The Musculoskeltal System

Objectives Name the structures that make up the musculoskeletal system State the functions of the musculoskeletal system Identify types of joints and where they are found in the body

Introduction Consists of bones, muscles, tendons, and ligaments Skeleton makes up the bony structure of the animal, providing support and protection for vital organs Muscular system allows animal to move Skeleton is adaptable to bend and grow

Bones Hard, active tissue that consists mostly of calcium and forms the skeleton of the animal Serve as a mineral reserve to the body, storing calcium and phosphorous for use when necessary and providing nutrients to aid in red blood cell formation Number varies with the age and species of animal

Structure and Classification Structure described as long, short, flat or irregular Structure is classified as compact or cancellous Compact bone is thick tissue that forms the outer layer of bone Can be repaired and it gives elasticity and rigidity to a bone Cancellous bone is sponge-like and softer and located inside the end of the bones

Formation Formed through the process of ossification Hollow center within the bone is a medullary cavity Produces blood cells within a fluid known as bone marrow

Other Structures of Bone Osteoblast Particles that begin ossification in young, developing bones Osteocyte Bone cells that begin to develop mature bone Osteocast Mature bone particles that form minerals and compact bone Periosteum Thin connective tissue covering outer bone Endosteum Thin connective tissue covering inner bone

Joints Area where two bones meet forms a joint Allow animals to bend in areas with level-like movement Three main types: Fibrous joint Cartilage joint Synovial joint

Types of Joints Fibrous joint- fixed joint with little to no movement Area where two bones of a fibrous joint meet is called a suture Cartilage joint- connects at the end of joint where cartilage forms to protect and cushion the area where two bones meet When animal is young and growing this is called the growth plate Synovial joint- movable and may be a hinge joint that opens and closes in a one-way movement Pivot joint rotates around a fixed point Ball and socket joint that rotates in numerous directions

Joint Movements Flexion- bend closing to cause joint to shorten Extension- opening to cause joint to lengthen Abduction- movement away from the body Adduction- movement toward the body

Muscles and Connective Tissues Muscles located throughout animals body and allow movement Attach to different locations of the body and serve as protection and provide the animal strength Ligaments are fibrous strands of tissue that connect one bone to another bone and serve as support to all areas of the body Also allow bending and movement of the limbs Tendons are fibrous strands of tissue that connect a bone to a muscle Aid in movement of the limbs

Skeleton Skeleton divided into two parts: Axial Skeleton Appendicular Skeleton

Axial Skeleton Contains the bones of the body that lie perpendicular or lengthwise Includes: skull, spinal column, ribs and sternum

Skull Holds and protects the brain and is made up of many bones Maxilla (upper jaw), mandible (lower jaw) Small open spaces located within the skull and nasal canal are called sinuses Spinal column contains the vertebrae which are individual bones that surround and protect the spinal cord

Spinal Column First section calls cervical vertebrae and extends over the head and neck area First vertebra located at base of skull is the atlas and is the first cervical vertebra that allows the up and down nodding motion of the head to occur Second cervical vertebra is the axis and allows for the rotation and shaking motion of the head

Spinal Column Continued Second section of vertebrae is thoracic vertebrae Lies over the shoulders and chest area Each rib attaches to an individual thoracic vertebra and protects the heart and lungs The sternum, or breastbone, helps to protect the organs of the chest

Spinal Column Continued Third section of vertebrae is lumbar vertebrae Lies over the lower back or loin area Sacral vertebrae form over pelvis and rump area Last section of the spinal cord is the coccygeal vertebrae Forms the tail area

Appendicular Skeleton The part of the body that contains the appendages or limbs Foreleg or forelimb is the front leg of an animal Includes the scapula (shoulder blade), olecranon (elbow), humerus (large upper bone of the forelimb), radius and ulna Lower leg forms the carpal bones (similar to wrist bones) Several small carpal bones that are arranged in two rows called the carpus joint

Appendicular Skeleton Metacarpal bones form the long bones of the front feet Hoofed animals: cannon bone Horses have two small bones that form at back of cannon bone called splint bones Phalanges form the toes or digits Short inside bone that forms the first digit and acts as an opposable thumb is a dewclaw

Appendicular Skeleton Hind limb or pelvic limb forms the rear leg of the animal Pelvic is formed by three sections: Ilium Ischium Pubis Pelvis holds rear limb in place by the acetabulum or ball and socket joint of the hip Femur or thigh bone forms the large bone of the upper rear leg

Appendicular Skeleton Patella forms joint between upper and lower bones of the rear leg (kneecap) Bones in lower leg called tibia or fibula Point where tibia and fibula meets is called the hock Forms several bones to ankle bone called tarsal bones Metatarsal bones form the long bones of the rear feet and the digits of both the front and rear limbs are all called phalanges