BIOL 2457 1st Edition Lecture 27Outline of Last Lecture Nervous Tissue Outline of Current LectureSpinal Cord and Spinal NervesSpinal Cord Anatomy Protective structures -protect the spinal cord and provide physical stability Vertebral column Meninges Dura mater Epidural and subdural spaces Arachnoid Subarachnoid space – contains CSF Pia materExternal Anatomy of the Spinal Cord Two enlargements: cervical and lumbar Conus medullaris Filum terminale Cauda equina Posterior (dorsal root) & anterior(ventral) root Posterior (dorsal root) ganglion Spinal nervesSpinal Cord Internal Anatomy Anterior median fissure Posterior median sulcus Gray and white commissures Central canal Anterior, posterior & lateral gray horns Anterior, posterior & lateral white columnsSpinal Nerves Number and type 31 pairs Mixed nerves Location Cervical (C1-C8) Thoracic (T1-T12) Lumbar (L1-L5) Sacral (S1-S5) Coccygeal Connective tissue coverings Epineurium Perineurium Endoneurium:Distribution of Spinal Nerves White ramus (myelinated axons) Gray ramus (unmyelinated axons that innervate glands and smooth muscle) Dorsal ramus (sensory and motor innervation to the skin and muscles of the back) Ventral ramus (supplying ventrolateral body surface, body wall and limbs) Each pair of nerves monitors one dermatomeDermatome Dermatome is the area of the skin that provides sensory input to the CNS via one pair of spinal nerves. [the trigeminal nerve]Brachial plexus Formed by the anterior rami of C5-C8 & T1. Supplies the shoulders and upper limbs. Roots → trunks → divisions → cords → nerves.Brachial plexus continued Important nerves that arise from the brachial plexuses are Axillary nerve Musculocutaneous nerve Radial nerve Median nerve Ulnar nerve Injuries to the Brachial Plexus Erb-Duchenne palsy (waiter’s tip)- loss of sensation along the lateral side of the arm. Wrist drop- inability to extend the wrist and fingers. Injuries to the Brachial Plexus Median nerve palsy- numbness, tingling and pain in the palm and fingers. Ulnar nerve palsy- inability to abduct or adduct fingers Winged scapula- the arm cannot be abducted beyond the horizontal
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