Mechanisms of Disease and Muscle Disorders: Anatomy and Pathology

What are the causal factors that increase muscle tension?

Causal factors include localized ischemia and edema, leading to pain, spasm, and inflammation.

What is ischemia?

A medical condition where an organ or part of the body receives inadequate blood supply.

What happens to the CNS when there is muscle tension?

Tense tissue bombards the CNS with information, leading to hyperactivity.

What cells are activated in response to muscle tension?

Macrophages and fibroblasts are activated.

What can chronic muscle tension lead to?

Chronic muscle tension can lead to chronic hypertension, fibrotic changes, and abnormal biomechanics.

What are myotatic units?

chains of muscle fibers that can react to sustained tension, leading to ischemia in tendinous areas.

What are some specific disorders caused by muscle tension?

Stress-induced muscle tension, cramps/spasms, fibromyalgia, and contractures.

What is Dupuytren contracture?

A condition where the connective tissue in the palm thickens, causing fingers to bend towards the palm.

What is anterior compartment syndrome?

Occurs after a severe injury to the leg, leading to increased pressure in the muscle compartment.

What is myalgia?

Pain in the muscle belly.

What is muscular dystrophy?

A group of genetic diseases characterized by progressive weakness and degeneration of skeletal muscles.

What is myositis ossificans?

A condition where bone tissue forms in the muscle, often following injury.

What are the four common patterns of muscle fascicle arrangement?

Parallel, convergent, pennate, and circular.

What is a parallel muscle?

Fascicles that are long and oriented parallel to the muscle's longitudinal axis.

What characterizes a convergent muscle?

A broad origin and converges to a smaller tendon, forming a triangular shape.

What is a unipennate muscle?

Fascicles that insert on only one side of a tendon.

What is a bipennate muscle?

Fascicles that insert into a tendon from both sides, resembling a feather.

What is a multipennate muscle?

Resembles many feathers inserted into one large tendon.

What is the function of circular muscles?

Also known as sphincters, contract to close external body openings.

How much can skeletal muscles shorten when contracted?

Skeletal muscles can shorten to about 50% of their resting length when contracted.

What is the trade-off of parallel muscle fibers?

Parallel muscle fibers can produce greater shortening but are not as powerful as pennate muscles.

What is the advantage of pennate muscle fibers?

Can pack more fibers into the same space, allowing for stronger contractions over a shorter range of motion.