A&P Test 5

What does PNS stand for?

Peripheral Nervous System

Function of PNS?

connecting the CNS to the body and external environment

What are the two divisions of the PNS?

Sensory and Motor

Which division of the PNS is afferent?

Sensory

Which division of the PNS is efferent?

Motor

What are the subdivisions of the Sensory PNS?

Somatic and visceral

What are the subdivisions of the motor PNS?

Somatic and visceral

Function of somatic sensory PNS?

Carry signals from muscles, bones, joints, and skin to the CNS for processing (also sends special sensory signals)

Function of visceral sensory PNS?

Carry sensory signals from organs (from abdominopelvic and thoracic cavities)

Function of somatic motor PNS?

carry signals to skeletal muscles

Function of visceral motor PNS?

carry signals to visceral organs (includes cardiac muscle, smooth muscle, secretory glands, etc)

What are the subdivisions of the visceral motor PNS system?

Sympathetic and parasympathetic

What is the main organ of PNS?

Teripheral nerves

Define mixed nerve

contains both sensory and motor neurons

Define motor nerve

contains mostly motor neurons

Define sensory nerve

contains only sensory neurons

Define spinal nerve

nerve that originates from the spinal cord and innervates structures inferior to the head

Define Cranial nerve

nerve attached to the brain and innervates structures of the head and neck

Define anterior root

axons of motor neurons that exit the anterior horn

Define posterior root

axons of sensory neurons entering the posterior horn

What is present in the posterior root?

the posterior root ganglion

Define ganglion

a collection of cell bodies in the PNS

What fuses to form the spinal nerve?

the anterior and posterior roots

How many pairs of spinal nerves are there?

31

What covering wraps the outside of the entire nerve?

Epinerium

What covering wraps nerve fascicles?

Perineurium

What covering wraps each individual neuron axon?

Endoneurium

CN stands for…

Cranial nerve

CN I

Olfactory

CN II

Optic

CN III

Oculomotor

CN IV

Trochlear

CN V

Trigeminal

CN VI

Abducens

CN VII

Facial

CN VIII

Vestibulocochlear

CN IX

Glossopharyngeal

CN X

Vagus

CN XI

Accessory

CN XII

Hypoglossal

Which cranial nerves are sensory (names not numerals)

Olfactory, optic, vestibulocochlear

Which cranial nerves are motor (names not numerals)

Oculomotor, trochlear, abducens, accessory, hypoglossal

Which cranial nerves are mixed (names not numerals)

Trigeminal, facial, glossopharyngeal, vagus

Difference between optic and oculomotor nerves?

The optic nerve is sensory and transmits visual stimuli, oculomotor nerve is motor and controls the eye muscles

The trochlear (IV) nerve controls

medial and inferior eye muscle movement (superior oblique muscles)

The trigeminal (V) nerve controls

facial sensation, and masseter and temporalis muscle innervation

The abducens (VI) nerve controls

lateral eye movement (lateral rectus muscle)

The facial (VII) nerve controls

taste, external ear, palate, and nasal cavity sensation, salivary, lacrimal, and nasal mucosal gland secretion

The vestibulocochlear (VIII) nerve controls

sound and body position, vestibular and cochlear nerve sensation

The glossopharyngeal (IX) nerve controls

taste (posterior portion of tongue), sensation of external ear, posterior pharynx, and innervation of swallowing muscles

The vagus (X) nerve controls

sensation for skin around ears, taste from pharynx, pharynx mucous membranes, blood CO2 concentration, and innervation of viscera and larynx muscles for speech and swallowing

The accessory (XI) nerve controls

muscles of speech and muscles for head/neck movement

The hypoglossal (XII) nerve controls

muscles of the tongue (no taste sensation)

Posterior ramus

major branch of spinal nerves that travels down posterior side of body

Anterior ramus

major branch of spinal nerves that travels to anterior side of body and upper/lower limbs

What kind of nerves are posterior and anterior rami?

Mixed

Rami communicantes

small branch from anterior ramus that contains visceral motor neurons of sympathetic NS

How many cervical spinal nerves are there?

8

How many thoracic spinal nerves are there?

12

How many lumbar spinal nerves are there?

5

How many sacral spinal nerves are there?

5

How many Coccygeal spinal nerves are there?

1

nerve plexus

where anterior rami of cervical, lumbar, and sacral spinal nerves come together

What arises from the cervical plexus and innervates the diaphragm?

the phrenic nerve

Where is the cervical plexus located?

deep in the neck lateral to C1-C4 vertebrae

What area does the brachial plexus innervate?

the upper limb

What nerves does the brachial plexus give rise to?

Axillary, radial, musculocutaneous, median, and ulnar

Where is the brachial plexus located?

C5-T1

What spinal nerves do not form a plexus?

The thoracic spinal nerves (except T1)

The lumbar plexus arises from…

L1-L4

What area of the body does the lumbar plexus serve?

pelvis and lower extremities

What is the largest nerve of the lumbar plexus?

femoral nerve

The sacral plexus arise from…

L4-S4

What is the largest nerve from the sacral plexus?

sciatic nerve

What area of the body does the sacral plexus serve?

pelvis, gluteal region, and lower extremities

Difference between encapsulated and free sensory nerve receptors?

Encapsulated is surrounded by supportive cells, free has none

What is the pathway of sensory signals?

Stimulus in PNS, transmission to CNS, integration and interpretation by CNS

What is receptor adaptation?

when receptors initially respond rapidly and with high intensity but step sending stimuli after a certain period of time.

Rapidly adapting receptors are important for

initial stimulus detection

Slowly adapting receptors

don’t diminish signaling over time

Exteroceptors detect

on the surface of the body

Interoceptors detect

interior of the body

Mechanoreceptors respond to

mechanical deformation of tissue

Thermoreceptors respond to

thermal stimuli

Chemoreceptors respond to

presence of certain chemicals

Photoreceptors respond to light

change in light

Nociceptors respond to

painful stimuli

Cell body of sensory neurons are located

in the posterior root ganglion

The speed at which neurons conduct action potentials depends on...

diameter of the axon and thickness of myelin sheath

The fastest sensory neurons are

nociceptors

The slowest sensory neurons are

pain and temperature

Receptive fields are

areas of the body served by a neuron

For receptive fields more branching =

larger receptive field

Dermatones are

divisions of skin based on the spinal nerve that serves the region

Referred pain is

pain originating from an organ that is perceived as cutaneous pain

What motor neurons initiate muscle contraction?

lower motor neurons

Which neurons relay messages to lower motor neurons?

Upper motor neurons

Groups of lower motor neurons are called

motor neuron pools

Cell bodies of lower motor neurons are in

the CNS

Axons of lower motor neurons are in

the PNS