Bones & Skeletal Tissues Flashcards
Cartilage
- Specialized, resilient, avascular connective tissue
- Surrounded by perichondrium (dense irregular CT)
- composed of 60-80% water, chondrocytes and much ECM
Types of Cartilage
- Hyaline - most abundant, costal, ends of long bones, nose, trachea, larynx
- Elastic - tolerates repeated bending, external ear and epiglottis** **
- ** Fibrocartilage** - resists strong compression/tension, in intervertebral discs, knee joint discs and pubic symphisis
Cartilage Growth
- 2 Types:
- Interstitial - from within, chondrocytes mitosize, separate into own lacunae, stops after cartilage matures
- Appositional - stem cells along perichondrium divide into chondroblasts which produce new ECM and eventually become chondrocytes in new lacunae
Bones
- Organs made up of bone tissue, nervous tissue, blood tissue with cartilage and epithelium in blood vessels
Perichondrium
Dense irregular connective tissue surrounding cartilage
Bone Functions
- Support - framework for body
- Movement - levers for muscles
- Protection - encasing organs (ex: ribcage)
- Mineral Storage
- Erythropoeisis (red marrow)
- Fat storage (yellow marrow)
4 Classes of Bones
- Long (femur, humerus, phalanges, etc.)
- Short (sesamoid, carpals, tarsals, etc.)
- Flat (sternum, cranial bones, ribs, etc.)
- Irregular (vertebrae, ethmoid, sphenoid, etc.)
of Bones in Adult Skeleton
206
Sesamoid Bones
Special type of short bone that forms within a tendon (ex: patella)
Compact Bone
Dense external layer of bones that looks smooth and solid
Spongy Bone
AKA trabecular bone
- lies deep to compact bone and appears like a honeycomb of thin, flat pieces called trabeculae, between which is red and yellow marrow
- contains no osteons
Diaphysis
- tubular body of long bones
- AKA shaft
Epiphysis
- ends of long bones
Metaphysis
Region between epiphysis and diaphysis where growth occurs
Epiphyseal Plate
Layers of hyaline cartilage that lengthen the diaphysis as the bone grows
- AKA growth plate
Epiphyseal Line
- a thin layer of compact bone in adult long bones where the epiphyseal plate used to be
Articular Cartilage
- thin layer of hyaline cartilage covering the joint surfaces of the epiphysis
Medullary Cavity
the center of long bone diaphyses filled with yellow marrow
AKA marrow cavity
Periosteum
connective tissue membrane covering entire outer surface of bones (except articular cartilage)
consist of superficial dense irregular CT layer and osteogenic deep layer
Endosteum
thinner osteogenic CT membrane covering internal bone surfaces
Red Marrow
site of erythropoiesis within bone
Yellow Marrow
Site of fat storage within bone
Nutrient Vein & Artery
Main blood vessels serving diaphysis
Epiphyseal Vein & Artery
Main blood vessels serving the epiphysis
Differences in Short, Irregular and Flat Bone Structure
- no diaphysis or epiphysis
- no marrow cavity (marrow only among the trebaculae)
Diploë
internal spongy bone of flat bones
Difference Between Bone and Cartilage Structure
- Same organic components (cells, fibers, ground substance) but bone has hardened inorganic components in its matrix (primparily calcium phosphate and hydroxyapatite crystals
Osteoprogenitor Cells
- Flat mesenchymal cells that divide & differentiate into osteoblasts
Osteoblasts
- peripherally located immature bone cells
- actively produce and secrete organic componoents of bone matrix (osteoid) at their surface
Osteocytes
- mature bone cells that exist within lacunae
- formed with osteoblasts are surrounded by new matrix
- less synthetic ability than osteoblasts, mostly act to maintain existing matrix
Osteoclast
- large, branched mutinucleate motile cells
- perform bone remodeling, renewal and resorption by secreting HCl and lysosomal enzymes
- exist on bone surface at the peri- and endosteums
Osteoid
Newly formed bone matrix synthesized by osteoblasts
Osteons
- AKA Haversian Systems
- long, cylindrical structures parallel to bone’s axis made of concentric tubes
Lamella
one of the concentric tubes making up an osteon or one of the circumferential tubes around the outer or inner edge of compact bone
Central Canal
AKA Haversian Canal
An osteogenic endostium-lined canal in the middle of each osteon that contains blood vessels and nerve fibers
Perforating Canals
AKA Volkmann’s Canals
Canals that run perpendicular to central canals connecting nerve and blood supplies of the periosteum, central canals and marrow cavity
Canaliculi
thin tubes within osteons in which osteocytes have long narrow cytoplasmic extensions that connect with neighboring cells via gap junctions
external/interneal circumferential lamellae
- lamellae around the circumference of the diaphysis and marrow cavity
interstitial lamellae
remains of old osteons that have been cut through by bone remodleing and appear as incomplete osteons between the new ones
Ossification
AKA osteogenesis
formation and development of bone
Intramembranous Ossification
- develops from mesenchyme to produce flat bones of skull, facial bones, mandible and some of clavicle
Endochondral Ossification
Bone develops from within hyaline cartilage
Appositional Bone Growth
- growth by addition to a bone’s surface, causing growth in diameter
Interstitial Bone Growth
Growth in bone length
Four Categories of Bone Markings
- Articulating Surfaces
- Depressions
- Projections
- Openings and spaces
Condyle
Large, smooth, rounded articulating oval structure
(ex: occipital condyles, medial condyle of femur)
Facet
Small, flat, shallow articulating surface
Head
Prominent, rounded epiphysis
(ex: proximal femur, proximal radius, distal ulna)
Trochlea
Smooth, grooved, pulley-like articular process
(ex: trochlea of (distal) humerus)
Alveolus
Deep pit or socket in the maxilla or mandible (where teeth articulate with jaws)
Fossa
Flattened or shallow depression
(ex: iliac fossas of ossa coxae)
Sulcus
Narrow groove
(ex: intertubercular sulcus of humerus)
Crest
Narrow, prominent ridglike projection
(ex: iliac crest of os coxae)
Epicondyle
Projection adjacent to a condyle
(ex: medial and lateral epicondyles of distal femur)
Line
Low ridge
Process
Any marked bony prominence
(ex: zygomatic process of temporal bone)
Ramus
Angular extension of a bone relative to the rest of its structure
(ex: ramus of mandible)
Spine
- Pointed, slender process
(ex: spinous processes of vertebrae, iliac spines of ossa coxae)
Trochanter
Massive, rough projection found only on femur
(ex: greater and lesser trochanter of femur)
Tubercle
Small, round projection
(ex: greater and lesser tubercles of (proximal) humerus)
Tuberosity
Large, rough projection
(ex: deltoid tuberosity of humerus, ischial tuberosity of oss coxae)
Canal
AKA Meatus, a passageway through a bone
(ex: internal and external acoustic meatuses of temporal bones)
Fissure
Narrow slit-like opening through a bone
(ex: inferior orbital fissure of skull between sphenoid and maxilla bones)
Foramen
Rounded passageway through a bone
(ex: foramen magnum of occipital bone, obturator foramen of oss coxae)
Sinus
Cavity or hollow space in a bone
(ex: ethmoid sinuses)
Bone Aging
- As bone ages it loses ability to produce its organic matrix (collagen) and loses calcium and other salts
- this can result in osteoporosis, a decrease in bone density
Perforating Fibers
AKA Sharpey’s fibers
Thick collagen bundles running from periosteum into bone matrix
