Skeletal Muscles:Head, Neck and Trunk Muscles

10-1

Muscles of the Neck

10-2

Fig. 11.8

Anterolateral Neck Muscles• Sternocleidomastoid

• One or both may contract

Posterior Neck Muscles• Trapezius

Fig. 11.10

Mylohyoid

Sternocleidomastoid

Trapezius

Geniohyoid

Hyoid bone

Clavicle

Semispinalis capitis (cut)

Splenius capitis (cut)

Sternocleidomastoid

Splenius capitis

Levator scapulae

Deep Deeper

Muscles of Facial Expression

10-3

Fig. 11.2Elevators• Levator labii superioris, Occipitofrontalis, Zygomaticus

Depressors• Depressor labii inferioris, Platysma

Other actions• Buccinator, Orbicularis oculi, Orbicularis oris

Frontal belly of occipitofrontalis

Orbicularis oculi

Levator labii superioris

Zygomaticus

Depressor labii inferioris

PlatysmaPlatysma

Depressor labii inferioris

Orbicularis oris

Zygomaticus

Levator labii superioris

Orbicularis oculi

Temporalis

Masseter

Orbicularis oris

Buccinator

Muscles of Facial Expression

10-4

Elevators• Levator labii superioris, Occipitofrontalis, Zygomaticus

Depressors• Depressor labii inferioris, Platysma

Other actions• Buccinator, Orbicularis oculi, Orbicularis oris

Muscles of Facial Expression

10-5Fig. 11.3

Muscles of Mastication

10-6

Major Muscles• Temporalis and Masseter

Temporalis:Origin - temporal lines of parietalInsertion - coronoid processMasseter:Origin - zygomatic archInsertion - lateral side of mandible

Fig. 11.5

Hyoid Muscles

10-7

Actions of hyoid muscles: move mandible and hyoid

Fig. 11.8

Mylohyoid

DigastricAnterior belly

Posterior belly

Geniohyoid

Hyoid bone

Clavicle

MylohyoidDigastricAnterior belly

Posterior belly

Trunk Muscles - Muscles of Vertebral Column

10-8

Fig. 11.11

Superficial:• Erector spinae (Iliocostalis, Longissimus, Spinalis), Semispinalis, and MultifidusDeep:• InterspinalisActions:• Extension, rotation, lateral flexion of the back

Multifidus

Iliocostalis

LongissimusSpinalis

Erector spinae

Deep Deeper

Semispinalis

Muscles of Respiration

10-9

Fig. 11.13

Inspiration:• Diaphragm is primary muscle of inspiration (depresses floor of thoracic cavity)• External intercostals elevate ribs

Expiration:• Internal intercostals depress ribs

TrapeziusExtend Head, Adduct, Elevate or Depress Scapula

Latissimus DorsiExtend, Adduct & Rotate Arm Medially

DeltoidAbduct, Flex & Extend Arm

Pectoralis MajorFlexes, adducts & rotates arm medially

Biceps BrachiiFlexes Elbow Joint

Triceps BrachiiExtend Elbow Joint

Rectus AbdominusFlexes Abdomen

External ObliqueCompress Abdomen

Forearm Muscles• Flexor carpi—Flexes wrist• Extensor carpi—Extends wrist• Flexor digitorum—Flexes fingers• Extensor digitorum—Extends fingers• Pronator—Pronates • Supinator—Supinates

Gluteus MaximusExtends & Rotates Thigh Laterally

Rectus Femoris

Flexes Thigh, Extends Lower Leg

GracilisAdducts and Flexes

Thigh

SartoriusFlexes Thigh, & Rotates Thigh

Laterally

Biceps Femoris

Extends Thigh & Flexes Lower Leg

Tibialis Anterior

Dorsiflexes and Inverts Foot

GastrocnemiusPlantar Flexes

Foot & Flex Lower Leg

Big Picture

• Function of all three major types of muscle (skeletal, cardiac, smooth) is integral to function of the entire body

• All three types of muscle tissue provide the movement necessary for survival

• Relative constancy of the body’s internal temperature is maintained by “waste” heat generated by muscle tissue

10-26