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.
a voluntary muscle is a muscle that move when you tell it to Muscles in our hands (skeletal muscle) are called voluntary, because these muscles act according to the impulses (â¦ orders) given by our conscious brain. Heart (cardiac muscle) is an example of an involuntary muscle.It works all the time with impulses from our brain stem, which is involuntary. Some more examples of voluntary muscles in our body are muscles of the chest, neck, abdomen, and legs. Involuntary muscles include the muscles of the digestive system.--- Skeletal muscles, like biceps (the muscles that flex your forearm/wrist toward your shoulder) are voluntary muscles.These muscles will not flex unless you think about flexing them, and your brain sends that signal to your arm.nvoluntary muscles include the muscles of the digestive system. --- Skeletal muscles, like biceps (the muscles that flex your forearm/wrist toward your shoulder) are voluntary muscles. These muscles will not flex unless you think about flexing them, and your brain sends that signal to your arm.