The physicians originally studying human anatomy thought the skull looked like an apple. The two bellies are connected by a broad tendon called the epicranial aponeurosis, or galea aponeurosis (galea = “apple”).
In other words, there is a muscle on the forehead ( frontalis) and one on the back of the head ( occipitals). The muscle has a frontal belly and an occipital belly (near the occipital bone on the posterior part of the skull). The occipitofrontalis muscle elevates the scalp and eyebrows. The orbicularis oris is a circular muscle that moves the lips, and the orbicularis oculi is a circular muscle that closes the eye.
BACK OF NECK DIAGRAM SKIN
Figure 11.4.1 – Muscles of Facial Expression: Many of the muscles of facial expression insert into the skin surrounding the eyelids, nose and mouth, producing facial expressions by moving the skin rather than bones. Because the muscles insert in the skin rather than on bone, when they contract, the skin moves to create facial expression ( Figure 11.4.1). The insertions of these muscles have fibers intertwined with connective tissue and the dermis of the skin. The muscles of facial expression originate from the surface of the skull or the fascia (connective tissue) of the face. AXIAL MUSCLES OF THE HEAD NECK AND BACK Muscles of Facial Expression The first grouping of the axial muscles you will review includes the muscles of the head and neck, then you will review the muscles of the vertebral column, and finally you will review the oblique and rectus muscles. Some of the axial muscles may seem to blur the boundaries because they cross over to the appendicular skeleton. This system reflects the bones of the skeleton system, which are also arranged in this manner. The skeletal muscles are divided into axial (muscles of the trunk and head) and appendicular (muscles of the arms and legs) categories. Axial muscles of the head neck and back.Identify the following muscles and give their origins, insertions, actions and innervations: By the end of this section, you will be able to:
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