1. PNS Anatomy and Physiology
The more attractive nervous system

2. Introduction
Tommy, MS1
Joey, MS1

3. Learning objectives
Students will be able to relate dermatomes and sensory neurons and explain how a dermatome map can be used to locate injury to a nerve root or spinal cord.
Students will be able to characterize the different reflexes arcs and their diagnostic value.
Students will be able to describe the cortico-spinal tract.
*Students will learn how to evaluate the PNS using nerve conduction studies (Dr. Kothari)

4. LO #1
Students will be able to relate dermatomes and sensory neurons and explain how a dermatome map can be used to locate injury to a nerve root or spinal cord.

5. What are Dermatomes?
I love learning! <3

6. Dermatomes are…
Ow!
…the areas of skin supplied by a single nerve originating from a single spinal nerve root.
Effectively, it’s a map of the body telling you where a sensory signal will enter the CNS.

7. Let’s take a Step back The Peripheral nervous system
All nerves outside of the CNS
Somatic (Motor and Sensory) and Autonomic (Sympathetic and parasympathetic)

8. 31 Pairs of nerves. Each nerve is attached to the spinal cord by two roots, an anterior or ventral, and a posterior or dorsal, the latter being characterized by the presence of a ganglion, the spinal ganglion.
C0, coccygeal plexus

9. Afferent and Efferent Afferent Efferent
Afferent – From the periphery (towards the spinal cord)
-Sensory
Efferent – To the periphery (away from the spinal cord)
-Motor signals
Efferent

10. Sensory Receptors
The afferent root brings back nerve impulses from sensory receptors.
- This is a pathway for receiving signals from the outside world
To the dorsal root!

11. Sensory receptors
Sensory receptors are nerve endings of sensory nerves. The ones in your skin (what we’re focusing on) detect everything from heat to pressure, to pain, etc.
These sensations induce a series of action potentials (remember me?) from the sensory nerves back to the dorsal root of your spinal nerve.
So…if you were to touch something dimpled, like a basketball, you will get one set of signals vs. if you touched a hot pumpkin spice latte (out now!)

12. Sensory receptors
Sensory receptors are nerve endings of sensory nerves. The ones in your skin (what we’re focusing on) detect everything from heat to pressure, to pain, etc.
These sensations induce a series of action potentials (remember me?) from the sensory nerves back to the dorsal root of your spinal nerve.
So…if you were to touch something dimpled, like a basketball, you will get one set of signals vs. if you touched a hot pumpkin spice latte (out now!)

13. Clinical Connection
Let’s think about this. We have these sensory receptors all over the body

14. Clinical Connection
Let’s think about this. We have these sensory receptors all over the body Each of these regions feeds sensory signals into one pair of spinal nerves

15. Clinical Connection
Let’s think about this. We have these sensory receptors all over the body Each of these regions feeds sensory signals into one pair of spinal nerves As physicians, why would it be useful to know what region(s) relate to which spinal nerve?
-Think numbness, and how widespread these signs and symptoms might be.
After some time to think, ask. Then talk about regional (single unilateral) vs bilateral vs widespread numbness. Causes (e.g herniated disc vs severed spine)

16. An Example
Herniated disc
Pain, numbness, tingling

17. Questions?

18. LO #2
Students will be able to characterize the different reflexes arcs and their diagnostic value.

19. Applying PNS Structure & Function to Medicine

20. The Reflex Arc

21. 1. Receptor - sense organ in skin, muscle, or other organ
2. Sensory neuron - carries impulse towards CNS
3. Interneuron - carries impulse within CNS
4. Motor neuron - carries impulse away from CNS
5. Effector - structure by which animal responds (muscle, gland, etc).

23.
Videos summarizing and visualizing the reflex arc