Peripheral Nervous System: Receptors, Cranial Nerves, and Brachial Plexus

Flashcards covering peripheral nervous system receptor classification, cranial nerve functional pathways, and brachial plexus anatomy based on lecture notes.

Exteroceptors

Receptors classified by location that detect sensory stimuli originating from the outside environment.

Interoceptors

Receptors classified by location that detect sensory stimuli originating from inside the body.

Proprioceptors (by location)

Receptors associated with joints, muscles, tendons, and ligaments that inform the body of its position in space.

Mechanoreceptors

Sensory receptors classified by stimulus type that respond to mechanical forces such as touch, vibration, and pressure.

Baroreceptors

Specialized mechanoreceptors classified by stimulus type that monitor and measure blood pressure.

Chemoreceptors

Sensory receptors classified by stimulus type that detect chemical substances in solution, including taste.

Nociceptors

Sensory receptors classified by stimulus type that respond to potentially damaging stimuli by detecting pain.

Free nerve endings

Unencapsulated nerve endings embedded beneath and within the epithelium that lack Schwann cell myelination and detect external environmental sensations.

Merkel discs (Tactile epithelial cells)

Free nerve endings located in the stratum basale layer of the epidermis that detect touch, vibration, and pressure.

Meissner's corpuscles (Tactile corpuscles)

Encapsulated, myelinated receptors located in dermal papillae that mediate discriminative touch in hairless areas such as the hands and feet.

Pacinian corpuscles (Lamellar corpuscles)

Encapsulated, rapidly adapting receptors situated in the hypodermis that detect deep pressure.

Ruffini corpuscles

Encapsulated receptors located within the dermis that respond continuously to pressure.

Muscle spindle

A structural proprioceptor that runs parallel to and wraps around muscle fibers to detect muscle stretch.

Golgi tendon organ

A structural proprioceptor located at the junction between muscle and tendon that detects tension and initiates protective stretch reflexes.

Kinesthetic receptors

Proprioceptors located at joints that communicate joint position and movement in space.

Cranial nerve I (Olfactory nerve)

A purely sensory cranial nerve associated with smell that passes from the olfactory bulb through the cribriform foramina.

Cranial nerve II (Optic nerve)

A purely sensory cranial nerve dedicated to vision that passes through the optic canal to form the optic chiasm and optic tract.

Cranial nerve III (Oculomotor nerve)

A cranial nerve exiting the superior orbital fissure that controls four extrinsic eye muscles and provides parasympathetic pupil constriction.

Cranial nerve IV (Trochlear nerve)

A motor cranial nerve exiting the superior orbital fissure that innervates the superior oblique extrinsic eye muscle.

Cranial nerve V (Trigeminal nerve)

A mixed cranial nerve with three branches ($V_1$, $V_2$, $V_3$) providing sensory coverage to the face and motor innervation to the muscles of mastication.

Cranial nerve VI (Abducens nerve)

A motor cranial nerve passing through the superior orbital fissure that innervates the lateral rectus muscle to abduct the eye laterally.

Cranial nerve VII (Facial nerve)

A mixed nerve exiting the internal acoustic meatus controlling muscles of facial expression, most salivary glands, and taste on the anterior two-thirds of the tongue.

Bell's palsy

A condition marked by paralysis or damage to the facial nerve (CN VII), causing loss of voluntary motor control in facial muscles on the affected side.

Cranial nerve VIII (Vestibulocochlear nerve)

A sensory cranial nerve running through the internal acoustic meatus that mediates hearing and equilibrium.

Cranial nerve IX (Glossopharyngeal nerve)

A mixed nerve passing through the internal jugular foramen that controls pharyngeal swallowing, the parotid gland, posterior one-third tongue taste, and carotid receptors.

Cranial nerve X (Vagus nerve)

A mixed nerve passing through the internal jugular foramen that provides 80% of parasympathetic body innervation, oral sensation, and larynx motor control.

Cranial nerve XI (Accessory nerve)

A motor nerve exiting via the internal jugular foramen that innervates the trapezius and sternocleidomastoid muscles to allow shoulder shrugging.

Cranial nerve XII (Hypoglossal nerve)

A motor cranial nerve exiting exclusively through the hypoglossal canal that controls tongue movements.

Dorsal root

The spinal nerve branch carrying sensory axons exclusively into the spinal cord.

Ventral root

The spinal nerve branch carrying motor axons exclusively out of the spinal cord.

Dorsal rami

The posterior branch of a spinal nerve containing mixed motor and sensory fibers that innervate the deep muscles and skin of the back and neck.

Ventral rami

The anterior branch of a spinal nerve containing mixed motor and sensory fibers that form nerve plexuses and innervate the limbs and anterior trunk.

Phrenic nerve

A cervical plexus nerve derived from spinal roots C3, C4, and C5 that innervates the diaphragm for respiration.

Brachial plexus cords

The lateral, medial, and posterior cord divisions derived from spinal roots C5 through T1, named based on their relationship to the axillary artery.

Musculocutaneous nerve

A lateral cord branch ($\text{C}_5$, $\text{C}_6$, $\text{C}_7$) providing motor innervation to anterior arm flexors and sensory reception to the lateral forearm.

Axillary nerve

A posterior cord branch ($\text{C}_5$, $\text{C}_6$) that provides motor innervation to the deltoid and teres minor muscles and sensory innervation over the shoulder.

Radial nerve

A posterior cord branch ($\text{C}_5$ through $\text{T}_1$) providing motor innervation to the posterior extensor muscles of the arm and forearm.

Median nerve

A nerve formed by both lateral and medial cords ($\text{C}_5$ through $\text{T}_1$) innervating anterior forearm flexors and skin of the lateral two-thirds of the anterior hand.

Ulnar nerve

A medial cord branch ($\text{C}_8$, $\text{T}_1$) supplying flexor carpi ulnaris, part of flexor digitorum profundus, and sensory areas of the hand.

Flexor digitorum profundus

A forearm flexor muscle featuring dual motor innervation from both the median nerve and the ulnar nerve to generate power for a full fist.

Ape hand (Hand of benediction)

A motor deformity caused by median nerve injury resulting in an inability to flex digits one, two, and three.

Claw hand

A motor deformity caused by ulnar nerve injury or entrapment at the carpal tunnel or medial epicondyle, resulting in paralysis of digits four and five.

Wrist drop

A motor deficit caused by radial nerve trauma or compression in the axilla, leaving forearm extensor muscles paralyzed.

Nerve flossing

A specialized mobilization and tensioning exercise designed to release an entrapped peripheral nerve from compressing soft tissues.