Muscular System

Agriculture, Food, and, Natural Resource Standards Addressed AS Evaluate the development and implications of animal origin, domestication and distribution on production practices and the environment. –AS a. Research and summarize major components of animal systems.

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.

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

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 the elbow joint

Triceps brachii

Pectorals – primary adductors of the forelimbs

Pectorals

Serratus ventralis – attaches forelimb to trunk (no collarbone!)

Brachiocephalicus

Deltoid

Intercostal

Semitendinous

Gastrocnemius