Major Muscles of Head and Neck
Muscles of the neck
These muscles can become painful when dental assistants use improper posture while assisting
sternocleidomastoid
Origin: Clavicle ( collarbone) and lateral surface of sternum.
Insertion: Posterior and inferior to external acoustic meats
Function : Divided neck region into anterior and posterior cervical triangle, serves as landmark of neck during extraoral examination.
Definition
To perform a thorough patient examination, it is necessary to determine the location and action of many muscles of the head and neck. Malfunction of muscles may be involved in malocclusion, TMD, and even spread of dental infection.
Muscles must expand and contract to make movement possible. Each muscle has a point of origin that is fixed (nonmovable) and a point of insertion (movable).
trapezius
origin : External surface of occipital bone.
insertion: lateral third clavicle and parts of scapula .
Function: lifts clavicle and scapula ( shoulder blade) an when shoulder are shrugged.
Major Muscles of Facial Expression
paired muscles (left and right) that originate from the bone and insert on skin tissue. These muscles cause wrinkles at right angles to the action line of the muscle. The seventh cranial (facial) nerve innervates all the muscles of facial expression.
Major Muscles of Mastication
are four pairs of muscles attached to the mandible that include the temporalis, masseter, internal (medial) pterygoid, and external (lateral) pterygoid
Muscles of the Floor of the Mouth
These muscles are located between the mandible and the hyoid bone. Different nerve branches innervate the muscles on the floor of the mouth.
Muscles of the Tongue
Intrinsic muscles are responsible for shaping the tongue during speaking, chewing, and swallowing.
Extrinsic muscles assist in the movement and functioning of the tongue and include the genioglossus, hyoglossus, styloglossus, and palatoglossus
All muscles of the tongue, except the palatoglossus, are innervated by the hypoglossal nerve. The palatoglossus muscle is discussed with the palate. Muscles of the tongue and the floor of the mouth attach to the hyoid bone.
Muscles of the Soft Palate