A&P Peripheral Nervous System

Efferent

Motor information from brain → Periphery

Afferent

Sensory information from periphery → brain

Autonomic nervous system

Involuntary nervous system

Regulates smooth muscles, cardiac, and glands

Separated into sympathetic and parasympathetic

Neurotransmitters for the autonomic NS

Acetylcholine, epinephrine, and norepinephrine

Type of action of autonomic NS

Excitatory or inhibitory

Autonomic NS is controlled by…

Homeostatic centers in the brain (Pons, hypothalamus, medulla oblongata)

Nerves of the sympathetic NS

Short pre-ganglionic neuron and long post-ganglionic neuron

Nerves of the parasympathetic NS

Long, heavily myelinated, pre-ganglionic neuron and short post-ganglionic neuron

Neurotransmitters of somatic NS

Only acetylcholine

Action of somatic NS

Always excitatory

Somatic NS is controlled by…

The cerebrum

Sympathetic

Response to unusual stimulus

Takes over to increase activities

Exercise, Excitement, Emergency, and Embarrassment (E division)

Parasympathetic

House keeping activities

Conserves energy

Maintains body functions

Digestion, Defecation, Diuresis (D division)

Sympathetic nerves originate from which vertebrae?

T1 through L2

The ganglia synapse located near the spinal cord

Parasympathetic nerves originate from which vertebrae?

The brainstem and S1 through S4

The ganglia synapse located near the targeted organ

Eddinger-Westphal nucleus _{(Paraympathetic)}

Part of the oculomotor complex

Cranial nerve III is attached, innervates the extraocular muscles

Super salivatory nucleus _{(Paraympathetic)}

Inferior salivatory nucleus _{(Paraympathetic)}

Dorsal nucleus of the vagus _{(Paraympathetic)}

Cranial nerve III

Cranial nerve VII

Cranial nerve XI

Cranial nerve X

Cilliary ganglion

Pterogopalatine ganglion

Submandibular ganglion

Otic ganglion

Lacrimal gland

Mucous membrane (Nose and palate)

Sublmaxillary gland

Sublingual gland

Mucous membrane (Mouth)

Parotid gland

Superior cervical ganglion

Main sympathetic ganglion associated with the eye

Innervates the dilator pupilae muscle

Influences blood vessels and sweat glands around the eye/forehead

Regulates vasoconstriction of the lacrimal gland

Mnemonic to remember the order of the cranial nerves

Olfactory nerve

Oculomotor nerve

Trigeminal nerve

Facial nerve

Glossopharyngeal nerve

Accessory nerve

Optic nerve

Trochlear nerve

Abducens nerve

Vestibulocochlear nerve

Vagus nerve

Hypoglossal nerve

The olfactory nerve originates from…

The cortex

The optic nerve originates from…

The retina

The oculomotor nerve originates from…

The midbrain

The Trochlear nerve originates from…

The midbrain

The trigeminal nerve originates from…

The lateral pons

The Abducens nerve originates from…

The ponto-medullary

The facial nerve originates from…

The ponto-medullary

The vestibulocochlear nerve originates from…

The ponto-medullary

The glossopharyngeal nerve originates from…

The lateral medulla

The vagus nerve originates from…

The lateral medulla

The acessory nerve originates from…

Spinal cord C1-C5

The hypoglossal nerve originates from…

The ventral medulla

Nerve I exits from the…

Cribriform plate of the ethmoid bone

Nerve II exits from the…

Optic canal

Nerve III exits from the…

Superior orbital fissure

Nerve IV exits from the…

Superior orbital fissure

Nerve V1 (First branch of nerve 5) exits from the …

Superior orbital fissure

Nerve V2 (Second branch of nerve 5) exits from the…

Foramen rotundum

Nerve V3 (Third branch of nerve 5) exits from the…

Foramen ovale

Nerve VI exits from the…

Superior orbital fissure

Nerve VII exits from the…

Internal auditory meatus

Nerve VIII exits from the…

Internal auditory meatus

Nerve IX exits from the…

Jugular foramen

Nerve X exits from the…

Jugular foramen

Nerve XI exits from the…

Jugular foramen

Nerve XII exits from the…

Hypoglossal canal

CN I path of travel

Axons begin at frontal cortex and lateral olfactory striae

They extend through the cribriform plate (Ethmoid) into the olfactory bulb

Function of CN I

Olfactory nerve

Provides sense of smell

Dysfunctions of CN1

Dysfunctions cause: Anosmia (Loss of smell)

• Esthensioneuroblastoma (Cancer)

• Cribriform plate fracture or anterior temporal lobe injury

Function of CN II

Optic nerve

Yeah you guessed it, visual images to the brain

Dysfunctions of CNII

Optic neuritis: Inflammation causing sudden, painful vision loss. Linked to auto immune diseases

Glaucoma: Intraocular pressure leads to loss of peripheral vision

Ischemic Optic neuropathy: Sudden, painful vision loss due to reduced blood flow

Medial rectus

Moves the eye inward (adduction)

Innervated by nerve III

Lateral Rectus

Moves the eye outward (abduction)

Innervated by nerve VI

Superior Rectus

Moves the eye upward and slightly inward

Innervated by nerve III

Inferior Rectus

Moves the eye downward and slightly inward

Innervated by nerve III

Superior Oblique

Moves the eye downward and outward

Innervated by nerve IV

Inferior Oblique

Moves the eye upward and outward (extorsion and elevation)

Innervated by nerve III

Pathway of the oculomotor nerve

Originates from the oculomotor nucleus and Edinger-Westphal nucleus

Arises from the ventral pons

Exits through the superior orbital fissure

CN III functions

Oculomotor nerve

Innervates:

• Superior rectus

• Levator palpabrae superioris

• Inferior rectus

• Medial rectus

• Inferior oblique

Splits off into the superior branch and the inferior branch

Superior branch of CNIII

Smaller branch

Innervates the superior rectus and levator palpabrae superioris

Levator palpabrae superioris

Raises the upper eye lid

Inferior branch of CNIII

Larger branch

Supplies inferior rectus, medial rectus, inferior oblique

LR₆(SO₄)₃

Mnemonic to remember which oculomotor muscles are innervated by each nerve

LR (Lateral rectus) → Nerve 6

SO (Superior Oblique) → Nerve 4

Rest are innervated by nerve 3

Parasympathetic function of CN III

Sphincter pupillae: Constricts pupil, reducing the amount of light entering the eye

Cilliary muscles: Contracts the lens to increase diopters

Dysfunctions of CNIII

Oculomotor ophthalmoplegia (Restricted eye movement)

Strabismus, ptosis (Eyelid droop), pupillary dilation

Pathway of CN IV

Originates from the dorsal aspect of the brainstem

Arises from the trochlear nucleus in the midbrain

Enters the orbit through the superior orbital fissure

Function of CN IV

The Trochlear nerve innervates the superior oblique muscle (Oculomotor)

CN IV measurements

Smallest cranial nerve _{But its really how you use it y’know}

Longest intra-cranial course (7.5 cm)

Dysfunction of CN IV

Paralysis of the superior oblique muscle results in outward rotation

Symptoms: Double vision, weakness in downward gaze, neck pain from head tilting

CN V pathway

The trigeminal nerve

Originates from the lateral mid-pons

Travels anteriorly through the pre-pontine cistern

Splits into three branches (V1, V2, V3)

CN V1 function

Ophthalmic division

Sensory to forehead, upper eyelids, and nose

Innervates cornea, nasal cavity

CN V2 function

Maxillary division

Sensory to lower eyelids, cheeks, upper lip

Innervates upper teeth, maxillary sinuses