PERIPHERAL NERVOUS SYSTEM REVIEW (Spinal Nerve Review)

PowerPoint® Lecture Slides presented by

Dr. Peter Reonisto, Moorpark College,

California

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

PERIPHERAL NERVOUS SYSTEM REVIEW (Spinal Nerve Review)


Spinal Nerves

Figure 14.7a

Dorsal root – contains sensory fibers Cell bodies – located in the

dorsal root ganglion

Ventral root – contains motor fibers arising from anterior gray column

Branch into dorsal ramus and ventral ramus

Dorsal and ventral rami contain sensory and motor fibers

Rami communicantes connect to the base of the ventral ramus

Lead to the sympathetic chain ganglia


Innervation of the Back

Figure 14.7b

A

B

DORSAL ROOTDORSAL ROOT GANGLIONVENTRAL ROOTSPINAL NERVEDORSAL RAMIVENTRAL RAMIRAMI COMMUNICANTES

SYMPATHETIC TRUNK GANGLION

C

DE

F

G

H


Introduction to Nerve Plexuses

Nerve plexus – network of nerves Ventral rami

Branch and join with one another Form nerve plexuses

In cervical, brachial, lumbar, and sacral regions

Primarily serve the limbs

Which spinal nerves do not contribute to Nerve plexuses?

T2 – T12


The Cervical Plexus

Buried deep in the neck Under the sternocleidomastoid muscle

Formed by ventral rami of first four cervical nerves ( C1 – 4)

Some innervate muscles of the anterior neck Phrenic nerve – the most important nerve of the

cervical plexus

?

?


The Cervical Plexus

Buried deep in the neck Under the sternocleidomastoid muscle

Formed by ventral rami of first four cervical nerves ( C1 – 4)

Some innervate muscles of the anterior neck Phrenic nerve – the most important nerve of the

cervical plexus


The Brachial Plexus and Innervation of the Upper Limb

Brachial plexus lies in the neck and axilla

Formed by ventral rami of C5 – C8

Figure 14.9d


The Brachial Plexus and Innervation of the Upper Limb What Cervical Root gives rise to the middle trunk of the

brachial plexus?

Figure 14.9d


The Brachial Plexus and Innervation of the Upper Limb What Cervical Root gives rise to the middle trunk of the

brachial plexus?

Figure 14.9d



What Cord from the Brachial plexus gives rise to the Median nerve?

Figure 14.9d



What Cord from the Brachial plexus gives rise to the Median nerve?

Figure 14.9d



This nerve is a continuation of the posterior cord?

Figure 14.9d



This nerve is a continuation of the posterior cord?

Figure 14.9d



The Ulnar nerve branches from what cord?

Figure 14.9d



What is the main branch of the Lateral cord from the Brachial plexus?

Figure 14.9d


The Brachial Plexus

Figure 14.9a


Posterior Cord extension - Axillary and Radial Nerves

Figure 14.11


The Lumbar Plexus and Innervation of the Lower Limb

Lumbar plexus Arises from L1– L4

Smaller branches innervate the posterior abdominal wall and psoas muscle

Main branches innervate the anterior thigh


The Lumbar Plexus

Figure 14.12a, b


The Sacral Plexus

Arises from spinal nerves L4–S4

Caudal to the lumbar plexus Often considered with the lumbar plexus

Lumbosacral plexus


Innervation of the Lower Limb

Sciatic nerve – the largest nerve of the sacral plexus 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

?

?



Sciatic nerve – the largest nerve of the sacral plexus 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



Superior and inferior gluteal nerves Innervate the gluteal muscles

Pudendal nerve Innervates muscles of the perineum


The Sacral Plexus

Figure 14.13

?

?


The Sacral Plexus

Figure 14.13


Innervation of the Skin: Dermatomes

Dermatome – an area of skin Innervated by cutaneous branches of a single spinal

nerve

Upper limb Skin is supplied by nerves of the brachial plexus

Lower limb Lumbar nerves – anterior surface Sacral nerves – posterior surface


Map of Dermatomes – Anterior View

Figure 14.14a


Map of Dermatomes – Posterior View

Figure 14.14b



Figure 14.14a

Which spinal nerve cutaneous branch is damaged when a person loses sensation at theDigits 1 and 2 (right hand)?



