Spinal Cord anatomy Flashcards
What does the ventral root contain?
Efferent motor neurones.
Their cell bodies make the grey matter in spinal cord
Can also contain preganglionic neurones that provide autonomic innervation
What does dorsal root contain?
Primary afferent neurones from periphery sensory receptors.
Cells bodies from these form the dorsal root ganglion
How many pairs of spinal roots?
31 pairs bilaterally
How many roots per spinal division?
Cervical - 8 Thoracic - 12 Lumbar - 5 Sacral - 5 Coccygeal - 1
What do dorsal root and ventral root combined make?
They pass through intervertebral foramina as spinal nerve.
What does spinal nerve divide into
After leaving the foramina the spinal nerve divides into thin dorsal ramus and thick ventral ramus
Dorsal ramus supplies skin and muscle of back region
Ventral ramus supplies muscles and skin of anterior
In relation to corresponding vertebra, at what level do the spinal nerves exit the vertbral canal?
C1-7 exit above corresponding vertebrae
C8 below C7 vertebrae
Remainder exit below the corresponding vertebrae
2 main types of cell in spinal cord
Interneurones (97%) - modulate sensory inputs and motor outputs, forming interlocal connections with other neurones
Projection neurones - subdivided into axons of ascending pathways (1%) and motor neurones (2%)
Subdivisions of interneurones
Inhibitory neurones: limit receptive field sizes or activity of other neurones through action of GABA, glycine and enkephalin
Excitatory neurones: activation evokes action potentials in other cells, using glutamate as neurotransmitter
Types of motor and sensory axons
Aalpha - biggest diameter, quickest speed. Proprioceptors of skeletal muscle
Abeta - mechanoreceptors of skin
Adelta - smallest diameter and slowest of alphas. Pain and temperature
C - smallest and slowest. Temperature, pain, itch
