Zoo 141 Chapter 13

1. Know the meningeal coverings of the spinal cord and their locations relative to the spinal cord.

1. 1. Dura mater (outer most layer) 2. Arachnoid Mater (middle layer) 3. Pia Mater (inner most layer).

10. Which important structure of respiration does the phrenic nerve serve and which plexus does it originate from?

10. Serves the diaphragm and it originates in C3-C5

13. In the sacral plexus, the sciatic nerve is actually composed of the _______ and _______ nerves

13. L4-L5 and S1-S4

15. What is the job of white matter tracts?

15. They are highways for nerve impulse reproduction. Sensory input travels along these tracts towards the brain, and motor output travels from the brain along these tracts towards skeletal muscles and other effecter tissues.

16. What is the job of gray matter tracts?

16. It receives and integrates incoming and outgoing information.

17. What is a dermatome? a) Loss of sensory input from the anterior femoral (see fig. 1.5) dermatomes are associated with damage to spinal nerves ________ and ________

17. It is an area of skin that provides sensory input in the CNS via the posterior toots of one pair of spinal nerves or via the trigeminal (V) nerve.

18. How does the fact that dermatomes overlap factor into the administration of an anesthetic?

18. Deliberate production on a region of complete anesthesia may require that at least three adjacent spinal nerves be cut or blocked by the anesthetic drug.

19. Understand the steps involved in the reflex arcs of figures 13.13 and 13.14.

19. 1. Nail sticks in skin 2. Activates chemicalseptor or oseseptor and action potential are generated and approach the spinal cord via the dorsal root. 3. Enter the spinal cord at the dorsal root's horn and synapse with an interneuron. And interneuron synapses with an alpha motor neuron. 4. Which then goes out to the appropriate skeletal muscle cells of the motor unit. So you can withdraw that portion of your body from the nail.

2. What purpose do the denticulate ligaments serve?

2. They protect the spinal cord from sudden misplacement that could lead to shock.

22. When the stretch reflex is activated, how does inhibition of the antagonist muscle(s) help prevent injury? (reciprocal innervation)

22. Because if we were to contract the antagonist muscle it would just add to the injury. It allows the muscle spindle to resist the stretch.

23. [Fig. 13.16] Understand how the flexor withdrawal reflex and cross extensor reflex work together in response to a painful stimulus (e.g. stepping on a piece of glass)

23. 1. Hand on iron flexion of the right elbow. Right glenoid humeral hyperextension. Thermal receptor activated so action potentials are made. 2. Action potentials travel up the spinal cord and synapse with the dorsal horn with an interneuron and will have to travel to many parts of the spinal cord which synapse with an alpha motor neuron. 3. And the motor neurons will travel to the lattisimis dorsi and biceps brachii so you are able to withdraw from the heat of the iron. 4. Interneuron crosses over travels up and down to different parts of the spinal cord and synapses with an alpha motor neuron that will then extend your knew and iliofemural joint.

24. Explain: a) Paraplegia b) Quadriplegia

24. a. Paralysis of the lower limbs b. Paralysis of all limbs.

25. Where does the Herpes Zoster virus hide after a bout of chickenpox?

25. They hide in the soma of the posterior ganglia.

26. How is axonal transport involved in a Shingles infection? a) Which type of transport (speed and direction)?

26. The virus got there by retro grade fast action transport. It hides from the red blood cells. You may see it when you are older or under a lot of stress because your immune system is over compromised.

27. Your text explains that poliovirus damages anterior horn neurons in the spinal cord. Why does this result in muscle weakness and loss of somatic reflexes?

27. You find alpha motor neurons in the anterior horn so of course it will affect your muscles and make them weak.

4. What is a spinal nerve? a) Is it part of the CNS or PNS?

4. They are the paths of communication between the spinal cord and specific regions of the body. a. PNS

7. What structures would you find in the three gray horns of the spinal cord?

7. Posterior (Dorsal) Gray horn- Contains cell bodies and axons on interneurons as well as axons of incoming sensory neurons. Anterior (ventral) Gray Horn- Contain somatic motor nuclei, which are clusters of cells bodies of somatic motor neurons. They provide nerve impulses to contract skeletal muscle. Lateral Gray Horn- Contain automatic motor nuclei, which are clusters of cell bodies of automatic motor neurons. They regulate the activity of cardiac muscle, smooth muscle, and glands.

8. Understand the steps for the processing of sensory input illustrated in Figure 13.4

8. 1. Sensory receptors detect a stimulus 2. Sensory neurons pass this sensory input in the form of a nerve impulse along their axons, which extend from sensory receptors into the spinal nerve, and then into the posterior root. From the posterior root, axons of sensory neurons may proceed along three possible paths (steps 3,4, and 5) 3. Axon of sensory neurons may extend into the white matter of the spinal cord and ascend to the brain as part of sensory tract. 4. Axon of sensory neurons may enter posterior gray horn and synapse with interneurons whose axons extend into the white matter of the spinal cord and then ascend to the brain as part of sensory tract. 5. Axons of the sensory neurons may enter the posterior gray horn and synapse with interneurons that turn synapse with somatic motor neurons that are involved in spinal reflex pathways. 6. Motor output form the spinal cord to skeletal muscles involved somatic motor neurons of the anterior gray horn. The brain regulates many somatic motor neurons. Axons from higher brain centers form motor tracts that descend from the brain into white matter of the spinal cord.