1. Spinal Cord and Nerves

2. The Nervous System
Coordinates the activity of muscles, organs, senses, and actions
Made up of nervous tissue
Has 3 main functions:
1. Receives sensory Input
2. Integration
3. Dictates motor output

3. Divisions of the Nervous System
Central Nervous System (CNS)
Brain and spinal cord
Interprets incoming sensory signals
Dictates motor responses
Peripheral Nervous System (PNS)
Ganglia
Nerves
Cranial nerves and spinal nerves
Communication between regions of body and CNS
pg 16

4. Review of Nervous Cells
Neuron
Cell body
Dendrite
Axon
Myelin Sheath
Neuroglia
Interneuron
Reflex Arc
Synapse

5. Organization of a Nerve
Endoneurium
Surrounds each axon (nerve fiber)
Myelinated and Unmyelinated axons
Motor and Sensory nerve fibers
Loose CT
Perineurium
Bundles axons into fascicles CT
Epineurium
Bundles fascicles into a nerve
Fibrous CT
CT layers contain blood vessels

6. Types of Nerve Signals/Fibers
Sensory (afferent)
Picked up by sensory receptors thru body
Carried by nerve fibers of PNS into CNS
Motor (efferent)
Carried away from the CNS by nerve fibers into PNS
Innervate muscles and glands
Causes these organs to contract or secrete
Remember: SAME

7. Sensory and Motor Signals/Fibers
Somatic sensory
Body senses
touch, pressure, temperature, vibration of body, muscles stretching, balance
Visceral sensory
Organ senses
Stretch, pain, temperature in organs
(eg) nausea, hunger, cramps
Somatic motor
Body movement
Voluntary contraction of skeletal muscles
Visceral motor
Organ movement
Contraction of smooth muscle, glands
= Autonomic Nervous System (involuntary)

8. Parasympathetic division
CNS
Brain
Spinal cord
PNS
Cranial nerves and spinal nerves
Sensory (afferent)
division
Motor (efferent)
division
Somatic sensory
General: Touch, pain, pressure, vibration
Special: hearing, equilibrium, vision, smell
Visceral sensory
General: Stretch, pain, temperature, nausea, hunger
Special: Taste
Somatic motor
General: Motor innervation of all skeletal muscles
Visceral motor
General: Motor innervation of smooth muscle, cardiac muscle, and glands;
= ANS
Parasympathetic division
Sympathetic division

9. CNS – Spinal Cord
Runs through vertebral canal of the vertebral column
Protected by bone, meninges, and cerebrospinal fluid
Spinal cord made of a core of gray matter surrounded by white matter
31 pairs of spinal nerves branch off spinal cord through intervertebral foramen
Functions in many ways:
Involved in sensory and motor innervation of body inferior to the head (through spinal nerves)
Provides a 2-way conduction pathway for signals between body and brain
Major center for reflexes
pg 63

10. Meninges of Spinal Cord
Membranes surrounding the spinal cord
3 Layers of connective tissue
Functions
Protect spinal cord
Contains cerebrospinal fluid
Protect blood vessels serving spinal cord

11. Meninges of Spinal Cord
Dura mater (superficial)
Spinal dural sheath
Does not attach to bone
Epidural space
Fat and veins
Between dura mater and vertebra
Subdural space
Between dura mater and arachnoid
pg 67

12. Meninges of Spinal Cord
Arachnoid mater (middle)
Impermeable layer = barrier
Raised off pia mater by rootlets
Subarachnoid space
Between arachnoid and pia mater
Contains CSF
Pia mater (deep)
Highly vascular
Adheres to brain/spinal cord tissue
pg 67

13. Regions of Spinal Cord Cervical Thoracic Lumbar Sacral Coccygeal
Cervical + Lumbar enlargements
Cauda equina
Conus medullaris
Filum terminale
CT & pia mater
Attaches to coccyx
pg 24
pg 63

