1. Spinal Cord and Spinal Nerves
EQ: What are the components of the spinal cord?

2. The Central Nervous System (CNS) consists of:
• The spinal cord • Integrates and processes information • Can function with the brain • Can function independently of the brain
• The brain • Integrates and processes information • Can function with the spinal cord • Can function independently of the spinal cord

3. Features of the Spinal Cord
• 45 cm in length • Passes through the Foramen Magnum
• Extends from the brain to L1
Consists of: • Cervical region • Thoracic region • Lumbar region • Sacral region • Coccygeal region

5. Transverse view:
White matter
Gray matter
Central canal
Dorsal root and ventral root: merge to form a spinal nerve
Dorsal root is sensory: axons extend from the soma within the dorsal root ganglion
Ventral root is motor

6. Features
Consist of:
Sensory nerves : transmit impulses toward the spinal cord
Motor nerves : transmit impulses away from the spinal cord

7. Spinal Meninges
Specialized membranes that provide protection, physical stability, and shock absorption
Denticulate ligaments help anchor the spinal cord in position

10. Sectional Anatomy of the Spinal Cord
Gray matter
Consists of somas (cell bodies) surrounding the central canal
Acts as insulator
White matter
Consists of axons Nerves are organized into tracts or columns
Located outside the gray matter area

11. Peripheral Nerves
Epineurium: outer layer – becomes continuous with the dura mater
Perineurium: layer surrounding a fascicle – a fascicle is a bundle of axons
Endoneurium: layer surrounding a single axon

13. Cervical Plexus (C1–C8) • Consists of cutaneous and muscular branches
• Cutaneous branch innervates: Head ,Neck, Chest

16. Thoracic Plexus
T1-T12

17. Lumbar Plexuses
L1-L5

18. Sacral Plexus
S1-S5

19. Vertebrae Anatomy Vertebrae Body Vertebrae Arch Accessory Processes
Drum shape body that bears weight and compression
Vertebrae Arch
Provides space and protection for spinal cord
Accessory Processes
Allows for muscle attachment

21. Intervertebral Discs
Each vertebrae is separated and cushioned by intervertebral discs.
Keeps the bones from rubbing together

22. Copyright 2009, John Wiley & Sons, Inc.
Reflex
A reflex is an automatic, sudden, involuntary response to a stimulus.
When the integration takes place in the spinal cord, the reflex is a spinal reflex.
Copyright 2009, John Wiley & Sons, Inc.

23. Copyright 2009, John Wiley & Sons, Inc.
Reflex Arc
A reflex arc includes:
a. sensory receptor- responds to stimulus with action potential
b. sensory neuron- sends impulse to grey matter
c. integrating center- relay info to motor neuron
d. motor neuron- sends message to effector
e. effector- muscle or gland that responds
Copyright 2009, John Wiley & Sons, Inc.

24. Reflex Arc 1 2 3 4 5 1 2 SENSORY NEURON (axon conducts impulses from
receptor to integrating center)
SENSORY RECEPTOR
(responds to a stimulus
by producing a generator
or receptor potential)
INTEGRATING CENTER
(one or more regions within the CNS
that relay impulses from sensory to
motor neurons)
MOTOR NEURON
integrating center to effector)
EFFECTOR
(muscle or gland that
responds to motor
nerve impulses)
Interneuron 2 3 4 5 1
SENSORY NEURON
(axon conducts impulses from
receptor to integrating center)
SENSORY RECEPTOR
(responds to a stimulus
by producing a generator
or receptor potential) 2

25. Left Side Activity Draw the spinal cord and label the main parts.
Explain how a reflex works.