Fig Cervical spinal nerves. Cervical enlargement C7. Dural sheath. Subarachnoid space. Thoracic. Spinal cord Vertebra (cut) spinal nerves

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1 Fig C1 Cervical enlargement C7 Cervical spinal nerves Dural sheath Subarachnoid space Thoracic spinal nerves Spinal cord Vertebra (cut) Lumbar enlargement Medullary cone T12 Spinal nerve Spinal nerve rootlets Posterior median sulcus Cauda equina Lumbar spinal nerves Subarachnoid space Epidural space L5 Posterior root ganglion Rib Arachnoid mater Terminal filum S5 Sacral spinal nerves Dura mater Col (a) (b) 1

2 Fig Posterior Spinous process of vertebra Fat in epidural space Subarachnoid space Meninges: Dura mater (dural sheath) Arachnoid mater Pia mater Spinal cord Denticulate ligament Posterior root ganglion Spinal nerve Vertebral body (a) Spinal cord and vertebra (cervical) Anterior Gray matter: Posterior horn Gray commissure Lateral horn Anterior horn Central canal Posterior median sulcus White matter: Posterior column Lateral column Anterior column Posterior root of spinal nerve Posterior root ganglion Spinal nerve Anterior median fissure Anterior root of spinal nerve Meninges: Pia mater Arachnoid mater Dura mater (dural sheath) (b) Spinal cord and meninges (thoracic) c: Ed Reschke/Getty Images (c) Lumbar spinal cord 2

3 Table

4 Fig Posterior column: Gracile fasciculus Cuneate fasciculus Ascending tracts Descending tracts Anterior corticospinal tract Posterior spinocerebellar tract Lateral corticospinal tract Anterior spinocerebellar tract Anterolateral system (containing spinothalamic and spinoreticular tracts) Lateral reticulospinal tract Tectospinal tract Medial reticulospinal tract Lateral vestibulospinal tract Medial vestibulospinal tract 4

5 Fig Somesthetic cortex (postcentral gyrus) Somesthetic cortex (postcentral gyrus) Third-order neuron Thalamus Third-order neuron Thalamus Cerebrum Cerebrum Midbrain Medial lemniscus Midbrain Gracile nucleus Second-order neuron Cuneate nucleus Second-order neuron Medulla Medial lemniscus Medulla First-order neuron Gracile fasciculus Cuneate fasciculus Spinothalamic tract Spinal cord Spinal cord First-order neuron Anterolateral system (a) Receptors for body movement, limb positions, fine touch discrimination, and pressure (b) Receptors for pain, heat, and cold 5

6 Fig Motor cortex (precentral gyrus) Internal capsule Cerebrum Midbrain Cerebral peduncle Upper motor neurons Medulla Medullary pyramid Decussation in medulla Spinal cord Spinal cord Lateral corticospinal tract Anterior corticospinal tract Decussation in spinal cord Lower motor neurons To skeletal muscles 6

7 Fig Rootlets Posterior root Posterior root ganglion Anterior root Spinal nerve Epineurium Perineurium Endoneurium Nerve fiber Fascicle Blood vessels Blood vessels (b) Fascicle Epineurium Perineurium Unmyelinated nerve fibers (a) Myelinated nerve fibers Endoneurium Myelin b: Dr. Kessel & Dr. Kardon/Tissues and Organs/Visuals Unlimited, Inc 7

8 Table

root Sensory pathway Posterior root ganglion Somatosensory neurons Sensory nerve

9 Fig Direction of signal conduction Spinal cord Posterior root ganglion Anterior root Sensory pathway Posterior root ganglion Somatosensory neurons Sensory nerve fibers Spinal nerve Posterior root Epineurium Blood vessels Anterior root Motor nerve fibers Motor pathway To spinal cord To peripheral receptors and effectors 9

10 Fig Vertebra C1 (atlas) Cervical plexus (C1 C5) Brachial plexus (C5 T1) Vertebra T1 Intercostal (thoracic) nerves (T1 T12) Lumbar enlargement C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 Cervical nerves (8 pairs) Cervical enlargement Thoracic nerves (12 pairs) Vertebra L1 Lumbar plexus (L1 L4) Sacral plexus (L4 S4) Coccygeal plexus (S4 Co1) T11 T12 L1 L2 L3 L4 L5 S1 S2 S3 S4 S5 Medullary cone Lumbar nerves (5 pairs) Cauda equina Sacral nerves (5 pairs) Coccygeal nerves (1 pair) Sciatic nerve 10

