Lab Activity 13 Spinal Cord Portland Community College BI 232 Definitions Tracts collections of axons in CNS Nerves collections of axons in PNS Ganglia collections of neuron cell bodies in PNS Nucleus nuclei collections of neuron cell bodies in CNS 2 Meninges Pia Mater Subarachnoid Space contains the spinal fluid Subdural Space Epidural Space out here between the dura mater and the bone Arachnoid Mater Dura Mater 3 Spinal Cord 4 Spinal Cord Conus Medullaris Conus Medullaris Ends at the level of L1 or L2 5 Spinal Cord Cauda Equina Cauda Equina These are spinal nerves that extend down the vertebral canal 6 past the level of the spinal cord Spinal Cord Gray Matter Posterior Horn Central Canal Anterior Horn The central butterfly is gray matter it contains cell 7 bodies dendrites and unmyelinated axons Gray Matter Horns Posterior gray horns contain somatic and visceral sensory nuclei Anterior gray horns contain somatic motor nuclei Lateral gray horns only located in the thoracic and lumbar segments contain visceral motor nuclei 8 Spinal Cord White Matter Posterior White Column Lateral White Column Anterior Median Fissure Anterior White Column The frame around the butterfly is white matter it contains 9 myelinated axons White Matter Columns Each column contains tracts axons Ascending tracts carry sensory information from the body toward the brain Descending tracts carry motor commands to the spinal cord 10 Spinal Cord Structures 11 Dorsal Root Afferent Sensory Posterior Dorsal Dorsal Root Ganglion Cell bodies of sensory neurons Anterior Ventral Spinal Nerve Mixed motor and sensory Ventral Root Efferent Motor 12 Poliomyelitis Polio means gray matter The polio virus causes inflammation of the gray matter in the anterior horn motor neurons These neurons innervate muscles Symptoms causes muscle paralysis 13 Lou Gehrig s Disease Amyotrophic Lateral Sclerosis ALS is a genetic disease that causes progressive destruction of anterior horn motor neurons Leads to paralysis and death 14 Spinal Nerves 31 Pair 8 12 5 5 1 31 Cervical 8 Thoracic 12 C1 C7 Emerge above the vertebra for which they are named C8 Emerges between C7 and T1 Lumbar 5 Thoracic Lumbar Sacral and Coccygeal spinal nerves emerge below the vertebra for which they are named Sacral 5 Coccygeal 1 15 Spinal Nerves 16 Spinal Nerves Nerve Plexus Dorsal and Ventral roots exit the spinal cord and join together to make a spinal nerve The spinal nerve then splits into dorsal and ventral rami ramus Some ventral rami give off branches to the sympathetic ganglion The other ventral rami mix and match to make up nerve plexuses 17 Ventral Rami The Dorsal Root only contains sensory neurons going toward the spinal cord The Ventral Root only contains motor neurons going out of the spinal cord Ventral Rami contain BOTH sensory and motor neurons As the spinal nerves rami and plexus are crisscrossing everything gets mixed around 18 Spinal Cord Ventral Roots Motor Dorsal Roots Sensory Spinal Nerve this is where sensory and motor mix Dorsal Ramus Ventral Ramus mixed mixed Nerve Plexuses Rami Communicantes White ramus Gray Ramus Sympathetic ganglia 19 Phrenic Nerve The cervical plexus is from C1 to C5 Phrenic Nerve C3 C4 C5 Supplies the diaphragm 20 Brachial Plexus The brachial plexus is from C5 to T1 21 Brachial Plexus 22 Brachial Plexus Nerves Axillary nerve C5 C6 Motor to the deltoid and teres minor muscles Sensory to the skin of the shoulder Musculocutaneous nerve C5 T1 Motor to the flexor muscles of the arm Sensory to the lateral surface of the forearm 23 Brachial Plexus Nerves Radial nerve C5 T1 Motor to muscles of the posterior arm and forearm Sensory to the posteriorlateral side of the hand but not the fingers purple in picture Radial Nerve 24 Brachial Plexus Nerves Median nerve C6 T1 Travels through the carpal tunnel of the wrist Motor to the flexor muscles on the radial side of the forearm Sensory to the anterolateral surface thenar side of the hand posterior fingers 1 2 lateral posterior finger 3 Median Nerve 25 Brachial Plexus Nerves Ulnar nerve C8 T1 Motor to many flexor muscles of forearm and hand on ulnar side Sensory to the medial surface of the hand Ulnar Nerve 26 Lumbar Plexus The Lumbar plexus is from T12 to L4 27 Lumbar Plexus The major nerves Femoral nerve L2 L4 Motor to Quadriceps group Pectineus and Iliopsoas muscles sensory anterior medial thigh and medial surface of leg and foot Injury to femoral nerve causes inability to extend leg loss of sensation in thigh Obturator nerve L2 L4 Motor to adductors of hip Sensory to medial surface of thigh Injury to obturator nerve causes paralysis of thigh adductors 28 Sacral Plexus The sacral plexus is from L4 to S4 29 Sacral Plexus Arises from L4 S4 and serves the buttock lower limb pelvic structures and the perineum The major nerves Sciatic nerve L4 S3 Branches behind the knee Common Fibular nerve Lateral and anterior muscles of the leg Tibial nerve Posterior muscles of the leg Pudendal nerve S2 S4 Muscles of the perineum 30 Sciatic Nerve Branches Common fibular nerve injury produces foot drop inability to dorsiflex foot or numbness on dorsum of foot Tibial nerve injury produces dorsiflexion and eversion with loss of sensation on plantar surface of foot Sciatic nerve Tibial nerve Common Fibular nerve 31 Popliteal fossa Sympathetic Chain Ganglia Next to the thoracic and lumbar regions The ventral root gives rise to a myelinated preganglionic fiber white rami to the sympathetic chain ganglia These fibers may synapse here or in collateral ganglia or in the adrenal medulla 32 33 Lab Activity 14 Reflexes Reflexes A reflex is a rapid predictable motor response to a stimulus Reflexes may Be inborn intrinsic or learned acquired Involve only peripheral nerves and the spinal cord aka spinal reflexes Involve higher brain centers as well 35 Reflex Arc There are five components of a reflex arc 1 Receptor site of stimulus 2 Sensory neuron transmits the afferent impulse to the CNS 3 Integration center either monosynaptic or polysynaptic region within the CNS 4 Motor neuron conducts efferent impulses from the integration center to an effector 5 Effector muscle fiber or gland that responds to the efferent impulse 36 Reflex Arc 37 Innate Reflexes Innate reflexes Reflexes you are born with The are genetically or developmentally programmed Examples Withdrawing from pain Suckling Chewing Tracking objects with the eyes 38 Acquired Reflexes Acquired reflexes are learned motor patterns Generally more complex than