Human Anatomy & Physiology: Ch 6 Lecture Bones Flashcards

Support, protection, movement, storage, blood cell formation

provides framework that supports and anchors all soft organs. Leg bones act as pillars to support the body trunk, and the ribs support the thorax wall.

skull and vertebrae surround soft tissue of the nervous system, and the rib cage protects vital thoracic organs.

skeletal muscles use the bones as levers to move the body.

fat stored in the interior of the bones. Bone matrix serves as a storehouse for various minerals (calcium, phosphate)

hematopoiesis occurs within the marrow cavities of the bones.

compact & spongy bone

dense and looks smooth and homogeneous

(cancellous bone) is composed of small needlelike or flat pieces of bone called trabeculae and has much open space. The trabeculae form an open network which is filled with bone marrow.

The shapes are long, short, flat, and irregular.

Long bones: Longer than they are wide. Reflects the elongated shape rather than the overall size. Consist of a shaft plus two ends and are constructed primarily of compact bone, but may contain substantial amounts of spongy bone. All bones of the limbs, except the patella, wrist and ankle bones, are long bones.

Short bones: Roughly cubelike, containing mostly spongy bone. Comprise bones of the wrist and ankle. Vary in size and number in different individuals.

Flat bones: Thin, flattened, and usually a bit curved, they have two roughly parallel compact bone surfaces, with a layer of spongy bone (diploe) between. Examples include the sternum, ribs, and most of the skull bones.

Irregular bones: Fit none of the previous classes. Include some skull bones, vertebrae, and hip bones. Have complicated shapes and consist mainly of spongy bone enclosed by thin layers of compact bone.

Red marrow (blood forming tissue) is found in the trabecular cavities in long bones (especially the head of the femur and humerus) and in the diploe of flat bones (especially the sternum).

"shaft" which constitutes the long axis of the bone. Constructed of a thick collar of compact bone that surrounds a cavity. The medulla cavity in adults contains fat (yellow marrow).

"ends" or extremities. They are usually more expanded than the diaphyses. A thin layer of compact bone forms the exterior and the interior contains spongy bone.

In young bones, cartilage is present at the junction of the diaphysis and epiphysis. This is the growth area that allows bones to lengthen.

remnant of the epiphyseal plate. After puberty the cartilage of the epiphyseal plate is converted to bone and no further growth is possible.

the outer surface of the diaphysis which is covered and protected by a double layered membrane. Provides an insertion or anchoring point for tendons and ligaments. It is secured to the bone by perforating (Sharpey’s) fibers which are made of collagen.

internal bone surfaces are covered with a delicate connective tissue membrane. Covers the trabeculae of spongy bone in the narrow cavities and lines the canals that pass through the compact bone.

where long bones articulate at epiphyseal surfaces, the bony surfaces are covered with articular (hyaline) cartilage which cushions the bone ends and absorbs stress during joint movement.

osteogenic cells (give rise to osteoblasts), osteoblasts (bone forming cells), and osteoclasts (bone destroying cells)

The other bones share a simple design. They consist of thin plates of periosteum-covered compact bone on the outside and endosteum covered spongy bone (diploe) within. They have no shaft or epiphyses.

osteon or Haversian system.

hollow tubes of bone matrix, one placed inside the next.

incomplete ones

They are found next to the periosteum and extend around the entire circumference of the bone to help the bone resist twisting.

central or Haversian canal

perforating or Volkmann's canals

They connect the vascular and nerve supplies of the periosteum to those in the central canals and medullary cavity.

hollowed-out spaces where osteocytes live

little canals that interconnect the lacunae and the big canals and allow passage of nutrients through bone to get to the cells

maintain the bone matrix and to monitor stress on bones in order to direct bone remodeling

Consists of trabeculae which are positioned where the bone is stressed. Only a few layers thick, the trabeculae contain irregularly arranged lamellae and osteocytes interconnected by canaliculi. No osteons are present.

