1. Spinal Cord

2. Length: 18 inches

3. Spinal Cord Length: 18 inches – terminates between L 1 and L 2 (at waist level)

5. Spinal Cord Length: 18 inches – terminates between L 1 and L 2 (at waist level) Diameter

6. Spinal Cord Length: 18 inches – terminates between L 1 and L 2 (at waist level) Diameter – ½ inch (at cervical and lumbar enlargements)

7. Spinal Cord Length: 18 inches – terminates between L 1 and L 2 (at waist level) Diameter – ½ inch (at cervical and lumbar enlargements) – ¼ inch (thoracic region)

8. Spinal Cord Other Features – Conus medullaris – Cauda equina –Dural sac

10. Protection of Spinal Cord – Vertebrae – Spinal Meninges – CSF

12. Cross-sectional organization – Grey matter: organized into “horns” – White matter: organized into “columns” – Columns composed of ascending tracts descending tracts

15. 31 spinal cord segments – each segment is associated with a pair of spinal nerves

18. Anatomy of Nerves

21. Ventral rami of:

22.  C 1 -C 5 form the cervical plexus

24. Ventral rami of:  C 1 -C 5 form the cervical plexus

25. Ventral rami of:  C 1 -C 5 form the cervical plexus  C 5 -T 1 form the brachial plexus

28. Ventral rami of:  C 1 -C 5 form the cervical plexus  C 5 -T 1 form the brachial plexus

29. Ventral rami of:  C 1 -C 5 form the cervical plexus  C 5 -T 1 form the brachial plexus  T 2 -T 12 form the intercostal nerves

31. Ventral rami of:  C 1 -C 5 form the cervical plexus  C 5 -T 1 form the brachial plexus  T 2 -T 12 form the intercostal nerves

32. Ventral rami of:  C 1 -C 5 form the cervical plexus  C 5 -T 1 form the brachial plexus  T 2 -T 12 form the intercostal nerves  T 12 -S 4 form the lumbosacral plexus

36. Examples of Peripheral Nerves

37. – Phrenic nerve

38. Examples of Peripheral Nerves – Phrenic nerve Emerges from the cervical plexus composed of axons from C 3 -C 5

40. b

41. Examples of Peripheral Nerves – Phrenic nerve Emerges from the cervical plexus composed of axons from C 3 -C 5

42. Examples of Peripheral Nerves – Phrenic nerve Emerges from the cervical plexus composed of axons from C 3 -C 5 – Median nerve

43. Examples of Peripheral Nerves – Phrenic nerve Emerges from the cervical plexus composed of axons from C 3 -C 5 – Median nerve From brachial plexus; axons from C 6 -T 1

45. Examples of Peripheral Nerves, cont’d – Femoral and Obturator nerves From lumbar plexus; axons from L 2 -L 4

47. Examples of Peripheral Nerves, cont’d – Pudendal nerve

48. Examples of Peripheral Nerves, cont’d – Pudendal nerve From sacral plexus; axons from S 2 -S 4

50. Examples of Peripheral Nerves, cont’d – Pudendal nerve From sacral plexus; axons from S 2 -S 4

51. Examples of Peripheral Nerves, cont’d – Pudendal nerve From sacral plexus; axons from S 2 -S 4 – Sciatic nerve

52. Examples of Peripheral Nerves, cont’d – Pudendal nerve From sacral plexus; axons from S 2 -S 4 – Sciatic nerve From sacral plexus; axons from L 4 -S 3

54. Dermatomes – Regions of skin served by the sensory axons of a specific spinal nerve

57. Neural Pathways

58. – Sensory

59. Neural Pathways – Sensory Some examples of ascending (sensory) spinal cord tracts

60. Neural Pathways – Sensory Some examples of ascending (sensory) spinal cord tracts – lateral spinothalamic

62. Neural Pathways – Sensory Some examples of ascending (sensory) spinal cord tracts – lateral spinothalamic

63. Neural Pathways – Sensory Some examples of ascending (sensory) spinal cord tracts – lateral spinothalamic – fasciculus gracilis

66. –Motor Pyramidal Pathways – conscious control of skeletal muscles – pyramidal tracts: » corticobulbar tract » corticospinal tracts

70. Extrapyramidal Pathways – unconscious control of skeletal muscles – example of extrapyramidal pathways in spinal cord » rubrospinal tract

71. Spinal Reflex Arc

74. Functional Divisions of Nervous System (Review) – Afferent Somatic Visceral – Efferent Somatic Autonomic – Sympathetic – Parasympathetic

75. Autonomic Nervous System Sympathetic (thoracolumbar) – “fight or flight” Parasympathetic (craniosacral) – “rest and repose”

77. Sympathetic system features – Preganglionic fibers in ventral roots of T 1 -L 2 short go to sympathetic ganglia or adrenal medulla release ACh

79. Sympathetic system features, cont’d. – Ganglia collateral ganglia (prevertebral) sympathetic chain (paravertebral) adrenal medulla

81. Sympathetic system features, cont’d. – Postganglionic fibers long extensive divergence from sympathetic ganglia release E or NE (sometimes ACh)

83. Parasympathetic system features – Preganglionic fibers in cranial nerves III, VII, IX, X and pelvic nerves from S 2 -S 4 long, go straight to ganglia very close to the target organs release ACh

85. Parasympathetic system features, cont’d. – Ganglia near target organs (e.g. ciliary ganglion near eye) in wall of target organ (intramural ganglia)

87. Parasympathetic system features, cont’d. – Postganglionic fibers very short little divergence release ACh

89. Comparison of Somatic and Autonomic Divisions

90. Comparison of Sympathetic and Parasympathetic Divisions

92. Comparison of Somatic and Autonomic Divisions