Skeletal Muscles Part 2

A few review questions Muscles of the face originate in the skull. Where do they insert? The skin What is the strongest muscle associated with chewing? Masseter What muscle action allows you to whistle? Buccinator What muscle closes the eye? Orbicularis oculi

Muscles of the spine Covered by superfical back muscles Erector spinae is chief extensor of vertebral column Opposed by quadratus lumborum and various abdominal muscles Iliocostalis, spinalis, longissimus

Muscles of the trunk Protect abdominal viscera Move vertebral column Assist in breathing (expiration) Assist in urination and defection Assist in childbirth

Muscles of trunk, continued Muscles associated with breathing –Diaphragm –External and internal intercostals –Other muscles become involved with forced breathing

Diaphragm separates thorax and abdomen Important for breathing Returning venous blood to the heart Three major openings –Aortic hiatus –Esophageal hiatus –Caval opening

Perineum: floor of pelvic cavity Levator ani –Pubococcygeis, iliococcygeus Coccygeus Support organs in pelvic cavity Resist pressure from coughing, urination, etc. Sphincters

Female and male perimeum Deep muscles are the same

Appendicular muscles Shoulders and upper limbs –Pectoral girdle: anterior and posterior thoracic muscles Pelvic girdle and lower limbs

Muscles of the neck, shoulder, and back

Muscles that position the pectoral girdle Muscles originate on axial skeleton and insert on clavicle or scapula

Muscles that move the arm AnteriorPosterior

Range of movement at shoulder Elevation of scapula- shrugging Depression- pull-up Abduction-push-up Adduction- pulling something toward you Upward rotation- lifting arm past horizontal Downward rotation- supporting weight with hands Deep muscles (rotator cuff) stabilize shoulder

Muscles that move the arm Deltoid, supraspinatus-abduction Rotator cuff-subscapularis, teres major (medial); infraspinatus, teres minor (lateral) Latissimus dorsi-extension, adduction Pectoralis major- flexion, adduction

Muscles of the upper limb Most muscles that insert on the forearm and wrist originate on the humerus Biceps brachii and triceps brachii originate on scapula Brachoradialis is opposed on triceps brachii Flexors of wrist are on anterior and medial surfaces of forearm; extensors are on posterior and lateral surface Flexor digitorum and extensor digitorum muscles perform flexion and extension of fingers

Muscles that move arm and hand ArmForearm

Trunk and proximal limbs

Muscles of the hip and lower limb Muscles that move the thigh (p. 298) –Gluteal group –Lateral rotator group –Adductor group –Iliopsoas group Muscles that move the leg (p. 303)(flexors, extensors) Muscles that affect the ankles and feet (p. 312) (flexors, extensors, intrinsic)

Muscles that move the thigh Gluteus maximusExtends hip Gluteus minimusAbducts thigh AdductorsAdduct thigh and flex hip GracilisAdducts thigh and flexes knee IliopsoasFlexes hip

Muscles that move the leg (anterior)

Muscles that move the leg (posterior)

Muscles that move the leg (lateral) lateralMajor groups Flexors of knee –Biceps femoris, semimembranosus, semitendinosus, sartorius, popliteus Extensors of knee –Quadriceps (rectus femoris, vastus intermedius, vastus lateralis, vastus medialis)

Muscles that move the leg Hamstring muscles (biceps femoris, semimembranosus, semitendinosus) Flex knee SartoriusFlexes hip and knee Quadriceps muscles (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) Extensors of knee

Muscles that move the foot and toes

Organization of leg muscles Muscles are in compartments, superificial and deep Anterior- extension Posterior- flexion Medial- adductor Lateral- eversion of foot, flexion (ankle)

Compartments Formed by fascia; allow independent movement

Review compartments of upper limb (p. 314, 315) armforearm

Review compartments of lower limb (p. 316)

Summary Extrinsic and intrinsic muscles in hand are important for fine motor skills Muscles that move spine are complex in organization Muscles that move femur and large and powerful Compartments are associated with types of movement Intrinsic muscles of foot are limited to support and movement