Bones & Joints

The stability of a synovial joint depends on three factors:

1. nature of articular surface - shapes of articular surfaces determine what movements are possible. 2. number and positioning of ligaments - Ligaments unite the bones, help direct bone movement, and prevent excessive or undesirable motion. 3. muscle tone - Muscle tendons that cross the joint are the most important stabilizing factor. The tendons are kept taut at all times by the tone of their muscles. Muscle tone is extremely important in reinforcing the shoulder and knee joints.

Movements Allowed by Synovial Joints

1. nonaxial- slipping motion only 2. uniaxial - movement in one plane 3. multiaxial - movement in or around all three planes of space or axes

Hyaline Cartilage

:Known as grisle it is both springy and tough. It is found on the ventral ends of the ribs, the larynx, trachea, and bronchi and on the articular surfaces of the bones. It consists of a slimy mass of a firm consistency, however, it is also extremely elastic. It is found between the ribs, around the windpipe, and between the joints. The cartilage between the joints is known as articular cartilage. It has a pearly bluish color

colle's fracture

A break in the distal portion of the radius is typically the result of reaching out to cushion a fall

Osteocytes

A cell in the bone that is located in the lacunae, a pocket sandwiched between the layers of the matrix of mature bone cells and accounts for most of the cell population. Osteocytes cannot divide and a lacuna never contains more than one osteocyte. -They maintain and monitor the protein and mineral content of the surrounding matrix. They release chemicals to dissolve the minerals in adjacent matrix, those minerals enter the circulation and then are replaced by through decomposition of new hydroxyapatite crystals. -They can participate in the repair of damaged bone by being released from their lacunae and will convert to an osteoblasts or an osteoprogenitor cell.

Rickets

A childhood disorder that reduces the amount of calcium salts in the skeleton; typically characterized by a bowlegged appearance, because the leg bones bend under the body's weight

Osteoclasts activating factor

A compound, released by cancers of the bone marrow, breast, and other tissues that produces a severe osteoporosis

sprain

A condition in which a ligament is stretched to the point at which some of the collagen fibers are torn. The ligament remains functional and the structure of the joint is not affected.

Scurvy

A condition involving weak, brittle bones as a result of a vitamin C deficiency.

arthritis

A group of rheumatic diseases that affect synovial joints. Involves damage to the articular cartilages but specific causes vary. Classified as chronic or acute

Osteomalacia

A softening of bone due to a decrease in its mineral content.

dislocation

Also known as luxation which is a condition that results in the articulating surfaces to be forced out of position

bursitis

An inflammation of a bursa, causing pain whenever the associated tendon or ligament moves.

rhematoid arthritis

An inflammatory arthritis that affects roughly 2.5 percent of the adult U.S. population. The cause is uncertain, although allergies, bacteria, viruses, and genetics factors have all been proposed. The primary symptom is swelling, inflammation of the synovial membrane, as well as synovitis

Marfan's Syndrome

An inherited condition linked to defective production of fibrillin, a connective tissue glycoprotein. Extreme height and long, slender limbs are the most obvious physical indications of this syndrome; cardiovascular problems are the most dangerous aspects of the disease.

Irregular Bones

Are generally complex shapes with flat, notched, or ridged surfaces. Examples include the spinal vertebrae, the bones of the pelvis, and several skull bones are irregular.

Short Bones

Are small and boxy. Examples include the carpel bones, and tarsal bones.

Symphyses

Articular surfaces of the bones are covered with articular hyaline cartilage which is fused to a pad or plate of fibrocartilage. Fibrocartilage acts as a shock absorber and permits limited movement. Designed for strength with flexibility. Examples: intervertebral discs, pubic symphysis.

suture

Articulating bone edges either overlap or interlock. Junctions completely filled by very short connective tissue fibers. Rigid. Examples are found between bones of the cranium.

Synovial joints

Articulating bones are separated by a fluid-filled joint cavity. Permits freedom of movement - diarthrotic joints. Examples: all joints of the limbs, most joints of the body.

