M5S4 Central Nervous System: Spinal Cord Flashcards
Where is the spinal cord located
Vertebral canal
What is the spinal cord supported by
Vertebral column
What is the spinal cord’s purpose
-facilitates communication between the central nervous system and peripheral nervous system through the spinal nerves
-spinal nerves exist at spinal cord to supply sensory and motor inner actions to regions close to the level of exit
Ex. Spinal nerves existing from upper cervical region will serve head and neck, while spinal nerves from the thoracic region will serve the thorax
External topography
-spinal cord begins at foramen magnum of the occipital bone
-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 the cauda equina
-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
*refer to goodnotes for image
Regions of the spinal cord
-same name as the regions of spinal cord of vertebral column
-as the spinal cord in adults is shorter than the vertebral canal, the lower regions of the spinal cord are not located within the area of the vertebral column with the corresponding name
Top to bottom
Cervical
Thoracic
Lumbar
Sacral
*refer to goodnotes
Spinal enlargements
-spinal cord enlarged at the cervical and lumbar levels
-enlargements occur because of the additional nerves exiting the spinal cord that supply the limbs
Note: cervical enlargement supplies innervation to the upper limb, while the lumbar enlargement serves the lower limb
*refer to goodnote images
Spinal Cord Injury
-When spinal cord damaged such that the signals between the brain and PNS have difficulty communicating
Levels of function in spinal cord injury and little pre summary
Spinal cord- in charge of relaying messages from the brain to the rest of the body
Spinal cord bruised or fractured - normal function above the point of injury remains but function below suffer impairment ranging a variety of degrees for things like motor and sensory deficits, bowel and bladder dysfunction and respiratory difficulties
Levels of function
Numbers like C4 or T2 for example refer to the level a spinal cord injury survivor has after an injury
-state where occurred
-HIGHER POINT OF INJURY= GREATER IMPAIRMENT
-injuries in C1-C3 result in limited movement of head only but paralysis below that region. Many survivors of these areas require ventilator and struggle talking
-injuries in C3-C4 have head movement and minimal shoulder movements, typically can talk and adjust to breathing without a ventilator
-C5 level injuries have head, neck, and shoulder control plus can bend the elbows and rotate hands. Self care manageable like push own wheel chair and driving with adaptive equipment
-C6 level injury movement of head, neck, shoulder, arms, wrist including bending elbows, extend wrist and rotate palms. Most do self care, light house keeping and manual wheelchair
-C7 injuries similar to C6 but manage more easily
INJURIES AT T LEVEL OF SPINAL CORD OCCUR ON THORACIC SPINE
-C8-T1 injury in addition to use of arms, neck, shoulders, hands, finger can also be used. Survivors in this range live independently
-T2-T6 range have normal upper body function but some degree of impairment in legs. Some walk with assisted devices
-t7-T12 similar to above but more control
L LEVEL INJURIES OCCUR IN LUMBAR REGION OF SPINE
-survivors have some ability to move hips and knees but walking possible with assistant devices
Support and protection of the spinal cord
-like brain, surrounded by protective layers of meninges
-appear in same order as do with brain - pia mater being most deep and the dura mater being most superficial
Dura mater
-unlike brain where double layer of connective tissue, it’s only 1 layer here
-between the external surface of the dura mater and the bones is the fat-filled epidural space
-fun fact: in patients receiving an epidural anesthetic, the drug is injected into the epidural space of the spinal cord
Arachnoid mater
-deep to the dura
-between the arachnoid and pia mater is the subarachnoid space, which continuous with the subarachnoid space of the brain, and contains CSF
Pia mater
-deep to the arachnoid mater
-directly attached to the spinal cord
- refer to goodnotes for image
Internal topography of spine
-In reverse to brain- spinal cord contains inner grey matter and outer while matter
-appearance of grey and white matter is evident in histological cross sections of spinal cord due to different cell types that populate the different matter types
Recall:
Grey matter - dendrites, neuron cell bodies, glial cells, unmyelinated axons
White matter - mainly myelinated axons
Grey matter of the spinal cord
-located on inside of spinal cord
-consists of 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, which carrries information from the sympathetic nervous system
*refer to goodnotes for image
White matter of spinal cord
-lines the outside of grey matter of spinal cord
-consists of tracts of fibers seperated into anterior, lateral, and posterior funiculi (bundles)
*refer to goodnotes for images
