1. Quiz #3 available today at 3pm
until Monday at 11pm

2. Use the diagram to label:
Sensory (afferent) neuron
Motor (efferent) neuron
CNS
PNS
Interneuron

3. Spinal cord and spinal nerves
spinal cord anatomy
spinal meninges
where to put that needle
spinal cord terminology
spinal nerves
ascending and descending tracts
where do spinal nerves go?
dermatomes
nerves plexuses
cervical plexus
brachial plexus
simple reflexes
anatomy of spinal cord injuries

4. 31 PAIR of spinal nerves 8 cervical 12 thoracic 5 lumbar 5 sacral
1 coccygeal
Medullary cone
Cauda equina

5. infant
adult

6. Meninges of the spinal cord
Dura mater (pink)
Pia mater
Subarachnoid
space
Arachnoid mater (blue)

7. Dura mater is continuous with epineurium of nerve fibers

8. Denticulate ligament
Coccygeal ligament

9. From which space is a spinal tap taken from?
Into which space is spinal anesthetic injected?
Into which space is an epidural anesthetic injected?
Dura mater and
arachnoid
Pia mater
Subarachnoid space

10. Spinal tap or spinal anesthesia
Epidural anesthesia

11. Anatomy of the spinal cord
Posterior (dorsal) sulcus
Posterior (dorsal) horn
Central canal
(CSF)
Spinal nerve
Anterior (ventral) horn
Nerve roots
Anterior (ventral) fissure
Fissure >> sulcus

12. Gray and White Matter White matter = myelinated nerve fibers
Gray matter = nerve cell bodies, dendrites, neuroglia & unmyelinated axons

13. Nerve Fiber = nerve process (axon or dendrite)
Nerve = bundle of nerve fibers in PNS (mixed)
Tract = bundle of nerve fibers in the CNS (mixed)
Ganglion = cluster of neuronal cell bodies in PNS
Nucleus = cluster of neuronal cell bodies in the CNS

14. Label anterior and posterior.
Label a nerve root and a spinal nerve.
What is in the central canal?
Label the posterior (dorsal) horn.
What is it composed of?

16. Sensory or ascending tracts
Motor or descending tracts
The spinal cord is very organized – anatomically & functionally

17. brain
midbrain
medulla
Ipsilateral
Contralateral
Decussation
spinal cord

18. Ascending tract (Sensory info) Midbrain Medulla Thalamus
3rd order neuron
Thalamus
Midbrain
2nd order neuron
Medulla
Decussation in medulla
1st order neuron

19. Fig. 14.4(TE Art) Gracile fasciculus Below T6 (legs)
Somatosensory cortex
Fig. 14.4(TE Art)
Thalamus
Midbrain
Midbrain
Gracile fasciculus
Below T6 (legs)
Cuneate fasciculus
Above T6 (arms)
Spinothalamic
tract
Medulla
Fine touch, proprioception, pressure
pain, heat, and cold

20. Ascending tract summary

21. Descending tracts Motor info Corticospinal tract Midbrain Medulla
Motor cortex
Upper motor neurons
Midbrain
Medulla
Lateral corticospinal tract
Ventral corticospinal tract
Lower motor neurons
To skeletal muscles

22. Damage to motor neurons…..
Paralysis
loss of muscle function
causes?
para, quad, hemi - plegia
Upper motor neurons
Spastic paralysis
Amyotrophic Lateral Sclerosis
degeneration of upper and lower motor neurons
paralysis of voluntary muscles
Lou Gehrig & Stephen Hawking 1942-
Poliomyelitis
degeneration of lower motor neurons
occurs in ventral horn
caused by polio virus
Lower motor neurons
Flaccid paralysis

23. Spinal nerves 31 PAIR of spinal nerves Vertebral level vs spinal level
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Vertebral level vs
spinal level

24. Spinal nerve anatomy
Dorsal root ganglion

25. Dorsal ramus
Ventral ramus
Thoracic cavity
Intercostal
nerve

26. Spinal Nerves
dermatomes
plexuses
reflexes

27. Each spinal nerve innervates 1 somite
Somite = skin, muscles, bones

28. Dermatome
area of skin supplied by the sensory nerve fibers of one spinal nerve
Characteristic pattern
No dermatome for C1 (motor only)
Use dermatomes to access spinal nerve damage

29. Ventral rami traveling together
Nerve Plexuses:
Ventral rami traveling
together
Cervical plexus (C1 –C5)
Brachial plexus (C5–T1)
Thoracic nerves (12 pairs)
No plexus in thoracic region
Lumbar plexus (L1–L4)
Sacral plexus (L4 –S4)
Sciatic
nerve
sciatica

30. Fig. 14.13(TE Art) Cervical plexus C1-C5 ventral rami neck & shoulder
phrenic nerve C3 C4 C5
Phrenic nerve C3-C5

31. Phrenic nerve
C3-5
motor to diaphragm
skeletal muscles

32. Brachial plexus
C5-T1
ventral rami
arm & shoulder

33. Brachial plexus passes deep to the clavicle
Damage to brachial plexus

34. Brachial plexus damage
Lower motor neuron lesion = flaccid paralysis

35. ** Don’t need the brain to have
A simple reflex arc
Information relayed
to brain - slower
Sensory neuron
Info processing
in CNS
Motor neuron
** Don’t need the brain to have
a reflex **

36. The Stretch Reflex Too much stretch, too fast
Contract muscles to protect them

37. You are an EMT
Frank dove into shallow end
you evaluate him and find:
his neck hurts
he can breath well on his own
he can’t feel or move his legs
he can’t feel his pinky
he can feel his thumb
Where is his injury??

38. Spinal cord injuries (SCI)
SCI’s are damage to the spinal
cord (vs vertebral column)
damage occurs from severing,
stretching or compression
result in loss of motor & sensory
function below injury site
can be complete or incomplete
flaccid paralysis immediately after
injury (due to spinal shock)
spastic paralysis after spinal shock
subsides

39. Back to Frank….. Can he breath on his own?
2. Will he be able to move/feel his legs? His arms?
3. Upper or lower motor neuron lesion?
4. What kind of paralysis will Frank have?
- during spinal shock = flaccid paralysis, no reflexes
- after spinal shock = spastic paralysis, uncontrolled reflexes