Intramembreanous Ossification

Begins when osteoblasts differentiate within a mesnechymal or fibrous connective tissue. Occurs within the deep layers of the dermis. Ex: Flat bones of the skull, the mandible, the clavicle

syndesmoses

Bones are connected by a cord or sheet of fibrous tissue (ligament or interosseous membrane). Amount of movement increases with the length of the connecting fibers (note: compare the radius-ulna interosseous membrane with that of the tibia-fibula).

Synchrondroses

Bones are united by a bar or plate of hyaline cartilage. During youth, provides sites and means for bone growth, while contributing to skeletal flexibility. After bone growth ends, ossification occurs and they become immovable. Most common example - epiphyseal plates of long bones, joint between 1st rib and manubrium

Osteoprogenitor

Bones contain a small number of mesenchymal cells known as osteoprogenitor cells that are better known as stem cells. These stem cells will divide to produce daughter cells that are different from osteoblasts. -They maintain the populations of osteoblasts and are important in the repair of a fracture. They are located in the periosteum, in an inner layer, or Endosteum, that lines the marrow cavities and I the lining of vascular passageways in the matrix

Fibrocartilage

Cartilage containing an abundance of collagen fibers. It is located around the edges of joints in the intervertebral discs, between the bones of the hips and pelvis as well as the menisci of the knee. Considered the toughest part of cartilage and can withstand heavy weights. It absorbs shock and helps prevent injury.

What is cartilage?

Cartilage is a type of connective tissue; it smoothes the surfaces of the bones at joints and it gives strength to structures such as the trachea. There are three different types of cartilage in the human body

Skeletal system includes

Cartilages, Ligaments, and other connective tissues that stabilize or connect bones.

______ run parallel to the surface of the bone. Other passageways known as the ______ extend roughly perpendicular to the surface. Blood vessels in these canals supply the Osteons deeper in the bone and to tissues of the marrow cavity

Central canals, perforating canals,

Central Canal (haversian)

Contains blood vessels and nerves

osteoarthritis

Degenerative disease resulting from cumulative wear and tear on the joints surfaces or it can be a genetic predisposition. 25 percent of women and 15 percent of men over the age of 60 show signs of this disease.

Endochondral Ossification

During development, most bones originate as hyaline cartilages. Each cartilage is a miniature model of a soon to be bone which will occupy that particular position in the adult skeleton. The cartilage is generally converted to bone. Ex: During fetal development up until 3 months old.

Epiphyseal fracture

Femur or tend to occur where the matrix of the bone is still undergoing calcification and chondrocytes are dying. A clean transverse fracture along this line generally heals well. Unless carefully treated, fractures between the epiphysis and the spiphyseal cartilage can permanently stop growth at this site

greenstick fracture

Fracture of the Radius. Only one side of the shaft is broken, and the other is bent. This type of fracture is generally occurs in children, whole long bones have yet to fully ossify.

Spiral fracture

Fracture of the Tibia. Produced by twisting stresses that spread along the length of the bone.

Comminutes fracture

Fracture of the femur, shatters the affected area into a multitude of bone fragments.

Transveres fracture

Fractures of the ulna, or break in the shaft bone across its axis.

Flat Bones

Have thin, roughly parallel surfaces. They form the roof of the skull, the sternum, the ribs, and the scapula. They provide protection for underlying soft tissues and offer an extensive surface area for the attachment of the skeletal muscles.

Endostium

Incomplete cellular layer, lines the marrow cavity. This layer is active during bone growth, repair, as well as remodeling it covers the trabecular of spongy bone and lines the inner surfaces of the central canals. It consists of simple flattened layers of osteoprogenitor cells that cover the bones matrix, generally without intervening connective tissue fibers.

tendonitis

Inflammation of a tendon which the thick cord that attaches the bone to the muscle. Symptoms: Pain, swelling, and stiffness.

Elastic Cartilage

It is a connective tissue fiber that stretches and recoils, providing elasticity to connective tissues. It is also known as yellow cartilage it is most springy and supple types of cartilage. It makes up the outside of the ear (pinna), some of the nose, and also the epiglottis. This is found between the vertebrae of the spine.

