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Muscles of the Head. There are 656 muscles in the human body. 327 of these muscles are in antagonistic pairs (654) Of these, only 2 muscles are unpaired Obicularis oris Diaphragm. Head Muscles. Are grouped into 2 categories: Facial muscles Provide movement for facial expressions
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There are 656 muscles in the human body. • 327 of these muscles are in antagonistic pairs (654) • Of these, only 2 muscles are unpaired • Obicularisoris • Diaphragm
Head Muscles • Are grouped into 2 categories: • Facial muscles • Provide movement for facial expressions • Chewing muscles • Control the mandible for mastication
Facial Muscles Frontalis • Covers the frontal bone • Starts at the cranial aponeurosis (a connective tissue that cover the top of the skull) and inserts at the skin of the eyebrows. • Functions to wrinkle the forehead and raise the eyebrows.
Occipitalis • Covers the posterior portion of the cranium. • Starts at the posterior cranial aponeurosis and connect to the skin at the back of the head. • Functions to pull the scalp posteriorly (used to wiggle your ears)
Orbicularis Oculi • Runs in a circular pattern around the eye. Also lies underneath the eyebrows. • Functions to close your eyes, squint, blink, and wink.
Orbicularis Oris • A circular muscle that surround the opening of the mouth. • Functions to close and compress the lips. Also allows you to protrude your lips. • AKA the “kissing” muscle
Buccinator • Runs horizontally across the cheek and inserts into the orbicularis oris. • Functions to flatten the cheek (when whistling or blowing a trumpet). • Also compresses the cheek to hold food in between the teeth during chewing.
Zygomaticus • Extends from the corner of the mouth to the cheekbone at a diagonal. This muscle has two bodies (major and minor). • Functions to raise the corners of the mouth. • Is often referred to as the “smiling” muscle.
Depressor AnguliOris • Found along the side of the chin • Functions to depress or pull down the corners of the mouth.
Nasalis • Located over the nasal bones. • Functions to close and open the nasal opening. • Allows you to flare your nostrils.
Chewing Muscles Masseter • Runs from the zygomatic process of the temporal bone to the mandible. • Covers the lateral surface of the angle of the lower jaw. • Functions to close the jaw.
Temporalis • A fan-shaped muscle lying on the temporal bone. • Passes under the zygomatic process and inserts into the mandible. • Functions to raise the jaw, close the mouth, and draw the jaw backward. • Acts as a synergist of the masseter
Neck Muscles • For the most part, these muscles move the head and the shoulder girdle. • These muscles cause the head to: • Flex • Extend • Rotate
Platysma • A broad sheet-like muscle that covers the anterolateral neck. • Orginates from the connective tissue covering the chest muscles and inserts into the area around the mouth. • Functions to pull the lower jaw inferiorly and backward.
Sternocleidomastoid • Found diagonally on each side of the neck. • Of the 2 heads: • the sternum • the clavicle • The heads fuse and insert into the mastoid process of the temporal bone. • If both contract, functions to flex the neck. • If one contracts, the head is rotated.
Identify the muscles that are being used in the following facial expressions