Skeletal System: Bones and Bone Tissue Unit 3 Skeletal System: Bones and Bone Tissue

Skeletal System Functions Support - provides hard framework for soft tissue Protection - Encloses underlying organs Movement – transmission of forces generated by contracting muscles Storage – of minerals such as Calcium and Phosphorous Blood cell production (Hematopoiesis) - Bone marrow produces blood cells and platelets

Bone Shapes Long- Longer than they are wide Short- vary in shape but typically have cuboid or trapezoid shape Ex. Carpals and tarsals Flat- Cancellous/Spongy bone sandwiched between compact bone Irregular- complex bones that do not fit in the other categories

Classification of Joints Gliding- ankle, wrist, carpals, and tarsals Hinge – Knee, elbow Pivot – atlas to the skull Condylar –Mandible (jawbone) Ellipsoid- base of fingers Saddle- base of thumb Ball and Socket-hip, shoulder Gliding-Flat or slightly flat surfaces move against each other allowing sliding or twisting without any circular movement Hinge -A convex projection on one bone fits into a concave depression in another permitting only flexion and extension Pivot -a bony ring rotates round the pivot (axis) of another bone Condylar -two bones fit together with an odd shape (e.g. an ellipse), and one bone is concave, the other convex Ellopsoid Saddle- touching surfaces of two bones have both concave and convex regions with the shapes of the two bones complementing one other and allowing a wide range of movement Ball and Socket-The ball-shaped end of one bone fits into a cup shaped socket on the other bone allowing the widest range of motion including rotation.

Bone Architecture- Bone Cells Osteoblasts Active in bone formation, a process known as ossification or osteogenesis. Bone-making. Osteocytes Essentially osteoblasts that have been trapped in the matrix Trapped Bone-making Osteoclasts. Very large cells used to breakdown bone - Bone Reabsorption Bone Architecture- Bone Cells

Bone Structure-Compact Bone Dense, solid bone Contain Haversian Systems with Osteocytes=bone making cells

Microscopic Structure of Compact Bones Figure 6.6

Cancellous (Spongy) Bone Located beneath compact bone along stress lines, made of a network of connecting bone spicules called trabeculae.

Components of Bone Diaphysis Cylindrical Shaft Thick wall of compact bone Epiphysis End of the bone Epiphyseal plate - responsible for growth in length of bone Medullary cavity - central, hollow cavity

Components of Bone Periosteum - membrane surrounding diaphysis Composed of 2 layers Fibrous Periosteum: the outer layer Osteogenic Layer- bone forming layer A single layer of bone cells including osteoblasts, osteoclasts and osteochondral progenitor cells Sharpey’s fibers - periosteal fibers that penetrate into the bone matrix and firmly anchor the periosteum to compact bone Endosteum- Lines all internal spaces including spaces in cancellous bone. Internal lining of bone

Components of Bone Endosteum- Lines all internal spaces including spaces in cancellous bone. Internal lining of bone

Structure of a Long Bone Figure 6.3a-c

Bone Development: Osteogenesis Bone formation occurs in 2 different ways Intramembranous ossification Occurs in connective tissue membrane Endochondral ossification Occurs in cartilage

Intramembranous Ossification Typical in the flat bones of the skull, parts of the clavicle, and mandible The process: Think Baby’s Skull Vascularized connective tissue forms collagen Mesenchymal cells of collagen slowly turn to osteoblasts Bone cells fill in the collagen matrix on the edge of the bone and slowly begin to ossify and weave together at joints called sutures.

Baby’s Fontanelles (Soft Spots)

Intramembranous cont’d Summary: Occurs in the skull and allows for the individual bones to fill in completely. No more “soft spots” The coming together/stitching of the bones are called sutures

Endochondral Ossification All bones except some bones of the skull and clavicles This process continues until a persons mid twenties

Endochondral Ossification-simplified Cartilage model is formed Ossification begins in the middle of the diaphysis Formation of periosteum: Periosteum forms around bone and gives rise to osteoblasts (early form of osteocytes) Formation of bone collar: Osteoblasts secrete osteoid against the shaft of the cartilage model. This serves as support for the new bone. Calcification of cartilage:. This can create cavities within the bone. (This would be spongy bone.)

Endochondral Ossification Invasion of periosteal bud: a periosteal bud, which consists of blood vessels, lymph vessels, and nerves invades the cavity, the center of the bone. Formation of Medullary Cavity: Osteoclasts break down spongy bone for the medullary cavity. Cartilage remain at epiphyseal plates of bones: the plates are where growth can continue to lengthen bones

Stages in Endochondral Ossification Figure 6.10

Bones • Children have more flexible bones than adults. • Your body has 206 bones. • Children have more flexible bones than adults. •Ligaments are bands of strong tissue that connect bones to other bones. Help with joints exist.

