1. The Peripheral and Autonomic Nervous System
Anatomy and Physiology Lab II
Medgar Evers College
Fall 2017

2. The Peripheral Nervous System
Nervous structures outside the brain and spinal cord
Nerves allow the CNS to receive information and take action
The peripheral nervous system is divided into 2 divisions based upon function!
Motor (efferent)
Sensory (afferent)

3. Sensory Input and Motor Output
Sensory (afferent) signals picked up by sensor receptors, carried by nerve fibers of PNS to the CNS
Motor (efferent) signals are carried away from the CNS, innervate muscles and glands
Divided according to region they serve
Somatic body region
Visceral body region
Results in four main subdivisions
Somatic sensory
Visceral sensory
Somatic motor
Visceral motor (autonomic nervous system)

4. Types of Sensory and Motor Information
Figure 12.3

5. The Autonomic Nervous System
2 branches; sympathetic and parasympathetic

6. sympathetic “fight or flight response”
SNS is activated by any excitement, emotion, or exercise. The axons release epinephrine, norepinephrine, and acetylcholine.
Leads to increased heart rate, increased blood pressure, dilation of blood vessels serving the skeletal muscles, dilation of the airways passages in the lungs, decreased urinary function, decreased digestive functions, increased metabolic rate, increased released of fatty acids and glucose and dilation of pupils

7. parasympathetic “rest and recovery role” Axons secrete acetylcholine
Leads to decreased heart rate, decreased blood pressure, dilation of blood vessels serving the skin and abdominal viscera, mild constriction of airways passages in the lungs, increased urinary function, increased digestive functions, storage of fats and glucose, adjustment of lens for near vision, and constriction of pupils.

8. Basic Structural Components of the PNS
Sensory receptors – pick up stimuli from inside or outside the body
Motor endings – axon terminals of motor neurons innervate effectors (muscle fibers and glands)
Nerves and ganglia
Nerves – bundles of peripheral axons
Ganglia – clusters of peripheral neuronal cell bodies

9. Nerves Nerves – cable-like organs in the PNS
Consists of numerous axons wrapped in connective tissue
Endoneurium – layer of delicate connective tissue surrounding the axon
Perineurium – connective tissue wrapping surrounding a nerve fascicle
Nerve fascicles – groups of axons bound into bundles
Epineurium – whole nerve is surrounded by tough fibrous sheath
Axon is surrounded by Schwann cells

10. Cranial Nerves
Attach to the brain and pass through foramina of the skull
Numbered from I–XII
Cranial nerves I and II attach to the forebrain
All others attach to the brain stem
Primarily serve head and neck structures
The vagus nerve (X) extends into the abdomen

11. The 12 Pairs of Cranial Nerves
Figure 14.5

12. Olfactory Nerves (I) Sensory nerves of smell olfactory nerve (I)
Olfactory bulb
Olfactory tract
Optic nerve (II)
Optic chiasma
Optic tract
Oculomotor nerve (III)
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Cerebellum
Medulla
Table 14.3 (1 of 12)

13. Optic Nerve (II) Sensory nerve of vision Optic nerve (II)
Filaments of
olfactory nerve (I)
Olfactory bulb
Olfactory tract
Optic nerve (II)
Optic chiasma
Optic tract
Oculomotor nerve (III)
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Cerebellum
Medulla
Table 14.3 (2 of 12)

14. Oculomotor Nerve (III)
Innervates four of the extrinsic eye muscles
Filaments of
olfactory nerve (I)
Olfactory bulb
Olfactory tract
Optic nerve (II)
Optic chiasma
Optic tract
Oculomotor nerve (III)
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Cerebellum
Medulla
Table 14.3 (3 of 12)

15. Trochlear Nerve (IV)
Innervates the superior oblique muscle (an extrinsic eye muscle)
Filaments of
olfactory nerve (I)
Olfactory bulb
Olfactory tract
Optic nerve (II)
Optic chiasma
Optic tract
Oculomotor nerve (III)
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Cerebellum
Medulla
Table 14.3 (4 of 12)

