SPINAL CORD -
The spinal cord is the part of CNS which is contained within the vertebral canal & is the prolongation of the brain.It is surrounded by a clear fluid called Cerebral Spinal Fluid (CSF), that acts as a cushion to protect the delicate nerve tissues against damage from banging against the inside of the vertebrae.
The anatomy of the spinal cord itself, consists of millions of nerve fibres which transmit electrical information to and from the limbs, trunk and organs of the body, back to and from the brain. The nerves which exit the spinal cord in the upper section, the neck, control breathing and the arms. The nerves which exit the spinal cord in the mid and lower section of the back, control the trunk and legs, as well as bladder, bowel and sexual function.
The brain and spinal cord are referred to as the Central Nervous System, whilst the nerves connecting the spinal cord to the body are referred to as the Peripheral Nervous System.
It develops from that portion of neural tube which lies caudal to the level of the 4th pair of somites.
It is about 45 cm (18'') long & about 1.25 cm (1/2'') wide.
Extention:
From the horizontal plane passing between the middle of the odontoid process of the 2nd cervical vertebrata & terminates below in a conical extremity , the conus medullaris at the lower border of the body of 1st lumber vertebra.
Enlargements:
It present two enlargements - Cervical & Lumber. The cervical enlargement extends from the level of 3rd cervical to the 2nd thoracic segment of the spinal cord. From this enlargement nerves for the upper extremities emerge out.
The lumbar enlargement extends from the ninth thoracic vertebra to the twelfth thoracic vertebra. From it nerves for lower extremities emerge out.
Filum terminale :
A delicate, thread like non-nervous filament, about 20 cms long. Extends from the lower end of conus medullaries and terminates by being attached to the dorsal aspect of first coccygeal vertebra.
Coverings :
It has three covering , from without in-words-dura mater, arachnoid & pia mater is subarachnoid space which contain CSF and extends as down as the 2nd sacral vertebra.
Parts of Spinal cord :
Onbcross section, the spinal cord has two parts-
1) Central _ grey mater :It is composed of a mass of nerve cells, nerve fibers consisting of both
axons & dendrons together witha framework of neuroglial cells.It is divided into two symetrical
halves which are connected by a transverse band , resemble the letter H. It has three column
(horn) -
a) Anterior horn.
b)Lateral horn (only in thoracic horn) &
c)Posterior horn.
2) Peripheral - white matter : It surrounds the grey matter and consists of nerve fibres & neuroglia. It appear as white because most of the fibre are myelinated.
3) Central canal : It exists through out the spinal cord and is continuous above with the inferior angle of 4th ventiricle and below it expands as far down as 2'' within filum terminale.
Function of Spinal cord :
1) It is the main pathway for all incoming and outgoing impulses from the higher center to the
periphery & vice versa.
2) It is the main center of reflex actives.
3) It exerts tropic control over the muscular system.
The spinal cord is the part of CNS which is contained within the vertebral canal & is the prolongation of the brain.It is surrounded by a clear fluid called Cerebral Spinal Fluid (CSF), that acts as a cushion to protect the delicate nerve tissues against damage from banging against the inside of the vertebrae.
The anatomy of the spinal cord itself, consists of millions of nerve fibres which transmit electrical information to and from the limbs, trunk and organs of the body, back to and from the brain. The nerves which exit the spinal cord in the upper section, the neck, control breathing and the arms. The nerves which exit the spinal cord in the mid and lower section of the back, control the trunk and legs, as well as bladder, bowel and sexual function.
The brain and spinal cord are referred to as the Central Nervous System, whilst the nerves connecting the spinal cord to the body are referred to as the Peripheral Nervous System.
It develops from that portion of neural tube which lies caudal to the level of the 4th pair of somites.
It is about 45 cm (18'') long & about 1.25 cm (1/2'') wide.
Extention:
From the horizontal plane passing between the middle of the odontoid process of the 2nd cervical vertebrata & terminates below in a conical extremity , the conus medullaris at the lower border of the body of 1st lumber vertebra.
Enlargements:
It present two enlargements - Cervical & Lumber. The cervical enlargement extends from the level of 3rd cervical to the 2nd thoracic segment of the spinal cord. From this enlargement nerves for the upper extremities emerge out.
The lumbar enlargement extends from the ninth thoracic vertebra to the twelfth thoracic vertebra. From it nerves for lower extremities emerge out.
Filum terminale :
A delicate, thread like non-nervous filament, about 20 cms long. Extends from the lower end of conus medullaries and terminates by being attached to the dorsal aspect of first coccygeal vertebra.
Coverings :
It has three covering , from without in-words-dura mater, arachnoid & pia mater is subarachnoid space which contain CSF and extends as down as the 2nd sacral vertebra.
Parts of Spinal cord :
Onbcross section, the spinal cord has two parts-
1) Central _ grey mater :It is composed of a mass of nerve cells, nerve fibers consisting of both
axons & dendrons together witha framework of neuroglial cells.It is divided into two symetrical
halves which are connected by a transverse band , resemble the letter H. It has three column
(horn) -
a) Anterior horn.
b)Lateral horn (only in thoracic horn) &
c)Posterior horn.
2) Peripheral - white matter : It surrounds the grey matter and consists of nerve fibres & neuroglia. It appear as white because most of the fibre are myelinated.
3) Central canal : It exists through out the spinal cord and is continuous above with the inferior angle of 4th ventiricle and below it expands as far down as 2'' within filum terminale.
Function of Spinal cord :
1) It is the main pathway for all incoming and outgoing impulses from the higher center to the
periphery & vice versa.
2) It is the main center of reflex actives.
3) It exerts tropic control over the muscular system.
.jpg)
.gif)
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)
0 comments:
Post a Comment