Muscle Disorders and Neuromuscular Diseases

Comprehensive vocabulary flashcards covering lecture concepts on autoimmune neuromuscular diseases, genetic muscular dystrophies, motor neuron disorders, musculoskeletal injuries, and soft-tissue anatomy.

Neuromuscular disease

Any disorder or disease that impairs or compromises synaptic transmission and interaction between a motor neuron and a muscle cell.

Myasthenia gravis

An autoimmune disorder where the immune system produces antibodies against the acetylcholine receptor on the muscle sarcolemma in approximately $80\%$ of cases (or against muscle-specific kinase in $0\text{--}10\%$ of cases), blocking acetylcholine from binding and preventing contraction signals.

Muscle-specific kinase (MuSK)

A postsynaptic muscle enzyme that is targeted by autoantibodies in $0\text{--}10\%$ of myasthenia gravis cases.

Neonatal myasthenia gravis

A transient condition affecting $1$ in $8$ infants born to mothers with myasthenia gravis, caused by maternal IgG antibodies crossing the placenta into fetal circulation; it typically resolves within six weeks to three months as maternal antibodies clear.

Congenital myasthenic syndromes (CMS)

A group of neuromuscular junction disorders clinically similar to myasthenia gravis that are caused by inherited genetic mutations rather than autoimmune antibodies.

Duchenne muscular dystrophy (DMD)

An X-linked genetic disorder caused by the absence of the structural protein dystrophin, leading to muscle wasting, calf hypertrophy, abnormal gait, elevated creatine kinase, and typically death by age $30\text{--}35$.

Dystrophin

The structural protein located at the neuromuscular junction that is absent in individuals diagnosed with Duchenne muscular dystrophy.

Gowers sign

A physical maneuver observed in young boys with muscular dystrophy who must use their hands to push against their legs and knees to walk themselves upright from a seated position on the floor.

Creatine kinase

An enzyme found at elevated concentrations in the blood of patients with Duchenne muscular dystrophy as a direct consequence of ongoing muscle degeneration.

Amyotrophic lateral sclerosis (ALS)

A progressive neurological disorder, also known as Lou Gehrig's disease, caused by the degeneration of upper and lower motor neurons controlling voluntary movement, while sparing bowel, bladder, and eye muscle control.

Tendinitis

Inflammation of a tendon caused by overuse, repetitive motion, or excessive strain placed upon a muscle.

Tendon

A tough band of fibrous connective tissue that connects muscle to bone.

Ligament

A tough band of fibrous connective tissue that connects bone to bone.

Achilles tendon

The fibrous tendon that connects the gastrocnemius muscle of the calf to the calcaneus bone of the ankle.

Cerebral palsy

A broad term for motor function impairment resulting from brain damage sustained in utero, during delivery (such as from oxygen deprivation), or rarely after birth, impacting muscle tone, movement, balance, and reflexes.

Rotator cuff

A musculotendinous group of four shoulder muscles consisting of the supraspinatus, infraspinatus, subscapularis, and teres minor.

Rotator cuff tear

Damage or tearing occurring in any of the four rotator cuff muscles or tendons resulting from trauma, overextension, repetitive stress, or age-related degeneration.

Sprain

An injury involving the stretching or tearing of ligaments that hold bones together at a joint.

Strain

An injury involving the stretching or tearing of a muscle or its associated tendon.