Potts fracture

Occurs at the ankle and effects bones of the leg.

Compression fracture

Occurs in vertebrae subjected to extreme stresses, such as those produced by the forces that arise when you land on your seat in a fall.

displaced fracture

Produce new and abnormal bone arrangements. Non-displaced fractures: retain the normal alignment of the bones or fragments.

Osteoblasts

Produce new bone matrix in a process known as osteogenesis. Osteoblast make and release the proteins and other organic components of the matrix. Before Calcium salt deposit, this organic matrix will be known as an Osteoid. -Function in elevating local concentrations of calcium phosphate and promoting the deposition of calcium salts in the organic matrix that convert the Osteoid to bone. Osteocytes develop from osteoblasts that have become completely surrounded by the bone matrix.

Osteoporosis

Reduction in bone mass is sufficient to compromise bone function. The fragile bones that result are likely to break when exposed to stresses that younger individuals could easily tolerate. For example, a hip fracture can occur when a woman in her nineties simply tries to stand. Any fractures that do occur lead to a loss of independence and an immobility which further weakens the skeleton system. The disorder accelerates in women after menopause, owing to a decline in circulating estrogen. Men are not as effected as women. can cause a secondary effect of many cancers. Such as cancers in the bone marrow, breast, or other tissues release a chemical known as osteoclasts-activating factor.

gomphoses

Refers to the way teeth are embedded in their sockets. Connection is by a short periodontal ligament

Osteoclasts

Removes bone matrix. These are giant cells with 50 or more Nuclei. They are not related to osteoprogenitor cells or their descendants. They are derived from the same stem cells that produce monocytes and macrophages. Acids and proteolytic enzymes secreted by the osteoclasts will dissolve the matrix and release stored minerals. The erosion process, called osteolysis is important in regulation of calcium and phosphate concentrations in body fluids

Joints/Articulation Sites

Sites where two or more bones meet. Two functions: 1. Secure bones together and 2. Allow rigid skeleton to move. With the exception of the hyoid bone, every bone forms a joint with at least one other bone.

Sesamoid Bones

Small, flat, and shaped somewhat like a sesame seed. They usually develop inside of tendons and are most commonly located near the joints at the knees, the hands, and thee feet. Ex: Patella. They usually form in 26 different locations and their variation accounts for disparities in the total amount of bones in the body.

Sutural Bones

Small, flat, irregular bones, between the flat bones of the skull. The individual variations in the number, shape, and position of the sutural. They appear similar to puzzle pieces.

Periostium

Superficial layer of compact bone that covers all bones. -Isolates the bones from surrounding tissue. -Provides the route for the circulator and nervous system supply. -Actively participates in bone growth and repair.

tendon sheaths

are elongated bursae that wrap completely around a tendon subjected to friction.

bursae

are flattened fibrous sacs lined with synovial membrane and containing a thin film of synovial fluid. common in sites where ligaments, muscles, skin, or muscle tendons overlie and rub against bone.

Long Bones

are relatively long and slender. They are longer than they are wide. Commonly located in the arm, forearm, thigh, leg, palms, soles, fingers and toes. The femur is the long bone of the thigh and it is considered the longest and heaviest bone in the body.

perforating canal ( volksman)

at rigt angles to the central canal, connect blood vesseks and nerves of the periostium and central canal

osteoprogenitor

bone stem cells

Inorganic portion

calcium, phosphate salts, hydroxyappetite

Woven bones

characterized by a haphazard organization of collagen fibers and is mechanically weak.

