1. SPINAL CORD ANATOMY & PHYSIOLOGY
HONORS ANATOMY & PHYSIOLOGY

2. Spinal Cord
w/spinal nerves contain neural circuits that mediate some of your most rapid reactions to environmental changes

3. Protective Structures
2 types of CT coverings surround & protect delicate nervous tissue
bony vertebrae
tough CT meninges, w/cushion of CSF

4. Meninges 3 CT coverings that encircle spinal cord & brain:
Spinal meninges covers spinal cord
Cranial meninges covers brain

5. Meninges Layers: Dura Mater
“tough mother”
most superficial layer
made of dense, irregular CT
continuous with cranial meninges
forms sac from foramen magnum  S2
layer of adipose tissue between dura mater & wall of vertebral cavity (epidural space)

7. Middle Meninges: Arachnoid Mater
“spider-like”
deep to dura mater, superficial to pia mater
contiguous with cranial arachnoid
between dura & arachnoid = subdural space

8. Innermost Meninges:Pia mater
“delicate”
thin, transparent CT
adheres to spinal cord & brain
between arachnoid & pia = subarachnoid space

10. Spinal Tap aka lumbar puncture
long needle inserted into subarachnoid space
adults: between L3 –L4 or L4 – L5 (inferior to lowest portion of spinal cord)
purpose: withdraw CSF for
diagnostic purposes
insert antibiotics/contrast media for myelography/ anesthetics/ chemotherapy

11. Spinal Cord cylindrical with flattening of its AP diameter
adults:extends from medulla oblongata  L2 vertebra
newborns: extends to L3 or L4
elongation of spinal cord stops ~age 3-4 but growth of vertebral column continues

12. Spinal Cord: External View
2 obvious enlargements noted:
cervical enlargement
C4 – T1
serve upper limbs
lumbar enlargement
T9- T12
serve lower limbs

14. Spinal Cord: External View
conus medullaris: tapered conical structure of spinal cord below lumbar enlargement L1 – L2
filum terminale: extension of pia mater extends inferiorly & anchors cord to coccyx
cauda equinae: “horse tail” nerves that arise from lumbar, sacral, & coccygeal portions of spine

15. Conus Medullaris

16. Filum Terminale

17. Cauda Equina

18. Spinal Nerves
31 pairs spinal nerves emerge thru intervertebral foramen
8 pair cervical nerves: C1 – C8
12 pair thoracic nerves: T1 - T12
5 pair lumbar nerves: L1 – L5
5 pair sacral nerves: S1 – S5
1 pair coccygeal nerves: Co1

19. Spinal Nerves
2 bundles of axons, called roots, connect each spinal nerve to segment of spinal cord

20. Spinal Cord Roots posterior (dorsal) root anterior (ventral) root
only sensory axons
each has dorsal root ganglion containing cell bodies of sensory neurons
anterior (ventral) root
only motor axons

21. Internal Anatomy of Spinal Cord
2 grooves penetrate white matter & divide it in right & left sides:
anterior median fissure
deeper, wider of the 2
posterior median sulcus
shallower, narrow furrow

23. Internal Anatomy of Spinal Cord
gray matter shaped like “H” or a butterfly & is surrounded by white matter
gray commissure forms the “H” crossbar
central canal small hole in its center
extends entire length of spinal cord
filled with CSF
@ superior end is contiguous with 4th ventricle of brain

25. Spinal Nerves & the nerves that branch off them are part of PNS
emerge from vertebral column thru intervertebral foramina

26. Spinal Nerves typically has 2 connections to spinal cord
dorsal root (sensory)
ventral root (motor)
classified as “mixed”

28. Distribution of Spinal Nerves

29. Spinal Nerve Plexuses
a network of nerves (or veins, or lymphatic vessels)

30. Cervical Plexus
supplies skin & muscles of the head, neck, & superior portion of shoulders, chest, & diaphragm
C1 – C 5

31. Brachial Plexus
supplies the shoulders & upper limbs

32. Lumbar Plexus
supplies anterolateral abd wall, external genitals, part of lower limb

33. Sacral Plexus
supplies buttocks, perineum, & lower limbs

34. Dermatomes
cutaneous area developed from one embryonic spinal cord segment & receiving most of its sensory innervation from one spinal nerve
knowing which spinal cord segments supply each dermatome makes it possible to locate damaged regions of the spinal cord

36. Reflexes & Reflex Arches
reflex: a fast, automatic, unplanned sequence of actions that occurs in response to a particular stimulus
can be:
inborn
pulling hand away from hot stove
learned or acquired
foot on brake when see dog run in front of car

37. 5 Parts of a Reflex Arc

38. Stretch Reflex

39. Pupillary Light Reflex
pupils of both eyes decrease in diameter when either eye is exposed to light
absence of a normal pupillary light refex indicates possibility of brain damage or injury

41. Spinal Cord Injuries most due to trauma paralysis
cervical, lower thoracic, upper lumbar most common regions involved
paralysis
depends on location, extent of damage
monoplegia: 1 limb
paraplegia: both lower limbs
hemiplegia: upper limb, trunk, lower limb on 1 side of body
quadriplegia: all 4 limbs & trunk

42. Extent Muscle Paralysis
C1 – C3: no function neck down, requires ventilator to breathe
C4 – C5: diaphragm, allows breathing
C6 – C7: some arm, chest, allows breathing, moving wheelchair
T1 – T3: intact arm function
T4 – T9: control of trunk above umbilicus
T10 – L1: most thigh muscles, walk w/long leg braces
L1 – L2: most leg muscles, walk w/short leg braces

43. Shingles acute infection of PNS caused by herpes zoster (chicken pox)
virus stays in posterior root ganglion
becomes reactivated normally immune system will prevent it from spreading
reactivated virus can overcome weakened immune system  leaves ganglion  travels down sensory neurons supplying skin

45. Medical Terminology
meningitis: inflammation of meminges due to infection, bacterial (worse) or viral, vaccine protests against some bacterial causes: headache, N/V, fever, stiff neck
neuralgia: pain along a sensory nerve, trigeminal neuralgia
neuritis: inflammation of 1 or several nerves
paresthesis: abnormal sensation