anatomy - the spinal cord

describe the shape of the spinal cord

about 18 inches long in adults, extending from foramen magnum to L1/L2

what is the relationship of spinal cord to the vertebral column?

the spinal cord is located with the vertebral column. the vertebral column act as a protective barrier.

how many spinal nerves are there?

31 pairs

how many level of the spinal cord are there?

30 levels

where does C1 nerve exit the vertebrae?

about the atlas (C1)

where does C2-C7 nerves exit the vertebrae?

about the vertebra with the correlating number.

where does C8 nerve exit the vertebrae?

below the C7 vertebra, between C7 and T1

where do the subsequential spinal nerves exit the vertebrae?

below the vertebra with the correlating number

why does cervical and lumbar enlargements exist?

there is an increased number of motor neurons in the gray matter of lumbar and cervical regions.

how many spinal meninges are there?

6

what is epidural?

fat filled space where spinal anesthetics are injected

what is dura mater?

outermost layer of the meninges, a connective, tough tissue

what is the subdural space?

potential space between dura mater and arachnoid mater

what is arachoid mater?

middle layer of the meninges, spider-web like containing filaments that attach to the spinal cord?

what is subarachnoid space?

space between arachnoid and pia mater, with cerebrospinal fluid

what is pia mater?

innermost layer of the meninges, cannot be removed

how does the spinal cord develop?

comes from the caudal part of the neural tube

what is spina bifida?

the absence of the vertebral laminae

what is myeloceles?

no spinal cord or brain due to the failure of the neural groove to close.

what is spina bifida occulta?

a vertebrae didn't properly close, however the spinal cord forms properly. this can be harmful, yet fixed by surgery.

what is meningocele?

the meninges do not fully form which develops a cyst, however the spinal cord does develop in the normal spot. surgery can fix this.

what is meningomyelocele?

a cyst of the meninges, however the spinal cord protrudes from the body. one can be paralysed from the located of the cyst down. the most common form!!

what does the neuroepithelium do?

gives rises to all of the spinal cord neurons. know that grey matter are the cell and the axons are the white matter.

what is grey matter?

cell bodies that process sensory and motor info.

what is white matter?

myelinated axons that transmit nerve signals between the spinal cord

what are dorsal horns?

interneurons that receive somatic and visceral sensory input

what are ventral horns?

somatic motor neurons whose axons exit the cord via ventral roots

describe the differential growth of the spinal cord.

at 8 weeks of pregnancy, the spinal cord and vertebra are the same length. as time progresses, the vertebral column exceeds the growth of the spinal cord.

what is the the cauda equina?

collection of nerve roots at the inferior end of the vertebral canal

what is the conus medullaris?

tapered end of spinal cord

what is the filum terminale?

thin strand of pia mater that helps anchor the conus medullaris to the coccyx

what is a lumbar puncture?

the procedure of taking fluid from the subarachnoid space, below the conus medullaris

what is epidural anesthesia?

anesthetic injected into the epidural space

what happens if a lumbar puncture or epidural anesthesia goes wrong?

one can be paralysed

what's the best safety measure for doing lumbar punctures?

go down to additional vertebraes.

what is the location for lumbar punctures in adults?

L3/L4

what is the location for lumbar punctures in child?

L4/L5

what are the ascending tracts of the spinal cord?

white matter that sends impulses to the brain

what are the descending tracts of the spinal cord?

carry motor impulses from the brain to muscles and glands

what is the somatosensory cortex?

area at the front of the parietal lobes that registers and processes body touch and movement sensations

what are dermatones?

circumscribed skin area that is supplied mainly from one spinal cord segment through a particular spinal nerve

what are the spinothalamic tracts?

important sensory tracts that pass through the brainstem, associated with crude touch, pain, and temp from the body

where do spinothalamic axons synapse upon entering the spinal cord?

within the dorsal horn of the spinal cord

what occurs at the first level of synapse in the spinothalamic tract?

cross over

what are dorsal columns?

two sets of ascending pathways in white matter, the fasciculus cuneatus and fasciculus gracilis, that carry sensory information faster with precise location. CONSCIOUS. cross over at the medulla

What are the spinocerebellar tracts?

convey information about muscle and tendon stretch to the cerebellum, UNCONSCIOUS