Muscles • Muscles are soft tissues. • Your body has over 600 different muscles. • Most muscles are attached to bones by strong tissues called tendons.

Joints • Joints= two or more bones coming together at one place. • Joints are held together by bands of fibers called ligaments. • When joints are moved beyond their normal range of motion/movement, ligaments stretch and tear.

Types of Injuries The four basic types of injuries to muscles, bones and joints are: •Fractures •Dislocations •Strains •Sprains

X-Rays X-rays are a form of radiation that can penetrate the body to form an image on film. Structures that are dense (such as bone) will appear white, air will be black

Fractures A fracture is a complete break, chip or crack in a bone. Treated by: Closed Reduction- Open Reduction- Traction-

Closed Fracture Closed fracture right wrist. (Radius & ulna)

Closed Fracture Posterior x-ray, closed fracture right lower leg. (Fibula)

Open Fracture Open fracture left collarbone. (Clavicle) More dangerous because of the risk of infection

Comminuted Fracture Comminuted-a fracture with many relatively small fragments. (right thigh/femur)

Ski Accident – Broken Fibula Spiral type fracture Dislocated Sprained

Ski Accident – Broken Fibula Spiral type fracture Dislocated Sprained

Dislocation A dislocation is the movement of a bone at a joint away from its normal position. The joint no longer functions properly.

Sprain • A sprain is the tearing of ligaments at a joint. • Mild sprains swell and usually heal quickly. • Do not ignore the signals of pain & swelling. If you become active too soon there is the chance the joint could be hurt again.

Type I Sprain The most common way the ankle can be injured is by an ankle sprain. Type I ankle sprain is mild. It occurs when the ligaments have been stretched or torn minimally.

Type II Sprain Type II ankle sprain is a moderate level of sprain. It occurs when some of the fibers of the ligaments are torn completely.

Type III Sprain Type III ankle sprain is the most severe. It occurs when the entire ligament is torn and there is instability of the ankle joint.

Knee and Shoulder Ligaments

General Care for Muscle, Bone or Joint Injuries The acronym RICE is helpful in remembering how to treat minor injuries: • "R" stands for rest. • "I" is for ice. • "C" is for compression. • "E" is for elevation.

Bursitis Inflammation of the Bursa (fluid filled sac surrounding the joint). Bursitis is typically identified by localized pain or swelling, tenderness, and pain with motion of the tissues in the affected area.

Carpal Tunnel Syndrome Any condition that causes swelling or a change in position of the tissue within the carpal tunnel can squeeze and irritate the median nerve. Irritation of the median nerve in this manner causes tingling and numbness of the thumb, index, and the middle fingers, a condition known as "carpal tunnel syndrome."

Osteoporosis Osteoporosis is a term that means "porous bones." It is a skeletal disease affecting women and men. Osteoporosis is a condition in which bones have lost minerals especially calcium-making them weaker, more brittle, and susceptible to fractures (broken bones). Any bone in the body can be affected by osteoporosis, but the most common places where fractures occur are the back (spine), hips, and wrists. **Ladies especially** Why???

Rheumatoid arthritis Systemic chronic inflammatory disease Autoimmune disease Joints become swollen and painful More common in women 3:1 Remissions and exacerbations 52

Osteoarthritis Most common joint disease, 80% of Americans Slow progressive degeneration of articular cartilage Weight bearing joints Fingers Primary: defect in cartilage, not an inflammatory disease Secondary: trauma, crystal deposits, infection Interphalangeal joints, knees, hips, cervical and lumbar spine 53

HERNIATED DISC Disc ruptures or protrudes.

Scoliosis Scoliosis is an abnormal curvature of the spine. If your child has scoliosis, the view from behind may reveal one or more abnormal curves. Scoliosis runs in families, but doctors often don't know the cause. More girls than boys have severe scoliosis.

Kyphosis With kyphosis, your spine may look normal or you may develop a hump. Kyphosis can occur as a result of developmental problems; degenerative diseases, such as arthritis of the spine; osteoporosis with compression fractures of the vertebrae; or trauma to the spine. It can affect children, adolescents and adults.

Lordosis A normal spine, when viewed from behind appears straight. However, a spine affected by lordosis shows evidence of a curvature of the back bones (vertebrae) in the lower back area, giving the child a "swayback" appearance.

Osteomyelitis Inflammation of bone caused by an infectious organism Staphylococcus, streptococcus, neisseria gonorrhea,….. Direct penetration Wounds, fractures, surgery Hematogenous Bloodstream, teeth; metaphyses Knee, ankle, hip

Bone Marrow Aspiration