Week 3

This week we started to discuss the brain and spinal cord in depth. I was pretty interested in the meninges. They are the protective membranes. The outermost layer is the dura mater. It is tough, thick, inflexible, vascular, and white in color. It is composed of dense irregular connective tissue. The brain has 2 layers of the dura, the periosteal layer and the meningeal layer. The spinal cord only has one layer. There are 3 extensions of the dura mater that help to separate portions of the brain; the falx cerebri, falx cerebelli, and the tentorium cerebelli. the next layer is the Arachnoid layer. It has fewer collagen fibers, areolar tissue, and more reticular/elastic fibers. The arachnoid layer is avascular. Between the dura mater and the arachnoid mater is the subdural space. The innermost layer is the Pia mater. This layer is vascular. It is very thin and clear in color. It contains collagen and elastic fibers. Between the arachnoid and pia maters is the subarachnoid space which contains CSF.
If someone gets hit in the head or back very hard they could get very sick very fast. A subarachnoid hemorrhage is when there is a bleed in the subarachnoid space. A subdural hematoma is when there is a blood clot in the subdural space. Often times when these situations occur a patient must go to the OR to remove the hematoma or stop the bleeding. Patients can also get tumors in any of the spaces in the brain and a craniotomy is performed to biopsy it or remove it.