بسم الله الرحمن الرحيم
Theory…lec. # 1 10-2-2011
spinal cord
as we took in the lab.. the nervous system is divided into:
- central nervous system (CNS) : consists of brain and spinal cord
# Brain : it consists of 4 parts :
•Cereberum : the largest part
•Cerebllum: it's found in the posterior cranial fossa
•Brain stem: ends in the medulla plongata which continues as spinal cord… consists of :
* mid brain
*pons
*medulla plongata
•Diencephalon: central portion of the brain.
-Perepheral nervous system (PNS) :consists of:
*12 pairs of cranial nerves that are originated from the brain ( brain stem and cereberum ).
*31 pairs of spinal nerves .
** functions of the nervous system:
1. sensory function: transmitting sensory from the periphery towards the CNS or from the interior of the body towards CNS.
2.integration: it occurs inside the brain and spinal cord (higher function).
3.motor function: the response in the effected organ, for example, contraction of the muscles and secretion of glands.
> now we'll talk about CNS
*It contains large number of excitable cells, that can make action potential and responsible of the transmission to other cells, called neurons and supporting cells called neuroglia cells and these cells have a role in nutrition, protection and support neurons.
*organized in gray mater and white mater.
-gray mater: formed of the cell bodies of the neurons and neuroglia cells (collection of nuclei)
- white mater: formed of axons and the neuroglia cells surrounding them (full of tracts inside nervous system or nerve fibers outside the nervous system) and the whitish color is due to lipid materials.
Autonomic nervous system (ANS)
*part of the nervous system concerned with innervation of involuntary structures such as the heart, smooth muscles and glands within the body.
*it consists of sympathetic and parasympathetic.
- sympathetic: in danger and emergency situations.
- parasympathetic: at rest.
***all this was only a revision of what we took in the lab!!!! Now we'll start with our topic!!!!!!!
ـــــــــــــــــــــــــــــــــ
Spinal cord
-roughly cylindrical begins superiorly of foramen called magnum (inside the vertebral canal)as a continuation of medulla plongata.
-terminates inferiorly in the lumbar region ( lower level of L1)
> note: the spinal cord doesn't continue till the end of vertebral canal and ends in the lower level of L1 and that's due to the growth of spinal cord which stops at a specific time while the vertebral canal keeps growing.
In this picture you can see that the spinal cord ends at the beginning of the lumbar region (lower level of L1).
- at the end of spinal cord , it tapers off into conus medullaris.
- protective layers around spinal cord:
*vertebral canal (VC)
*meninges: around brain and spinal cord, they are 3 layer (from out to in):
> epidural space
1•Dura mater
> subdural space with fluid
2•Arachnoid mater
> subarachnoid space
3•Pia mater
*CSF ( cerebrospinal fluid ) which is a shock absorber.
- CSF is found in:
1. subarachnoid space.
2. central canal of spinal cord
3. ventricles (spaces) inside the brain.
- CSF is not static but a dynamic fluid.
- from the apex of conus medullaris there is prolongation of pia mater called filum terminale descends to attach to the back of coccyx and the function of filum terminale is fixation of spinal cord.
ـــــــــــــــــــــــــــــــــ
> External anatomy of the spinal cord
1- cervical enlargement due to brachial plexus.
2- lumbar enlargement due to lumbosacral plexus.
3- conus medullaris.
4- filum terminale.
5- spinal nerves: 31 pairs (31 nerves in each side).
* 8 pairs of cervical nerves.
* 12 pairs of thoracic nerves.
* 5 pairs of lumbar nerves.
* 5 pairs of sacral nerves.
* 1 pair of coccygeal nerves.
*each segment of spinal cord there will be a pair of spinal nerves ( from the corresponding vertebra) except the nerves below the level of L1 (L2-5, S1-5 and the coccygeal nerves).
6- cauda equina: the group of spinal nerves below the level of L1 in the vertebral canal.
ـــــــــــــــــــــــــــــــــــــــ
> Internal anatomy of the spinal cord
* it's formed of gray mater ( the inner portion) and white mater ( the outer portion).
> REMEMBER: in the brain.. the white mater is the inner portion and the gray mater is the outer portion.
* the inner gray mater: full of nuclei and appears as H shaped area with two anterior (ventral) horns and two posterior ( dorsal ) horns.
* the central of the H shape is called gray commissure and in the central of the gray commissure is the central canal (which contains the CSF) which will divide the gray commissure into ventral and dorsal area.
* the outer white mater: full of tracts and is divided into:
1. anterior column.
2. lateral column.
3. posterior column.
> column = funiculus.
And the function of this white mater is conduction.
All of this is only an introduction for the next lecture!!!!! 9 pages of introduction!!!!!!!!!!!.
Have fun in studying the sheet :P
Done by: Zein Abu-Zeitoon
Dedicated to:
-Esra'a Al Bawab.
- Lara mazahreh.
- Doha Nairat
- special dedication to Maryam Bader .. you are one of the best people I've ever met.. thank you for being always there for me.. I'm really glad to have you in my life... love u sweetie <3 <3.
1