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BIO 117
Muscular System (Major Muscles of the body)
Muscle | Location, Description | Function |
---|---|---|
Orbicularis oculi | circular muscle around eye | closes eyes; winking, blinking, and squinting |
Levator palpebrae superioris | origin on bony orbit of eye; inserts on upper eyelid | Elevates eyelid (opens eye) |
Orbicularis oris | Encircles mouth | closes, purses lips; kissing muscle |
Buccinator | Horizontal cheek muscle; origin on maxilla and mandible; inserts on orbicularis oris | flattens cheeks; trumpeter's muscle; whistling muscle; helps with chewing by positioning food between teeth |
Zygomaticus | Origin on cheekbone; inserts on corner of mouth | elevates corner of mouth; smiling muscle |
Platysma | Origin in fascia of shoulder and anterior chest; inserts on mandible, angle of lower mouth, soft tissue of lower face | pouting muscle; "open your mouth wide" muscle |
Temporalis | flat fan-shaped muscle over temporal bone (origin); inserts on mandible | closes jaw; retracts jaw |
Masseter | covers lateral part of lower jaw; origin on maxilla, zygomatic process of the temporal bone; inserts on mandible | closes jaw; retracts jaw |
Sternocleidomastoid | extends along each side of neck; strong narrow muscles that extend obliquely from sternum and clavicle; origin upward to mastoid process of temporal bone (insertion) | contraction of both muscles flexes the head at the neck; contraction of one rotates head toward opposite side |
Trapezius | large, flat, trapezoid-shaped muscle on back of neck and upper back; origin on occipital bone, C7, and all thoracic vertebrae; inserts on clavicle and scapula | hyperextends head so as to look up in the sky; lateral flexion of head |
Scalenes | Origin on cervical vertebrae (C1-C7); insert on rib 1 and 2 | act synergistically with sternocleidomastoid to flex neck |
Frontalis | Flat muscle covering forehead; origin on cranial aponeurosis; inserts on skin above eyebrows | Raises eyebrows; surprised look; wrinkles forehead |