MadSci Network: Anatomy |
Rafe- good question! The 20 or more facial expression muscles are of many different types; e.g. pennate, circular etc. Most connect via tendons to the bones of the face/skull just as most of the skeletal muscles do. A few, such as the frontalis, attaches at its origin on the galea aponeurotica and inserts on the skin of the eyebrow. The obicularis oculi, a circular muscle, has its origin on the bones of the orbit and inserts on the skin of the eyelid. The platysma has its origin on the fascia of the neck and it inserts on the inferior surface of the mandible. These are just a few examples to give you the idea that their points of attachments vary greatly due to location, size and shape as well as function. When a muscle attaches directly to "skin", it really is attaching to the hypodermis which is technically not the skin, but as the name says, under the skin. Some other muscles have unusual attachent sites also. The internal obliques for example, attach to the linea alba for part of their insertion. ( the linea alba is fascia ) Any muscle that is directly under (deep to) the skin has some attachment to the skin but in most cases it is not the muscle's origin nor insertion points. Several extrinsic tongue muscle attach to the tongue, another muscle. So, as you can see, the variety of attachemnts is highly variable and depends on those factors that I mentioned above. I hope that I answered your question. J. Bridger
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