Paul McMenamin; Week 2 MED1022; Anatomy
Mixed spinal nerves can be long if the segment of cord is far from the vertebral level of exit since the spinal cord is shorter than the vertebral column. DRG lies at the opening of the intervertebral foramina and splits into dorsal and ventral rami which innervate the posterior and anterior of the body respectively. Spinal nerve is distal to the DRG and between the two are grey and white rami communicantes. White rami send sympathetic signals to sympathetic ganglia, grey brings information from sympathetic chain. In the brachial plexus, anterior divisions supply the flexors, pronators and adductors. Posterior divisions control the extensors, supinators and abductors.
Rootlets go to roots which fuse to form mixed spinal nerve proper, which then divides to dorsal and ventral rami. The connections to the spinal chain are grey and white rami communicantes.
AFFERENT is towards the CNS from a receptor. EFFERENT is away.