arteries, ventricles, CSF of brain.

Where is CSF produced, and what produces it?

Mainly by the choroid plexuses in the brain's ventricles, where blood plasma is filtered and modified.

What is the flow of CSF through the ventricles and around the brain?

Lateral ventricles →

passes interventricular foramina

→ third ventricle →

cerebral aqueduct →

fourth ventricle →

passes median and lateral apertures →

subarachnoid space around the brain and spinal cord.

How is CSF reabsorbed into the blood?

Mainly through arachnoid granulations (villi) into the dural venous sinuses, especially the superior sagittal sinus.

What are the functions of CSF?

Cushions the brain and spinal cord, provides buoyancy, and helps maintain a stable chemical environment and remove waste.

What is hydrocephalus?

Abnormal accumulation of CSF in the ventricles due to impaired flow, absorption, or, less commonly, excessive production; it can increase pressure and enlarge the ventricles.

What are the four major arteries supplying blood to the brain?

Right and left internal carotid arteries and right and left vertebral arteries.

Right side: anterior circulation

Left ventricle → aortic arch → brachiocephalic trunk → right common carotid → right internal carotid → brain.

right side posterior circulation

Left ventricle → aortic arch → brachiocephalic trunk → right subclavian → right vertebral artery → foramen magnum.

Left side anterior circulation

Left ventricle → aortic arch → left common carotid → left internal carotid → brain.

left side posterior circulation

Left ventricle → aortic arch → left subclavian → left vertebral artery → foramen magnum.

What are the branches of the internal carotid artery?

Anterior cerebral artery (ACA), middle cerebral artery (MCA, posterior communicating artery

What does the anterior cerebral artery supply?

Primarily the medial frontal and parietal lobes

What does the middle cerebral artery supply?

Much of the lateral cerebral hemispheres

Where do the vertebral arteries travel to enter the skull?

They travel superiorly through the transverse foramina of the cervical vertebrae then enter the skull through the foramen magnum.

branches of vertebral arteries?

Basilar artery, which gives rise to posterior cerebral arteries, which give rise to posterior communicating arteries

What is the basilar artery, and where does it travel?

Formed by the union of the two vertebral arteries; travels along the anterior surface of the pons and ends by dividing into the two posterior cerebral arteries.

What does the posterior cerebral artery supply?

Primarily the occipital lobes and inferior portions of the temporal lobes; it also supplies important deep structures through branches.

What is the overall division of brain blood supply between the anterior and posterior circulations?

The internal carotid system supplies most of the anterior circulation; the vertebral-basilar system supplies the posterior circulation, including the brainstem, cerebellum, and occipital lobes.

What is the Circle of Willis?

An arterial ring at the base of the brain that connects the internal carotid and vertebrobasilar circulations.

What arteries form the circle of willis?

2 posterior cerebral arteries

2 posterior communicating arteries

2 internal carotid arteries

2 anterior cerebral arteries

1 anterior communicating artery

What is the clinical importance of the Circle of Willis?

It can provide alternative routes for blood flow if one contributing artery becomes narrowed or blocked, although collateral circulation may be insufficient.

How are the ACA, MCA, and PCA distinguished by the regions they supply?

ACA: medial frontal/parietal lobes; MCA: lateral cerebral hemispheres; PCA: occipital and inferior temporal lobes.