Muscular System

Muscular System

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

Types of Muscle

• Skeletal Muscle– Allow for all voluntary movement– Appears to be striated under a microscope

• Cardiac Muscle– Controls the involuntary beating of the heart– Appears striated under a microscope

• Smooth Muscle– Responsible for all other involuntary movement, such as

breathing, digesting, peristalsis, blinking, etc.

Movement• Ambulation

– Moving from one place to another

• Abduction– Moving away from the median plane

• Adduction– Moving towards the median plane

• Flexion– Moving the distal part of the limb towards the body

• Extension– Moving the distal part of the limb away from the body

Muscle Function

• All muscles can do is CONTRACT of RELAX– Generally work in pairs

• Agonist-Prime mover of a joint• Antagonist-Opposes movement of the agonist

• Example– Elbow flexion

• AgonistBicep• AntagonistTricep

Major Muscles

• Masseter-Superficial muscle of the cheek

• Trapezius-Superficial triangular muscle of the shoulder

• Latissimus dorsi-Long, superficial, dorsal muscle that attaches the humerus to the lumbar region of the back.

• Abdominal obliques-Large flat muscles that support digestive and reproductive organs

Major Muscles

• Gluteals-Large muscle of the upper hindquarters.

• Biceps femoris-lateral superficial muscle, one of the three which forms the “hamstrings”

• Biceps brachii-primary flexor of the elbow joint

• Triceps brachii-primary extensor of the elbow joint

• Pectorals-Primary adductors of the forelimbs

• Serratus ventralis-attaches forelimb to the trunk

MasseterBrachiocephalicus

Biceps femoris

Gastrocnemius

Semitendinous

Intercostal

Triceps brachii

Deltoid

Gluteals

Trapezius

Latissimus dorsi

External abdominal oblique

Pectorals