Peripheral Nervous System

Peripheral Nervous System
Objective: Describe the structure and function of nerves.
Nerves are the white matter of the PNS: bundles of axons enclosed in connective tissue wrappings.
1) ___Cranial__ nerves- Twelve pairs of nerves that carry information in and out of the brain.
2) ___Spinal___ nerves- Thirty-one pairs of nerves that carry information in and out of the spinal cord.
3) ___Nerve Plexus________ – interlacing nerve network formed by several spinal nerves that join then
branch again.
4) Dermatome________- region of the skin monitored by a nerve.
5) ___Epineurium_______- layer of dense irregular connective tissue that covers the surface of the
nerve.
6) ___Perineurium______- thin connective tissue membrane that surrounds bundles of axons called
nerve fascicles.
7) ___Endoneurium___- loose areolar connective tissue that surrounds individual axons within a nerve
fascicle.
Objective: List the cranial nerves and for each describe the major functions, central and peripheral
connections, and pathway through cranium.
Cranial Nerves: Twelve pairs of nerves carry information in and out of the brain.
8) ____Olfactory___ (CNI): sensory- carries the sense of smell.
• Foramen (F): cribriform foramina, Origin (O): nasal cavity, Destination (D): olfactory bulb
9) ____Optic___________ (CNII): sensory- carries the sense of vision. Contains axons of retinal
ganglion cells that travel through optic chiasm, optic tract, to lateral geniculate nucleus of thalamus.
• F: optic canal, O: retina, D: optic chiasm
10) Vestibulocochlear______ (CNVIII): sensory- carries the sense of hearing (audition)
• F: Internal acoustic meatus, O: Inner ear, D: medulla oblongata
11) Oculomotor_ (CNIII): motor- excites most extraocular muscles (including medial rectus,
superior rectus, inferior rectus, and inferior oblique), excites levator palpebrae superioris (muscle that
opens the eyelid), carries parasympathetic efferent fibers that stimulate intraocular muscles (ciliary
muscles, and circular pupillary constrictor muscles of the iris).
• F: superior orbital fissure, O: Midbrain, D: Ocular region including extraocular muscles and
intraocular muscles
12) ____Trochlear_____ (CNIV): motor- excites the superior oblique extraocular muscles leading to
inferior and lateral rotation of the eye (down and away from the midline).
• F: Superior Orbital Fissure, O: Midbrain, D: superior oblique
13) ___Abducens___ (CNVI): motor-lateral rectus extraocular muscles
• F: Superior Orbital Fissure, O: Pons, D: lateral rectus
14) ____Accessory____ (CNXI): motor- excites the trapezius and sternocleidomastoid.
• F: Jugular foramen, O: medulla oblongata and spinal cord, D: trapezius and sternocleidomastoid
15) ____Hypoglossal______ (CNXII): motor- excites muscles that move the tongue including
styloglossus, genioglossus, and hyoglossus.
• F: Hypoglossal canal, O: medulla oblongata, D: tongue
Trigeminal (CNV): both sensory and motor- carries the sense of touch from the face and excites the
muscles of mastication including the masseter and temporalis Three major braches:

16) ___Ophthalmic____ branch of trigeminal nerve- somatosensory from superior facial region
including ocular regions.
• F: superior orbital fissure, O: frontal and orbital regions, D: Pons
17) ___Maxillary___ branch of trigeminal nerve -somatosensory from middle face including superior
oral region
• F: foramen rotundum, O: middle facial region, D: Pons
18) ___Mandibular____ branch of trigeminal nerve- motor to masseter and temporalis and
somatosensory from the inferior facial region including inferior oral region.
o F: foramen ovale, O/D: Pons, inferior racial region, Masseter, Temporalis, Pons
19) ____Facial____ (CNVII): both sensory and motor- carries the sense of taste from the anterior 2/3 of
the tongue and excites the muscles of facial expression including frontalis, orbicularis oris, orbicularis
oculi, depressor anguli oris, depressor labii inferioris, carries parasympathetic efferent fibers that
stimulate the lacrimal gland, sublingual salivary gland and submandibular salivary gland.