16. Trigeminal Nerve (V) Provides sensory innervation to the face
Motor innervation to chewing muscles
Filaments of
olfactory nerve (I)
Olfactory bulb
Olfactory tract
Optic nerve (II)
Optic chiasma
Optic tract
Oculomotor nerve (III)
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Cerebellum
Medulla

17. Abducens Nerve (VI)
Abducts the eyeball – innervates lateral rectus muscle
Filaments of
olfactory nerve (I)
Olfactory bulb
Olfactory tract
Optic nerve (II)
Optic chiasma
Optic tract
Oculomotor nerve (III)
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Cerebellum
Medulla
Table 14.3 (6 of 12)

18. Facial Nerve (VII) Innervates muscles of facial expression
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Table 14.3 (7 of 12)

19. Vestibulocochlear Nerve (VIII)
Sensory nerve of hearing and balance
Facial nerve (VII)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Table 14.3 (8 of 12)

20. Glossopharyngeal Nerve (IX)
Innervates structures of the tongue and pharynx
Facial nerve (VII)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Table 14.3 (9 of 12)

21. Vagus Nerve (X)
A mixed sensory and motor nerve - “Wanders” into thorax and abdomen
Facial nerve (VII)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Table 14.3 (10 of 12)

22. Accessory Nerve (XI)
An accessory part of the vagus nerve -innervates trapezius muscle
Facial nerve (VII)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Table 14.3 (11 of 12)

23. Hypoglossal Nerve (XII)
Runs inferior to the tongue - innervates the tongue muscles
Facial nerve (VII)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Accessory nerve (XI)
Hypoglossal nerve (XII)
Table 14.3 (12 of 12)

24. Spinal Nerves 31 pairs – contain thousands of nerve fibers
Connect to the spinal cord
Named for point of issue from the spinal cord
8 pairs of cervical nerves (C1–C8)
12 pairs of thoracic nerves (T1–T12)
5 pairs of lumbar nerves (L1–L5)
5 pairs of sacral nerves (S1–S5)
1 pair of coccygeal nerves (Co1)

25. Spinal Nerves
Connect to the spinal cord by the dorsal root and ventral root
Dorsal root – contains sensory fibers
Dorsal root ganglion – of afferent cell bodies
Ventral root – contains motor fibers arising from anterior gray column
Branch into dorsal ramus and ventral ramus both contain sensory and motor fibers and a small meningeal branch.

26. Innervation of the Back
Dorsal rami
Innervate back muscles, the skin, and joints

27. Innervation of the Thoracic region
Ventral rami arranged in simple, segmented pattern
Intercostal nerves – supply intercostal muscles, skin, and abdominal wall
Each gives off lateral and anterior cutaneous branches

28. Introduction to Nerve Plexuses
Nerve plexus – a network of nerves
Ventral rami ,Form nerve plexuses
Cervical
Brachial
Lumbar
Sacral
Primarily serve the limbs

29. The Cervical Plexus
Buried deep in the neck under the sternocleidomastoid muscle
Formed by ventral rami of first four cervical nerves (C 1 – 4)
Most are cutaneous nerves
Some innervate muscles of the anterior neck

30. Brachial Plexus Brachial plexus lies in the neck and axilla
Formed by ventral rami of C5 – T1 give rise to cords
Cords give rise to main nerves of the upper limb
Figure 14.9d

31. Lumbar Plexus
Arises from L1– L4 , small contribution from T12
Smaller branches innervate the posterior abdominal wall and psoas muscle
Main branches innervate the anterior thigh

32. The Sacral Plexus Arises from spinal nerves L4–S4
Often considered with the lumbar plexus referred to as the lumbosacral plexus
Sciatic nerve – the largest nerve of the sacral plexus is actually two nerves in one sheath
Tibial nerve – innervates most of the posterior lower limb
Common fibular (peroneal) nerve – innervates muscles of the anterolateral leg

33. Stretch reflex