11-1 Nervous Tissue I: Functional Organization, Spinal Cord and Spinal Nerves Lecture 12

11-2 Nervous Tissue Found in brain, spinal cord and nerves Property –Ability to produce action potentials (electric signals) Cells –Nerve cells or neurons –Neuroglia or support cells –Oligodendrocytes and Schwann cells

11-3 The Nervous System Subdivisions –Central nervous system (CNS) –Peripheral nervous system (PNS) Sensory receptor –Receptor of sensory information Nerve –Made up of a bundle of axons Ganglion –Collection of cell bodies of neurons Plexus –Network of spinal nerves

11-4 Central Nervous System Consists of –Brain Located in cranial vault of skull –Spinal cord Located in vertebral canal Brain and spinal cord –Continuous with each other at foramen magnum Tract Fig. 14.1

11-5 Peripheral Nervous System Two subcategories –Sensory or afferent –Motor or efferent Divisions –Somatic nervous system –Autonomic nervous system (ANS) »Sympathetic (fight or flight) »Parasympathetic (rest and digest) Fig. 14.2

11-6 Spinal Cord Extends from foramen magnum to second lumbar vertebra Segmented –Cervical –Thoracic –Lumbar –Sacral Gives rise to 31 pairs of spinal nerves Not uniform in diameter throughout length Fig. 16.1

11-7 Meninges Connective tissue membranes surrounding spinal cord and brain –Dura mater –Arachnoid mater –Pia mater Spaces –Epidural: Anesthesia injected –Subdural: Serous fluid –Subarachnoid: cerebrospinal fluid (CSF) Fig. 16.2

11-8 Cross Section of Spinal Cord White matter –Myelinated axons forming tracts –Three funiculi (columns) Gray matter –Neuron cell bodies, dendrites, axons –Three horns Fig Fig. 16.4

11-9 Spinal Nerves Cervical Plexus C1-C4 Phrenic nerve –from C3-C5 (cervical and brachial plexus) –innervates diaphragm Fig. 16.8

11-10 Brachial Plexus C5-T1 Major nerves –Radial –Ulnar –Median Fig. 16.9

11-11 Lumbar Plexus Fig

11-12 Sacral Plexus Fig

11-13 Review Question Compression of the ________ nerve against the medial epicondyle of the humerus will produce strong tingling sensations along the forearm and hand. (a)Radial (b)Median (c)Phrenic (d)Femoral (e)Ulnar

11-14 Points to Remember Nervous system consists of central nervous system (brain and spinal cord) and peripheral nervous system (all nervous tissue outside of central nervous system) Sensory (afferent) neurons carry sensory information to brain and spinal cord Motor (efferent) neurons carry motor away from brain and spinal cord to spinal nerves and cranial nerves Spinal nerves have a dorsal root (sensory neurons) and a ventral root (motor neurons) Names of nerves in plexuses generally describe the body region they travel

11-15 Questions?