Muscles Head, Neck and Torso

Over 600 Muscles

Muscles 2 separate groups: for every bone, there’s a muscle on the back of the bone and a muscle on the front Frontal muscles: in general function is to flex, flexor muscles Back: in general  exstensors (of arm or leg) Flex: joint angle decreasing Extend: straightening

Muscles are Named By: # of origins: Action Direction of muscle fibers: Rectus - straight Transverse – horizontal Oblique – diagonally Location: Pectoralis – chest Frontalis – over the frontal bone Shape: Serratus – saw toothed Deltoid – triangular Origin and insertion Sternocleidomastoid # of origins: Biceps Triceps Action Adductor Flexor – extensor Supinator – pronator

Muscles of Facial Expressions * * * * * * * * * *

Muscles that Move the Head Sternocleidomastoid Depresses(flexes neck), rotates head Scalenes Anterior, middle and posterior Help turn head side to side Lifts the first 2 ribs to assist inspiration

Anterior Abdominal Rectus Abdominis External Oblique Internal Oblique “six pack” Flexes spine/torso Stabilizes body External Oblique Rotation of torso Stabilize Internal Oblique Same as above

Anterior Abdominal Diaphragm Main muscle in inspiration Separates abdomen from thorax

Intercostal Muscles Internal Intercostals External Intercostals Forced Expiration External Intercostals Aid in inspiration

Muscles that Move the Shoulder Girdle (anterior) Pectoralis major Prime mover in shoulder flexion, flexes, adducts arm medially Pectoralis minor Pulls scapula forward (anteriorly) and downward Serratus Anterior Rotates scapula upward & laterally

Muscles that Move the Shoulder Girlde (posterior) Trapezius: Extends head, shrugs shoulder Adducts scapulae Levator Scapulae Elevates scapula Rhomboid major and minor Pulls scapula inward

Muscles that Move the Humerus Latissimus dorsi Arm extension and adduction Pulls arm posteriorly Teres Major and Teres Minor Work synergistically with above (adduction) Deltoid Shoulder abduction