1. Biology 211 Anatomy & Physiology I
Dr. Thompson
The Peripheral Nervous System

3. Recall: All organs are composed of Epithelial tissue Muscle tissue
Connective tissue
Nervous tissue
Nervous tissue: Excitable cells (neurons)
Nonexcitable (supporting) cells
Connective tissue: Meninges in central nervous system
Endoneurium
Perineurium in peripheral nervous system
Epineurium
Epithelium
found only in blood vessels of PNS
Muscle (smooth)

4. Cells of Nervous Tissue:
1) Excitable cells = Neurons
Carry electrical signals
from one place to another
Pass these signals to other cells
2) Nonexcitable cells = Glia in CNS
Satellite cells
Schwann cells
in PNS

5. In Peripheral Nervous System:
Neuron cell bodies
grouped into ganglia
(single = ganglion)
Axons grouped into
nerves

6. Nerve:
Each axon surrounded by Schwann cells, which may or may not form a myelin sheath.
Outside the Schwann cells, each axon is surrounded by layer of connective tissue called endoneureum

7. Axons (surrounded by Schwann cells and endoneureum) form bundles called fascicles, each of which is surrounded by a thicker layer of connective tissue called perineureum

8. Fascicles group together to form a nerve, which is surrounded by an even
thicker layer of connective tissue called epineureum

10. Cranial Nerves connect to the brain
Cranial Nerves connect to the brain. Three carry only sensory information, five carry mostly motor information (with a small amount of sensory), and four carry both motor and sensory information
Spinal Nerves connect to the spinal cord. All of these carry both motor and sensory information

11. - Originate from the brain
Cranial Nerves:
- Originate from the brain
Pass through foramina in the
skull to reach the periphery
12 pairs, numbered from superior to inferior.
They carry the special senses (smell, vision, hearing, taste,
and equilibrium)
They carry sensory information from the head, face, and
much of the neck.
They carry motor innervation to muscles of the eye, face,
larynx, and tongue; some muscles of the neck and back.
One (CN X) carries autonomic information to organs of the
thorax and abdomen.

12. You will not be asked to identify cranial nerves on either diagrams or specimens

13. The names, functions, origins, terminations, foramina, and effects of damage are listed and described in your Saladin text for all of the cranial nerves.
Using this information, you will be expected to know
a) The names and numbers of all 12 pairs of cranial nerves,
including the subdivisions of cranial nerve V
b) The foramen through which each cranial nerve passes
c) The primary functions of each cranial nerve
d) The effects of damage to each cranial nerve

14. Using this information, you will be expected to know
a) The names and numbers of all 12 pairs of cranial nerves,
including the subdivisions of cranial nerve V
b) The foramen through which each cranial nerve passes
c) The primary functions of each cranial nerve
d) The effects of damage to each cranial nerve
Example: The abducens nerve (VI) originates from the pons and exits the skull through the superior orbital fissure. It innervates the lateral rectus muscle which causes the eye to rotate laterally. Injury to this nerve on either side causes an inability to rotate that eye laterally, and unopposed function of the other muscles often cause the eye rotate medially.

15. - Pass between vertebrae
Spinal Nerves:
- Originate from the
spinal cord by dorsal
and ventral roots
- Pass between vertebrae
through intervertebral
foramina to reach the
periphery

16. - Pass between vertebrae
Spinal Nerves:
- Originate from the
spinal cord by dorsal
and ventral roots
- Pass between vertebrae
through intervertebral
foramina to reach the
periphery
- 31 pairs, numbered from
superior to inferior in
each region of the back

17. Naming Spinal Nerves:
Cervical nerves #1 through #7 leave the vertebral canal through the intervertebral foramina ABOVE the vertebrae with the same numbers.
Example: Cervical nerve #3 passes above cervical vertebra #3 (between cervical vertebra #2 and #3)
Cervical nerve #8 leaves the vertebral
canal through the intervertebral foramen between cervical vertebra #7 and thoracic vertebra #1 .

18. Naming Spinal Nerves:
Cervical nerve #8 leaves the vertebral canal through the intervertebral foramen between cervical vertebra #7 and thoracic vertebra #1 .
All thoracic, lumbar, and sacral
nerves plus the single coccygeal
nerve leave the vertebral canal
through the intervertebral foramina
BELOW the vertebrae with the same numbers.
Example: Thoracic nerve #3 passes below thoracic vertebra #3 (between thoracic vertebra #3 and #4)

19. Spinal nerves passing through intervertebral foramina

20. Spinal nerve passing through intervertebral foramina

21. Immediately distal to the intervertebral foramen, each spinal nerve divides into a dorsal ramus and a ventral ramus.
Both rami are mixed, carrying both afferent & efferent information

22. Dorsal rami of all spinal nerves innervate the muscles and the skin of the back at their level.
For example: the dorsal ramus of nerve thoracic-2 innervates the muscles and skin of the back at the level of vertebra thoracic-2