Bone is made of both organic and inorganic components. The organic components consist of cells and the osteoid (organic part of the matrix, made of ground substance and collagen). The osteoid makes up 1/3 of the matrix, which contributes to the bone's structure, flexibility and tensile strength. The inorganic components consist of hydroxyapatites (mineral salts), largely calcium phosphate. Calcium salts are present in the form of tiny crystals, which accounts for bones hardness.

The process in which cartilage becomes bone

hyaline cartilage (covers ends of bones at movable joints, connect ribs to sternum, forms larynx, supports external nose), elastic cartilage (external ear, epiglottis), and fibrocartilage (knee menisci, intervertebral disks).

• Bone develops from fibrous membranes
• Mostly in flat bones (cranial bones) and clavicle
• Osteoid is laid down in a random manner between embryonic blood vessels, giving rise to trabeculae
• Outer edges become compact bone

• Bone develops by replacing hyaline cartilage
• First the perichondrium becomes periosteum.
• Next a bone collar forms around the hyaline cartilage model of the future bone in the area of the diaphysis.
• Then cartilage in the center calcifies and develops cavities.
• A periosteal bud (consists of artery, vein, lymphatic vessels, nerve fibers, red marrow, osteoblasts, and osteoclasts) invades the internal cavities and spongy bone forms.
• The diaphysis elongates and medullary cavity forms. Cartilage continues to be ossified.
• Secondary ossification centers formed in the epiphyses.
• Epiphyses then ossify. The only remaining hyaline cartilage is the epiphyseal plate and articular cartilage.

Growth of the bone at the epiphyseal plate. New hyaline cartilage is laid down on the epiphyseal-facing side and is subsequently ossified on the diaphysis-facing side.

Osteoblasts beneath the periosteum secrete bone matrix on the external bone surface as osteoclasts on the endosteal surface remove bone (but more is built up than is broken down).

Give rise to osteoblasts

Form bone cells

destroy bone cells

bone is injured or added strength is required. This osteoblast activity needs a diet containing protein, vitamins (C, D, A) and minerals (Ca, P, Mg, Mn).

osteoclasts digest the organic matrix of bone and convert calcium salts into soluble form that passes easily into solution, eventually to the blood.

Tuberosity: large rounded projection

Crest: narrow ridge of bone, usually prominent

Trochanter: very large, blunt, irregularly shaped process

Tubercle: small rounded projection or process

Epicondyle: raised area on or above a condyle

Spine: sharp, slender, often pointed projection

Head: bony expansion carried on a narrow neck

Condyle: rounded articular projection

Ramus: arm-like bar of bone

Meatus: canal-like passageway

Sinus: cavity within a bone, filled with air and lined with mucous membrane

Fossa: shallow basin-like depression in a bone often serving as an articular surface

Fissure: narrow, slit-like opening

Foramen: round or oval opening through a bone

Hematoma Formation, fibrocartilaginous callus formation, Bony callous Formation, remodeling

simple - bone breaks cleanly, does not penetrate the skin

compound - broken ends of bone protrude through skin

comminuted - bone fragments into many pieces

compression - bone is crushed

depressed - broken bone portion is pressed inward

impacted - broken bone ends are forced into each other

spiral - ragged break occurring when excessive twisting forces are applied to bone

greenstick - bone breaks incompletely similar to a green twig

A mass of clotted blood forms at fracture site. Bone cells begin to die and tissue becomes swollen, painful, and inflamed.

Capillaries grow into the area and macrophages clean up debris. Fibroblasts and osteoblasts migrate to the area and begin reconstructing bone. Fibroblasts produce collagen fibers that begin to connect broken ends. Some fibroblasts become chondroblasts which make cartilage. Osteoblasts begin forming spongy bone. All of the repair tissue at this stage is called the fibrocartilage callus.

The fibrocartilage callus is converted to a hard bony callus of spongy bone by the action of the osteoblasts and osteoclasts. This begins 3-4 weeks post injury and continues until a firm union forms 2-3 months later.

During bony callus formation and the following several months remodeling occurs. Excess material outside the shaft is removed and compact bone is laid down to reconstruct the shaft. The final structure will resemble unbroken bone because it is under the same set of mechanical stimuli.