BIO 206 Lecture Notes - Lecture 2: Cranial Cavity, Facial Nerve, Tertius Of Iconium
Document Summary
The peripheral nervous system is composed of: 31 pairs of spinal nerves, 12 pairs of cranial nerves. Cranial nerves arise directly from the brain whereas spinal nerves originate from the spinal cord. Ventral rami are large branches off of spinal nerves that supply the flank of the body and anterior aspects of the thorax, abdomen and pelvic regions. Ventral rami also give rise to the nerve plexuses that innervate the upper and lower limbs. A nerve plexus is a braiding or twining together of nervous tissue. There are four major plexus systems that supply separate regions of the body. These include: cervical plexus brachial plexus lumbar plexus sacral plexus. The brachial plexus is comprised of the ventral rami of cervical and thoracic spinal nerves c5, The brachial plexus forms a network arrangement of nerves starting with the. The five roots combine together to form three trunks (superior, middle and inferior).