1. The Central Nervous System Poudre High School By: Ben Kirk

2. The Spinal Cord Protection: Vertebral column primarily Coverings: – Meninges: Connective tissue coverings around spinal cord and brain – Spinal meninges cover and surround the spinal cord – Cranial meninges cover and surround the brain They meet at the magnum foramen of the skull, where they become continuous. Meningitis: Inflammation of the meninges –Infections (viral or bacterial) that are contagious: DORMS

3. The Spinal Cord Meninges and Coverings: – Epidural Space: Space between the spinal cord and the vertebral column Packed with adipose tissue (fat) Common place for injections due to localized effects Loss of sensation to total paralysis (giving birth) – Dura Mater: Outer most layer “tough mother” Longitudinal, densely packed collagen fibers Very tough, protective covering

4. The Spinal Cord Meninges and Coverings – Arachnoid Mater: Middle Layer Delicate, web of elastin and collagen fibers – Subarachnoid Space: Space between the arachnoid mater and the pia mater Filled with Cerebrospinal fluid Spinal Tap: Remove fluid from this space – Pia Mater: Inner most layer “Delicate Mother” Network of elastin and collagen fibers connected directly to neural tissue of the spinal cord. Highly vascularized and nourished

5. The Spinal Cord

6. General Features – Length: 42-45 cm (16-18 inches) Extends from foramen magnum to 2 nd lumbar vertebrae (not entire length of vertebral column) – Cauda Equina: lumbar and sacral nerves extending distal from L2. http://www.spineuniverse.com/displaygraphic.php/133/dp_caudaeq uina-BB.gif

7. The Spinal Cord General Features – Cervical Enlargement: Contains upper extremity nerves – Lumbar Enlargement: Contains lower extremity nerves – 31 Spinal Segments (C8-T12-L5-S5-Cox1)

8. The Spinal Cord Cross Sectional Structure – Anterior Median fissure: large, anterior indentation – Posterior Median Sulcus: small, posterior indentation – Gray Matter: “H”/butterfly shape surrounded by white matter Cell bodies and dendrites – White Matter: Surrounding gray matter Myelinated axons

9. The Spinal Cord Cross Sectional Anatomy http://en.wikipedia.org/wiki/Image:Medulla_spinalis_-_Section_-_Latin.png

10. The Spinal Cord Functions: – Impulse Conduction Spinothalamic Tracts: (Ascending) Pain, temperature, deep pressure, crude touch Posterior Column Tracts: (Ascending) proprioception, discriminative touch, pressure, vibration Pyramidal Tracts: (Descending) Precise skeletal muscle movements Extrapyramidal Tracts: (Descending) head movement, muscle tone, posture, equilibrium

11. http://www.unm.edu/~jimmy/spinal_tracts.jpg

12. The Spinal Cord Functions – Reflex Center Reflex: An automatic, rapid, predictable response to a stimuli –Responds the same every time Spinal Nerves: –Dorsal Root (Posterior): Sensory Information TO the CNS –Dorsal Root Ganglia: Swelling on dorsal root, composed of sensory neuron cell bodies –Ventral Root (Anterior): Motor Information to peripheral effectors Dorsal and ventral roots converge in the periphery to form spinal nerves

13. Spinal Nerves http://www.coventrypainclinic.org.uk/treatment-nerverootblocks.htm

14. The Spinal Cord Functions: – Reflex Arc: A single reflex (5 steps) 1. Receptor: stimuli activates receptor and generates impulse 2. Activation of Sensory neuron: Impulse reaches spinal cord via dorsal root 3. Information Processing: Sensory impulse relayed and interpreted by interneuron or motor neuron directly If sufficient excitation, #4 occurs 4. Activation of Motor Neuron: Impulse sent via ventral root 5. Effector Response: Peripheral glands or muscles activated Have both EPSP and IPSP arcs Ex. Hot Stove

15. Spinal Nerves Spinal Nerves: Part of the Somatic Nervous System (SNS) – Connect CNS to sensory receptors and peripheral effectors (muscles and glands) – 31 Pair Names: Based on region and level of spinal cord where they emerge – 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal – 1 st pair exit between atlas and occipital bone, all others exit through intervetebral foramen (between vertebrae)

16. Spinal Nerves Composition: – Anterior and Posterior roots attach peripherally – Mixed Nerves: Both sensory and motor fibers Distribution: – Branches: Rami – Ventral and Dorsal Both sensory and motor axon bundles Dorsal: to back/posterior region Ventral: to anterior/ventral region

17. Spinal Nerves Branches/Rami: http://mywebpages.comcast.net/wnor/terminologyana tplanes.htm

18. Spinal Nerves Distribution: – Plexuses: Ventral Rami of all spinal nerves except T 2 -T 11 cervical, brachial, lumbar, sacral Stretched/pulled plexuses (ex. Falling off a horse) – Intercostal Nerves/Thoracic Nerves: T 2 -T 11 Muscles between ribs, abdominals, chest and back

19. Spinal Nerve Plexuses Brachial Plexus Lumbar Plexus