1. Chapter 14: Peripheral Nervous System
PowerPoint by John McGill
Supplemental Notes
by Beth Wyatt

2. Nervous System Organization

3. I. SPINAL NERVES OVERVIEW DEFINITION NUMBER: 31 Pair
Nerves That Extend Off the Spinal Cord (Emerge From the Spinal Cavity)
NUMBER: 31 Pair

4. Spinal Nerves

5. I. SPINAL NERVES C1-C8 T1-T12 L1-L5 SACRAL NERVES COCCYGEAL NERVES
CERVICAL NERVES
T1-T12
THORACIC NERVES
L1-L5
LUMBAR NERVES
SACRAL NERVES
S1-S5
COCCYGEAL NERVES
1 PAIR

6. SPINAL NERVES are IDENTIFIED BY LETTERS AND NUMBERS
They are NOT “named.”
LETTERS
INDICATE REGIONS OF VERTEBRAL COLUMN
NUMBERS
INDICATE HOW MANY OF EACH TYPE (EACH PAIRED)

7. SPINAL NERVES are IDENTIFIED BY LETTERS AND NUMBERS
THE LETTERS AND NUMBERS INDICATE WHERE THE NERVES EXIT SPINAL CAVITY
C1-C7 Exit Above C1-C7 Vertebrae
C8 Exits Below C7 Vertebra
Thoracics and Lumbars Exit Below Their Respective Vertebrae
Sacrals Exit Through Openings in Sacrum
Coccygeals Pass Over Coccyx

9. CAUDA EQUINA ( Horse’s Tail )
Describes the Appearance of the Bottom of the Spinal Cord
Reason: Spinal Cord Ends at Bottom of the 1st Lumbar Vertebra;

10. CAUDA EQUINA ( Horse’s Tail )
Means That Lumbar, Sacral, and Coccygeal Nerves Hang in a Bundle at the Bottom of the SC Before Exiting at Their Respective Locations
Causes the Bottom of the Spinal Cord to Resemble a Cauda Equina

11. SPINAL NERVES ARE MIXED NERVES
The spinal nerves carry both sensory and motor messages and are called “mixed nerves.”

12. SPINAL NERVE STRUCTURE
NERVE ROOTS: Join Spinal Nerves to Spinal Cord
VENTRAL ROOTS
NF OF EFFERENT NEURONS
DORSAL ROOTS
NF OF AFFERENT NEURONS

13. SPINAL NERVE ROOTS

14. RAMI (RAMUS) The Major Branches of a Spinal Nerve
Each Spinal Nerve Has 2 Rami

15. RAMI (RAMUS) DESCRIPTION
The spinal nerve trunk emerges laterally from the intervertebral foramen
The trunk divides into two major branches (The anterior (ventral) and posterior (dorsal) primary rami (ramus, singular))
The posterior primary rami go to the back.
The anterior primary rami go to the sides and front of the body, and to the upper and lower members.

16. DORSAL RAMUS AREAS SUPPLIED
Provides Nerve Supply to Posterior Head, Neck, and Trunk
Contains Both Afferent and Efferent (Somatic) Nerve Fibers

17. VENTRAL RAMUS (More Complex)
AREAS SUPPLIED
Lateral and Anterior Neck and Trunk as well as Extremities
Contains Both Afferent and Efferent (Somatic & Autonomic) Nerve Fibers

18. VENTRAL RAMUS (More Complex)
NERVE PLEXUSES are only found on ventral rami
DEFINITION
Complex Nerve Network
The Ventral Rami of Most Spinal Nerves Form Plexuses (Not T2 ‑ T12)
Formed when the Ventral Rami of Several Spinal Nerves Exchange Fibers
(Fibers Recombine) to Form New Nerves that Supply Specific Areas

19. Plexus

20. Plexus

21. VENTRAL RAMUS (Comments from the text)
Fibers of several rami join to form individual nerves.
Each nerve emerging from a plexus contains all the fibers that innervate a body region.
Destination is basis for nerve’s name.
The plexus reduces the number of nerves needed to supply a body part.
Since plexi are composed of fibers from different spinal nerves, damage to one spinal nerve does not mean a complete loss of function in a body region
But Instead, Partial Loss of Function in Several Areas

22. MAJOR PLEXUSES (ALL ARE PAIRED): CERVICAL PLEXUS
Formed by the Ventral Rami of C1‑C4 and a Branch of Ventral Ramus of C5
Provides Nerve Supply to Neck and Upper Shoulders and Part of Head

23. CERVICAL PLEXUS

24. MAJOR PLEXUSES (ALL ARE PAIRED):BRACHIAL PLEXUS
Formed by the Ventral Rami of C5‑T1
Provides Nerve Supply to Lower Shoulders and Arms