• F: Internal Acoustic Meatus, O/D: Pons, tongue, Facial muscles, and medulla oblongata
20) ___Glossopharyngeal____ (CN IX): both sensory and motor- carries the sense of taste from the
posterior 1/3 of the tongue, sense of touch from the posterior tongue and pharynx, sense of blood
pressure and sense of blood gas concentrations from arterial baroreceptors and chemoreceptors
located in the carotid sinus, and excites muscles of the pharynx important for swallowing, and carries
parasympathetic efferent fibers that stimulate the parotid salivary gland.
• F: Jugular foramen, O/D: Medulla oblongata, Tongue, parotid gland, and cervical region
21) ___Vagus___ (CNX): both sensory and motor- sensory information from visceral organs, sense of
blood pressure and gas concentrations from arterial baroreceptors and chemoreceptors in the aortic
arch, carries the majority of parasympathetic efferent fibers that regulate visceral organs. Decreases
heart rate and stimulates digestive organs. Longest cranial nerve and the only one to leave the
cephalic and cervical regions.
• F: Jugular foramen, O/D: Medulla oblongata, Tongue, Visceral organs
Objective: Describe the structure and function of the major spinal nerves connected to the
cervical plexus, brachial plexus, lumbar plexus, and sacral plexus.
22) ____Cervical___ plexus – forms from C1 – C5: innervates skin and muscles of the neck and
shoulder.
23) ____Phrenic____ nerve – forms from ventral rami of C3-C5, excites the diaphragm
24) ____Brachial___ plexus – forms from C5 – T1: innervates pectoral girdles and upper limbs
• Spinal nerves trunks C5-T1 are called the roots of the brachial plexus that converge to form 3
trunks of the brachial plexus: Superior (C5- C6), Middle (C7), & Inferior (C8-T1)
o Each trunk divides into 2 divisions: Anterior & Posterior divisions
These six divisions unite to form 3 cords:
25) Lateral__ cord – formed from anterior divisions of superior & middle trunks
26) Medial____ cord – formed by anterior division of inferior trunk
27) Posterior_ cord – formed by union of all 3 posterior divisions
Cords give rise to branches of the brachial plexus that form the specific peripheral nerves that travel
through the upper limb:
28) ____Ulnar___ nerve- travels down the medial brachial and antebrachial regions innervates: Flexors
of medial forearm and hand; flexor carpi ulnaris, flexor digitorum profundus
• Forms from C8-T1 by way of the medial cord16) ___Ophthalmic____ branch of trigeminal nerve- somatosensory from superior facial region
including ocular regions.
• F: superior orbital fissure, O: frontal and orbital regions, D: Pons
17) ___Maxillary___ branch of trigeminal nerve -somatosensory from middle face including superior
oral region
• F: foramen rotundum, O: middle facial region, D: Pons
18) ___Mandibular____ branch of trigeminal nerve- motor to masseter and temporalis and
somatosensory from the inferior facial region including inferior oral region.
o F: foramen ovale, O/D: Pons, inferior racial region, Masseter, Temporalis, Pons
19) ____Facial____ (CNVII): both sensory and motor- carries the sense of taste from the anterior 2/3 of
the tongue and excites the muscles of facial expression including frontalis, orbicularis oris, orbicularis
oculi, depressor anguli oris, depressor labii inferioris, carries parasympathetic efferent fibers that
stimulate the lacrimal gland, sublingual salivary gland and submandibular salivary gland.
• F: Internal Acoustic Meatus, O/D: Pons, tongue, Facial muscles, and medulla oblongata
20) ___Glossopharyngeal____ (CN IX): both sensory and motor- carries the sense of taste from the
posterior 1/3 of the tongue, sense of touch from the posterior tongue and pharynx, sense of blood
pressure and sense of blood gas concentrations from arterial baroreceptors and chemoreceptors
located in the carotid sinus, and excites muscles of the pharynx important for swallowing, and carries
parasympathetic efferent fibers that stimulate the parotid salivary gland.
• F: Jugular foramen, O/D: Medulla oblongata, Tongue, parotid gland, and cervical region
21) ___Vagus___ (CNX): both sensory and motor- sensory information from visceral organs, sense of
blood pressure and gas concentrations from arterial baroreceptors and chemoreceptors in the aortic
arch, carries the majority of parasympathetic efferent fibers that regulate visceral organs. Decreases
heart rate and stimulates digestive organs. Longest cranial nerve and the only one to leave the
cephalic and cervical regions.
