Equine SCI 2 – Unit 3 Objective 3.01: Understand body surfaces, systems, and how they function

Four Basic Surfaces Dorsal: Upper surfaces of the animal Ventral: Lower (abdominal) area of the animal Anterior (Cranial): Head (front part) of the animal Posterior (Caudal): Tail (rear part) of the animal

Body systems Skeletal System: Made up of bone and cartilage that give the body shape and protect internal organs Muscular System: Provides movement both externally and internally Digestive System: Converts feed into a form that can be used by the body for maintenance, growth, and reproduction Urinary System: Maintains water and mineral balance while holding and excreting wastes when needful

Body systems Respiratory System: Takes in oxygen and delivers it to the tissues and cells and picks up carbon dioxide from the tissues and cells to deliver to the environment

Body systems Circulatory System: Distributes blood throughout the body Nervous System: Supplies the body with information about its internal and external environment through electrical impulse between the brain, spinal cord, and others parts of the body

Body systems Reproductive System: Contains the organs necessary for the creating of new organisms Endocrine System: Produces hormones that influence vital functions

Two Main Divisions plus articulations Skeletal system The skeletal systems has: Two Main Divisions plus articulations

Skeletal system Axial Skeleton Consists of the bones in the trunk area which includes the skull, spine (vertebral column), ribs and breastbone (chest cavity), pelvis, and tail Bones of the skull are flat or irregular in shape and form the framework for the brain, mouth, eyes, and nasal cavities. The vertebral column consists of a flexible column of small bones (vertebrae) that forms the basis of the skeleton Hip bones are 2 large flat bones attached to the spine and sacrum that form the pelvis or pelvic girdle and cavity The ribs and breastbone (sternum) along with the thoracic vertebrae form the chest cavity

Axial skeleton

Skeletal system Appendicular Skeleton Consists of the forelegs and hind legs that are used for locomotion, grooming, and to some extent, for defense and feeding. The forelimbs have no skeletal attachments to the axial skeleton or trunk, but are connected by muscles The hind limbs are attached to the pelvis at the hip joint

Appendicular skeleton

Skeletal system Articulations (joints) are the union of two or more bones or cartilages held together by ligaments, tendons, or a tough fibrous capsule. Joints are classified by their structure and movability Freely movable joints have a joint cavity between the two surfaces, the bones are covered with a smooth cartilage, and the bones are held by ligaments

articulations

Muscular system Muscles are red, lean meat that compose about 50% of the equine’s total body weight that are stimulate to contract or change shape by nerve impulses from the brain and in turn send nerve impulses back to the brain indicating the degree of contraction so that movement is smooth.

Muscular system There are three basic muscle types in the muscular system: Smooth Muscles are involuntary muscles Sometimes called visceral muscle Found in the digestive system and in the uterus of females Capable of prolonged activity without fatigue

Muscular system Cardiac Muscles are involuntary striated muscles Found only in the heart Contractions of the cardiac muscles require no nerve stimulus Contractions are rhythmic and require no conscious control

Muscular system Striated (Skeletal) Muscles are usually attached to bones of the skeletal system either directly or by tendons and act voluntarily Bones serve as levers and the muscles move the body voluntarily under the direct control of the will Skeletal muscles are usually arranged in opposite sets so that one set of muscles bend the limb (flexor muscle) and the other set straightens it (extensor muscle) Voluntary muscles become fatigued and need rest after a short period of time

Muscular system Tendons eliminate undue friction to allow muscles to act more freely The tendon sheath is a synovial sac through which a tendon passes and which provides synovia to lubricate the surrounded tendon. The tendon bursa does the same thing as the sheath except the tendon does not pass through it. The tendon bursa is a synovial sac interposed between the tendon and the surface over which it comes in contact which lubricates and cushions the tendon Both are found mainly near joints