Figure 14.14a



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PERIPHERAL NERVOUS SYSTEM REVIEW (Cranial Nerve)


Cranial Nerves

Attach to the brain and pass through foramina of the skull

Numbered from I–XII Which Cranial nerves are attached to the forebrain?

All others attach to the brain stem Which Cranial nerves are attached to the Midbrain? at the Pons? at the Medulla?

Primarily serve head and neck structures Which of Cranial nerve extends into the abdomen?

CN I and II

CN III and IVCN V and VII

CN VIII and XII

CN X


The 12 Pairs of Cranial Nerves

Figure 14.5

CN ICN IICN IIICN IVCN VCN VICN VIICN VIIICN IXCN XCN XICN XII

ABC

D

EF

GH

IJ

K

L

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.3 (1 of 12)

Olfactory Nerves

Sensory nerves of smell

Limbic lobePiriform lobe


Optic Nerve

Sensory nerve of vision


Oculomotor Nerve (EOM)

Innervates four of the extrinsic eye muscles

Table 14.3 (3 of 12)


Oculomotor Nerve (Pupillary Constriction)

Innervates four of the extrinsic eye muscles

Table 14.3 (3 of 12)

Pupillary constriction


Trochlear Nerve

Innervates the superior oblique muscle (an extrinsic eye muscle)

Superior midbrain


Abducens Nerve

Abducts the eyeball – innervates lateral rectus muscle

Table 14.3 (6 of 12)

Inferior


EXTRAOCULAR MUSCLS

Medial Rectus

Superior Rectus

Inferior Rectus

Inferior Oblique

(Levator Palpebrae)

Superior Oblique Lateral Rectus

CN III CN IV CN VI

LASOT


Trigeminal Nerve

Provides sensory innervation to the face Motor innervation to chewing muscles

(THROUGH THE MANDIBULAR DIVISION)


Trigeminal Nerve

Table 14.3 (5 of 12)

OPTHALMICPons

Trigeminal n.Trigeminal gang.

Sup. Orbital fissureSupraorbital foramen

MAXILLARYPons

Trigeminal n.Trigeminal gang.

Foramen rotundumInfraorbital foramen

MAXILLARYPons

Trigeminal n.Trigeminal gang.Foramen ovale

Mandibular foramenMental foramen foramen


Facial Nerve

Innervates muscles of facial expression

PonsInternal Acoustic Meatus

1) Chorda tympani to tasteAnterior 2/3 tongue

2) Somatic motor to facial Muscles

3) Parasympathetic to Pterygopalatine (lacrimal)

and Submandibular (salivary) ganglion -


Vestibulocochlear Nerve

Sensory nerve of hearing and balance

Table 14.3 (8 of 12)


Glossopharyngeal Nerve

Innervates structures of the tongue and pharynx

Table 14.3 (9 of 12)

MedullaCN IX

Superior gang.Inferior gang.

Jugular foramen 1) Parasymp. to parotid

gland via Otic gang.2) Carotid sinus 3) Tongue 4) Pharynx and throat


Vagus Nerve

A mixed sensory and motor nerve “Wanders” into

thorax and abdomen Parasympathetic

innervation of organs

Table 14.3 (10 of 12)

MedullaJugular foramenThorax and Abdomen


Accessory Nerve

An accessory part of the vagus nerve Innervates trapezius muscle

Cranial + Spinal root from medullaJugular foramen1) Cranial root goes w/ Vagus n.2) Spinal root to a) Sternocleidomastoid b) Trapezius


Hypoglossal Nerve

Runs inferior to the tongue Innervates the tongue muscles

MedullaHypoglossal canalTongue (movement)



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PERIPHERAL NERVOUS SYSTEM REVIEW (Autonomic Nervous System Review))