Axial Skeleton

composed of the entire vertebral column including the sacrum & tailbone (coccyx), the skull, the ribs & sternum, and the hyoid bone which is located under the lower jaw

endostium

delicate membreane on internal surfaces of bone also contain osteoblasts and osteocytes

Periostium containts an outer ____ layer and a inner ____ layer

fibrous, osteogenic

diarthroses

freely movable joints

canaliculi

hair like canals that connect lacunae to each other and the central canal

synarthroses

immovable joints

extension

increase angle

gliding

intercarpal/tarsal, intervertebral, sternoclavicular joints

cartilage

involve tearing of the knee menisci due to high pressure and twisting motions occurring simultaneously. Being avascular tissue, cartilage rarely can repair itself. Fragments can interfere with joint function by causing locking or binding of the joint. Must be removed surgically (usually arthroscopically). Removal of some or all of a meniscus does not severely impair knee joint mobility, but the joint is definitely less stable.

Lamellar bones

is characterized by a regular parallel alignment of collagen into sheets (lamellae) and is mechanically strong.

Two types of joint classfication

joint & functional

The ____ are the remnants of osteons whose matrix components were recycled by the osteoclasts. The ______ are produced during bone growth.

lamellae

The ____ of each osteon forma series of nested cylinders around the _____.

lamellae, central canal, lamellae,

osteocytes

mature bone cells

abduction

move laterally

adduction

move medially

circumduction

movement of the distal portion of a limb in a circular pattern so that the movement of the entire limb describes a cone

Spongy Bone

only found on the ends of bones where stresses are few or come from many directions such as the epiphysis of some bones. It's hard but it has lots of holes- which gives it the appearance of a sponge. It's where red marrow is kept and blood is made! Ribs are made if this.

Bone matrix is made up of ______ and ______ portion

organic, inorganic

Osteogenic layer contains

osteoblast, osteoclasts, osteogenic

In living bones, ______ are constantly removing matrix and _____ are always adding to it.

osteoclasts, osteoblasts

the _____ are arranged in a concentric layers around a _____ or ______. This canal contains one or more blood vessels (normally capillary and a venule, a very small vein) that carries blood to and from the ____.

osteocytes,central canal or Haversian canal, osteon

Organic portion

osteoid- organic bone matrix secreted by osteoblasts, flexibility and ability to withstand stress. collagen fibers and elastic

osteoclasts

part of bone remodeling unit, bone dissolving, breaks down reabsorbed bone matrix

osteoblasts

part of bone remodeling unit, bone forming laying down new bone

A bone is covered by the _______ and lined with an _______

periostium, endostium

Ossification

process of replacing other tissues with bone, term refers specifically to the formation of bone.

flexion

reduce angle

Appendicular Skeleton

refers to the bones of our appendages -- includes all the bones of the arms and hands plus the pectoral girdle, which is formed by the collar bone (clavicle) and the shoulder blade (scapula).legs & feet plus the pelvic girdle, which attaches the lower appendages to the axial skeleton at the sacrum.

Calcification

refers to the process of deposition of calcium salts, occurs during ossification, but it can also occur in other tissues. When it occurs in tissues other than the bone, the result is a calcified tissue. This does not resemble bone

amphiarthroses

slightly movable joints

lacunae

small cavities that contain osteocytes

Osteon

structural unit

Functions of skeletal system

support, storage of minerals and lipids, blood cell production, protection, leverage

Compact Bone

the outer most part of the bone. The basic functional unit of compact bone is the osteon which contains osteocytes arranged around a central canal. Perforating canals extend perpendicularly to the bone surface. They are located where stresses come from a limited range of directions, such as along the diaphysis of some bones. It is dense, strong and made up of many layers.

rotation

turning movement of a bone around its own long axis. Only movement allowed by atlas-axis joint; common at the hip and shoulder joints

lamellae

weight bearing, column like matrix tubes

cartilaginous joints

•Articulating bones are united by cartilage. •Lack a joint cavity. •Two types (synchondroses and symphyses).

functional classification

•Based on the amount of movement allowed •synarthroses •amphiarthroses •diarthroses

structural classification

•Based on the material binding the bones together •Presence or absence of a joint cavity •Examples: fibrous, cartilaginous, synovial joints

fibrous joints

•Bones are joined by fibrous tissue. •No joint cavity present. •Most are synarthrotic (no movement). •Three types based on type and length of intervening fibers (sutures, syndesmoses, gomphoses).