PAS 313 Lecture 12 Peripheral Nervous System

PNS

Structure of Nerves outside the CNS

PNS

Sensory and Motor nerves make this up, begins in ventral grey horn, and innervates muscles at neuromuscular junction

Photoreceptors

(Rods and cones in retina)

Sensory Receptor that detects light

chemoreceptors

Sensory Receptor that responds to chemicals

Olfactory nerves

Chemoreceptor that reacts to smell.

Taste Buds

Chemoreceptor that reacts to tastes

carotid body and sinus

Chemorecptor that reacts to changes in blood carbon dioxide (CO2) levels and blood pressure.

Mechanoreceptor

Sensory Nerve that reacts to touching/pressure

Meissner’s corpuscle and Pacinian corpuscle

Meissner’s corpuscle

Light pressure aka tactile corpuscle

Pacinian corpuscle

Deep pressure aka lamellar corpuscle

Thermoreceptor

Sensory Nerve that reacts to Temperatures, free nerve endings

Nociceptors

Sensory Nerve that reacts to pain, free nerve endings

Proprioceptor

Sensory receptors that react to changes in muscle lengths, tendon tension, and joint position, providing information about body movement and orientation

Neuromuscular Spindles

Sensory (Proprioceptor) Nerve that reacts to stretching

Golgi Tendon

Sensory (Proprioceptor) Nerve that reacts to muscle force

Vestibular System

Sensory (Proprioceptor) Nerve that controls Balance

>Inner ear

Spinal Nerves

31 pares 

C8, T12, L5, S5, C1

Number of Spinal Nerves found in the Cervical

There are 8 cervical nerves

Number of Spinal Nerves found in the Thoracic Region

There are 12 Thoracic nerves

Number of Spinal Nerves found in the Lumbar

There are 5 lumbar nerves

Number of Spinal Nerves found in the Sacral

There are 5 Sacral nerves

Number of Spinal Nerves found in the Coccyx region

There is 1 Coccygeal nerve

Rami

Sensory and Motor nerves that send impulses to different parts of the body

>Primarily found on the spine

Dorsal Ramus

spinal nerve that carries both motor and sensory signals to the deep muscles and skin of the back

Ventral Ramus

spinal nerve that carries both sensory and motor information to the anterior (front) part of the body

Dermatones

"Map" of sensory innervation of skin

T4 Dermatome

Nipple

T 10 Dermatome

Belly Button

Key factor regarding Dermatomes

Dermatomes overlap above and below

>Ie: if Navel(T10) is affected T9 and T11 are affected

Referred Pain

Generalization of where the pain is not the actual location

Involves visceral (organas) and somatic (skin) sensory

Referred pain examples : Myocardial Ischemia

Poor or no blood supply to cardiac, pain in upper left limb, and pain can radiate to right limb,jaw, and neck

Nervous Plexuses

Ventral Rami that are organized into specific parts, Intertwined network of nerves

What are the 4 Plexuses

Cervical, Lumbar, Sacral, Brachial

Cervical Plexus

C1 to C4, arises from cervical enlargements, muscles for the skin and neck(Ventral Remember)

phrenic nerve

Cervical Plexus Nerve that controls the Diaphragm from C3, C4, C5

Brachial Plexus

C5-T1, Ventral Rami that controls shoulder muscles/skin of the shoulder and upper limbs

Nerves found in the Brachial Plexus

C5-T1, axillary, musculocutaneous, radial, median, ulnar (AMMUR)

Axillary nerve

Brachial plexus, deltoid muscle and skin of shoulder

Damage to the Axillary Nerve results in (Brachial Plexus)

Limited Abduction in the arm

Musculocutaneous Nerve

Brachial plexus, muscles of anterior arm (biceps brachii and brachialis), and lateral skin of forearm

Damage to the Musculocutaneous Nerve results in (Brachial Plexus)

Reduced Arm Flexion and Supuniation

Radial nerve

Brachial plexus, extension of arm, forearm, wrist, and digits

Portions of posterior and lateral arm, forearm

Damage to the Radial s Nerve results in (Brachial Plexus)

Reduced Arm Flexions, and Opposition can't occur.

Occurs if the Radial Nerve is damaged (Brachial)

Wrist Drop

Ulnar nerve

Brachial plexus, Flexor carpi ulnaris, part of flexor digitorum profundus, hypothenar muscles, lumbricals III and IV

Numbness/pain - medial skin of hand and half of digit IV

Occurs if the Ulnar Nerve is damaged (Brachial)

Claw Hand

Medial Nerve

Brachial plexus, flexors of wrist, thenar muscles, lumbricals 1 and 2

Numbness/pain, skin of palm and digits, half of digit 4

Damage to the Median Nerve (Brachial Plexus) results in

Carpal Tunnel and Ape Hand

> Oppostion can't occur

Lumbo-sacral Plexus

L1 to S4, ventral Rami that Provides motor and sensory innervation to the lower limbs

Nerves found in Lumbo-sacral Plexus

Femoral Nerve, Obturator nerve, Sciatic nerve, Tibial Nerve, Common Fibular Nerve, and Pudendal Nerve

(Find Our Silly Tiny Cat Paws)

Femoral nerve

Lumbosacral plexus, quadriceps and senses anterior thigh of leg

Damage to the Femoral Nerve (Lumbo-Sacral) (Find)

Knee Extensions can't occur and numbness/pain in skin of anterior lower limb

Obturator nerve

Lumbosacral plexus, adductor muscles

Damage to the Obturator Nerve (Lumbo-Sacral) (Our)

Thigh Adduction can't Occur

Sciatic nerve

Lumbosacral plexus, hamstring and senses posterior thigh

Damage to the Sciatic Nerve (Lumbo-Sacral) (Silly)

Thigh Extension and Leg Flexion can't occur

Clinical consideration : Sciatica

Posterior lower limb pain/numbness and possible weakness of posterior lower limb muscles

Tibial Nerve

Lumbosacral plexus

All posterior leg muscles (gastrocnemius, soleus, tibialis, flexor hallucis longus)

Damage to the Tibial Nerve (Lumbo-Sacral) (Tiny)

Reduced ability to plantarflex, flex digits, inverts

Common fibular nerve

Lumbosacral trunk and two common fibular nerve: deep and superficial fibular nerve

Deep Fibular nerve

Lumbosacral trunk, Muscles of anterior leg

Superficial fibular nerve

Lumbosacral trunk, muscles of lateral leg

Damage to the Deep Common-Fibular nerve (Lumbo-Sacral)

Reduced or absent dorsiflexion, digit flexion, inversion

Damage to the Superficial Common-Fibular nerve (Lumbo-Sacral)

Eversion

Damage to Deep common fibular nerve

Foot drop (inability to dorsiflex the foot)

Pudendal Nerve

Lumbosacral plexus, motor and sensory to the pelvic floor/diaphragm

Damage to the Pudendal nerve (Lumbo-Sacral) (Paws)

prolapsing & inability to hold wastes