11 Fig Posterior Posterior root Posterior ramus Posterior root ganglion Anterior ramus Anterior root Vertebral body Spinous process of vertebra Deep muscles of back Spinal cord Transverse process of vertebra Spinal nerve Meningeal branch Communicating rami Sympathetic ganglion Anterior 11

12 Fig Posterior and anterior rootlets of spinal nerve Posterior root Posterior root ganglion Spinal nerve Posterior ramus Anterior ramus Communicating rami Intercostal nerve Anterior root Spinal nerve Sympathetic chain ganglion Anterior ramus of spinal nerve Thoracic cavity Sympathetic chain ganglion Posterior ramus of spinal nerve Communicating rami Lateral cutaneous nerve Intercostal muscles Anterior cutaneous nerve (a) Anterolateral view (b) Cross section 12

13 Fig C5 C6 C7 C8 Posterior scapular nerve Suprascapular nerve Lateral cord Posterior cord Medial cord Lateral cord Posterior cord Medial cord Axillary nerve Musculocutaneous nerve Median nerve Radial nerve T1 Long thoracic nerve Roots Trunks Anterior divisions Posterior divisions Cords Musculocutaneous nerve Axillary nerve Radial nerve Median nerve Ulnar nerve Ulna Ulnar nerve Median nerve Radial nerve Radius Superficial branch of ulnar nerve Digital branch of ulnar nerve Digital branch of median nerve 13

14 Fig Integrating center (spinal gray matter) Afferent nerve fiber Receptor (sensory nerve endings in muscle) Efferent nerve fiber (motor neuron) Effector (quadriceps muscle) 14

15 Fig Bone Peripheral nerve (motor and sensory nerve fibers) Tendon Gamma motor fiber Muscle spindle Skeletal muscle Extrafusal muscle fibers Connective tissue sheath (cut open) Intrafusal muscle fibers Motor nerve fibers: Gamma Alpha Sensory nerve fibers: Primary Secondary 15

16 Fig Muscle spindle 4 7 Primary afferent fiber 2 Alpha motor nerve fiber to quadriceps Alpha motor nerve fiber to hamstrings Tap on patellar ligament excites nerve endings of muscle spindle in quadriceps femoris. Stretch signals travel to spinal cord via primary afferent fiber and dorsal root. Primary afferent neuron stimulates alpha motor neuron in spinal cord. EPSP IPSP 4 Efferent signals in alpha motor nerve fiber stimulate quadriceps to contract, producing knee jerk. 5 At same time, a branch of the afferent nerve fiber stimulates inhibitory motor neuron in spinal cord. 6 That neuron inhibits alpha motor neuron that supplies hamstring muscles. 7 Hamstring contraction is inhibited so hamstrings (knee flexors) do not antagonize quadriceps (knee extensor). 16

17 Fig Sensory neuron activates multiple interneurons 3 Ipsilateral motor neurons to flexor excited 5 Contralateral motor neurons to extensor excited 4 Ipsilateral flexor contracts 6 Contralateral extensor contracts 1 Stepping on glass stimulates pain receptors in right foot Withdrawal of right leg (flexor reflex) Extension of left leg (crossed extension reflex) 17

18 Fig Nerve fibers Tendon organ Tendon bundles Muscle fibers 18

Copyright McGraw-Hill Education. Permission required for reproduction or display. C1. Cervical spinal ner ves. Thor acic. T12 Spinal nerve rootlets

Copyright McGraw-Hill Education. Permission required for reproduction or display. C1. Cervical spinal ner ves. Thor acic. T12 Spinal nerve rootlets Fig. 13.1 C1 Cervical enlar gem ent C7 Cervical spinal ner ves Dural sheath Subarachnoi d space Thor acic spinal ner ves Vertebra (cut) Lum bar enlar gem ent Medullar y T12 rootlets cone Posterior median