14. Gray Mater
Consists of neuron cell bodies, unmyelinated axons, dendrites, and neuroglia
Shaped like an “H”
Gray commissure (crossbar)
Central canal
Posterior horns
Anterior horns
pg 63

15. Gray Mater Posterior horns
Consist of interneurons that transmit in from outside spinal cord into it
Dorsal root contain sensory fibers
Somatic Sensory (SS)
Visceral Sensory (VS)
Dorsal root ganglia - swelling in dorsal root that these interneurons pass through
Anterior horns
Cell bodies of motor neurons send info out of spinal cord to muscles and glands
Ventral Root contains Motor Fibers
Visceral Motor
Somatic Motor
pg 63

16. White Mater Surrounds gray matter
Composed of myelinated and unmyelinated axons
Divided into white columns (funiculi)
Posterior funiculus
Anterior funiculus
Lateral funiculus
Allow for communication between
Parts of the spinal cord
Spinal cord and brain
pg 63

17. White Mater 3 types of nerve fibers: Ascending
Carry sensory info from sensory neurons of body to brain
touch, pressure, pain, temperature
Descending
Carry motor instructions from brain to spinal cord
Contraction of muscles and secretion of glands
control precise, skilled movement = writing, maintain balance, create movement
Commissural
Cross from one side of cord to the other

18. Spinal Nerves (31 Pairs) Part of the PNS (Somatic)
Lie in intervertebral foramina
Send lateral branches to body
Named according to their point of issue from the vertebral column
8 pairs of cervical spinal nerves; C1-C8
12 pairs of thoracic spinal nerves; T1-T12
5 pairs of lumbar spinal nerves; L1-L5
5 pairs of sacral spinal nerves; S1-S5
1 pair of coccygeal spinal nerves; C01
pg 71-2

19. Spinal Nerves
Each spinal nerve connected to spinal cord via dorsal (sensory) and ventral (motor) root
Spinal nerves branch into dorsal ramus and ventral ramus
Ventral ramus
Connects to rami communicans, which then lead to sympathetic chain ganglia
Supply anterior and lateral regions of the neck, trunk, and limbs
Dorsal ramus
Supply the dorsum of the neck and trunk (back)
pg 81

20. The Big Picture
Just lateral to intervertebral foramen, each spinal nerve then splits in 2
Dorsal Rami
Ventral Rami
Contain BOTH Sensory and Motor fibers!!
pg 68

21. Parasympathetic division
CNS
Brain
Spinal cord
Autonomic Nervous System = Visceral Motor
PNS
Cranial nerves and spinal nerves
Sensory (afferent)
division
Motor (efferent)
division
Somatic sensory
General: Touch, pain, pressure, vibration
Special: hearing, equilibrium, vision, smell
Visceral sensory
General: Stretch, pain, temperature, nausea, hunger
Special: Taste
Somatic motor
General: Motor innervation of all skeletal muscles
Visceral motor
General: Motor innervation of smooth muscle, cardiac muscle, and glands;
= ANS
Parasympathetic division
Sympathetic division

22. Autonomic Nervous System
Visceral Motor Function
Not easily controlled by will
Get nervous and sweat
Innervate smooth muscle, cardiac muscle, glands
Regulate visceral function
Heart rate, blood pressure, digestion, urination
Has 2 divisions:
Parasympathetic
Sympathetic

23. Autonomic Nervous System
Parasympathetic
“rest and digest”
Enables body to unwind and calm down
Most active when body at rest
Routine maintenance functions
Craniosacral division
Fibers emerge from brain and sacral spinal cord
Sympathetic
“fight or flight”
Mobilizes the body during extreme situations
Becomes active when extra metabolic effort needed
Thoracolumbar division
Fibers arise from thoracic and lumbar parts of spinal cord

24. Somatic Nervous System
Innervates skeletal muscle
Neurons runs from CNS directly to muscle
Consists of single neuron plus skeletal muscle cells
Voluntary control
Running, moving limbs, typing on a computer!