week 7 Flashcards
meninges
three connective tissue membranes that lie just external to the CNS organs
what are four major functions of the meninges
- cover and protect the CNS
- Protect blood vessels and enclose venous sinuses
- Contain cerebrospinal fluid
- Form partitions in the skull
list the meninges from external to internal
dura mater, arachnoid mater, pia mater
describe the layers of the dura mater
There is the more superficial periostreal layer which attaches to the inner surface of the skull, and there is also a deeper meningeal layer.
dural venous sinuses
the brain’s two dural layers are fused together except in certain areas, where they separate to enclose dural venous sinuses that collect blood from the brain and direct it into the internal jungular veins of the neck, heading for the heart
dural septa
extensions of the dura mater which separate parts of the brain and limit excessive movement of the brain within the cranium
- Falx cerebri
- Falx cerebelli
- Tentorium cerebelli
Falx cerebri
separates the two hemispheres of the cerebrum
Falx cerebelli
separates the two hemispheres of the cerebellum
Tentorium cerebelli
separates the cerebrum from the cerebellum
subdural space
A narrow cavity containing a film of fluid which separates the dura mater from the arachnoid mater.
Veins of the brain (“bridging veins”) are situated within this space and carry venous blood to the dural sinuses
subarachnoid space
Spider-web-like extensions span this space and secure the arachnoid mater to the underlying pia mater.
It is filled with CSF and contains the largest blood vesels serving the brain.
arachnoid villi
Knoblike projections of the arachnoid mater which protrude through the dura mater and into the superior sagittal sinus.
They absorb CSF into the venous blood of the sinus
pia mater
layer which “hugs” the brain like cellophane wrap
Inner blood vessels circulate within this layer
Cerebrospinal Fluid
forms a liquidy cushion that gives buoyancy to CNS structures and protects the brain from physical and chemical injuries via the CSF-brain barrier
helps nourish the brain by supplying it with nutrients and oxygen
CSF is produced by:
plasma filtration via the ependymal cells in the choroid plexus (make and filter CSF from blood)
where is the choroid plexus situated
within both lateral and 3rd ventricles
lateral ventricles
one in each cerebral hemisphere; separated by transparent septum pellucidum
third ventricles
between two thalami; receives CSF from the lateral ventricles via foramina of monro (interventricular foramina)
fourth ventricle
situated between the cerebellum and the brainstem
what is the subarachnoid circulation path of CSF
- CSF is produced in the choroid plexus of each lateral ventricle
- CSF flows from the lateral ventricles to the third ventricle
- CSF flows from the third ventricle to the fourth ventricle
- CSF then enters the subarachnoid space via two lateral foramena of Luschka (lateral aperatures), and one middle foramen of Magendie (median aperature)
- CSF circulates around the brain and the spinal cord within the subarachnoid space
- CSF is gradually reabsorbed into the blood through arachoid villi in the dural sinuses
how does CSF reach the sagittal dural sinuses?
CSF is delivered into the sagital dural sinuses by the arachnoid granulations of the subarachnoid space
what are the two main arteries that supply the brain with blood
where do they originate from?
1 pair of Internal carotid arteries & 1 pair of vertebral arteries
both pairs originate from subclavian arteries (branches from the brachio-cephalic trunk of the aorta)
as two vertebral arteries climb via inter-vertebral foramena toward the brain, they unite on the frontal surface of the pons and form the _____ _____
basilar artery
the basilar artery divides into a pair of _____ _____ _____
posterior cerebral arteries
the posterior cerebral arteries supply:
the occipital lobes and the inferior parts of the temporal lobes (partially the cerebellum)
the two internal carotid arteries give off:
a middle cerebral artery, which corresponds to the lateral aspects of the brain/upper part of the body and the head
an anterior cerebral artery, which corresponds to the top of the brain and the lower parts of the body
the circle of willis
the joining area of several arteries at the botom side of the brain. Here, the internal carotid arteries branch into smaller arteries that supply oxygenated blood to over 80% of the cerebrum
which major artery is made by the merging of two vertebral arteries, and is situated as climbing over the pons
Basilar artery
which major arteries originate from sub-clavian arteries of the brachio-cephalic trunk
vertebral and common carotid arteries
what pair of major arteries provide arterial circulation to the occipital lobe of the brain cortex and the cerebellum
posterior cerebral arteries
which pair of major arteries climbs to the side of the circle of willis via cavernous sinuses on each side
internal carotid arteries
which pair of major arteries supplies the lateral side of the cerebrum, is responsible for the arterial blood delivery to the brain parts, and responsible for the upper trunk and upper extremities
middle cerebral arteries
which pair of major artiers supplies the oxygenated blood to the top of the brain, which is responsible for the lower trunk and lower extremities
anterior cerebral arteries
arachnoid meninges
The layer between the dura and pia which is avascular. it contains arachnoid villi and granulations
list the layers of the meninges and their corresponding spaces in between from external to internal
skull epidura dura mater (perosteal layer and meningeal layer) sub dural space arachnoid mater subarachnoid space pia mater
what is the path of deoxygenated blood once it reaches the dural sinuses
superior sagittal sinus, inferior sagittal sinus, straight sinus, transverse pair (run by each ear) + cavernous pair (receives blood from each eye), sigmoid sinus pair, internal jugular vein, right heart
what anatomical structures pass via the cavernous sinus
internal carotid artery and oculomotor group of cranial nerves
