section 4 Flashcards
Describe the structure and function of the spinal cord.
- Located in the vertebral canal and is supported by the vertebral column
- Facilitates communication between the central nervous system and peripheral nervous system through the spinal nerves
- spinal nerves exit the spinal cord to supply sensory and motor innervations to regions close to the level of exit
- for example, spinal nerves exiting from the upper cervical region will serve the neck and head, while spinal nerves from the thoracic region will serve the thorax
Where is the spinal cord located/attached to? (from top to bottom)
- it begins at the foramen magnum of the occipital bone
- it extends inferiorly to the level of L2, known as the conus medullaris
- inferior to L2, the axons emerging from the spinal cord are known as cauda equina (looks like horses tail)
- within the cauda equina, a small thin strand of pia mater, known as the filum terminale, anchors the spinal cord to the sacrum and coccyx
Why is the spinal cord enlarged at the cervical and lumbar levels?
Because of the additional nerves exiting the spinal cord that supply the limbs.
The cervical enlargement supplies innervation to the upper limb, while the lumbar enlargement serves the lower limb.
What happens when the spinal cord is injured?
The messages being sent from the bottom no longer flow through the injured part of the spinal cord.
This means that the functions of the body ABOVE the point of injury occur normally, but the functions BELOW the point of injury will experience some degree of impairment
What happens when the spinal cord is injured?
The messages being sent from the bottom no longer flow through the injured part of the spinal cord.
This means that the functions of the body ABOVE the point of injury occur normally, but the functions BELOW the point of injury will experience some degree of impairment.
e.g (motor and sensory deficits, bowel and bladder dysfunction, and respiratory difficulties)
What are the different protective layers of meninges of the spinal cord?
Dura mater
Arachnoid mater
Pia mater
What is dura mater?
- in the brain the dura mater consists of a double layer of connective tissue, but in the spinal cord the dura mater consists of only one layer
- between the external surface of the dura mater the bone is the fat-filled epidural space
*in patients receiving an epidural anesthetic, the drug is injected into the epidural space of the spinal cord
What is the arachnoid mater?
- deep to the dura
What is the subarachnoid space? Where is it?
- between the arachnoid and pia mater is the subarachnoid space which is continuous with the subarachnoid space of the brain, and contains CSF
Where is the pia mater?
Deep to the arachnoid mater is the pia mater, which is directly attached to the spinal cord
What are the white/grey areas in spinal cord topography?
Grey matter is mainly composed of dendrites, neuron cell bodies, glial cells, and unmyelinated axons.
White matter is mainly composed of myelinated axons.
Describe grey matter of the spinal cord.
- located on the inside of the spinal cord
- consists of a ventral horn which carries motor information, and a dorsal horn which carries sensory information
- between the anterior and posterior horns is the lateral/intermediate horn. it carries information from the sympathetic nervous system
Describe the white matter of the spinal cord.
- lines the outside of the grey matter
- consists of tracts of fibers separated into anterior, lateral, and posterior funiculi (bundles)
Compare dura mater or brain vs spinal cord.
dura mater in the BRAIN consists of a DOUBLE layer of connective tissue
whereas dura mater in the spinal cord consists of a SINGLE layer of connective tissue
