Lecture 10 Muscular System II Head Neck and

Lecture 10 Muscular System II: Head, Neck and Trunk Muscles 1

Muscles of the Neck Superficial Mylohyoid Digastric Anterior belly Posterior belly Deeper Semispinalis capitis Sternocleidomastoid Geniohyoid Hyoid bone Splenius capitis Semispinalis capitis (cut) Splenius capitis (cut) Levator scapulae Sternocleidomastoid Trapezius Fig. 11. 10 Clavicle Fig. 11. 8 Anterolateral Neck Muscles • Sternocleidomastoid • One or both may contract Posterior Neck Muscles • Semispinalis capitis, Splenius capitis, Trapezius 2

Muscles of Facial Expression Superficial Deep Frontal belly of occipitofrontalis Temporalis Orbicularis oculi Levator labii superioris Zygomaticus Orbicularis oculi Levator labii superioris Masseter Zygomaticus Buccinator Depressor labii inferioris Orbicularis oris Platysma Elevators • Levator labii superioris, Occipitofrontalis, Zygomaticus Depressors • Depressor labii inferioris, Platysma Depressor labii inferioris Platysma Other actions Fig. 11. 2 • Buccinator, Orbicularis oculi, Orbicularis oris 3

Muscles of Facial Expression Elevators • Levator labii superioris, Occipitofrontalis, Zygomaticus Depressors • Depressor labii inferioris, Platysma Other actions • Buccinator, Orbicularis oculi, Orbicularis oris 4

Muscles of Facial Expression Fig. 11. 3 5

Muscles of Mastication Fig. 11. 5 Major Muscles • Temporalis and Masseter Temporalis: Origin - temporal lines of parietal Insertion - coronoid process Masseter: Origin - zygomatic arch Insertion - lateral side of mandible 6

Hyoid Muscles Superficial Deep Digastric Anterior belly Mylohyoid Posterior belly Mylohyoid Digastric Anterior belly Posterior belly Geniohyoid Hyoid bone Clavicle Fig. 11. 8 Actions of hyoid muscles • move mandible and hyoid 7

Trunk Muscles - Muscles of Vertebral Column Deeper Semispinalis Erector spinae Iliocostalis Longissimus Spinalis Multifidus Fig. 11 Superficial: • Erector spinae (Iliocostalis, Longissimus, Spinalis), Semispinalis, and Multifidus Deep: • Interspinalis Actions: • Extension, rotation, lateral flexion of the back 8

Muscles of Respiration Inspiration: • Diaphragm is primary muscle of inspiration (depresses floor of thoracic cavity) • External intercostals elevate ribs Fig. 11. 13 Expiration: • Internal intercostals depress ribs 9

Review Question Axial muscles of the spine control the position of the (a) Head, neck, and pectoral girdle (b) Head, neck, and vertebral column (c) Vertebral column only (d) Vertebral column and pectoral and pelvic girdles 10

Points to Remember • Muscles of the face move the skin rather than a joint allowing a vast range of facial expressions • Muscles that move the mandible are also known as muscles of mastication because they provide the chewing action • Complexity of muscles of the vertebral column required for flexibility and maintaining posture 11

Questions? 12