness, nausea, double vision, etc
dural sinus
dura has an outer periosteal layer adherent to bone and a meningeal layer which splits to form adural sinus
falx
the two meningeal layers may form partitions that segregate areas of the brain in distinct manners
communication between veins and sinuses
periosteal veins
diploic veins
emissary veins
dural sinus
skull
tri-layered (1-2) outer & inner compact (3) spongy layer between (diploe) housing diploic veins and red marrow
dural partition
diaphragma sellae “covering of the saddle”
single circular partition rroofs over the pituitary gland; pierced by pituiatry stalk
attachment: hypophyseal fossa
attachments of falx cerebri
crista galli, midline of calvarium, occipital protuberance, occipital bone
straight sinus
fuses at midline of falx cerebri & tentorium cerebelli
transverse sinus
attach at posterolateral margins of tentorium cerebelli
confluence of sinuses
joining of sup. sag., straight & transverse sinus
dura: arterial blood supply
from middle meningeal artery - branch of maxillary foramen spinosum. grooves in skull to accomodate meningeal arteries
dura innervation
sensory innervation from all 3 componentsof trigeminal (V1, V2, V3)
middle miningeal nerve
branch of V3 foramen spinosum
pia
delicate, transparent membrane closely applied to the brain, carrying extensive network of blood vessels supplying brain; follows folds and fissues (sulvi of brain tissue); innermost of 3 layers
arachnoid
spider like; middle layer, extending from pia to dura, forming the subarachnoid space
subarachnoid space: between arachnoid and pia
the dura and arachnoid are attached to each toher; no space between them
content of subarachnoid space
vessels supplying the brain; liquor cerebrospinalis (cerebrospinal fluid); arachnoid trabeculae: between arachnoid and pia
network of fibers
arachnoid trabeculae
CSF
found in subarachnoid space
drains into dural sinuses via arachnoid villi, stalk-like extensions extending from subarachnoid space into the dural sinuses
arachnoid granulations
clusters of arachnoid villi; extend into lateral expansions of the dural sinuses
lateral lacunae
lateral expansions of dural sinuses; contain clusters of arachnoid villi
leptomeninges
arachnoid, arachnoid trabeculae, pia
circulation of cerebrospinal fluid
made by choroid plexus in ventricles; gets out from brain via three foramens at the level of medulla; covers brain and spinal cord and floats the brain; absorbed by arachnoid granulations
extradularal hematoma
between skull and periosteal dura; e.g., following skull fractures that damage meningeal arteries. usually localized (because of adherent periosteal dura) & cause compression of underlying brain tissue. potentially life threatening
subdural hematoma
between dura and arachnoid; e.g., following trauma that jerks brain inside the skull, tearing cerebral veins as they enter venous sinuses
subarachnoid hemorrhage
bleeding in the subarachnoid space; e.g. following cerebral lacerations, tearing cerebral arteries; clinical diagnostic: lumbar puncture
cavernous sinus
at base of skull in close proximity to pituitary gland; contains segment of internal carotid artery; contains segments of several crainial nerves (III, IV, V-1, V-2, VI); clinically significant; area with pituitary tumors, cavernous sinus tumors, deep skull fractures
course of the interal carotid artery & relationship to the cavernous sinus
internal carotid artery enters base of skull via carotid canal; travels anteriorly and horizontally within the carotid canal; enters interior of cranial vault via foramen lacerum; then proceeds superiorly, traveling through the cavernous sinus, forming s-shaped bend as it course through sinus
lymphatic circulation of the meninges and brain
the brain has no lymphatic circulation; the dura mater has lymphatic circulation; the vessels penetrate the skull and drain the lymph twoard lymph noedsin the face
close connection between liquor cerebrospinalis and lymph around fila olfactoria (crainial nerve #1) in the lamina cribrosa of the nose; method of drug delivery to the CNS
anterior fossa
raised posterior ridge, formed by lesser wing of the sphenoid bone
middle fossa
raised posterior ridge, formed by petrous crest of temporal bone
posterior fossa
contains brainstem, occipital lobes and cerebellum
what covers the floor of the crainial vault
dura