• F: Jugular foramen, O/D: Medulla oblongata, Tongue, Visceral organs
Objective: Describe the structure and function of the major spinal nerves connected to the
cervical plexus, brachial plexus, lumbar plexus, and sacral plexus.
22) ____Cervical___ plexus – forms from C1 – C5: innervates skin and muscles of the neck and
shoulder.
23) ____Phrenic____ nerve – forms from ventral rami of C3-C5, excites the diaphragm
24) ____Brachial___ plexus – forms from C5 – T1: innervates pectoral girdles and upper limbs
• Spinal nerves trunks C5-T1 are called the roots of the brachial plexus that converge to form 3
trunks of the brachial plexus: Superior (C5- C6), Middle (C7), & Inferior (C8-T1)
o Each trunk divides into 2 divisions: Anterior & Posterior divisions
These six divisions unite to form 3 cords:
25) Lateral__ cord – formed from anterior divisions of superior & middle trunks
26) Medial____ cord – formed by anterior division of inferior trunk
27) Posterior_ cord – formed by union of all 3 posterior divisions
Cords give rise to branches of the brachial plexus that form the specific peripheral nerves that travel
through the upper limb:
28) ____Ulnar___ nerve- travels down the medial brachial and antebrachial regions innervates: Flexors
of medial forearm and hand; flexor carpi ulnaris, flexor digitorum profundus
• Forms from C8-T1 by way of the medial cord

29) _____Median____nerve- travels down the anterior brachial and antebrachial regions just lateral to
the ulnar nerve, innervates: Flexors of lateral forearm, and hand; flexor carpi radialis, flexor
digitorum superficialis
• Forms from C6-T1by way of the lateral and medial cords
30) ___Musculocutaneous____nerve- travels down the anterior of the brachial region deep to biceps
brachii and superficial to brachialis, innervates: Flexor arm muscles; biceps brachii & brachialis
• Forms from C5-C7 by way of the lateral cord
31) ____Radial_____ nerve- travels down the posterior lateral brachial and antebrachial regions,
innervates: Arm and forearm extensor muscles; triceps brachii, extensor carpi, extensor digitorum
• Forms from C5-T1 by way of the posterior cord
32) ___Axillary____ nerve- travels through axillary region, innervates: Deltoid, Teres Minor
• Forms from C5-C6 by way of the posterior cord
33) Lumbar plexus – T12 – L4: innervates lower abdomen, medial and anterior portions of the
thigh
34) Femoral_nerve – travels down anterior femoral region (thigh); innervates quadriceps femoris
• Forms from L2-L4
35) ___Obturator__nerve – travels down medial femoral region, innervates adductor magnus, adductor
longus
• Forms from L2-L4
36) Sacral__ plexus – L4 – S4: innervates lateral and posterior portions of femoral and sural regions
37) Sciatic nerve- largest nerve in the body, Forms from L4-S3, travels down the posterior femoral
region; Excites hamstrings
branches to form two large nerves:
• Tibial nerve – innervates posterior compartment of lower leg; gastrocnemius & soleus
• Common fibular nerve branches again to form two more nerves:
o Superficial fibular nerve – innervates lateral compartment of leg (fibularis longus and
fibularis brevis muscles)
o Deep fibular nerve – innervates anterior compartment of lower leg, dorsi flexors and toe
extensors; tibialis anterior, extensor digitorum longus
Objective: List and describe the five steps of the patellar tendon stretch reflex.
Patellar Tendon Stretch Reflex Arc:
38) ___ Muscle spindles_________ in quadriceps femoris are sensory receptors that detect stretching.
39) ___ Femoral nerves_________ contain the afferent pathway that relays the signal into CNS through
spinal roots L2-L4.
40) ___Spinal cord _____________ segments L2-L4 contain the integration center where axons of
afferent neurons synapse directly with efferent neurons.
41) ___Efferent fibers__________ carry action potentials out through spinal nerve roots L2-L4 and the
femoral nerve.
42) ___Quadriceps femoris______ muscle group is the effector that contracts producing extension of the
leg at the knee joint