23. Ventral rami of spinal nerves Thoracic innervate muscles and skin of body wall (thorax and abdomen)

24. Ventral rami of spinal nerves Thoracic innervate muscles and skin of body wall (thorax and abdomen)
But:
Ventral rami of all other spinal nerves
Cervical 1-8,
Thoracic 1,
Lumbar 1-5,
Sacral 1-5
enter into plexes
(singular = plexus)

25. A plexus is an interchange which allows nerves from different spinal cord levels to combine to serve common structures.
1. Each nerve distal to a
plexus carries axons to
& from more than
one level of the spinal
cord.
Example: Radial nerve
carries information to
& from five levels of
the spinal cord:
C5, C6, C7, C8, T1

26. 1. Each nerve distal to a plexus carries axons to / from
more than one level of the spinal cord.
Example: Radial nerve carries information to and from
five levels of the spinal cord: C5, C6, C7, C8, T1
2. Axons carrying
information to / from a
single spinal cord level
are distributed through
more than one nerve
distal to the plexus
Example: Spinal cord
level C7 sends and
receives information
through more than 20
different nerves

27. Four plexes:
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus

28. Cervical Plexus
Originates from ventral rami of nerves C1, C2, C3, C4 (+C5)
Carries efferent neurons to many muscles of the neck.
Carries afferent neurons from skin of the neck, shoulder, and scalp near ear

29. Brachial Plexus
Originates from ventral rami of nerves C5, C6, C7, C8, T1, (+C4)
Carries efferent neurons to muscles of the shoulder, arm, forearm, and hand
Carries afferent neurons from skin of the shoulder, arm, forearm, and hand

30. Lumbar Plexus
Originates from ventral rami of nerves L1, L2, L3, L4, (L5)
Carries efferent neurons to muscles of the anterior pelvis, anterior and medial thigh
Carries afferent neurons from skin of the anterior pelvis, anterior and medial thigh, and medial leg.

31. Sacral Plexus
Originates from ventral rami of nerves (L4), L5, S1, S2, S3, S4, (S5, Cx1)
Carries efferent neurons to muscles of the posterior pelvis, posterior thigh, anterior and posterior leg, and foot
Carries afferent neurons from skin of the posterior pelvis, posterior thigh, anterior and posterior leg, and foot.

32. Genitofemoral Pudendal Inferior and superior gluteal Tibial (Sciatic)
We will go into greater detail about the bracheal plexus, but you will not be held responsible for details of the cervical, lumbar, or sacral plexes EXCEPT:
You need to know which spinal nerves contribute their ventral rami to each plexus.
You need to know which plexus gives rise to each of the following nerves, and which area of the body each of them innervates:
Ansa cervicalis
Femoral Obturator
Fibular (common peroneal) Phrenic
Genitofemoral Pudendal
Inferior and superior gluteal Tibial
(Sciatic)

33. Summary of the Brachial Plexus

34. Roots

35. Trunks Upper
Middle
Lower

36. Divisons
Anterior
Posterior

37. Cords:
Lateral
Posterior
Medial

39. More than 20 nerves leave the brachial plexus to supply both afferent (sensory) and efferent (motor) innervation to the shoulder, arm, forearm, hand, and parts of the neck and thoracic wall.
We will follow five of these:
1. Musculocutaneous nerve: Arises from the lateral cord of the brachial plexus.
Innervates muscles of the anterior compartment of the arm; skin of lateral forearm

40. 1. Musculocutaneous nerve: Arises from the lateral cord of the brachial plexus.
Innervates muscles of the anterior compartment of the arm; skin of lateral forearm
2. Ulnar Nerve: Arises from the medial cord of the brachial plexus.
Innervates muscles in the anterior compartment of the forearm & some intrinsic muscles of the hand; skin on medial third of hand (both anterior and posterior surfaces)

41. 2. Ulnar nerve: Arises from the medial cord of brachial plexus
2. Ulnar nerve: Arises from the medial cord of brachial plexus. Innervates muscles of the anterior compartment of forearm & some muscles of hand; skin on medial third of hand (posterior & anterior)
3. Median Nerve: Arises from medial AND lateral cords of the brachial plexus.
Innervates muscles in the anterior compartment of the forearm & some intrinsic muscles of the hand; skin on anterior surface of lateral two-thirds of hand

42. 3. Median Nerve: Arises from medial AND lateral cords of the brachial plexus. Innervates muscles in the anterior compartment of the forearm & some muscles of hand; skin on anterior surface of lateral two-thirds of hand
4. Radial Nerve: Arises from posterior cord of brachial plexus.
Innervates muscles in posterior compartment of arm & posterior compartment of forearm; skin on posterior surface of lateral two-thirds of hand & skin on posterior surfaces of forearm and arm

43. 4. Radial Nerve: Arises: posterior cord of brachial plexus.
Innervates muscles in posterior compartments of arm & forearm; skin on posterior surface of lateral two-thirds of hand & skin on posterior surfaces of forearm and arm
5. Axillary Nerve: Arises from posterior cord of brachial plexus.
Innervates shoulder joint, deltoid and teres minor muscles; skin of shoulder

45. Cutaneous Innervation
Axillary
(Medial antebrachial cutaneous)
Radial
Musculocutaneous
Ulnar
Median
Anterior
Posterior