Muscles are contractile organs responsible for the voluntary and involuntary movements of animals

•Muscles are contractile organs responsible for

the voluntary and involuntary movements

of animals.

1. Skeletal muscle

- allows for all voluntary movement

- appears to be striated when looked at under a microscope.

2. Cardiac muscle

- controls the involuntary beating of the heart

- appears striated under a microscope.

3. Smooth muscle

- responsible for all other involuntary movement, such as breathing, digestion, peristalsis, blinking, etc.

AmbulationAmbulation

moving from one place to another

Abduction Abduction

moving away from the median plane

AdductionAdduction

moving towards the median plane

FlexionFlexion

moving the distal part of the limb towards the body

ExtensionExtension

moving the distal part of the limb away from the body

All muscles can do is CONTRACT

or RELAX,

so they generally work in pairs.

For any particular action, the muscles involved can be

classified as:

1) Agonist

2) Antagonist

Agonist

prime mover of a joint

Antagonist

opposes movement of the agonist

Example

For elbow flexion,

the agonist is the bicep

the antagonist is the tricep.

Example

For elbow extension,

the agonist is the tricep

the antagonist is the bicep.

Masseter

– superficial muscle of the cheek

Masseter

Trapezius

– superficial triangular muscle of the shoulder

Trapezius

Latissimus dorsi

– long, superficial, dorsal muscle that attaches the humerus to the

lumbar region of the back

Latissimus dorsi

Abdominal obliques

– large flat muscles that support digestive and reproductive organs

External abdominal oblique

Gluteals

– large muscle of the upper hindquarters

Gluteals

Biceps femoris

– lateral superficial muscle, one of three which forms the

“hamstrings”

Biceps femoris

Biceps brachii

– primary flexor of the elbow joint

Triceps brachii

– primary extensor of theelbow joint

Triceps brachii

Pectorals

– primary adductors of the forelimbs

Pectorals

Serratus ventralis

– attaches forelimb to trunk(no collarbone!)

Brachiocephalicus

Deltoid

Intercostal

Semitendinous

Gastrocnemius