Chapter 8

Osseous Tissue

or bone, the process of bone formation is ossification.

Spongy Bone

or cancellous bone is less dense, located primarily at the ends of long bones (holes here contain red bone marrow) and in the center of other bones.

Ossification of Flat Bones

osteoblasts in the region of flat bones secrete calcium and other minerals into the spaces between membranes.

Bone Remodeling

this is accomplished by the combined actions of osteoblasts (bone forming cells), and osteoclasts (bone destroying cells). Osteoblasts on the undersurface of the periosteum continuously deposit bone on the external surface of bone. Osteoclasts found on the inner surface of bone surrounding the medullary cavity, breakdown bone tissue, hollowing out the interior of the bone.

Fontanels

'Soft spot' in fetal skull, the areas that are not yet covered by bone, these are covered by fibrous tissue.

Vokmans Canal

Much like the haversian system, although these canals run side to side.

Vertebral Column

7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 fused sacrum coccyx Padded by intervertebral discs, which bears the weight of vertebrae above. attachment sites for ligaments, tendons, muscles and ribs. Vertebral foramen is the opening which the spinal cord runs through.

Freely Moveable joints

Articular Cartilage: smooth lining of cartilage on the surface of each bone in the joint. Joint Capsule: strong covering made of connective tissue. Synovial Membrane: lining of the joint capsule that secretes synovial fluid. Synovial fluid lubricates the bones in a joint to reduce friction. Bursae: small sacs of synovial fluid that allow tendons crossing over the joint to slide smoothly. Supporting Ligament: join the articulating bones and stabilize the joint.

Bone Growth Inhibitors

Bedridden or sedentary people, bones lose mass and are easily broken with stress. Weightlessness experienced by astronauts also causes loss of bone mass.

Osteoblasts

Bone cells, they secrete intercellular matrix, conataining calcium, and other minerals, and protein fibers. Osteoblasts mature into osteocytes that sit within the hard bone matrix and maintain the bone.

Resorption

Bone resorption widens the bone and moves calcium from the bone to the blood. This plays a crucial role in regulation of blood calcium levels.

Arrangement of Long Bone

Diaphysis: long shaft of the bone, comprised primarily of compact bone giving it strength. Epiphysis: enlarged ends of the long bones, this articulates with a second bone at a joint. Epiphysis consists of a thin layer of compact bone over spongy bone and are covered by cartilage. Epiphyseal Disc: A growing bone contains a band of hyaline cartilage located near the proximal and distal ends of the long bone. This is where longitudinal bone growth occurs. Medullary Cavity: hollow center in the diaphysis. In infants this is filled with red bone marrow for blood cell production. In adults the medullary cavity is filled with yellow bone marrow, which stores fat. The inside of the medullary cavity is lined with endosteum. Periosteum: Tough, fibrous, connective tissue membrane covering the outside of the diaphysis. this protects the bone, serves as a point of attachment for muscle and contains blood vessels that nourish the underlying bone. Articular cartilage: found on the outer surface of the epiphysis forming a smooth shiny surface that decreases surface friction within joints.

Irregular Bones

Different shaped, do not fall into any other classification. they include the pelvic bone, vertebrae and various bones in the skull.

Types of Joint Movement

Flexion: moving joint so angle between bones decrease Extension: moving bones so angle between bones increase Abduction: movement away from midline of body Adduction: movement toward midline of body Hyperextension: moving bones beyond their normally straightened position Plantar Flexion: bending foot down, pointing toes/tip-toe Dorsiflexion: bending foot up, toward leg Eversion: turning sole of foot outward Supination: turning hand so the palm is facing upward. Pronation: turning hand so palm is facing down toward ground Circumduction: combination of movements, as in pitching a softball

Functions of the Skeletal System

Form of the human body. Bones of lower extremities support weight of the whole body. Bones support and protect the soft body organs. With the assistance of muscles, the bones allow body movement. Storage for minerals. Production of RBC's, WBC's and platelets in red bone marrow.

