Osteology Flashcards
Bones of the back
- Cervical vertebrae (CI-CVII)
- Thoracic vertebrae (TI-TXII)
- Lumbar vertebrae (LI-LV)
- Sacrum (5 fused sacral vertebrae I-V)
- Coccyx (3-4 fused coccygeal vertebrae I-IV)
Bone
- Consists of cells, fibers,matrix
- Protectivefunction
- Serves as a lever
- Storage of calcium ions
- Houses blood-forming marrow
WOLFF’S LAW
-Bone grows and remodels in response to the forces that are place upon it in a healthy person (placing specific stress)
FORMS: COMPACT and CANCELLOUS
Long bones
Found in the limbs
E.g. humerus, femur, tibia ulna
Composed of cancellous (ends) surrounded by thin layer of compact bone
Articular surfaces at the ends - hyaline cartilage
Short bones
metacarpals, metatarsals, phalanges
Flat bones
found in the vault of the skull (frontal and parietal)
E.g. ilium
Irregular bones
Composed of a thin shell of compact bone w interior made of cancellous
E.g. vertebra
Sesamoid bone
Patella (largest); reduce friction on the tendon
Membranous
Bone is developed directly from a CONNECTIVE TISSUE MEMBRANE
Endochondral Ossification
A CARTILAGINOUS MODEL (hyaline cartilage) is first laid down and is later replaced by bone
Allow long bones to growth in length
Hyaline cartilage is present in
- Articular- end of long bones (epiphyseal)
- Costal- connects ribs to sternum
- Respiratory- makes up larynx, reinforces air passages
- Nasal- supports nose
Elastic cartilage
Similar to hyaline but contains elastic fibers
Found in external ear and epiglottis
Fibrocartilage
-highly compressed with great tensile strength
-contains collagen fibers (limited amt. cells & ground substances)
Function of skeletal system
- Support
- Storage of minerals
- Storage of lipids
- Blood cell production
- Protection
- Leverage (force of motion)
Canaliculi
Forms pathways for blood vessels; exchange nutrients and wastes
Bone matrix
2/3 of bone matrix is calcium phosphate Ca3(PO4)2
Reacts w calcium hydroxide, Ca(OH)2 to form crystal of hydroxyapetite, Ca10(PO4)6(OH)2 w/ch incorporates other calcium salts and ions
1/3 collagen fibers
Intramembranous ossification develops from a
FIBROUS MEMBRANE
-Essential process during the natural healing of bone structures
[formation of woven/primary bone]
The process of intramembranous ossification starts when
A small group of adjacent MSCs (within medullary/marrow cavity) begin to replicate and form a nidus—>osteoprogenitor cell—>osteoblasts—>then blasts create an extracellular matrix containing Type 1 collagen fibrils (osteoid)—>osteoblasts incorporte w osteoids—>osteocytes
Primary center of ossification (lamellar/secondary bone)
The area where bone growth occurs between the periosteum and the bone —> osteogenic cells (orig. periosteum) increase appositional growth and a bone collar is formed —> mineralized & lamellar bone is formed
Osteoclasts (bone resorption)
Found lining in endosteum lining of the marrow cavity; derived from stem cells that produce macrophages
How can bone homeostasis occur?
Bone FORMATION (osteoblasts and osteocytes) and bone RESORPTION (destruction of bone tissue) (osteoclasts) MUST BE BALANCED
-exercise causes osteocytes to build bone
Osteon
Basic structural unit of mature compact bone
-are osteocytes arranged in concentric lamella around a central canal containing blood vessels
Lamella
Weight bearing, column-like matrix tubes composed mainly of collagen
Types of Lamellae (3)
- Concentric lamellae
- Circumferential lamellae- wrapped wound the long bone; binds inner osteons together
- Interstitial lamellae- found between osteons that have been partially digested and remodeled by osteoclast/osteoblast activity
Spongy bone (Trabecular bone)
-most in short, flat, and irregularly shaped bones & the head of long bones (epiphyis)
E.g. proximal femur
-also found in the narrow rim around the marrow cavity of the diaphysis
Characteristic of spongy bone
-no osteons
-matrix forms an open network of trabeculae
-trabeculae have no blood vessels
Bone marrow
Found in intramedullary cavity
Yellow bone marrow
stores fat (STARTS TO APPEAR AT 7 YR OLD)
Red bone marrow
supplies nutrients to osteocytes in trabeculae (forms RBC &WBC)
Location of hematopoietic tissue (red marrow) in infants
Medullary cavity and all areas of spongy bone
Location of hematopoietic tissue in adults
Diploe of flat bones, head of femur and humerus
Periosteum
Double layered protective membrane covers all bones EXCEPT parts enclosed in joint capsules (shoulder and hip)
-source of growth in rib esp. in children in w/ch is thicker than in adults
Collagen fibers of the outer fibrous layer of periosteum, connecting with collagen fibers in bone
Sharpey’s (perforating) fibers
The Sharpey’s fibers connect with
