1. Peripheral Nervous System
Department of Biology, WCU

2. Introduction
Composition
receptors
peripheral nerves

3. Spinal nerves Location 31 pairs 8 cervical nerves 7 vertebrae
Supplies all except head and neck

4. Formation Dorsal root: sensory afferent Ventral root: motor efferent
Length varies
Rootlets
Dorsal and ventral ramus

5. Innervation of the body
1. Back
dorsal rami
Innervate thoracis, lattisimus dorsi, rhomboid etc.

6. Innervation of the body
2. Abdomen
ventral rami branch into intercostal nerve
intercostal muscles
abdominal muscles
skin

7. Plexuses Lateral network of nerves Except T2 - T12 Regions cervical
brachial
lumbar
sacral

8. Plexuses 1. Cervical under sternoceidomastoid C1 – C5 (common)
subcutaneous nerves
phrenic nerve

9. Plexuses 2. Brachial C5 - C8, T1 innervate upper limb organization
roots, trunks, divisions, cords

10. Plexuses 3. Lumbar L1 - L4 Muscles Proximal: abdomen
Distal: anterior and medial thigh, skin of leg

11. Plexuses 4. Sacral L4 (common) - S4 Muscles Sciatic nerve
buttocks, lower limb, pelvis genitals
Sciatic nerve
hamstrings, adductor magnus, toes

12. Cranial nerves 12 pairs Numbering system
Forebrain (I & II), brain stem (III-XII)
Supply head and neck (vagus)
Naming
olfactory
optic
facial
trigeminal

13. Sensory receptors Sensory function Types
Exteroceptors (touch, temperature)
Interoceptors (pH, temperature, heart rate)

14. Sensory receptors Proprioceptors (muscle stretch)
skeletal muscle, joints, tendons, CT

15. Sensory receptors Distribution 1. Free dendritic endings
naked dendrites
Merkel discs
root hair plexus

16. Sensory receptors 2. Encapsulated dendritic endings Types
enclosed in CT capsule
Types
Pacinian Corpuscle
Meissner’s Corpuscle
Muscle spindle