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

10-2 Muscles of the Neck Fig Anterolateral Neck Muscles Sternocleidomastoid One or both may contract Posterior Neck Muscles Semispinalis capitis, Splenius capitis, Trapezius Fig Mylohyoid Digastric Anterior belly Posterior belly Sternocleidomastoid Trapezius Geniohyoid Hyoid bone Clavicle SuperficialDeep Semispinalis capitis (cut) Splenius capitis (cut) Semispinalis capitis Sternocleidomastoid Splenius capitis Levator scapulae DeepDeeper

10-3 Muscles of Facial Expression Fig Elevators Levator labii superioris, Occipitofrontalis, Zygomaticus Depressors Depressor labii inferioris, Platysma Other actions Buccinator, Orbicularis oculi, Orbicularis oris SuperficialDeep Frontal belly of occipitofrontalis Orbicularis oculi Levator labii superioris Zygomaticus Depressor labii inferioris Platysma Depressor labii inferioris Orbicularis oris Zygomaticus Levator labii superioris Orbicularis oculi Temporalis Masseter Orbicularis oris Buccinator

10-4 Muscles of Facial Expression Elevators Levator labii superioris, Occipitofrontalis, Zygomaticus Depressors Depressor labii inferioris, Platysma Other actions Buccinator, Orbicularis oculi, Orbicularis oris

10-5 Muscles of Facial Expression Fig. 11.3

10-6 Muscles of Mastication Major Muscles Temporalis and Masseter Temporalis: Origin - temporal lines of parietal Insertion - coronoid process Masseter: Origin - zygomatic arch Insertion - lateral side of mandible Fig. 11.5

10-7 Hyoid Muscles Actions of hyoid muscles move mandible and hyoid Fig Mylohyoid Digastric Anterior belly Posterior belly Geniohyoid Hyoid bone Clavicle SuperficialDeepMylohyoid Digastric Anterior belly Posterior belly

10-8 Trunk Muscles - Muscles of Vertebral Column Fig Superficial: Erector spinae (Iliocostalis, Longissimus, Spinalis), Semispinalis, and Multifidus Deep: Interspinalis Actions: Extension, rotation, lateral flexion of the back Multifidus Iliocostalis Longissimus Spinalis Erector spinae DeepDeeper Semispinalis

10-9 Muscles of Respiration Fig Inspiration: Diaphragm is primary muscle of inspiration (depresses floor of thoracic cavity) External intercostals elevate ribs Expiration: Internal intercostals depress ribs

10-10 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

10-11 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

10-12 Questions?