Muscle Biology

Tendons consist of dense regular connective tissue fascicles encased in dense irregular connective tissue sheaths. Normal healthy tendons are composed mostly of parallel arrays of collagen fibers closely packed together.

Cyclobenzaprine is a muscle relaxant medication used to relieve skeletal muscle spasms and associated pain in acute musculoskeletal conditions.It is the most well-studied drug for this application, and it also has been used off-label for fibromyalgia treatment.

The cremaster muscle raises and lowers scrotum to help regulate temperature and promote spermatogenesis.

Anerobic respiration takes place in cases of vigorous physical exercise when oxygen gets used up faster in muscle cells than is being supplied by blood. This can cause sudden build up of lactic acid, which causes cramps.

Taurine helps regulate the contraction and pumping action of the heart muscle and it helps regulate blood pressure and platelet aggregation.

The latissimus dorsi is the larger, flat dorso-lateral muscle on the trunk. Latissimi dorsi are commonly known as lats, especially among bodybuilders. These muscles are responsible for extension, adduction and internal rotation of the shoulder joint.

The tibialis posterior is the most central of all the leg muscles, and is located in the posterior compartment of the leg. It is the key stabilising muscle of the lower leg.

While the muscle fiber does not have a smooth endoplasmic reticulum, it contains a sarcoplasmic reticulum. The sarcoplasmic reticulum surrounds the myofibrils and holds a reserve of the calcium ions needed to cause a muscle contraction.

In contrast to skeletal muscle, cardiac muscle requires extracellular calcium ions for contraction to occur. Like skeletal muscle, the initiation and upshoot of the action potential in ventricular muscle cells is derived from the entry of sodium ions across the sarcolemma in a regenerative process.

Cricothyroid muscles lengthen and tenses the vocal folds.

Myofibrils are the rod-like contractile elements within muscle fibers, composed of overlapping thick (myosin) and thin (actin) filaments. These filaments slide past each other during muscle contraction. Neurons transmit nerve signals, mast cells are involved in immune response, and sarcolemma is the muscle cell membrane.

Lactic acid accumulates in muscles during intense exercise when oxygen supply is insufficient for aerobic respiration. This buildup causes muscle fatigue, soreness, and the characteristic burning sensation. The other options - fumaric acid, maleic acid, and acetic acid - are not typically associated with muscle fatigue or exercise physiology.

These are features of striated muscles

In humans, the flexor digitorum profundus is innervated by the ulnar and median nerves and supplied the ulnar artery and the radial artery.

Muscle fatigue during intense exercise is primarily caused by lactic acid accumulation. When oxygen supply is insufficient, muscles switch to anaerobic respiration producing lactic acid as a byproduct. This buildup lowers pH, interferes with muscle contraction, and causes the sensation of fatigue and burning.