spinal nerves and their distribution (week 10) Flashcards
what is the lumbar cistern and where does it extend from?
the area of subarachnoid space that surrounds the cauda equine. Extends from disc between L1 and L2 and end at the lower border of S2
where is the needle inserted for a lumbar puncture?
between L3 and L4 or L4 and L5
if a line is drawn from the top of the iliac crests which vertebrae does it reach?
crosses the L4 spinous processes
which type of mesoderm do the somites develop from?
paraxial mesoderm
where do the cell bodies of the somatic motor neurones lie in the neural tube in embryology?
anteriorly within the neural tube
what are dermatomyotomes?
developed from somites and will become dermatomes and myotomes
what is the best definition of a myotome?
a section of muscle(s) with similar functions supplied by motor neurons from the SAME spinal segments of the spinal cord.
what do the dorsal root ganglia develop from?
neural crest cells
where do sensory neurone cell bodies lie?
in the dorsal root ganglia
what is a dermatome?
an area of skin innervated by sensory neurones from a specific region of spinal cord. (e.g. skin on lateral side of forearm develops adjacent from the C6 somite
which infection can show rash patterns to specific dermatomes?
shingles (caused by varicella zoster virus lying dormant in a dorsal root ganglion)
how many pairs of spinal nerves are there?
31 pairs
how many cervical spinal nerves are there and how many vertebrae?
8 cervical spinal nerves and 7 vertebrae.
do cervical spinal nerves emerge above or below the corresponding vertebrae?
above
do thoracic spinal nerves arise above or below the corresponding vertebrae?
below (via the intervertebral foramen)
where do the somatic motor nerves arise from that supply the intrinsic back muscles (the erector spinae muscles)?
the posterior ramus
what do the sympathetic neurones do?
control structure in the body wall which control temperature (blood vessels, sweat glands etc)
what are the three main components of the mixed nerves that make up the dorsal rami of the thoracic spinal nerves?
motor neurones which control the erector spinae muscles; sensory neurones from the skin of the back and from vertebral joints; sympathetic neurones to blood vessels and sweat glands of the skin
what are the three main components of the mixed nerves which make up the ventral rami of the thoracic spinal nerves?
motor neurons which control the intercostal muscles (muscles between the ribs involved in breathing); sensory neurones from thoracic skin and pleura and vertebral joints; sympathetic neurones which control blood vessels and sweat glands of the skin
what is the six step process of the reflex arc?
receptor, sensory neurone, integration centre, motor neurone and effector
where do motor neurone cell bodies lie in the spinal cord?
in the anterior horn of the gray matter of spinal cord (axon travels in ventral root
where do the cell bodies of sensory neurons lie and what shape of neurone are they?
in the dorsal root ganglion (of the dorsal root); pseudo unipolar shape of neurone
what is the efferent nervous system?
motor neurones
what is the afferent nervous system?
sensory neurones
