Spinal cord and PNS* Flashcards
What is the PNS comprised of?
12 pairs of cranial nerves, and 31 pairs of spinal nerves.
Each nerve connects the sensory receptors with the CNS and then to the muscles.
What does grey matter comprise?
Dendrites, cell bodies and synapses.
What does white matter comprise?
Axons.
What 2 things does the peripheral white matter comprising axons form?
Ascending sensory pathways which transmit information from sensory spinal nerves to the brain.
Descending motor pathways transmitting information from the brain to the motor spinal nerves.
Explain the structure of the Spinal Cord?
Grey matter forms a central H-shape.
Upward extensions are the dorsal horns.
Downward extensions are ventral horns.
Where do sensory axons enter the dorsal horn of the spinal cord?
The dorsal root
Where do motor axons leave the spinal cord?
By the ventral root.
Where do the 2 roots join?
They join to form the spinal nerve as the nerve passes out between the vertebrae.
Where do the cell bodies of sensory neurons lie?
They lie on the dorsal root where they form the dorsal root.
Where do motor neuron cell bodies lie?
In the ventral horn of the spinal cord.
