214 Chapter 9Table 9- 2 Muscles of Mastication and the Muscles That Move the Eyes(^) Muscles of Mastication
Muscle Function
(^) Masseter Closes jaw (^)
(^) Temporalis Raises mandible and closes mouth; draws mandible backward (^)
(^) Medial pterygoid Raises mandible; closes mouth (^)
Lateral pterygoid (two-headed) Brings jaw forward
Extrinsic Muscles of the Eye
(^) Muscle Function
(^) Superior rectus Rolls eyeball upward (^)
Inferior rectus Rolls eyeball downward (^)
Medial rectus Rolls eyeball medially (^)
(^) Lateral rectus Rolls eyeball laterally (^)
(^) Superior oblique Rotates eyeball on axis (^)
Inferior oblique Rotates eyeball on axis
Table 9- 3 Muscles of the Head and Shoulder Girdle
Muscles Moving the Head
Muscle Origin Insertion Function
Sternocleidomastoid Two heads sternum and Temporal bone Flexes vertebral column;
clavicle rotates head
Muscles Moving the Shoulder Girdle
Muscle Origin Insertion Function
Levator scapulae^ Cervical vertebrae^ Scapula^ Elevates scapula^
Rhomboid major 2nd–5th thoracic vertebrae Scapula Moves scapula backward
and upward; slight
rotation
Rhomboid minor Last cervical and Scapula Elevates and retracts
1st thoracic vertebrae scapula
Pectoralis minor Ribs Scapula Depresses shoulder and
rotates- scapula downward
Trapezius Occipital bone Clavicle Draws head to one side;
7th cervical rotates scapula
12th thoracic
Serratus anterior 8th, 9th rib Scapula Moves scapula forward
away from spine and
downward and inward to-
ward chest wall