11/15/17 The Skeletal System The Skeletal System 1 Functions of the Skeletal System Provide support and structure Protects vital internal organs Storage site for minerals Site for blood formation Bones and joints form system of levers and pulleys 1
Bones How they re classified: Compact thick tissue forming outer layer of bones Cancellous sponge-like inner portion of bones Ossification process in which bones are formed Joints Where two bones meet Three main types: fibrous joint cartilage joint synovial joint Cartilage cushions joint surfaces 2
Joints Fibrous joint fixed joint with little to no movement Suture the area that two bones of a fibrous joint meet Cartilage joint connects at the end of a joint where cartilage forms to protect and cushion the area where two bones meet Joints Synovial joint movable and may be a hinge joint Pivot joint rotates around a fixed point Ball and socket joint rotates in numerous directions 3
Joints: Articulations Joints are classified: structure and move ability Free moving joints contain a joint cavity between the two surfaces, bones covered with smooth cartilage (which cushions the joint) and held together by ligaments 7 Types of Joints and Locations Location Skull Type of Joint Fibrous joint Growth plates at end of bones Elbow Vertebrae Hip Cartilage joint Synovial joint (hinge) Synovial joint (pivot) Synovial joint (ball and socket) 4
Muscles and Connective Tissues Ligament strong, white bands of tissue that connect two bones together at a joint Tendon shiny, white bands of tissue that connect muscles to bone Two Divisions Appendicular Skeleton Limb Bones Axial Skeleton (Trunk) Skull Vertebrae Ribs Sternum 5
Skeleton Divisions Appendicular Skeleton RED Axial Skeleton - YELLOW ACT - The Skeletal System 11 Skeletal System - Divided Two main divisions of skeleton: Trunk (axial skeleton) Skull, spine, ribs, breastbone, and tail Segments of vertebral column: Cervical, thoracic, lumbar, sacral, and coccygeal Limbs (appendicular skeleton) Forelegs, hind legs, and pelvis 6
Axial Skeleton Includes the: skull, spinal column, ribs, & sternum Skull holds and protects the brain, many bones Maxilla/upper jaw/mandible lower jaw that makes up part of the skull Axial Skeleton Sinuses small, open spaces in the skull and nasal canal Spinal column vertebrae, extends from skull to tail, protects spinal cord and allows movement cervical or neck area, involved with head and neck movement, most flexible part of the axial skeleton 7
Axial Skeleton Cervical vertebrae Head and neck area Atlas: first cervical vertebra; allows nodding motion of the head Axis: second cervical vertebra; allows rotation and shaking motion of the head The remaining vertebrae are the same shape and size Axial Skeleton Lumbar group - lower back Framework for loin area; more flexibility and extension for movements; attach to muscles in abdomen 8
Axial Skeleton Sacral group - rump and pelvis area Several vertebrae fused into one bonesacrum; Connected by a firm joint with the hip (pelvis) bones on each side of sacrum; Supports rear end of the body Coccygeal - tail area 15-20 vertebrae, Essentially no spinal cord, Caudal area Appendicular Skeleton Connected to axial skeleton by muscles and/or bones and joints Forelimb contains Scapula (shoulder blade), Olecranon (the elbow), Humerus (upper bone of forelimb), Radius, and Ulna 9
Appendicular Skeleton Carpal bones (carpus) the wrist bones arranged in 2 rows; absorbs actions Metacarpal bones Long bones of feet; long bone called Cannon bone, Horses also have 2 splint bones - located behind cannon Phalanx digits or toes The Skeletal System Why do we learn about the skeletal system? It makes us better skilled for: Restraint giving injections drawing blood radiography 10
Appendicular Skeleton Functions: Forelegs and hindlegs used for locomotion, grooming, defense and feeding Forelegs connected to axial skeleton by muscles, not skeletal attachment Hindlegs attached to pelvis at the hip joint Classification of Bones Bones are classified by shape -Long (i.e. femur) -Short (i.e. phalanges) -Flat (i.e. skull) -Irregular (i.e. vertebrae) 11
Bone Parts Hyaline cartilage Epiphysis Cancellous bone Epiphyseal plate Diaphysis Compact bone Periosteum Medullary cavity Cartilage covers the ends of the bones. The smooth surfaces stops thebones rubbing together and absorbsshock. This is the name for the extremity of the bones. This is sometimes called Spongy Bone and stores the red bone marrow where blood cells are manufactured. A line across the bone from where the bone grows inlength. The shaft ofthe bone. The word "compact" suggests a hard part of the bone. It surrounds the yellow bone marrow in the diaphysis and gives strength to the hollowpart of the bone. Where there is no hyaline cartilage, the periosteum covers the surface of the bone. Ligaments and tendons are attached to the periosteum. This space inside the diaphysis contains the yellow bone marrow. 12
Types of Fractures ACT - The Skeletal System 25 Equine Muscular System ACT - The Skeletal System 26 13
Muscular System Provides movement both internally and externally Muscles contract or change shape when stimulated Comprises approximately 50 percent of body weight Supported by fuel systems providing ATP for energy Muscular System Made up of three types of muscles: Smooth or involuntary Found in digestive system and uterus Perform wavelike contractions for hours Cardiac Found only in heart Controlled by autonomic nervous system (continued) 14
Muscular System Made up of three types of muscles: Striated or skeletal Voluntarily move the body Often a found in extensor-flexor pairs Muscles red, lean meat, composes 50% of total body weight. Stimulated to contract or change shape by nerve impulses from the brain, then sends nerve impulses back to the brain indicating the degree of contraction so movement is smooth. ACT - The Skeletal System 30 15
Three Basic Muscle Types 1. Smooth muscles (involuntary) - Visceral muscle - Location Digestion system & Uterus -Prolonged activity w/o fatigue 2. Cardiac Muscle (Involuntary Striated) - Contractions require no nerve stimulus - Rhythmic contractions w/ no conscious control - Only in heart ACT - The Skeletal System 31 Three Basic Muscle Types 3. Striated, Skeletal Muscles attached to bones of skeletal system either directly or by tendons and act voluntarily. Bones serve as levers and muscles move the body voluntary. Arranged in opposite sets one set of muscles bend the limb (flexor muscle), one set straightens the limb (extensor muscle) Voluntary muscles become fatigued & need short rest periods. ACT - The Skeletal System 32 16
Tendons Tendons fibrous cords of connective tissue attach a muscle to bone, cartilage or other muscle. insert into bone or cartilage by means of small spikes known as Sharpey s fibres. 33 Tendons Tendons eliminate undue friction, allows muscle to move freely. Tendon sheath is a synovial sac through which a tendon passes. Synovial lubricates the surrounding tendon. 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 found near joints 17
Ligaments connect Bone to Bone Help to limit the movement of joints according to their functions Poorly supplied with blood Very slow to heal after injury Do not withstand prolonged stretching Rich in nerve endings making injuries here painful for the horse Made of bands of white and yellow fibrous tissue, the white being inelastic, and the yellow elastic 18
Ligaments There are four different types of ligament: Supporting or suspending - the Suspensory ligament. Annular - a broad band of ligament, which directs the pull on a tendon. Inter-osseous - ties bone together, e.g. the pedal and navicular, canon and splint Funicular (or cord like) - holds bones together. ACT - The Skeletal System 38 19
Functional Anatomy Flexors bend the limb - Decrease angle of a joint Extensors straighten the limb - Increase the angle of a joint Functional Anatomy Abductors Move a limb away from the center plane of the equine Ex: Deltoid (front leg) Adductors Pulls a limb toward the center plane of the equine Ex: Pectoral muscles (front leg) 20