Chapter 16 Bones and Soft Tissues

Objectives Explain the difference between the axial and appendicular skeleton. Define the functions of the skeletal system. Define the types of fractures. Explain the difference between skeletal, smooth, and cardiac muscle.

Planes Anatomical position –Forward facing, arms at side, palms facing forward Frontal: divides body into front and back Sagittal: divides body into left and right Transverse: divides body into top and bottom

Directional Terms Anterior: front of the body Posterior: back of the body Medial: Closer to the midline Lateral: Farther from midline Proximal: Towards an attachment Distal: Away from an attachment Superior: Higher Inferior: Lower

Movements Flexion: bending of the joint Extension: extending the joint Abduction: moving away from the midline Adduction: moving towards the midline Pronation: turning down Supination: turning up

Movements Inversion: sole of foot is turned inward Eversion: sole of foot is turned outward Protraction: glides forward Retraction: glides backward Rotation: turning on an axis Circumduction: ball and socket joint, one movement in several directions

Skeletal System Average adult has 206 bones Two main parts –Axial: skull, spine, ribs, sternum, approx 80 bones –Appendicular: shoulder and pelvic girdle, limbs, approx 126 bones Types: Long, Flat, Irregular, Short

Functions of Bone Aid in movement of body Support and protect internal organs Produce red and white blood cells Provide storage for minerals

Joints Diarthrodial: synovial joints, good mobility –Hinge –Ball and Socket Amphiarthrodial: very little movement –Ex: where ribs meet sternum Synarthrodial: fibrous joints, immovable –Ex: bones in skull, tib/fib

Fractures Simple or closed fracture: incomplete or complete breaks in the bone but the skin remains intact Comminuted fracture: bone shatters in three or more pieces Compound or open fracture: fractured end of bone penetrates the skin

Fractures

Fractures Avulsion Fracture: a ligament or tendon pulls away from bony attachment

Fractures Spiral fracture: caused by a torsional force Stress fracture: occurs in a bone that’s subjected to repetitive stress

Fractures Longitudinal fracture: usually caused by impact, runs the length of the bone Transverse fracture: fracture is perpendicular to the bone Oblique fracture: looks like a diagonal line across the bone

Fractures Greenstick fracture: occurs in adolescents and children. Bone is still soft so the fracture is incomplete. Epiphyseal fracture: fracture of growth plate, Salter-Harris

Fractures Blowout fracture: when eye is pushed backwards and down in socket Depressed fracture: direct impact to the skull

Fractures Compression fracture: occurs when opposing forces are applied to a bone from both ends at the same time

Muscles 3 different types –Skeletal –Smooth –Cardiac 4 characteristics –Contractibility: ability to shorten or reduce distance –Excitability: ability to respond to stimuli –Extensibility: ability to lengthen and increase distance –Elasticity: ability to return to original form after being compressed

Smooth Muscle Involuntary muscle Found in organs such as digestive tract, urinary bladder, and blood vessels Long, spindle shaped with no striations

Cardiac Muscle Involuntary Found in the heart Short, branching fibers with a centrally located nucleus No distinct striations

Skeletal Muscle Voluntary Attached to skeleton and located in wall of pharynx and esophagus Long, cylindrical, multinucleated, light/dark striations

Muscle Contraction Muscles contract to move the skeleton Muscles work in pairs Prime mover: major contributor to single movement Antagonist: major contributor to opposite movement of prime mover Synergist: works with prime mover to produce smooth movement

Muscle Tone Atrophy: wasting or loss of muscle –Disease –Lack of use Hypertrophy: increase in mass of muscle