A&P 001.4 - The Membrane System
Ξ November 20th, 2008 | → | ∇ Anatomy & Physiology |
*As with all anatomy I suggest you search for each new term on google then click on the ‘Images’ tab at the top of the page. Look at as many different pictures of each structure, from as many different angles as you can. Then look at it on the Visible Body. This will help you get a 3 dimensional image of the structure in your head.
The Membrane System is made up of three layers-
❍ Pia mater This is the innermost layer and it adheres to the
surface of the brain and spinal cord.
❍ Arachnoid mater This is the middle layer and is close to the dura.
❍ Dura mater This is the outer most layer and is very tough.
It is firmly attached to the bones of the skull, C2, C3, and S2.
It is free floating around the rest of the spine.
These three sheaths of membrane are known collectively as the
meninges. They surround and enclose the central nervous
system or brain and spinal cord. The space between each
layer is filled with cerebrospinal fluid. The space between the
arachnoid and dura mater is called the Sub arachnoid space.
It is the Sub arachnoid space that contains the majority of the
cerebrospinal fluid.
The Cranial Dura is further sub-divided into two layers.
The outer layer lines the inside of the cranuim and the inner
layer forms several folds or infoldings called -
❍ The Falx Cerebri - A sickle-shaped membrane running from
the front the to back of the cranium along the mid line between
the two Cerebral hemispheres.
❍ The Falx Cerebelli - A much smaller sickle-shaped membrane
passing down the midline of the Occipital region between the
two Cerebellar hemispheres.
❍ The Tentorium Cerebelli - A tent-shaped membranous
structure passing almost horizontally across the Cranium
dividing the Cerebrum above from the Cerebellum below.
❍ The Diaphragma Sellae - A small horizontal membrane
forming a roof over the Sella Turcica of the Sphenoid bone and
enveloping the Pituitary Gland.
It is helpful to think of the Cranial Dura as being like a balloon
with four infoldings inside. Restrictions in this membrane can
pull the cranial bones into compression and restrict areas of the
brain.
As stated previously, but it is worth saying again, all parts of
the Membrane system are interconnected forming a Reciprocal
Tension Membrane System. Meaning that tensions within any
part of the Membrane System are liable to influence all other
parts of the Membrane System.