By contracting, the muscles pull on the skin and Muscle of the facial expression their effects. They are the only group of muscles that insert into skin. These muscles have a common embryonic origin — the 2nd pharyngeal arch. They migrate from the arch, taking their nerve supply with them. As such, all the muscles of facial expression are innervated by the facial nerve. The facial muscles can broadly be split into three groups; orbitalnasal and oral.
The orbital group of facial muscles contains two muscles associated with the eye socket. These muscles control the movements of the eyelidsimportant in protecting the cornea from damage. They are both innervated by the facial nerve. It has three distinct parts — palpebral, lacrimal and orbital. If the facial nerve becomes damaged, the orbital muscles will cease to function. The nasal group of facial muscles are associated with movements of the noseand the skin around it.
There are three muscles in this group, and they are all innervated by the facial nerve. They serve little importance in humans. The nasalis is Muscle of the facial expression largest of the nasal muscles. It is split into two parts; transverse and alar.
The procerus is the most superior of the nasal muscles. It also lies superficially to the other muscles of facial expression. Fig 2 — The nasal muscles of facial expression. "Muscle of the facial expression" the nasalis muscle is comprised of two parts. These are the most important group of the facial expressors — the are responsible for movements of the mouth and lips. Such movements are required in singing and whistling, and add emphasis to vocal communication.
The oral group of muscles consists of
Muscle of the facial expression orbicularis oris, buccinator, and various smaller muscles. There are other muscles that act of the lips and mouth. Anatomically, they can be divided into upper and lower groups:. Fig 3 — The main oral muscles of facial expression. Note how the fibers of buccinator and obicularis oris blend togther. If the facial nerve is dysfunctional, the oral muscles can become paralysed.
The patient may present with difficulty eatingwith food collecting between the teeth and cheeks. In addition, the tissue around the mouth and cheeks sags, and is drawn across to the opposite side while smiling.
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Oliver Jones Last Updated: July 28, Revisions: Contents 1 Orbital Group 1. Paralysis to the Oral Muscles. By TeachMeSeries Ltd Paralysis to the Orbital Muscles If the facial nerve becomes damaged, the orbital muscles will cease to function. This is known as exposure keratitis. The lower eyelid droops, called ectropion. Lacrimal fluid pools in the lower eyelid, and cannot be spread across the surface of the eye.
This can result in a failure to remove debris, and ulceration of the corneal surface.
The test for facial nerve palsy involves raising the eyebrows and closing the eyelids. Paralysis to the Oral Muscles If the facial nerve is dysfunctional, the oral muscles can become paralysed. Which cranial nerve innervates the orbicularis oculi muscle?
The muscles of facial expression are located in the subcutaneous tissue, originating from bone or fascia, and inserting onto the skin. There are close to 12 types of facial expressions which are possible which have been listed below and for each expression, there are multiple muscles which.
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