Proprioception and Motor Neuron Vocabulary

A set of vocabulary flashcards covering motor neurons, muscle spindles, Golgi tendon organs, and joint receptors based on the provided lecture transcript.

Alpha Motor Neurons (E2erent)

Neurons that innervate extrafusal fibers to produce force and cause voluntary skeletal muscle contraction.

Group Ia A2erent (primary endings)

Sensory fibers that detect speed and size of rapid stretch (velocity of muscle length) and initiate the stretch reflex, such as the monosynaptic patellar tendon reflex.

Group II A2erent (secondary endings)

Sensory fibers that detect sustained muscle length and static stretch to maintain posture and joint position, such as holding the elbow at $90$ degrees.

Group Ib A2erent

Tension receptors that detect muscle tension or force, most active during active muscle contraction, which travel to the spinal cord to prevent excessive force production.

Muscle Spindle

A proprioceptor and intrafusal stretch sensor located within the muscle belly, arranged parallel with extrafusal muscle fibers.

Golgi Tendon Organ

A proprioceptor and tension receptor located within the tendon near the myotendinous junction, arranged in series with extrafusal muscle fibers.

Autogenic Inhibition (Inverse Stretch Reflex)

A process where muscle contraction increases tendon tension, causing GTO (group $Ib$) to fire; the $Ib$ interneuron then inhibits the Alpha Motor Neuron to the same muscle, causing it to relax to prevent injury.

Gamma Motor Neurons (E2erent)

Neurons that innervate intrafusal fibers and contract the central region of spindle ends to keep the spindle taut and maintain sensitivity while the muscle contracts.

A2erent

Nerve fibers that "Arrive" at the Central Nervous System ($CNS$), traveling from sensors like muscle spindles.

E2erent

Nerve fibers that "Exit" the Central Nervous System ($CNS$) to reach targets like muscles or tendons.

Joint Receptors

Receptors that respond to chemical deformation of the capsule and ligament; they include Ru2ini endings, Paciniform Corpuscles, and Free Nerve Endings.

Ru2ini Endings

A type of joint receptor categorized as Type $II$ A2erents.

Paciniform Corpuscles

A type of joint receptor categorized as Type $II$ A2erents.

Free Nerve Endings

Sensory receptors in joints categorized as Type $III$ a2erent and type $IV$ a2erent.

Ligament Receptors

Receptors similar to the Golgi Tendon Organ ($GTO$) that utilize Type $Ib$ A2erent fibers to detect force.