muscle functions

Muscles of the Face

Masseter – closes jaw by elevating mandible, chewing

Temporalis – closes jaw by elevating mandible, chewing

Mentalis – raises and protrudes lower lip

Orbicularis Oris – closes lips, protrudes lips, shapes lips during speech

Orbicularis Oculi – closes eyes, squinting, blinking

Muscles of the Head and Neck

Sternocleidomastoid (SCM) – rotates head toward opposite side, neck flexion when both SCMs activated

Muscles of the Anterior Truck

            Pectoralis Major – adduction of shoulder, horizontal adduction of shoulder,        and internal rotation of shoulder

            Pectoralis Minor – moves scapula anteriorly, elevates ribs during breathing

            Rectus Abdominis – flexes trunk

            External Obliques – rotates trunk, flexes trunk

Muscles of the Upper Extremity & Shoulder Girdle

            Deltoid – abducts the shoulder, also flexes, extends, internally rotates,                           and externally rotates shoulder       

     (*)  Biceps Brachii – flexes the elbow, supinates forearm, flexes shoulder

     (*)  Triceps Brachii – extends elbow, extends shoulder

Subscapularis – internally rotates shoulder   (RTC)

Supraspinatus – abducts shoulder (works along with shoulder ERs)    (RTC)

            Infraspinatus – externally rotates shoulder    (RTC)

            Teres Minor – externally rotates shoulder   (RTC)

            Teres Major – internally rotates shoulder, extends shoulder

            Levator Scapulae – elevates scapula (pectoral girdle)

Muscles of the Forearm 

            Brachioradialis - flexes elbow

            Extensor Digitorum – extends fingers

Muscles of the Posterior Trunk

            Trapezius – extends neck, elevates, depresses, rotates, adducts, and stabilizes        scapula

            Latissimus dorsi – extends humerus, adducts humerus, internal rotates             shoulder

            Erector Spinae – extends trunk

Muscles of the Lower Extremity (thigh and hip)

            Gluteus Maximus – extends hip

            Gluteus Medius – abducts hip, stabilizes pelvis during stance phase of gait

            Gluteus Minimis – internal rotation of hip, trunk extension

            Tensor Fascia Latae (TFL) – abducts hip, flexes hip

            Psoas Major – flexes hip

            Iliacus – flexes hip

     (*)  Rectus Femoris – flexes hip, extends knee

            Vastus Lateralis – extends knee

            Vastus Medius - extends knee

            Adductor Group – adducts hip

      (*)  Gracilis – adducts hip, flexes knee

      (*)  Sartorius – flexes hip, flexes knee, externally rotates hip

      (*)  Biceps Femoris – extends hip, flexes knee

      (*)  Semimembranosus – extends hip, flexes knee

      (*)  Semitendinosus – extends hip, flexes knee

Muscles of the Lower Extremity (lower leg)

     (*)  Gastrocnemius – plantarflexes ankle

            Tibialis Anterior – dorsiflexes ankle, inverts ankle

            Extensor Hallucis Longus (EHL) – extends great toe

Identify muscles that cross more than one joint (*)

RTC – Rotator Cuff muscle group