EXSC 440- PNS

What are the three functions of the NS?

• Sensory Input

• Integration Function

• Motor Function

Where do we get sensory input from?

• Internal and External Environments

What is the integration function of the NS?

• Assimilates and processes sensory input

• Current and past experiences in form of memory, learning, and intelligence

What is the motor function of the NS?

• Organized and coordinated motor output

What are the components of the NS?

• *all neural tissue in the body

• Brain

• Spinal Cord

• Sense nerves (eye ear)

• Nerves

What are dendrites?

• Branched extensions (receptor sites) that receive info and convey it to the cell body. They are typically very short.

What is the cell body?

• (control center) integrates info from the dendrites, if signal is strong enough it is passed along the axon.

What is the axon?

• Single extension of the neuron that carries the signal towards its destination. Can be very long. 

• Each nerve only has ONE axon. 

What is the myelin sheath?

• layers of lipid and protein substances wrapped around some axons, which greatly increase impulse velocity. 

What is a synapse? 

What is a nerve fiber?

• A single axon with its myelin sheath.

What is the endoneurium?

• Delicate connective tissue immediately surrounding single nerve fibers. 

• Is NOT conductive. 

• Outside of the myelin sheath.

What is a nerve fascicle?

• A bundle of nerve fibers that share a common function, origin, and termination. 

What is the perineurium?

• Slightly thicker connective tissue enclosing a fascicle of nerve fibers. 

What is a nerve?

• A group of multiple nerve fascicles grouped together.

What is the epineurium?

• Thick connective tissue sheath that surrounds a bundle of fascicles, forming the outermost covering of the nerve. 

What are the two divisions of the NS?

• Central NS

• Peripheral NS

What is the CNS made up of?

• Brain (cranial cavity)

• Spinal Cord (in the vertebral foramen of spinal column)

• *Optic Nerve II

What is the PNS made up of?

• 11 pairs of cranial nerves coming from the brain and brain stem

• 31 pairs of spinal nerves coming from the spinal cord. 

How many nerve pairs does each region of the spinal cord have?

• 8 cervical

• 12 thoracic

• 5 lumbar

• 5 sacral

• 1 coccygeal 

What are the two divisions of the PNS?

• Afferent NS

• Efferent NS

What is the afferent NS?

• Sensory division

• Transmitting nerve impulses from sensory receptors in external AND internal environments TO the CNS.

What is the efferent NS?

• Motor division

• Transmits impulses from CNS TO effectors like muscles and glands.

• Activities may be voluntary or involuntary

Which side does the spinal column does sensory impulses come into?

• POSTERIOR

What side of the spinal column does motor neuron inpulses travel along?

• ANTERIOR

What are the three divisions of the efferent NS?

• Somatic NS

• Autonomic NS

• Enteric NS

What is the somatic NS?

What is the autonomic NS?

• Supplies motor impulses to cardiac and smooth muscle, and glandular epithelium. 

• Involuntary NS

• *Maintain homeostasis (HR, BP, Temp, BR)

What is the enteric NS?

• Independent network of nerve fibers that innervate the viscera. 

• Innervate longitudinal and circular muscle layers. 

• Capable of integrative functions independent of CNS functioning, including motility, secretion, digestion, etc.  

What are the two divisions of the autonomic NS?

• Sympathetic NS

• Parasympathetic NS

What is the sympathetic NS?

• Thoracolumbar division of ANS

• Prepares body for increased physical activity.

• Fight or flight response

• Accelerates the cardiovascular system (increased HR, BP, dilates pupils, etc)

What is the parasympathetic NS?

• Craniosacral division of ANS. *Vagus CN 10

• Prepares body for…

List all 12 Cranial Nerves

Where does the olfactory nerve go through?

The olfactory foramina of cribriform plate in the ethmoid bone

Where does the optic nerve go through?

The optic canal

Where do the abducens, occulomotor, trochlear, and opthalmic nerves goes through?

The superior orbital fissure

Where does the maxillary division go through?

Foramen rotundum

Where does the mandibular division go?

Foramen Ovale

Where do the vestibulocochlear and facial nerves (exits stylomastoid foramen) go through?

Internal Acoustic Meatus

Where does the hypoglossal nerve go through?

Hypoglossal canal

Where do the glossopharyngeal, vagus, and spinal accessory nerves go through?

Jugular Foramen

Characteristics of Olfactory CN I

• Purely a sensory nerve. Sense of smell

• Damage = anosmia (loss of smell)

• Olfactory bulb descends through the olfactory foramina

Characteristics of Optic CN II

• Purely sensory nerve. Sense of vision.

• Optic chiasma- crossing of sensory signal on way to occipital lobe. 

• Passes thru optic canal

• Damage= Anopsia (vision loss) 

Characteristics of Occulomotor CN III

• Pure motor nerve. Majority of eye movement.

• Innervates ciliary muscles to focus lens of eye. 

• Innervates eyelids for blinking.

• Passes thru superior orbital fissure.

• Damage= Ptosis (eyelid drooping), Strabismus (uneven pupils), Diplopia (double vision)

Characteristics of Trochlear CN IX

• Purely motor nerve. Eye movement.

• Inferior and lateral eye movement. Innervates superior oblique eye muscle. 

What are the three divisions of the trigeminal CN X?

• Opthalmic 

• Maxillary

• Mandibular

Characteristics of the Opthalmic Division

• Purely sensory. Skin around and above eyes

• Passes thru superior orbital fissure

Characteristics of the Maxillary Division

• Purely sensory nerve. Skin below eyes and above mouth, and cheek, teeth, and gums.

• Passes thru foramen rotundum.

Characteristics of the Mandibular Division

• Mixed nerve (sensory and motor).

• Sensory innervation: Skin of mandible and temporal areas, lower teeth, floor of mouth 

• Motor innervation: muscles of mastication

• Passes thru foramen ovale

Results of Damage to Trigeminal CN X

• Trigeminal neuralgia (pulsating pain in your face) 

Characteristics of Abducens CN XI

• Purely Motor nerve. Medial to lateral eye movement (abduction)

• Passes thru superior orbital fissure. 

• Damage= diplopia 

Characteristics of Facial CN XII

• Mixed nerve.

• Sensory Innervation- Anterior 2/3 of gustatory, nasal, and palatal sensation.

• Motor Innervation- Facial muscles, lacrimal and salivary glands.

• Enters Skull- Internal Acoustic Meatus

• Exits Skull- Stylomastoid Foramen

• Damage= decreased tearing and salivation, loss of taste, Bell’s palsy (one or both of facial nerves stop functioning)

Characteristics of Vestibulocochlear CN XIII

• Purely sensory nerve. Hearing and equilibrium

• Passes thru internal acoustic meatus

• Damage= loss of balance, nausea, deafness, vertigo

Characteristics of Glossopharyngeal CN IX

• Mixed nerve.

• Sensory Innervation- Posterior 1/3 gustatory, sensation of tonsils and carotid arteries.

• Passes thru jugular foramen

• Damage= reduced salivation, loss of taste, or difficulty swallowing.

Characteristics of Vagus CN X

• Mixed nerve

• Sensory Innervation- the pharynx, larynx, esophagus, and visceral organs.

• Motor Innervation- Parasympathetic functions (slows HR, bronchoconstriction, esophageal peristalsis)

• Passes thru jugular foramen

• Damage= complete/partial loss of voice, difficulty swallowing, impaired GI system mobility

Characteristics of Accessory CN XI

• Purely motor nerve. Muscles of pharynx, larynx, soft palate, upper back, and neck (sternocleidomastoid, trapezius)

• Passes thru jugular foramen

• Damage= paralysis