25. BRACHIAL PLEXUS

26. MAJOR PLEXUSES (ALL ARE PAIRED): LUMBAR PLEXUS
Formed by the Ventral Rami of L1‑L4
SACRAL PLEXUS
Formed by the Ventral Rami of L4, L5, & S1‑S4
*Note: Together the Lumbar and the Sacral Plexuses (also the Coccygeal Plexus) Are Known as the Lumbosacral Plexus that Provides Nerve Supply to the Lower Trunk and the Legs

27. LUMBOSACRAL PLEXUS

28. Plexus Notes
* Coccygeal Plexus: Formed by S4, S5, and Coccygeal Nerves

29. GENERALIZATIONS ABOUT SPINAL NERVES
Spinal Nerves Are Not Named;
However, the Nerves That Emerge From Plexuses Often Are Named
Examples: Phrenic Nerve, Sciatic Nerve
There is a Close Relationship Between Where a Spinal Nerve Exits the Spinal Cavity and the Area the Nerve Supplies

30. CRANIAL NERVES DEFINITION
Nerves That Attach to the Undersurface of the Brain (Mainly the Brainstem)
12 Pair

31. CRANIAL NERVES IDENTIFICATION NAMES NUMBERS By Names and Numbers
MAY INDICATE NERVE’S FUNCTION
MAY INDICATE AREA THE NERVE SUPPLIES
NUMBERS
ROMAN NUMERALS
ORDER IN WHICH NERVE EMERGES FROM ANTERIOR TO POSTERIOR

32. NERVE TYPES
Some Cranial Nerves Are Mixed, Some Are Sensory, Some Are Motor
Saying to Remember Nerve Types: Some Say Marry Money, But My Brothers Say Bad Business Marry Money
MIXED NERVES: V, VII, IX, X
SENSORY NERVES: I, II, VIII
MOTOR NERVES: III, IV, VI, XI, XII

33. NAMES, NUMBERS, FUNCTIONS CRANIAL NERVE I
OLFACTORY NERVE
Sensory
Function: Smell

34. CRANIAL NERVE II
OPTIC NERVE
Sensory
Function: Vision

35. CRANIAL NERVE III OCULOMOTOR NERVE Motor Functions: Eye Movements
Regulation of Pupil Size
Accomodation

36. CRANIAL NERVE IV
TROCHLEAR NERVE
Motor
Function: Eye Movements

37. CRANIAL NERVE V TRIGEMINAL NERVE Mixed Functions:
Sensory: Sensations of Head and Face
Motor: Chewing

38. CRANIAL NERVE V

39. CRANIAL NERVE VI
ABDUCENS NERVE
Motor
Function: Lateral Eye Movements

40. CRANIAL NERVE VII FACIAL NERVE Mixed Functions: Sensory: Taste Motor:
Facial Expressions
Secretion of Saliva and Tears

41. CRANIAL NERVE VIII Vestibulocochlear
Sensory Functions: Hearing and Equilibrium

42. CRANIAL NERVE IX GLOSSOPHARYNGEAL NERVE Mixed Functions:
Sensory: Taste (and General Sensations of Tongue)
Motor: Swallowing, Secretion of Saliva
NOTE: This nerve is also involved in the reflexes of BP and respiration.

43. CRANIAL NERVE X X VAGUS NERVE Mixed Functions:
Sensory: Sensations in Organs Supplied
Motor: Movements of Organs Supplied (i.e., Slows Heart, Increases Peristalsis)

44. CRANIAL NERVE XI ACCESSORY NERVE Motor Functions:
Turning Movements of Head
Shoulder Movements
Movements of Organs Supplied
Voice Production

45. CRANIAL NERVE XII
HYPOGLOSSAL NERVE
Motor
Function: Tongue Movements

46. Saying Used to Remember the Names of the Cranial NervesOn
Old
Olympus‘
Tiny
Tops A On
Old
Olympus‘
Tiny
Tops A
Friendly
Viking
Grew
Vines
And
Hops” 
Friendly
Viking
Grew
Vines
And
Hops” 

47. Only
Old
Octopi
Trade
Tracks At
Friendly
Vertebrate
Grasslands In
Vagus Ad
Hoc

52. III. FUNCTIONAL DIVISIONS OF THE PERIPHERAL NERVOUS SYSTEM
Based on Direction in Which Neurons Conduct Nerve Impulses
AFFERENT (SENSORY) DIVISION
aa, like baa
Af = toward
Consists of all Afferent Neurons
Includes all Spinal Nerves (Afferent Fibers)as well as Cranial Nerves Which are Sensory and Mixed (Afferent Fibers)

