Lecture 3 - Meninges, Ventricular System, and Arterial Blood Supply Flashcards
Describe the arachnoid mater
The arachnoid is the intermediate layer on the meninges. It is a delicate, transparent membrane that does not dip into the sulci. It is connected to the pia mater by fine strands of connective tissue (arachnoid trabecula).
What is the subarachnoid space?
In between the arachnoid mater and pia mater, we have the subarachnoid space. The subarachnoid space is a wide space that is cushioned by the CSF. The subarachnoid space contains blood vessels and have arachnoid villi which project into it. Sometimes se have enlargements of the subarachnoid space called cistern.
Describe the pia mater
The pia mater is the deepest layer of the meninges. It is a very delicate layer which sends prolongations into the brain tissue along with blood vessels to form the perivascular space. The pia mater helps contour the brain, surrounds blood vessels, is closely associated with choroid plexus and ependyma, and helps form the roof of the ventricles.
How does the spinal meninges differ from the brain meninges?
Only one dural layer - due to more movement
Has epidural space
What is the epidural space?
The epidural space exists between the dural sheath and vertebral bony wall. The epidural space contains fat tissue (which can also provide cushioning) and the venous plexus. It is largest at the L2 and is used clinically for epidural anaesthesia.
Describe the ventricular system
We have 4 ventricles in the ventricular system, lateral (2), third, and fourth. Each ventricle contains CSF and they are all interconnected as one system.
What connects the lateral and third ventricle?
The interventricular foramen
What connects the third and fourth ventricles?
Cerebral aqueduct
What connects the fourth ventricle and central canal?
Lateral aperture
Describe the lateral ventricle
The lateral ventricle consists of a body and 3 horns, the anterior, posterior, and inferior. These horns go into different lobes of the brain. The anterior with the frontal lobe, posterior with the occipital lobe, and inferior with the temporal lobe. Within the lateral vesicles we have the choroid plexus which sits in the body and inferior horn. The choroid plexus generates CSF.
Where is the choroid plexus located in the third ventricle?
The choroid plexus in the third ventricle exists in the roof.
Where is fourth ventricle located?
The fourth ventricle lies between the cerebellum and the pons & medulla.
Where does CSF exit the fourth ventricle?
Through either of the three openings. Two of these openings are lateral apertures (foramina of Luschka) and the third is the median aperture (foramen of Magendie).
What makes up the fourth ventricle floor?
The floor is formed by the brainstem.
What makes up the fourth ventricle roof?
The roof is formed by both the superior medullary velum and the inferior medullary velum.
