1. PNS Terminology Ganglia – neuron cell bodies & dendrites
Nerves – bundles o myelinated axons
PNS neuroglia
Satellite cells
Enclose neuron cell bodies in ganglia
Schwann cells
Cover peripheral axons

2. -cranial nerves – 12 pairs
I - Olfactory
II - Optic
III - Oculomotor
IV-Trochlear
V - Trigeminal
VI - Abducens
VII - Facial
VIII – Acoustic/Vestibulocochlear
IX - Glossopharyngeal
X - Vagus
XI – Accessory/Spinal Accessory
XII - Hypoglossal
-cranial nerves – 12 pairs
-olfactory, optic & acoustic contain only sensory axons = sensory nerves
- oculomotor, trochlear, abducens, accessory & hypoglossal carry only motor information = motor nerves
-remaining are mixed nerves – both motor and sensory axons
“some say my mother bought my brother some bitter beer – my, my”

3. VII
VIII V VI IX X
III I II
Optic Chiasma XI

4. The Olfactory Nerve (I)
Sensory Nerve
Carries sensory information
Sense of smell
Synapse within olfactory bulbs

5. Sensory Nerve The optic nerve (II)
carries visual information to occipital lobe

6. The Vestibulocochlear Nerve (VIII)
Sensory Nerve
also called the Acoustic nerve
Vestibular nerve
Monitors sense of balance, position and movement
Cochlear nerve
Monitors hearing

7. Motor Cranial Nerves The oculomotor nerve (III)
Primary source of innervation for extra-ocular muscles
Move the eyeball
The trochlear nerve (IV)
Smallest cranial nerve
Innervates superior oblique eye muscle
The abducens nerve (VI)
Innervates lateral rectus muscle of eye
Motor Cranial Nerves

8. The accessory nerve (XI) – Motor nerve
innervates swallowing muscles & controls sternocleidomastoid and trapezius muscles and other muscles of pectoral girdle
two branches: cranial part (internal branch) & spinal part (external branch)
The hypoglossal nerve (XII) – motor nerve
voluntary motor control over tongue movements

9. The Trigeminal Nerve (V)
Largest cranial nerve
Mixed nerve
Ophthalmic branch
sensory – upper eyelid, eyeball
lacrimal glands, side of nose, forehead
and scalp
Maxillary branch
sensory – nose, palate, part
of pharynx, upper teeth, upper
lip and lower eyelid
Mandibular branch
sensory – tongue, cheek,
lower teeth, skin over mandible
and side of head anterior to ear
-motor – muscles of chewing

10. The Facial Nerve (VII) Mixed nerve
controls muscles of scalp and facial expression
transmits pressure sensations from face & taste sensations from tongue
major branches:
Temporal
Zygomatic
Buccal
Mandibular
Cervical

11. The Glossopharyngeal Nerve (IX)
Mixed nerve
Innervates the tongue & controls swallowing

12. The Vagus Nerve (NX) Mixed nerve
vital to autonomic control of visceral function
major nerve of the ANS/parasympathetic system

13. 31 Pairs of Spinal Nerves Ensheathed by three connective tissue layers
Outermost epineurium
dense network of collagen fibers around the peripheral nerve
Middle perineurium
partitions nerve into fascicles
Inner endoneurium
delicate connective tissue fibers surrounding each axon
under the endoneurium is the myelin sheath
outer layer of the myelin sheath is called the neurilemma
neurilemma covers the myelin sheath and Schwann cells
myelin sheath covers the axon

14. Spinal Nerves
connected to the spinal cord via roots (bundles of axons)
Posterior root = sensory axons into the posterior gray horn
Anterior root = motor axons from the anterior gray horn

15. Spinal Nerves
before the posterior root is the dorsal root ganglion = cell bodies of incoming sensory neurons (axons continue on to form the root)

16. Spinal Nerve
spinal nerves emerge from intervertebral foramina as mixed nerves
after passing through intervertebral foramina the spinal nerve branches into three rami
Dorsal ramus
Ventral ramus
Rami communicantes

17. Spinal Nerve Dorsal ramus
-sensory/motor innervation to and from skin and muscles of back
Ventral ramus
- sensory/motor innervation to and from skin and structures of ventral and lateral body wall, muscles of the upper and lower limbs
Dorsal
Ramus
Ventral
Rami
Communicantes
Dorsal Root
Root
Dorsal Root Ganglion
Epidural space
Dura and
Arachnoid
maters
rami communicantes
-carries nerves of the ANS

18. SPINAL NERVE Dorsal Root of SN Ventral Root of SN Dorsal Ramus Ventral
Rami
Communicantes
Sensory – IN
Motor – OUT
SKIN
BACK MUSCLES
Sensory – IN
Motor – OUT
TRUNK
LIMBs
Signals to and from the
ANS
VISCERA – cardiac and
Smooth muscle

19. Nerve Plexuses Four major plexuses
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
nerve networks formed by the ventral rami of spinal nerves
found in neck, arm, low back & sacral regions
no plexus in thoracic region
intercostal nerves this region

20. Cervical Plexus C1-C4 ventral rami Some fibers from C5
Innervates muscles of the neck and diaphragm
major nerve from plexus = Phrenic nerve

21. Brachial Plexus Ventral rami of C5-T1
Innervates pectoral girdle and upper limbs

22. Brachial Plexus Lateral cord: musculocutaneous, median nerves
nerves arise from cords & trunks
Superior, middle and inferior trunks
Lateral, medial and posterior cords
musculocutaneous, radial, median and ulnar nerves arise from these cords
Lateral cord: musculocutaneous, median nerves
Medial cord: ulnar, median nerves
Posterior cord: radial, axillary nerves

23. Lumbar Plexus ventral rami of T12–L4
Innervate pelvic girdle and lower limbs
femoral nerve gives off many muscular branches
posterior segment gives off branches to the quads and branches to the knee + large saphenous nerve

24. Sacral Plexus ventral rami of L4–S4
innervates pelvic girdle and lower limbs
sciatic nerve becomes the tibial nerve, sural nerves & common fibular nerve in the leg