The Muscular System-Ch 8.9-8.10

Producing Movement

- Skeletal muscles pull on tendons which pulls on bone

- By contracting the muscle pulls one bone toward another

- Origin: the stationary bone that remains in its original position

- Insertion: the moveable bone

ORIGINSfrom scapula

BELLY of biceps brachii muscle

INSERTIONon radius

ORIGINS from scapulaand humerus

INSERTIONon ulna

Tendons

Tendon

Tendon

BELLY of triceps brachii muscle

Group Actions

- Muscles act in groups to produce movements

- Opposing pairs- Flexors/Extensors- Abductors/Adductors

- Agonist: muscle causing desired action

- Antagonist: muscle that is relaxed

Agonist

Agonist

Antagonist

Antagonist

Aging of Muscular Tissue

- Skeletal muscle becomes fibrous and adipose tissue

- Mainly due to decreased physical activity

- Number of SO Fibers increase

- Aerobic and strength training activities can reverse effects