Paranasal Sinuses

Functions to reduce the weight of the skull and increase the volume of the voice. Sinuses, along with mucus membranes, trap debris and dirt before they reach the lungs. Increases air temperature when cold and lowers air temperature when hot.

Types of Freely Moveable Joints

Hinge Joint: elbows, knees, fingers. Ball-and-socket Joints: shoulders, hips. Pivot Joint: atlas-axis joint. Saddle Joint: carpometacarpal joint (wrist, hand) Condyloid Joint: metacarpophalangeal joint (hand, finger).

Disorders of the Vertebral Column

Scoliosis- most common, 80% of those with scoliosis are women. Kyphosis-hunchback Lordosis-swayback, common during pregnancy

Long Bones

Longer than they are wide, found in the upper and lower extremities, palms, fingers, instep.

Ossification of Long Bones

Most bones are formed by endochondral ossification as bone tissue replaces cartilage. Fetal skeleton is composed largely of cartilage, as the fetus matures, osteoblasts invade the cartilage and gradually replace the cartilage with bone. this continues in each long bone until all but the articular cartilage is replaced by bone.

Osteon

Or haversian system, each system consists of mature osteocytes arranged in concentric circles around large blood vessels (looks like long cylinders). The area surrounding the osteocytes is filled with protein fibers, calcium and other minerals. Protein fibers provide elasticity, minerals make bone tissue hard and strong.

Bone Markings

Projections/Processes: Condyle-large knob that usually articulates with another bone. Epicondyle-enlargement near or above a condyle. Head-enlarged and rounded end of bone. Facet-small flattened surface. Crest-ridge on bone. Process-prominent projection on a bone. Spine-sharp projection. Tubercle (tuberosity)-knoblike projection. Depressions/openings: Foramen-opening through a bone, usually passage for nerves, blood vessels, ligaments. Fossa-depression or groove. Meatus-tunnel or tubelike passageway. Sinus-cavity or hollow space.

Compact Bone

Refers to dense, hard bone tissue found primarily in the shaft of long bones and on the outer surface of other bones. Tightly packed, so its density can provide a great deal of strength. Consists of many haversian systems running parallel to each other. Pereosteal lining surrounds the outer surface of long bone, similar to tendon tissue. Conatinas yellow bone marrow which is primarily lipid storage. The Epiphiseal disk is a growth plate on the long bone breaking up the spongy bone.

Short Bones

Shaped like cubes, found primarily in the wrist and ankles.

Bone Fractures

Simple Fracture: a break in which overlying skin remains intact. Compound Fracture: a broken bone that has pierced the skin, ends of the broken bone have caused extensive tissue damage. High risk for infection. Greenstick Fracture: incomplete break in the bone, usually occurs in children. Spiral Fracture: the line of the fracture extends in a spiral direction along the diaphysis. Caused by twisting force. Communited Fracture: more than two bone fragments, and/or floating fragments. Fissured Fracture: incomplete, longitudinal fracture, stress fracture.

Overview of Skeletal System

Skeletal System is composed of: Bones, Joints, Cartilage, Ligaments (tie bone to bone). There are 206 bones in the body. 7 true ribs, 3 floating, 2 false.

Joint Names

Temporomandibular: temporal bone-mandible Tibiofemoral: tibia-femur Metacarpophalangeal: metacarpal bine-phalange Glenohumeral: glenoid cavity-humerus

Ossification

The process of bone formation, this begins in the late embryonic period with the formation of fibrous connective tissue and hyaline cartilage that is shaped like a mini skeleton. As the fetus develops, the cartilages and connective tissue change into bone by way of osteoblasts. Bone is replaced in two ways: intramembraneous ossification and endochondral ossification.

Flat Bones

Thin, flat, and curved. Ribs, sternum, skull and scapula are flat bones.

Bone Growth

Things that stimulate bone growth and remodeling: Weight bearing activities, exercise. These keep calcium in the bones and increase bone mass.