ANAT 215 Lecture Notes - Lecture 8: Dorsal Root Ganglion, Cranial Nerves, Spinal Nerve

• School: Queen's University
• Department: Anatomy and Cell Biology
• Course: ANAT 215
• Professor: Leslie W Mac Kenzie

Document Summary

Spinal nerves (info to and from sc) Cranial nerves (info to and from brain) Sensory (afferent -> to the cns) division. Somatic (skin, skeletal muscles, joints -> somatic afferents) Motor (efferent -> from the cns) division. Autonomic involuntary (cns to smooth, cardiac, glands) 31 pairs of spinal nerves (1000 s of nerve axons) Formed by union of dorsal and ventral routes of spinal cord. Named for their inferior vertebrae, except c8. Each spinal nerve is ensheathed by a series of connective tissue layers. Epineurium (most outer) -> dense network of collagen fibers. Perineurium (middle) -> partitions the nerve into a series of bundles (fascicles) and forms the blood-nerve barrier) Endoneurium (most inner) composed of delicate ct fibers that surround individual axons. Brachial plexus (c5-t1 -> gives rise to all nerves that supply muscles of upper limbs) Lumbosacral plexus (t12-s4 -> provides innervation to muscles of lower limbs) Area of skin innervated by cutaneous branches of a single spinal nerve.