The symptoms of a stroke are different, depending on where in the brain the stroke is located, and doctors can use the symptoms to pinpoint the site of the stroke. In the case of a brain stem stroke, the patient often experiences vertigo, slurred speech, and difficulty speaking.
The smallest functional unit in a myofibril is a sarcomere. A sarcomere is composed of thin (actin) and thick (myosin) filaments. Actin slides past myosin when the muscle contracts.
Myofibrils contract because of the sliding action of two filamentous cytoskeletal proteins, called actin and myosin: 1  Actin filaments, or thin filaments, consist of two strands of actin wound around each other. 2  Myosin filaments, or thick filaments, contain groups of myosin.