Collagen fibers in bone, fibers in joint capsules, attached tendons & ligaments
Functions of periosteum
- Isolate bone from surrounding tissues
- Provide a route for circulatory & nerve supply
- Participate in bone growth and repair
Endosteum contains
Osteoblasts, osteoprogenitor cells, osteoclasts
Endosteum lines the
Incomplete cellular layer; lines the marrow cavity; covers the trabeculae of spongy bone; lines the central canal
Active in bone growth and repair
Osteogenesis is the process of
Bone formation
Ossification is the process of
replacing other tissues w bone
Calcification
Process of depositing calcium salts
-occurs during bone ossification and in other tissues
Formation of the bony skeleton begins at
8 week of embryo development
Fibrocartilage is found in the
MENISCI OF THE KNEE and in INVERTEBRAL DISCS
Intramembranous ossification occurs in the
DERMIS (also called dermal ossification)
Intramembranous ossification produces and forms the
Produces dermal bones such as mandible and clavicle
Forms most of the FLAT BONES of the skull & clavicles
Endochondral Ossification begins in the
2nd month of development
List the fetal primary ossification centers
-parietal, occipital, frontal bone of the skull
-Mandible
-Clavicle
-scapula
-ribs
-vertebra
-ilium
-femur
-tibia
-humerus
-radius
-ulna
Stage 1 of endochondral ossification
Formation of bone collar around hyaline cartilage model
Stage 2 of E.O.
Cavitation of the hyaline cartilage
Stage 3 of E.O.
Invasion of internal cavities by the periosteal bud and spongy bone formation
Stage 4 of E.O.
Formation of the medullary cavity; appearance of SECONDARY ossification center in the EPIPHYSES in prep for stage 5
Stage 5 of E.O.
ELONGATION Ossification of the epiphyses; when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages
What are the remodeling units?
Adjacent osteoblasts and osteoclasts deposit and resorb bone at periosteal & endosteal surfaces
Wolff’s law observations
- Long bones are thickest midway along the shaft (bending stress is great)
- Curved bones are thickest (most likely to buckle)
- Trabeculae form along lines of stress (proximal femur)
- Large bony projections occur where heavy active muscles attach (adductor tubercles, medial part of distal femur)
The increase in the mobility and potential size of the pelvis during childbirth is due to
Estrogen, Testosterone, Relaxin
During infancy and childhood, epiphyseal plate activity is stimulated by
GROWTH HORMONE
During puberty, testosterone and estrogens initially promote
ADOLESCENT GROWTH SPURTS
Later induce epiphyseal plate closure, ending long bone growth
Type of cartilage which provides support, flexibility, resilience and usually found in the ends of long bone
Hyaline cartilage
Type of collagen found in bone
Type 1
Type of cartilage growth wherein the cells in the perichondrium secrete matrix against the face of existing cartilage
Appositional
Unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen becomes calcified later
OSTEOID
MSCs that divide to produce osteoblasts
Osteoprogenitor cells
Sites of bone resorption where ruffled border meets bone surface
Howship’s lacunae
How are osteoclasts formed?
Monocyte progenitors fuse together to form mature multinuclear cells
System of lacunar networks used among osteocytes to communicate
Canaliculi (??)
Mesenchymal cells differentiate into
Osteoblasts, chondrocytes, myocytes, adipocytes
This zone is characterized by proliferation of chondrocytes w/ longitudinal growth stacking of chondrocytes
Proliferative zone
Region of the physis that collagen type X play a prominent role
Hypertrophic zone
The red marrow is composed of
40% fat (??)
When does bone appear?
7th embryonic week
Type of collagen predominantly present in elastic cartilage
Type 2
Area between the pelvic inlet and the pelvic outlet
Pelvic cavity
The typical female pelvis present in about 41% of women
Gynecoid
It is the male or funnel shaped pelvis w/ a contracted outlet. Present in about 33% of white females and 16% of Black females
Android type
Long, narrow, oval shaped pelvis present in about 24% of white females and 41% of black females.
Anthropoid
Wide pelvis flattened at the brim, with the promontory of the sacrum pushed forward.
Platypelloid type
The two hip bones articulate with each other anteriorly at the
Symphysis pubis
The two hip bones articulate posteriorly with the sacrum at the
Sacroiliac joints
The pelvic brim is formed behind by the
Sacral promontory (anterior and upper margin of the first sacral vertebra)
Pelvic brim, laterally by the
Iliopectineal lines (line that runs downward and forward around the inner surface of the ileum)
Pelvic brim, anteriorly by the
symphysis pubis (Joint between bodies of pubic bones)
