Chapter 13

1. Chapter 13 Spinal Cord, and the Autonomic Nervous System

2. Gross Anatomy of the Adult Spinal Cord

3. Anatomy of the Spinal Cord • Extends from the foramen magnum to L1 or L2 • Conus medularis - it is the end of the spinal cord • Denticulate ligaments – pia mater attaching the spinal cord t the vertebral wall • Filum terminale – pia mater extension from the conus medularis to the coccix

4. Anatomy of the Spinal Cord • Lumbar tap – removal of CSF from the vertebral canal bellow L3 • Cervical and lumbar enlargements • 31 pairs of spinal nerves leave the spinal cord • Cauda equina – collection of spinal nerves at the end of the spinal cord

5. The Spinal Cord and Spinal Meninges

6. Spinal meninges • Three layers • Dura mater • Single layer • Epidural space – between the vertebra and dura. Filled with fat and blood vessels • Arachnoid • Subarachnoid space – between arachnoid and pia. Filled with CSF • Pia mater

7. The Spinal Cord and Spinal Meninges

8. Sectional Organization of the Spinal Cord

9. Structures of the spinal cord • Gray Matter • Cell bodies, unmyelinated axons, dendrites and neuroglia • Posterior or dorsal horns – interneurons and sensory fibers coming from the dorsal root ganglion • Anterior or ventral horns – cell bodies of the somatic motor neurons that send their axons to the ventral root

10. Gray matter • Lateral gray horns contain visceral motor neurons • Gray commissures contain axons that cross from one side to the other • Central canal – filled with CSF

11. White matter • Divided into six columns (funiculi) containing tracts • Posterior funiculi • Posterior median sulcus • Anterior funiculi • Anterior median fissure • Lateral funiculi

12. White Matter • Spinal cord tracts • axons with the same origin, terminus and function • Ascending or sensory tracts • Anterior spinothalamic • Lateral spinothalamic • Fasciculus gracilis • Fasciculus cuneatus • Anterior spinocerebellar • Posterior spinocerebellar

13. White Matter • Descending or motor tracts • Direct or pyramidal • Lateral corticospinal • Anterior corticospinal • Indirect or extrapyramidal • Rubrospinal • Tectospinal • Vestibulospinal • Reticulospinal

14. Spinal Nerves

15. 31 pairs of spinal nerves (mixed) • 8 pairs of cervical • Above C7 all nerves emerge above the corresponding vertebra • C8 emerge between C7 and T1 • 12 pairs of thoracic • 5 pairs of lumbar • 5 pairs of sacral • I pair of coccygeal

16. Spinal nerves • Origin • Dorsal root and dorsal root ganglion • Ventral root • Dorsal ramus • sensory and motor innervation to the skin and muscles of the back

17. Spinal nerves • Ventral ramus • sensory and motor to the ventrolateral body surface, body wall and limbs • T2 – T12 form intercostal nerves • All other will form plexuses

18. Nerve plexus • Complex interwoven network of nerves • Four large plexuses • Cervical plexus • Brachial plexus • Lumbar plexus • Sacral plexus

19. Peripheral Nerves and Nerve Plexus

20. The Cervical Plexus • Ventral rami of spinal nerves C1 to C5 • Innervate muscles of the neck • Innervate the diaphragm • Phrenic nerve(C3, C4,C5)

21. Cervical Plexus

22. Brachial Plexus

23. Brachial Plexus

24. The Brachial Plexus • Axillary nerve • Shoulder • Musculocutaneous nerve • Anterior brachial area

25. The Brachial Plexus • Radial nerve • Posterior arm and hand • Median nerve • Anterior antebrachial area

26. The Brachial Plexus • Ulnar nerve • Anterior antebrachial area

27. The Lumbar and Sacral Plexuses

28. Lumbar Plexus

29. The Lumbar Plexus • Lower abdominopelvic region and the anterior thigh • L1 – L4 • Femoral Nerve • Anterior muscles of femoral area • Obturator Nerve • Adductors of leg

30. The Sacral Plexus • Posterior thigh, gluteal region, leg and foot • L4 – S4 • Sciatic nerve • Tibial nerve • Common fibular nerve • Pudendal nerve • Muscles and skin of perineum

31. The Autonomic Nervous System (ANS) • Parasympathetic is the “resting and digesting” division • Sympathetic is the “fight or flight” division • Sympathetic chain ganglia