Spinal Nerves in Rabbit

The nerves arising from the spinal cord are called spinal nerves. There are 37 pairs of spinal nerves in Rabbit. Each spinal nerve arises from the spinal cord by two roots, a dorsal or sensory root and a ventral or motor root. These roots unite to form a nerve. The dorsal root contains a small dorsal ganglion just outside the neural canal. After originating from the spinal cord thus formed passes out of neural canal through intervertebral foramen.

Each spinal nerve divides into 3 branches. These are:

1. Ramus dorsalis (dorsal branch): It divides into several branches which enter the skin and muscles of dorsal body wall. It contains somatic sensory fibres.
2. Ramus ventrails (ventral branch): It is a long main branch. It supplies nerves to the muscles of belly (Ventral body wall). It contains somatic motor fibres. The prominent ventral branch is generally considered as the spinal nerve.
3. Ramus communicans (visceral branch): It joins with sympathetic ganglion. It contains both visceral sensory and visceral motor fibres.

The brachial phlexus is formed by the ventral branches of 4^th to 9^th spinal nerves. The lumbar phlexus is formed by the ventral branches of 24^th to 27^th spinal nerves. Sacral phlexus is formed by the ventral branches of 28^th to 31^st spinal nerves.

The posterior spinal nerves run backward in the neural canal before they comeout as a bunch. This bunch along with filum terminal resembles to the tail of horse, hence called cauda equina.

Summary

Spinal Nerves in Rabbits:

1. Origins and Roots:
   • Nerves arising from the spinal cord are called spinal nerves.
   • There are 37 pairs of spinal nerves in rabbits.
   • Each spinal nerve has two roots: dorsal (sensory) and ventral (motor).
   • These roots unite to form a nerve, with the dorsal root containing a dorsal ganglion.
2. Nerve Pathway: The nerve formed after originating from the spinal cord passes out through the intervertebral foramen.
3. Branches of Each Spinal Nerve:
   • Ramus dorsalis (dorsal branch): Enters the skin and muscles of the dorsal body wall, containing somatic sensory fibers.
   • Ramus ventralis (ventral branch): Main branch supplying nerves to the muscles of the ventral body wall, containing somatic motor fibers (considered the spinal nerve).
   • Ramus communicans (visceral branch): Joins with sympathetic ganglion, containing both visceral sensory and visceral motor fibers.
4. Plexuses:
   • Brachial Plexus: Formed by the ventral branches of the 4th to 9th spinal nerves.
   • Lumbar Plexus: Formed by the ventral branches of the 24th to 27th spinal nerves.
   • Sacral Plexus: Formed by the ventral branches of the 28th to 31st spinal nerves.
5. Cauda Equina:
   • Posterior spinal nerves run backward in the neural canal before emerging as a bunch.
   • This bunch, along with the filum terminale, resembles the tail of a horse, hence referred to as cauda equina.