# 8.4: MODELS- Head and Neck and Torso

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 Name Action Origin Insertion Muscles of facial expression Frontalis (epicranius) Raises eyebrows , wrinkles forehead Frontal Bone Skin of the brow Occipitalis (epicranius) Pull scalp posteriorly Occipital bone Aponeurosis connecting to frontalis Orbicularis oris Closes mouth Maxillae and Mandible Lips Zygomaticus (major/minor) smile  Zygomatic Bone mouth Orbicularis oculi Closes eye Margin of Orbit Eyelid Masseter Elevates mandible Zygomatic Arch Mandible Temporalis Elevates mandible Temporal Bone Mandible Buccinator Presses cheek inward Maxillae and Mandible orbicularis oris Muscles of the head, vertebral column and abdominal wall Splenius capitis extend + laterally flex head upper spine Temporal & occipital Sternocleidomastoid Flexes + rotates neck (also elevates ribs) Sternum & Clavicle Mastoid Process Scalenes Flexes neck (also elevates ribs) Cervical Vertebrae 1st Two Ribs Rectus abdominus Flexes vertebral column , compresses abdomen Pubis Lower Ribs and Xiphoid External oblique Flexes + rotates vertebral column, compresses abdomen Lower Ribs Linea alba and Ilium Internal oblique Flexes + rotates vertebral column, compresses abdomen Lumbar Vertebrae & Ilium Lower Ribs, Linea alba, Sternum Transverse abdominus Compresses abdomen Lower Ribs, Ilium, Lumbar Vertebrae Linea Alba & Pubis Erector spinae group Extends vertebral column Ilium, Sacrum, Ribs, Vertebrae Ribs, Vertebrae, Base of Skull Levator scapulae Extends neck (also elevates scapula) Cervical Vertebrae Scapula Name Action Origin Insertion Thoracic & shoulder muscles Pectoralis major Flexes, adducts + medially rotates arm at shoulder Sternum & Clavicle Humerus Pectoralis minor Elevates ribs (also moves scapula anterior and inferior) Ribs Scapula External intercostals Elevates ribs Inferior Rib Superior rib Internal intercostals Depresses ribs Superior rib Inferior Rib Diaphragm Increases thoracic volume Xiphoid Process, Ribs, Lumbar Vertebrae Central Tendinous Sheet Arm movers Serratus anterior Moves and fixes scapula anteriorly Ribs Scapula Trapezius Elevates, retracts, depresses+ rotates scapula upward (also extends neck) Occipital Bone & Thoracic Vertebrae Scapula Rhomboids (major & minor) Elevates + adducts scapula Cervical & Thoracic Vertebrae Scapula Latissimus dorsi Extends, adducts + medially rotates arm at shoulder Thoracic, Lumbar Vertebrae, Ribs Humerus Deltoid Abducts arm at shoulder (also anterior fibers flex + posterior fibers extend arm at shoulder) Clavicle & Scapula Humerus Teres major Medially rotate arm Scapula Humerus Rotator cuff (SITS) Infraspinatus Laterally rotates shoulder Scapula Humerus Supraspinatus Abducts shoulder Scapula Humerus Subscapularis Medially rotates shoulder Scapula Humerus Teres minor Laterally rotates shoulder Scapula Humerus

This page titled 8.4: MODELS- Head and Neck and Torso is shared under a CC BY-SA license and was authored, remixed, and/or curated by Laird C. Sheldahl.