CH 12 - The Muscular System: Appendicular Musculature

Muscles Acting on the Arm (Anterior)

• Pectoralis Major

• Deltoid

• Coracobrachialis

Pectoralis Major

flexes, adducts, and medially rotates humerus

Deltoid

can flex and medially rotate, abduct or extend and laterally rotate the arm, depending on which fibers are active

Coracobrachialis

can flex the arm and pull it towards the trunk

Muscle Acting on the Arm (Posterior)

• Teres Major

• Latissimus dorsi

Teres Major

 extends and medially rotates humerus

Latissimus Dorsi

adducts and medially rotates humerus, extends shoulder joint

Rotator Cuff Muscles (in relation to scapula)

SITS

• Supraspinatus

• Infraspinatus

• Teres Minor

• Subscapularis

Muscles Acting on Forearm

• Brachilalis

• Biceps Brachii

• Brachioradialis

• Triceps Brachii

Brachialis

prime mover of elbow flexion

Biceps Brachii

 supinates forearm and flexes both elbow and shoulder

Brachioradialis

flexes the elbow

Triceps brachii

extends the elbow 

Actions of the Rotator Muscles on the Forearm

• Supinatore

• Biceps Brachii

• Pronator teres

• Pronator Quadratus

Supinator and Biceps Brachii

supinate forearm

Pronator teres and pronator quadratus

pronate forearm

Muscles that Act on Hip and Femur

• iliopsoas

• medial compartment of thigh

medial compartment of thigh

• adductor muscles (magnus, brevis, and longus

• pectineus

iliopsoas

• iliacus

• psoas major

• both flex the thigh

Anterior Muscles of Thigh

• Rectus Femoris

• Vastus Lateralis

• Vastus Medialis

• Vastus Intermedius

• Sartorius → spans the anterior thigh (over the quads) - flexes, weakly abducts, and rotates the thigh laterally

Posterior Gluteal Muscles

• Gluteus Maximus

• Gluteus Medius

• Gluteus Minimus

Gluteus Maximus

extends and abducts the thigh

Gluteus Medius and Gluteus Minimus

abduct and medially rotate the thigh

Posterior (Flexor) Compartment of the Thigh

Hamstrings → flex the knee and consist of 3 muscles

• Biceps Femoris

• Semitendinosus

• Semimembranosus

Muscles of the Leg (Anterior)

Muscles dorsiflex the foot an extend the toes (hallux and digits)

• Tibialis anterior

• Extensor digitorum longus

• Extensor hallucis longus

Superficial Muscles of Leg (Posterior)

all posterior compartment muscles plantar flex the foot and flex the toes (hallux and digits)

• Superficial

  • Gastrocnemius

  • Soleus

• Deep

  • Flexor hallucis longus

  • Tibialis Posterior

  • Flexor Digitorum Longus

Deep muscles of the Leg (Lateral)

all lateral compartment muscles evert the foot

• Fibularis longus

• Fibularis Brevis

Muscle Injuries

• Often result from sudden, intense stress

• Risk increases with improper conditioning or inadequate warm-up

• Initial remedies involve - rest, ice, compression, and elevation (“RICE”)

• For example, a pulled hamstring involves strained posterior thigh muscles or a partial tear in the tendons of those muscles

Sports Muscle Injuries

• Pitchers Arm

• Blockers Arm

• Shin Splints

• Tennis (Golfer’s Elbow)

Pitchers Arm

• Inflammation at the attachments of the wrist flexors

Blockers Arm

• calcification in the lateral margin of the forearm resulting from repeat impact seen in football

Shin Splints 

 general term for several kinds of injury with pain in the crural region – tendonitis of tibialis posterior and inflammation of the periosteum. May result from unaccustomed jogging, walka-thons, walking on or vigorous activity of legs after a period of inactivity

Tennis (Golfer’s Elbow)

• inflammation at the attachment  of extensor carpi muscles that attach to lateral epicondyle