Lower Motor Neurons: Flaccid Paralysis Pt. 2

These flashcards cover key terms and concepts related to lower motor neurons, their functions, related reflexes, and clinical implications.

Lower Motor Neurons (LMNs)

Neurons in the spinal cord that innervate skeletal muscles.

Flaccid Paralysis

A condition where muscles are weak and cannot contract due to LMN damage.

Spinal Cord Organization

The arrangement of motor nuclei in the anterior/ventral horn of the spinal cord, with proximal muscles more medial and distal muscles more lateral.

Cervical Enlargement

Region in the spinal cord associated with innervation of arm and shoulder muscles.

Lumbar Enlargement

Region in the spinal cord associated with innervation of the lower limbs.

Myotomes

Muscles innervated by a single spinal cord segment.

Phrenic Nerve

Nerve arising from C3, C4, and C5 that innervates the diaphragm.

LMN Syndrome

A condition caused by lesions in the CNS or PNS resulting in flaccid paralysis and decreased reflexes.

Myotatic Reflex

A reflex involving the contraction of a muscle when it is stretched, also known as the stretch reflex.

Inverse Myotatic Reflex

Reflex action that protects tendons from injury by inhibiting lower motor neurons in response to muscle tension.

Gamma Loop

A mechanism of muscle spindle regulation involving gamma motor neurons and intrafusal muscle fibers.

Diminished Deep Tendon Reflexes (DTR)

Reduced or absent reflexes resulting from lower motor neuron injury.

Muscle Atrophy

Decrease in muscle mass due to prolonged injury to lower motor neurons.