Muscular System

• Functions •Voluntary movement• Forms some sphincters• Protection of some organs• Stabilization of some joints• Posture• Heat production

Muscular System

• Organs

– Muscles

Muscular System

• Organs

– Muscles (includes tendons and aponeuroses)

• Structure of Skeletal Muscles

– Muscle fibers

• Structure of Skeletal Muscles

– Muscle fibers

• Structure of Skeletal Muscles

– Muscle fibers

• Contractile units within:

• Structure of Skeletal Muscles

– Muscle fibers

• Contractile units within:

– Sarcomeres

• Structure of Skeletal Muscles

– Muscle fibers

• Contractile units within:

– Sarcomeres

• Structure of Skeletal Muscles

– Muscle fibers

• Contractile units within:

– Sarcomeres

– Sarcomeres linked end-to end

• Structure of Skeletal Muscles

– Muscle fibers

• Contractile units within:

– Sarcomeres

– Sarcomeres linked end-to end; form myofibrils

• Muscle fibers bundled into fascicles

• Muscle fibers bundled into fascicles

• Fascicles bundled to form the muscle

• Connective Tissue in Muscle

• Connective Tissue in Muscle

– Endomysium

• Connective Tissue in Muscle

– Endomysium

– Perimysium

• Connective Tissue in Muscle

– Endomysium

– Perimysium

– Epimysium

• How Muscles Create Movement at Joints

– Muscles must cross joints

– Insertion pulled towards origin

Fascicle Organization

• Parallel

– Greatest range of motion

Fascicle Organization

• Parallel

• Pennate

Fascicle Organization

• Parallel

• Pennate

– Strongest force of contraction

Fascicle Organization

• Parallel

• Pennate

• Convergent

• Fascicle Organization

• Parallel

• Pennate

• Convergent

– Greatest versatility

• Fascicle Organization

• Parallel

• Pennate

• Convergent

• Circular

Muscle-Bone Lever Systems

F

Muscle-Bone Lever Systems

F

Muscle-Bone Lever Systems

R

F

Muscle-Bone Lever Systems

R

F

E

Third-class lever

Muscle-Bone Lever Systems

R

F

E

Third-class lever

Muscle-Bone Lever Systems

F

E R

Third-class lever

R

F

E

Third-class lever

F

E R

Third-class lever

F

E R

Third-class lever

Amplifies speed and

distance at the expense of

force

R

F

E

Third-class lever

Muscle-Bone Lever Systems

R

F

E

Third-class lever

Muscle-Bone Lever Systems

R

F

E

Third-class lever

Muscle-Bone Lever Systems

R

F

E

Second-class lever

Muscle-Bone Lever Systems

R

F

E

First-class lever

Muscle-Bone Lever Systems

Muscle Interaction

• Prime Mover

– Muscle most responsible for an action

• e.g.: abduction of arm: deltoid

Muscle Interaction

• Synergistic muscles

– Assists prime mover

• e.g.: supraspinatus assists deltoid in abduction

Muscle Interaction

• Fixator muscles

– Holds bone of origin steady

• e.g.: serratus anterior holds deltoid’s bone of origin steady during abduction

Muscle Interaction

• Antagonistic muscles

– Action opposite that of the prime mover

• e.g.: lats and pects adduct

• must not contract during abduction

•  Muscle names may indicate the direction of the muscle fibers (e.g., transversus abdominis, external oblique). 

•  Muscle names may indicate the direction of the muscle fibers (e.g., transversus abdominis, external oblique).

• A muscle may be named according to its location (e.g., temporalis, tibialis anterior).

• The size of the muscle may be indicated in the name (e.g., gluteus maximus, adductor Iongus).

 

• Some muscles are named on the basis of shape (e.g., deltoid, serratus anterior).

• Muscles may be named after their origin and insertion (e.g., sternocleidomastoid).

• A muscle may be named according to its location (e.g., temporalis, tibialis anterior).

• Muscles may be named for their number of origins (e.g., triceps brachii, quadriceps femoris).

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