Autonomic nervous system + CNs

ANS has two divisions with both structural AND functional differences:

1. Parasympathetic – Rest and Digest

1. Craniosacral output

2. Digestion, “housekeeping”

3. Postganglionic axons release Acetylcholine (Cholinergic)

2. Sympathetic- Fight or Flight

1. Thoracolumbar output

2. Heart Rate, Respiration

3. Vasoconstriction

4. Postganglionic axons release epinephrine and norepinephrine (Adrenergic)

Parasympathetic – Rest and Digest

1. Craniosacral output

2. Digestion, “housekeeping”

3. Postganglionic axons release Acetylcholine (Cholinergic)

Sympathetic- Fight or Flight

1. Thoracolumbar output

2. Heart Rate, Respiration

3. Vasoconstriction

4. Postganglionic axons release epinephrine and norepinephrine (Adrenergic)

PT CASE: Horner’s syndrome

• Ptosis: Drooping of the upper eyelid

• Miosis: Constricted pupil

• Anhidrosis: Decreased sweating on the affected side of the face

All only on one side of the face

Horners→ a condition that affects the nerves controlling the eye and face

Cranial Nerves

Cranial Nerves

● Twelve pairs of nerves associated with brain

● Two attach to forebrain; rest with brain stem

● Most mixed nerves; two pairs purely sensory

● Each numbered (I through XII) and named from rostral to caudal

memory tool for basic functions:

Some Say Marry Money, But My Brother Says Big Brains Matter More

CI: The Olfactory Nerves

● Sensory nerves of smell

● Pathway terminates in primary olfactory cortex→ Temporal lobe

● Purely sensory (olfactory) function

PT CASE: anosmia

• pt was skating, fell down → concussion

• went evaluated, noticed he couldn’t smell 

Finding = anosmia → loss of smell, damage to C1 must have occured

CII: The Optic Nerves

● Pass through optic canals, converge and partially cross over at optic chiasma

● Purely sensory (visual) function

PT CASE: optic chiasma

pt very tall F on college BB team → parents normal height… → never had brain scan

temporal eye fields blind, can see in the medial field → partial vision loss

Finding: inc. GH releases as a child, pituitary adenoma pressing on optic chiasma → brain surgery

CIII: The Oculomotor Nerves

● Function in raising eyelid, directing eyeball, constricting iris (parasympathetic), and controlling lens shape

LR6SO4AO3

lateral rectus → controlled by C6

superior oblique → controlled by C4

all other eye muscles → controlled by C3

CV: The Trigeminal Nerves

● Largest of the cranial nerves; fibers extend from pons to face

● Three divisions/ branches: Ophthalmic (V1), Maxillary (V2), Mandibular (V3)

Convey sensory impulses from various areas of face (V1) and (V2), Supply motor fibers (V3) for mastication

Ophthalmic (V1)

passes through superior orbital fissure→ supraorbital foramen(notch). Supraorbital nerve, branch of frontal nerve, branch of ophthalmic nerve (V1 of CN 5)

Maxillary (V2)

passes through foramen rotundum→ Infraorbital foramen Infraorbital nerve, branch of maxillary nerve (V2 of CN 5)

Mandibular (V3)

passes through the foramen ovale→ Mental Foramen as inferior alveolar nerve, branch of mandibular nerve (V3 of CN 5)

trigeminal neuralgia

a chronic nerve disorder that causes severe, sudden, and excruciating pain in the face

VI: The Abducens Nerves

● Fibers from inferior pons enter orbits via superior orbital fissures

● Primarily a motor, innervating lateral rectus muscle

PT CASE: C6

pt eyes pointing different directions, pt hit head → paralysis of lateral rectus because C6 is affected

CVII: The Facial Nerves

● Chief motor nerves of face with 5 major branches

● Motor functions include facial expression, parasympathetic impulses to lacrimal and salivary glands

● Sensory function (taste) from anterior two-thirds of tongue

Bell’s Palsy

temporary weakness or paralysis of the facial muscles on one side of the face. It is caused by inflammation of the facial nerve, which controls the muscles of the face. 

CX: trauma near ear/ c7 or viral infection like herpes

sx: asymmetrical smile, dec. wrinkling of forehead, Weakness or paralysis of facial muscles on one side, Drooping of the eyelid, etc.

C12 name:

Hypoglossal nerve

C11 name:

Accessory nerve

C10 name:

Vagus nerve

C9 name:

Glossopharyngeal nerve

C8 name:

Vestibulocochlear nerve

C7 name:

Facial nerve

C6 name:

Abducens nerve

C5 name:

Trigeminal nerve

C4 name:

Trochlear nerve

C3 name:

Oculomotor nerve

C2 name:

Optic nerve

C1 name:

Olfactory nerve

CVIII: The Vestibulocochlear Nerves

● Afferent fibers from hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass from inner ear through internal acoustic meatuses, and enter brain stem at pons-medulla border

Otoliths

a tiny, heavy crystal made of calcium carbonate (also called an ear stone or otoconium) located in the inner ear's otolith organs (the utricle and saccule). When the head moves, these crystals shift, bending hair-like sensory cells and sending signals to the brain to indicate linear acceleration (like in a car) and the head's position relative to gravity, which are crucial for balance and spatial orientation.  

CIX: The Glossopharyngeal Nerves

● Sensory functions - fibers conduct taste and general sensory impulses from pharynx and posterior one third tongue, and impulses from carotid chemoreceptors and baroreceptors

CX: The Vagus Nerves

● Only cranial nerves that extend beyond head and neck region

● Fibers from medulla exit skull via jugular foramen

● Most motor fibers are parasympathetic fibers that help regulate activities of heart, lungs, and abdominal viscera

PT CASE: hoarseness

• Pt is older F, playing bridge w/ friends who all get sick w/ same virus and put on antibiotics

• During physical exam, strange heart/ chest rhythm, otherwise asymptomatic besides hoarseness/ loss of voice

• refer to cardiology → surgery found aortic aneurysm

• Cx - vagus nerve connects to heart and circles back to left recurrent laryngeal branch → affected left side of vocal cord to cx hoarseness

CXI: The Accessory Nerves

● Accessory nerves exit skull via jugular foramina to innervate trapezius and sternocleidomastoid muscles

Injury- Pt could have winged scapula or inability to shrug shoulder on affected side