SUPERIOR TARSAL MUSCLE Meaning and
Definition
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The term "superior tarsal muscle" refers to a small, thin muscle located in the upper eyelid of mammals, including humans. Also known as Müller's muscle, it runs parallel to the eyelid margin and is responsible for controlling the position and movement of the upper eyelid.
The superior tarsal muscle is classified as a smooth muscle, meaning it lacks the striated appearance commonly found in skeletal muscle. It is innervated by the sympathetic nervous system, specifically by the branches of the oculosympathetic pathway. This innervation allows for the contraction of the muscle, which results in the elevation of the upper eyelid.
The main function of the superior tarsal muscle is to open the eyelids wider, known as eyelid retraction or lid elevation. When stimulated, it raises the upper eyelid to uncover the cornea and create a larger exposed area of the eye. This action is vital for proper vision, especially in dark or dimly lit environments where it enhances the amount of light entering the eye.
Disorders related to the superior tarsal muscle can affect the eyelid's ability to elevate properly, resulting in conditions such as ptosis (droopy eyelid) or Horner's syndrome. In cases of eyelid surgery, the superior tarsal muscle plays a crucial role in achieving the desired aesthetic outcome and maintaining normal eyelid function.