53. III. FUNCTIONAL DIVISIONS OF THE PERIPHERAL NERVOUS SYSTEM
EFFERENT (MOTOR) DIVISION
ee, like Lee or eff, like Jeff
Ef = away from
Consists of all Efferent Neurons
Includes all Spinal Nerves (Efferent Fibers)as well as Cranial Nerves Which are Motor and Mixed (Efferent Fibers)

55. Two Efferent Subdivisions OF THE PERIPHERAL NERVOUS SYSTEM
Two Subdivisions (Based on Effectors)
SOMATIC MOTOR NERVOUS SYSTEM
Effectors are Voluntary: Skeletal Muscles
THE AUTONOMIC NERVOUS SYSTEM (Sympathetic & Parasympathetic
Effectors are Involuntary: Cardiac Muscle, Smooth Muscle, and Glands

57. ANS has 2 Divisions: Sympathetic and Parasympathetic
SYMPATHETIC DIVISION
THORACOLUMBAR
Nerves of the Sympathetic Division Branch from Thoracic Spinal Nerves (T1‑T12) and from some Lumbar Spinal Nerves (L1‑L4)
Explanation: Spinal Nerves are Mixed, Their Efferent Nerve Fibers are Somatic and Autonomic; The Autonomic Fibers are Sympathetic Nerves

58. ANS has 2 Divisions: Sympathetic and Parasympathetic
PARASYMPATHETIC DIVISION
CRANIOSACRAL
Nerves of the Parasympathetic Division Branch from some Cranial Nerves (III, VII, IX, X, XI) and from some Sacral Spinal Nerves (S2‑S4)
Explanation: Cranial Nerves III and XI are Motor, the Remaining Cranial Nerves Listed (VII, IX, X) are Mixed; Spinal Nerves are Mixed; Efferent Fibers in All These Nerves are Somatic and Autonomic; The Autonomic Fibers are Parasympathetic Nerves

60. b. FUNCTIONS OF THE ANS OVERVIEW OF ANS FUNCTIONS
ANS REGULATES AUTONOMIC EFFECTORS IN WAYS THAT MAINTAIN HOMEOSTASIS
BOTH DIVISIONS:
CONTINUALLY CONDUCT NI'S TO AUTONOMIC EFFECTORS (TONICALLY ACTIVE)

61. b. FUNCTIONS OF THE ANS
EXERT ANTAGONISTIC INFLUENCES ON AUTONOMIC EFFECTORS
Ex: If Sympathetic Division Stimulates an Autonomic Effector, then the Parasympathetic Division will Inhibit the Autonomic Effector
*NOTE: ACTUAL EFFECT DEPENDS ON WHICH DIVISION DOMINATES (SITUATION)
ANS INFLUENCED BY CEREBRAL CORTEX AND HYPOTHALAMUS

62. FUNCTIONS OF SYMPATHETIC DIVISION
MAJOR FUNCTION
DURING STRESS PRODUCES THE FIGHT OR FLIGHT REACTION
(SERVES AS THE BODY'S EMERGENCY SYSTEM)
Dominates during Stress (Physical or Psychological)
During Stress Produces "Fight or Flight“ Reaction

63. Fight or Flight" Reaction
A Collection of Changes in Autonomic Effectors which are Designed to Prepare the Individual to Respond to the Stress
The Major Goal of all the Changes is to Get Skeletal Muscles Prepared to Expend Maximum Energy

64. SUMMARY OF MAJOR CHANGES THAT OCCUR IN THE FIGHT OR FLIGHT REACTION:
*CARDIAC MUSCLE:
Rate/Strength of Heartbeat Increases
*SMOOTH MUSCLE:
Of Blood Vessels
Coronary, Skeletal Muscle: Dilate
Digestive Organ:
Constrict
Of Hollow Organs
Respiratory Airways: Dilate
Digestive Tract: Peristalsis Decreases
*GLANDS
Sweat Glands: Production of Sweat Increases
Liver: Glycogen -----> Glucose
Adrenal Medulla: Secretion of Epinephrine (Adrenalin) Increases

65. SYMPATHETIC DURING NONSTRESS
DOMINATES SOME AUTONOMIC EFFECTORS
MAINTAINS THEIR NORMAL FUNCTION
Ex: Cardiac Muscle

66. FUNCTIONS OF PARASYMPATHETIC DIVISION
DOMINATES MOST AUTONOMIC EFFECTORS DURING NONSTRESS
Rest and Repair Division
Promotes Normal Digestive System Activities
(For Example: Peristalsis and Elimination)