Module 20: Brain II – Blood Supply, Meninges, Ventricles, and CSF
Module 20: Brain II – Blood Supply, Meninges, Ventricles, and CSF
Learning Objectives:
By the end of this class, students will be able to:
- List the names, locations, and functions of the meninges of the brain.
- List the names of the ventricles in the brain.
- Describe the production and circulation of cerebrospinal fluid.
- Explain the Circle of Willis and blood flow through the brain.
Terms to Know
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Blood Supply to the Brain
Meninges
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Ventricles
Other
*Covered only in lecture, not in this text ^Covered in the self-study slides on Canvas |
Arterial Supply to the Brain
This information will be covered in lecture.
There are multiple routes for blood to get to the brain. The right and left internal carotid arteries branch from the common carotid artery on each side and enter the cranium through the carotid canal in the temporal bone. The vertebral arteries branch off of the subclavian arteries on each side, and they are protected as they pass through the neck region by the transverse foramina of the cervical vertebrae. The vertebral arteries enter the cranium through the foramen magnum of the occipital bone.
The circle of Willis is a confluence of arteries that can maintain perfusion of the brain even if narrowing or a blockage limits flow through one part. Given the central role and vital importance of the brain to life, it is critical that blood supply to this organ remains uninterrupted.
The two vertebral arteries merge into the basilar artery, which gives rise to branches to the brain stem and cerebellum. The basilar artery then ends by dividing into the right and left posterior cerebral arteries, which supply the occipital lobe and inferior aspect of the posterior temporal lobe.
The internal carotid artery continues through the carotid canal of the temporal bone and enters the base of the brain through the carotid foramen. Then it branches into the anterior and middle cerebral arteries. The anterior cerebral artery that supplies blood to the anterior, medial, and very superior portions of the frontal lobe. The middle cerebral artery supplies blood to the posterior frontal lobe and most of the temporal and parietal lobes.
The right and left anterior cerebral arteries join together to form an anastomosis called the anterior communicating artery. The initial segments of the anterior cerebral arteries and the anterior communicating artery form the anterior portion of the arterial circle. The posterior portion of the arterial circle is formed by a left and a right posterior communicating artery that runs from the internal carotid artery to the posterior cerebral artery on each side.
Venous Return from the Brain
This information will be covered in lecture.
After supplying the brain with oxygen and nutrients, venules and veins merge and eventually send blood back toward the heart through a series of dural venous sinuses and veins. The superior sagittal sinus runs in the groove of the median longitudinal fissure, where it absorbs CSF from the meni