Week 1: Blood Supply, Venous Drainage, and CSF Circulation,

What are the two sets of arteries that supply the brain?

1. Internal carotid arteries (anterior circulation): branch from the common carotid arteries.

2. Vertebral arteries (posterior circulation): join to form the basilar artery.

Where does the internal carotid artery originate, and where does it travel?

It branches from the common carotid artery at the superior edge of the thyroid cartilage and enters the brain via the carotid canal.

Where do the vertebral arteries originate, and what do they form?

They arise from the subclavian arteries, ascend through the foramina in the cervical vertebrae, and merge to form the basilar artery.

What is the Circle of Willis, and why is it important?

A circular arterial network at the base of the brain providing collateral circulation to maintain blood supply in case of occlusion.

What are the components of the Circle of Willis?

1. Internal carotid arteries (continuing as middle cerebral arteries).

2. Anterior cerebral arteries (connected by the anterior communicating artery).

3. Posterior cerebral arteries (terminal branches of the basilar artery).

4. Posterior communicating arteries (connect posterior cerebral arteries to the internal carotid arteries).

What is the function of the anterior cerebral artery (ACA)?

Supplies the medial surface of the frontal and parietal lobes, including the lower limb portion of the primary motor and sensory cortices.

What symptoms might occur if the anterior cerebral artery is blocked?

Sensory and motor deficits in the lower limb.

What is the function of the middle cerebral artery (MCA)?

Supplies the lateral surface of the cerebral hemispheres, including the face, upper limb, and speech areas (Broca’s and Wernicke’s areas in the dominant hemisphere).

What symptoms might occur if the middle cerebral artery is blocked?

1. Motor and sensory deficits in the face and upper limb.

2. Aphasia (if in the dominant hemisphere) affecting Broca’s or Wernicke’s areas.

What is the function of the posterior cerebral artery (PCA)?

Supplies the inferior surface of the temporal lobe and the occipital lobe (visual cortex).

What symptoms might occur if the posterior cerebral artery is blocked?

1. Visual disturbances or blindness.

2. Memory or olfactory changes (if temporal lobe affected).

What are penetrating arteries, and what do they supply?

Small arteries supplying deep white and grey matter, including the internal capsule, basal nuclei, and thalamus.

What are the lenticulostriate arteries, and why are they important?

Branches of the middle cerebral artery supplying the basal nuclei, internal capsule, and deep white matter; vulnerable to hypertension-related strokes.

What are the medial lenticulostriate arteries, and where do they originate?

Arise from the anterior cerebral artery, supply deep brain structures.

What are the lateral lenticulostriate arteries, and where do they originate?

Arise from the middle cerebral artery, supply deep brain structures including the internal capsule.

What is the venous drainage system of the brain, and how does it function?

Venous drainage occurs through dural venous sinuses, which are channels between the dura mater layers that drain blood from the brain into the internal jugular vein.

What are dural venous sinuses, and how are they formed?

They are spaces between the periosteal and meningeal layers of the dura mater that collect venous blood and CSF.

What is the ventricular system, and what is its function?

A series of interconnected cavities that produce, circulate, and drain cerebrospinal fluid (CSF).

What are the components of the ventricular system?

1. Two lateral ventricles: located beneath the corpus callosum.

2. Third ventricle: Between the thalamic hemispheres.

3. Cerebral aqueduct: Connects the third and fourth ventricles.

4. Fourth ventricle: Located between the pons and cerebellum.

Where is cerebrospinal fluid (CSF) produced?

In the choroid plexus located within the lateral, third, and fourth ventricles.

What happens if CSF flow is blocked?

Hydrocephalus, characterized by enlargement of the ventricles due to CSF buildup.

What are the types of hydrocephalus?

1. Communicating hydrocephalus: CSF absorption is impaired (e.g., due to subarachnoid hemorrhage blocking arachnoid granulations).

2. Non-communicating hydrocephalus: CSF flow is obstructed within the ventricles (e.g., at the cerebral aqueduct).

What are basal cisterns, and why are they important in CSF circulation?

Widened subarachnoid spaces around the brainstem where CSF flows before being reabsorbed.

How can subarachnoid hemorrhage lead to hydrocephalus?

Blood in the subarachnoid space can block the arachnoid granulations or basal cisterns, preventing CSF reabsorption.

What is the significance of the superior sagittal sinus in CSF drainage?

It reabsorbs CSF from the subarachnoid space into the venous system via arachnoid granulations.

Why is understanding CSF circulation important in clinical cases?

Disruptions in CSF flow, production, or absorption can lead to conditions like hydrocephalus.

How is CSF-related pathology linked to the PBL case of Heather?

Heather's case involves a subarachnoid hemorrhage, which can block CSF flow, leading to hydrocephalus and increased intracranial pressure.