Spinal nerves, dermatomes and myotomes Flashcards
Where should a lumbar puncture be performed and why?
L3/L4
because the spinal cord ends at L1/L2
Where is the lumbar cistern?
- surrounds cauda equina
- area of subarachnoid space
What does the neural plate develop into
the epidermis
What does the neural crest develop into?
spinal ganglion
How is the neural tube and neural crest cells developed?
- folding process to give neural fold controlled by notochord
- neural crests pulled together to make neural groove
- neural crest cells move down to allow joining of neural plate above them
- two neural crests join to form one crest
- neural tube formed and this forms neural canal
What is a myotome?
the dorsal part of each somite in a vertebrae embryo, giving rise to the skeletal musculature
Where do sensory neurons lie?
in the dorsal root ganglia which develop from neural crest cells
Where do motor neurons lie?
anteriorly within the neural tube
What is a dermatome?
the strip of skin supplied by a single spinal segment
What does each pair of spinal nerves consist of?
- axons of motor neurons that innervate a group of muscles arising from the same somite
- axons of sensory neurons that innervate a defined area of skin
- axons of sympathetic neurons to structures in the body wall that control body temperature
What do dorsal rami of thoracic spinal nerves carry?
- motor neurons to erector spinae
- sensory neurones from the skin of the back and from vertebral joints
- sympathetic neurons to blood vessels and the sweat glands of the skin
What do ventral rami of thoracic spinal nerves carry?
- motor neurons to intercostal muscles
- sensory neurons from thoracic skin and pleura and vertebral joints
- sympathetic neurons to blood vessels and sweat glands of the skin
What is a reflex?
rapid, involuntary motor responses to stimulus
What makes up a reflex arc?
receptor sensory neuron integration centre motor neuron effector
