THORACIC AND HEAD/NECK MUSCLES Origin and Insertion Ms. Treto

HEAD AND NECK MUSCLES

TEMPORALIS ORIGIN: Temporal fossa and temporal fascia. The fibers blend together to pass between the zygomatic arch and the side of the skull. INSERTION: The upper anterior border and inner surface of the coronoid process and the ramus of the mandible. ACTION: elevates the mandible, retracts the mandible

MASSETER test you on this ORIGIN:Superficial portion: from the maxillary process of the zygomatic bone, and the anterior two-thirds of the inferior border of the zygomatic arch Deep portion: I will not test you on this INSERTION:Superficial portion: the angle and ramus of the mandible. ACTION: Elevation and protraction of the mandible. Clenching of the teeth

LEVATOR SCAPULAE ORIGIN: Posterior tubercles of the transverse processes of C1-C4 INSERTION: Superior part of the medial border of the scapula ACTION:Elevation of the scapula, downward rotation of the scapula

Thoracic Muscles

Trapezius Origin – occipital bone/spinous processes of c7 – T12. Insertion – acromion/spine of scapula; lateral 1/3 of scapula. Action – stabilizes/elevates/ retracts/ rotates scapula

Latissimus Dorsi Origin –spinous processes of T7 – L5, iliac crest, ribs, and inferior angle of scapula Insertion – intertubercle groove of humerus Action – adducts, extends and internally rotates the arm. Also, a very powerful rotator of the trunk.

Infraspinatus Origin – infraspinous fossa of the scapula Insertion – greater tubercle of the humerus Action – lateral rotation of the arm and stabilizes the humerus

Rhomboid Major and Minor Major action – retracts the scapula and rotates it to depress the glenoid cavity. Minor action – retracts and rotates scapula

Sternocleidomastoid Origin – manubrium and medial portion of the clavicle Insertion – mastoid process of the temporal bone Action – 1. Unilaterally – cervical rotation and lateral flexion. 2. Bilaterally – cervical flexion and raises the sternum

Pectoralis Major Origin –Clavicle, sternum and upper ribs Insertion – greater tubercle on humerus Action – 1. adduction of humerus. 2. flexion and extension of humerus.

Rectus Abdominis Origin – crest of pubis Insertion – costal cartilage of ribs 5 – 7, xiphoid process of sternum Action – flexion of the lumbar spine

External Obliques Origin – Ribs 5 - 12 Insertion – Iliac crest Action – Contralateral rotation of torso