1. Skeletal Muscles
“Muscle Man”

2. Muscles are arranged as levers to make work easier.

4. Each muscle has an origin (immovable end) and an insertion (movable end).
The muscle can only contract.

5. Muscles are arranged in pairs - antagonistic muscle pairs to allow continuous movement.
ex: biceps brachii flexes forearm
triceps brachii extends forearm

6. The muscle with the main responsibility for movement of a body part is the prime mover or agonist.
The opposing muscle is the antagonist.
Other muscles that aid in movement are synergists.
Synergists that immobilize a bone or joint are fixators.

7. Muscle names derive from:
Location frontalis

8. Muscle names derive from:
Shape deltoid

9. Muscle names derive from:
Size
gluteus maximus

10. Muscle names derive from:
direction of fibers
external oblique

11. Muscle names derive from:
number of origins
biceps brachii

12. Muscle names derive from:
6. location of origin and/or insertion sternocleidomastoid

13. Muscle names derive from:
action of muscle
flexor digitorum

14. Sometimes several of these are combined.
ex: extensor carpi radialis longus

15. Muscles to learn name (correct spelling), general location, and action.
Muscle Name
Action of Muscle
orbicularis oris pucker mouth
orbicularis oculi squint eye
frontalis raises eyebrows
masseter closes jaw
sternocleidomastoid head flexion
deltoid abduct / rotates arm
pectoralis major adduct arm; flexes arm

16. Muscles to learn name (correct spelling), general location, and action.
Muscle Name
Action of Muscle
external oblique trunk flexion / rotates
rectus abdominis flex / rotates lumbar
trapezius raises / rotates scapula
latissimus dorsi extend / adduct arm
biceps brachii flexes forearm
triceps brachii extends forearm
flexor digitorum flexes wrist and fingers
extensor digitorum extends wrist and fingers

17. Muscles to learn name (correct spelling), general location, and action.
Muscle Name
Action of Muscle
rectus femoris knee extensor
sartorius flexes / laterally rotates thigh
gracilis flexes / medially rotates thigh
gluteus maximus thigh extensor
hamstrings thigh extension; knee flexion
gastrocnemius flex foot
diaphragm inspiration