1. The Spinal Cord

2. Protection Vertebrae Spinal meninges Three layers of connective tissue
Dura mater
Arachnoid mater
Pia mater
Continuous with cranial meninges
Cerebrospinal fluid (CSF)

3. Spinal Meninges Epidural space: between vertebrae and dura mater
Dura mater- tough, dense connective tissue
Arachnoid mater: resembles spider’s web
Extends into subarachnoid space
Subarachnoid space
CSF circulates in this space
Pia mater: thin, delicate layer
Adheres to surface of spinal cord (and brain)
Contains blood vessels

4. Spinal Meninges

5. Spinal Meninges

9. Structure of the Spinal Cord

11. Structure of the Spinal Cord

12. Spinal Nerves Nerves attached to spinal cord by 2 roots
Dorsal root: made of axons of sensory neurons
Dorsal root ganglion: swelling containing cell bodies of sensory neurons
Ventral root: composed of axons of motor neurons
Both somatic motor and autonomic motor

13. Spinal Cord Functions Pathways for nerve impulses within tracts
Ascending (sensory)
Descending (motor)
Reflexes: fast, involuntary sequences of actions in response to stimuli
Can be simple (withdrawal) or complex (learned sequence such as driving car)

14. The Reflex Arc Sensory receptor: responds to stimulus
Sensory neuron: through dorsal root ganglion and root  posterior horn
Integrating center: single synapse between sensory and motor neurons
Motor neuron: from anterior horn  ventral root  spinal nerve 
Effector: muscle or gland responds

15. The Reflex Arc