The Peripheral Nervous System

Autonomic nervous system (ANS) General visceral motor part of the PNS ANS has two divisions

Parasympathetic Sympathetic


Functional Organization of the PNS

Figure 14.1


Basic Anatomical Scheme of the PNS in the Region of a Spinal Nerve

Figure 14.2


MOTOR NEURONS

ANS includes a chain of 2 motor neurons:1) Pre-ganglionic neuron – cell body lies within the

spinal cord or brain. a) Preganglionic axon- synapses with the

ganglionic neuron2) Ganglionic neuron- cell body lies in the peripheral

location. a) Postganglionic axon- extends to the visceral

organs


DIVISIONS OF THE ANS

1) Sympathetic- “fight, flight, or fright response”

2) Parasympathetic- body at rest, conserving body energy; directs vital “housekeeping activities” (digestion , urination); “rest and digest”

Both divisions have chains of motor neurons that mostly innervate the same visceral organ, but they cause opposite effects.


Anatomical and biochemical difference:

SYMPATHETIC originate at the

thoracolumbar region of the spinal cord.

Long postganglionic fibers. Sympathetic fibers branch

profusely. Neurotransmitter released at

postganglionic axons are Norepinephrine mostly.

PARASYMPATHETIC originate from the cranial

(brain) and sacral (spinal cord) outflow

Short postganglionic fibers Parasympathetic fibers not

profusely branched. Neurotransmitter released

are Acetylcholine

The preganglionic axon terminals of both divisions release acetylcholine

Refer to Table 15.1, page 434


PARASYMPATHETIC NERVOUS SYSTEM

CRANIAL OUTFLOW

- comes from the brain.

- Innervate the head, neck, thorax, and most of the abdomen.

- Preganglionic fibers come from CNIII, VII, IX, X.

SACRAL OUTFLOW

- comes from the sacral sinal cord

- Supplies the rest of abdominal organs and the pelvic organs


Sacral outflow

Cranial outflow


SUMMARY OF NEURONS CONNECTED TO THE SPINAL CORD


SUMMARY OF ANS FUNCTIONS

EFFECTOR ORGAN

SYMPATHETIC STIMULI PARASYMPATHEITIC STIMULI

HEART Rate

Contractility

SA NODE Conduction velocity

AV NODE Conduction velocity

VENTRICLES Conduction velocity

LUNGS Bronchial smooth muscle

ARTERIOLES Skin, resistance vessels

Skin surface vessels

Mucosa

Increase Decrease

Increase Decrease

Increase Decrease

Increase ------

Relaxation smooth Muscle B2

Contraction smooth Muscle A1

Constriction(direct A1)Dilation(circ Epi at B2)

Both dilation (circAcH at M2) (minor)

Constriction (direct A1) ------



EFFECTOR ORGAN


ARTERIOLES Abdominal viscera

Skeletal muscles

Coronary

Glands

VEINS

(SYSTEMIC)

GIT Motility and tone

Sphincter contraction

Constriction (direct A1) ------

Dilation (circ Epi at B2) Dilation (circ AcH at M2)

Dilation (circ Epi at B2) Dilation (circ AcH at M2)

Constriction (direct at A1) Dilation (circ AcH at M2)

Constriction (direct at A1) ------

Decrease Increased

Contraction Relaxation



EFFECTOR ORGAN


SKIN Pilomotor muscle

Sweat glands

SPLEEN CAPSULE

EYE Radial muscle of iris

Sphincter muscle of th iris

Ciliary muscle

GLANDS Gastrointestinal

Piloerection ------

Secretion ------

Contraction ------

Contraction (mydriasis) ------

------ Contraction (miosis)

Relaxation (far vision) Contraction (near vision)

Inhibition of secretion Secretion



EFFECTOR ORGAN


GLANDS Lacrimal

Nasopharyngeal

Respiratory

Salivary

------ Secretion

------- Secretion

Inhibition of secretion Secretion

Thick secretion Thin secretion

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PERIPHERAL NERVOUS SYSTEM REVIEW (Spinal Nerve Review)