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Spinal Cord & Nerves Spinal Cord Extends from the base of the skull to the first or second lumbar vertebra 31 pairs of spinal nerves arise from the spinal cord Spinal Cord Anatomy Figure 7.20 (1 of 2) Spinal Cord Anatomy Figure 7.20 (2 of 2) Spinal Cord Anatomy Figure 7.21 Spinal Cord Anatomy Meninges cover the spinal cord Spinal nerves leave at the level of each vertebrae Dorsal root Ventral root Pathways Between Brain and Spinal Cord Figure 7.22 Peripheral Nervous System (PNS) Nerves outside the central nervous system Nerve = bundle of neuron fibers Neuron fibers are bundled by connective tissue PNS: Structure of a Nerve endoneurium perineurium epineurium fascicle Figure 7.23 PNS: Classification of Nerves Mixed nerves Both sensory and motor fibers SENSORY (afferent) nerves Carry impulses toward the CNS MOTOR (efferent) nerves Carry impulses away from the CNS Cranial Nerves PNS: Cranial Nerves 12 pairs of nerves that mostly serve the head and neck Only the pair of vagus nerves extend to thoracic and abdominal cavities 3 are SENSORY only 5 are MOTOR only 4 are MIXED Diagram & Chart Open up your notebook to next empty page. You will be using both pages on either side of spiral. LEFT: (refer to p. 260) Color code CRANIAL NERVES diagram and paste it into your notebook. RIGHT: Draw chart # Nerve S Function or M? I OLFACTORY II OPTIC III OCULOMOTOR IV TROCHLEAR V TRIGEMINAL VI ABDUCENS VII FACIAL VIII VESTIBULOCOCHLEAR IX GLOSSOPHARYNGEAL X VAGUS XI ACCESSORY XII HYPOGLOSSAL 2 lines each row PNS: Cranial Nerves I Olfactory nerve — SENSORY for smell II Optic nerve — SENSORY for vision III Oculomotor nerve — MOTOR fibers to eye muscles IV Trochlear — MOTOR fiber to eye muscles PNS: Cranial Nerves V Trigeminal nerve — SENSORY for the face; MOTOR fibers to chewing muscles VI Abducens nerve — MOTOR fibers to eye muscles VII Facial nerve — SENSORY for taste; MOTOR fibers to the face VIII Vestibulocochlear nerve — SENSORY for balance and hearing PNS: Cranial Nerves IX Glossopharyngeal nerve — SENSORY for taste; MOTOR fibers to the pharynx X Vagus nerves — SENSORY and MOTOR fibers for pharynx, larynx, thoracic and abdominal areas XI Accessory nerve — MOTOR fibers to neck and upper back XII Hypoglossal nerve — MOTOR fibers to tongue CRANIAL NERVES function Figure 7.24 Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII.Vestibulocochlear IX. Glossopharyngeal X. Vagus XI. Accessory XII.Hypoglossal I. PNS: Cranial Nerves PNS: Cranial Nerves Device Oh Oh Oh To Touch And Feel Very Green Vegetables A H Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII.Vestibulocochlear IX. Glossopharyngeal X. Vagus XI. Accessory XII.Hypoglossal I. PNS: Cranial Nerves PNS: Spinal Nerves There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Formed by the combination of the ventral and dorsal roots of the spinal cord Named for the region from which they arise Cervical nerves Thoracic nerves Lumbar nerves Sacral nerves C1 2 3 4 5 6 7 8 T1 2 3 4 5 6 7 8 9 10 11 Ventral rami form cervical plexus (C1 – C5) Ventral rami form brachial plexus (C5 – C8; T1) No plexus formed (intercostal nerves) (T1 – T12) 12 L1 2 3 4 Ventral rami form lumbar plexus (L1 – L4) 5 (a) S1 2 3 4 Ventral rami form sacral plexus (L4 – L5; S1 – S4) Figure 7.25a PNS: Spinal Nerve Plexuses Plexus–networks of nerves serving motor and sensory needs of the limbs Form from ventral rami of spinal nerves in the cervical, lumbar, and sacral regions Four plexuses: • • • • Cervical Brachial Lumbar Sacral Axillary nerve These nerves arise from the BRACHIAL PLEXUS Humerus Ulna Radius Ulnar nerve Radial nerve (a) The major nerves of the upper limb Figure 7.26a These nerves arise from the LUMBAR PLEXUS Femoral Lateral femoral Obturator Anterior femoral Saphenous (b) Lumbar plexus, anterior view Figure 7.26b These nerves arise from the SACRAL PLEXUS Superior gluteal Inferior gluteal Sciatic Posterior femoral cutaneous Common fibular Tibial Sural (cut) Deep fibular Superficial fibular Plantar branches (c) Sacral plexus, posterior view Figure 7.26c Summary On a half sheet of paper, use today’s notes to write a summary on the spinal cord. Then, answer these… Which cranial nerves are mixed? Which ones control the eye? Taste & chewing?
