What is the pinna? The pinna is the only visible part of the ear (the auricle) with its special helical shape. It is the first part of the ear that reacts with sound. The function of the pinna is to act as a kind of funnel which assists in directing the sound further into the ear. Without this funnel the sound waves would take a more direct route into the auditory canal.
Smooth muscle is called involuntary muscle because you can not control this type of muscle movement. These muscles line internal organs, blood vessels, and organs such found in the digestive and reproductive systems. Structurally, these muscle fibers appear non-striated (not striped) when magnified, have one nucleus per cell, and are usually short.
Skeletal muscles can do a short, single contraction (twitch) or a long, sustained contraction (tetanus), and might ache after strenuous exercise. The stomach is an organ of the alimentary canal, a muscular tube that forms part of the digestive system. The wall of the stomach contains smooth muscle tissue.keletal Muscles Bodily movement is carried out by the interaction of the muscular and skeletal systems. For this reason, they are often grouped together as the musculo-skeletal system. Muscle is attached to bone by tendons and other tissues, and exerts force by converting chemical energy into tension and contraction.