The spinal cord and others Final Flashcards
The spinal cord
- Elongated almost cylindrical part of the nervous system which lies in the upper 2/3 of the vertebral canal.
How long is the spinal cord and where does it start and end.
- 45 cm in length
- Extends from atlas to the lower boarder of the 1st lumbar.
what name is given to the extremity where the spinal cord ends in the lumbar region.
Conus medullaris
How many pairs of nerves arise from the spinal cord.
- 31 pairs of nerves
- Each nerve rises by two roots, an anterior root and posterior root
another name of anterior root
ventral root
THE ANTERIOR ROOT
- Contains the efferent fibres of the autonomic nervous system.
another name of posterior root
dorsal root
The posterior root
- Contains sensory fibres passing into the spinal cord.
Arrangement of spinal nerves in the spinal cord.
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
Composition of the spinal cord.
- The spinal cord is composed of
- white matter,
- grey matter
- neuroglial tissue.
The grey matter of spinal cord
- Lies centrally
- On the transverse of the cord it appears to have an H arrangement
- The limbs of the H are symmetrical and each has an exterior and posterior horn.
The anterior horn of the grey matter.
contains nerve cells the axons of which form the motor fibres of the anterior nerve roots
what forms the motor fibres
axons
The posterior horn of the spinal cord
contains nerve cells of the connector type
How is synapse formed by posterior root fibres.
- The posterior horn of the spinal cord contain nerve cells of connector type which form the synapse
The white matter of the spinal cord
- Surrounds the grey matter
- Divided by the limbs of grey matter into 3 columns
Columns of the white matter of the spinal cord.
- Posterior
- Lateral
- Anterior
Types of fibres within the white matter
- Ascending fibres
- Descending fibres
- Intersegmental fibres
Ascending fibres
Carry sensory impulses to the brain
Descending fibres
carry motor impulses from the brain to the cells of the anterior horn of the spinal cord.
Intersegmental fibres
carry impulses from one level
of the cord to another
The sensory pathways
- Sensory impulses enter the spinal cord in the posterior nerve roots
- Sensations that enter the spinal cord in the posterior never roots are of pain, temp, light touch, pressure
Motor pathways
- Motor impulses which produces contractions of voluntary muscles
- Initiated in the cells of the motor area of the cerebral cortex
- They finally form synapses with anterior horn cells at the level of the cord for which they are destined
Reflexes
reflexes are automatic motor responses to sensory stimuli and they occur without the direct involvement of the
brain.
