Lecture 3- Meninges, Ventricular System and Arterial Blood Supply Flashcards
How is the arachnoid mater different to the pia mater?
Pia mater adheres tightly to the sulci, arachnoid mater does not (sits above: does not go into grooves)
How is the arachnoid mater connected to the pia mater?
By fine strands of connective tissue called arachnoid trabecula
What exits between the arachnoid mater and pia mater? What is found here?
- The Subarachnoid space filled with CSF
- Contains blood vessels which are prone to bursting/ bleeding blood into the CSF in what is known as subarachnoid haemorrhage
What is concussion due to?
Usually CSF in the subarachnoid space provides a watery cushion meaning that when we move our head the brain doesn’t get squished against the hard skull. However, if the head is severely knocked it doesn’t provide enough cushioning and the tissue becomes squished + damaged.
What are arachnoid granulations?
- Arachnoid villi are projections of the arachnoid mater
- Arachnoid granulations= Aggregations of arachnoid villi which drain CSF into the venous sinuses (veins). In other words they connect the subarachnoid space with a drainage system.
What is a cistern?
Enlarged subarachnoid space created where there are major sulci in the brain (Extra space for CSF to pool)
What are the major cisterns? (LABEL THEM)
- Interpeduncular cistern
- Pontine cistern (smallest)
- Superior cistern
- Cerebellomedullary cistern (cisterna magna)
Describe the Pia Mater
- Delicate membrane, follows contours of brain
- Surrounds blood vessels
- Sends prolongations into brain tissue along with blood vessels (forming perivascular space)
- Helps form the roof of the ventricles, closely associated with choroid plexus and ependyma
How are the spinal meninges different to the meninges of the brain? Why is the necessary?
For the meninges of the brain there is two layers of dura the periosteal layer and the meningeal layer. For the spinal meninges there is no periosteal layer. This means instead there is an epidural space. The benefit of this is there is an increase in the range of movement for the spinal chord as opposed to the brain (essential!)
Where is the epidural space? Where is it largest? What is contained there?
- Between spinal Dural sheath and vertebral bony wall
- Largest at L2 (where spinal chord finnishes)
- Contains fat tissue & venous plexus
What is the idea of an epidural anesthesia?
-Inject at L2 into the epidural space. Means there is numbness from this point down. Useful in child birth.
Is there are subarachnoid space in the spinal meninges?
Yes, same as brain between the pia mater and arachnoid mater
What is the lumbar cistern and it’s clinical significance?
- Lumbar cistern= inferior to the spinal chord (below L1). A pool of CSF;
- The clinical significance is that a lumbar puncture can be performed where CSF is drawn from this region. this can be investigated to determine is subarachnoid hemorrhage has occurred and in illnesses such as meningitis
What are the two types of spinal pia mater and what role do they take in anchoring the spinal chord?
- Denticulate ligament (support spinal cord within dural sheath laterally)
- Filum terminale (conus medularis to the coccyx to anchor in the vertical direction)
What is meningitis? What are the symptoms/ treatment? How is it diagnosed?
-characterized by inflammation of the pia/ arachnoid mater
-usually caused by a bacterium or a virus
-common symptoms: fever, headache, vomiting and stiff neck
-diagnosis: performing a lumbar puncture examining
the CSF
-treatment: antibiotics quickly, to prevent infection spreading across pia mater to injure neurons in brain
How many ventricles are there? What are they?
4=
• lateral (2)
• third
• fourth
What structures connect the different ventricles? What is the benefit of this?
- Interventricular foramen connects the lateral and third ventricle
- Cerebral aqueduct connects the third and forth ventricles