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The orbitalis muscle is a vestigial or rudimentary nonstriated muscle (smooth muscle) of the eye that crosses from the infraorbital groove and sphenomaxillary fissure and is intimately united with the periosteum of the orbit. It was described by Johannes Peter Müller and is often called Müller's muscle.
The postauricular reflex is a vestigial myogenic [4] muscle response in humans that acts to pull the ear upward and backward. [5] Research suggests neural circuits for auricle orienting have survived in a vestigial state for over 25 million years. It is often assumed the reflex is a vestigial Preyer reflex (also known as the pinna reflex). [6] [7]
The thumb apparatus (and particularly the thenar muscle group) then started developing in the hominin branch, and consequently the Palmaris longus became vestigial. As there is no apparent evolutionary pressure (positive or negative) concerning the muscle, it has remained largely unaffected by evolutionary processes. [17]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function.. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
The orbitalis muscle is a vestigial or rudimentary nonstriated muscle (smooth muscle) that crosses from the infraorbital groove and sphenomaxillary fissure and is intimately united with the periosteum of the orbit. It was described by Heinrich Müller [1] and is often called Müller's muscle.
In human anatomy, the levator claviculae is a very rare [1] accessory [2] and vestigial [3] skeletal muscle in the posterior triangle of the neck.It originates on the transverse processes of the upper cervical vertebrae and is inserted in the lateral half of the clavicle. [4]
There does not appear to be a definitive source counting all skeletal muscles. Different sources group muscles differently, regarding physical features as different parts of a single muscle or as several muscles. There are also vestigial muscles that are present in some people but absent in others, such as the palmaris longus muscle.
It is the vestigial remnant of the nictitating membrane (the "third eyelid") which is drawn across the eye for protection, and is present in other animals such as birds, reptiles, and fish, but is rare in mammals, mainly found in monotremes and marsupials. [2] Its associated muscles are also vestigial. [3]