PPT Notes Chapter 6 Flashcards
Skeletal cartilages contain no __ or __
blood vessels or nerves (avascular)
Define: perichondrium
dense connective tissue girdle that contains blood vessels for nutrient delivery to cartilage
peri-
around
Chondr-
cartilage
Name the 3 types of skeletal cartilages
- Hyaline -provide support, flexibility and resilience -most abundant
- Elastic -similar to hyalin, but contains elastic fibers (pinna of ear)
- Fibrocartilage -collagen fibers -> have great tensile strength (intervertebral disc)
2 types of cartilage growth
- Appositional -cells secrete matrix against the external face of existing cartilage
- Interstitial -chondrocytes divide and secrete new matrix, expanding cartilage from within
calcification of cartilage occurs during (2)
- -normal bone growth
- -old age
Name the two groups of skeleton
- -Axial
- -Appendicular
The appendicular skeleton is attached to the axial skeleton by which two girdles?
- -pectoral
- -pelvic
Define: Long bones
longer than they are wide
-Humerus, Femur, Tibia, Fibia, etc
Define: Short bones; two examples
wide as they are long
- -cube shaped bones in wrist and ankle
- -sesamoid bones (within tendons, eg patella)
Define: Flat bones
Thin, flat, slightly curved
-ribs, cranial bones
Define: Irregular bones
Complicated shapes
-sternum
Name the 6 functions of bones
- Support -for the body and soft organs
- Protection -for brain, spinal cord and vital organs
- Movemment -acts as levers for muscle action
- Storage -Minerals (calcium, phosphorus) and growth factors
- Blood cell formation-hematopoiesis in marrow cavities
- Triglyceride (energy/fat) storage in bone cavities
Define: Bone markings
Bulges, depressions and holes that serve as
- -sites of attachment for muscles, ligaments and tendons
- -joint surfaces
- -conduits for blood vessels and nerves
Name the 8 bone marking projections that serve as sites of muscle and ligament attachment
PECSTTTL
- Process
- Epicondyle
- Crest
- Spine
- Tuberosity
- Trochanter
- Tubercle
- Line
Tuberosity
rounded projection eg tibial tuberosity
Crest
narrow, prominent ridge eg iliac crest
Trochanter
large, blunt, irregular surface eg greater and lesser trochanters of the femur
- Trochanter is only found in the femur
Line
narrow ridge of bone eg intertrochanteric line similar to crest, but less prominent
Tubercle
small, rounded projection eg supraglenoid tubercle
Epicondyle
raised area above a condyle eg lateral epicondyle of humerus can be found any place where two bones touch
Spine
sharp, slender projection eg ischial spine
Process
any bony prominence eg spinous process
Name the 4 bone marking projections that help to form joints
HFCR
- Head
- Facet
- Condyle
- Ramus
Head
bony expansion carried on a narrow neck eg femoral head (ball carried on narrow neck)
Facet
Smooth, nearly flat articular surface eg superior articular facet of vertebrae
Condyle
Rounded articular projection eg lateral and medial condyle of the distal femur
- condyle=knuckle
Ramus
armlike bar of bone eg ramus of the mandible
Name the 3 bone markings that are depressions and openings that serve for passage of blood vessels and nerves
GFF
- Groove
- Fissure
- Foramen
Groove
Furrow eg mandibular groove
Fissure
Narrow, slit-like opening eg inferior orbital fissure of the eye socket
Foramen
round or oval opening through a bone eg vertebral foramen
Name the 3 other bone markings found on bones
MSF
- Meatus
- Sinus
- Fossa
Meatus
Canal-like passageway eg meatus in skull
Sinus
Cavity within a bone eg maxillary sinus
Fossa
Shallow, basin-like depression eg glenoid fossa
- Often serves as an articular surface
Name the two types of bone textures
- Compact bone - dense outer layer
- Spongy (cancellous) bone - honeycomb of trabeculae
What kind of bone is a diaphysis found in?
Long bone
What is the diaphysis
shaft of a long bone; compact bone collar that surrounds the medullary cavity
What does the medullary cavity in adults contain?
fat
What kind of bone is an epiphyses found in?
Long bone
Name the 4 characteristics of the epiphyses
- Expanded ends
- Spongy bone interior
- Epiphyseal line (remnant of growth plate)
- Articular (hyaline) cartilage on joint surfaces
What are the two bone membranes?
- Periosteum
- Endosteum
Sharpey’s fibers
Fiber that secures periosteum to underlying bone
Name the 4 characteristics of the periosteum
Outer fibrous layer
Inner osteogenic layer
- -osteoblasts (bone building cells)
- -osteoclasts (bone killing cells)
- -osteogenic cells (stem cells)
Nerve fibers, nutrient blood vessels and lymphatic vessels enter the bone via nutrient foramina
Secured to underlying bone by Sharpey’s fibers
Name the 2 characteristics of the endosteum
- Delicate membrane on internal surfaces of bone
- Also contains osteoblasts/clasts
Structure of Short, Irregular and Flat bones
Periosteum-covered compact bone on outside
Endosteum-covered spongy bone within
Spongy bone called diploe in flat bones
Bone marrow between the trabeculae
Location of Hematopoeitic tissue in adults (red bone marrow)
Trabecular cavities of:
- the heads of the femur and humerus
- the diploe of flat bones
Location of Hematopoeitic tissue of newborn infants (red marrow)
medullary cavities and all spaces in spongy bone
Cells of bones
Osteogenic (osteoprogenitor) cells
- Stem cells in periosteum and endosteum that give rise to osteoblasts
Osteoblasts
- Bone-forming cells
Osteocytes
- Mature bone cells
Osteoclasts
- Cells that break down (resorb) bone matrix
Anatomy of Compact bone
Haversian system, or osteon—structural unit
Lamellae
- Weight-bearing
- Column-like matrix tubes
Central (Haversian) canal
- Contains blood vessels and nerves
Perforating (Volkmann’s) canals
At right angles to the central canal
Connects blood vessels and nerves of the periosteum and central canal
Lacunae—small cavities that contain osteocytes
Canaliculi—hairlike canals that connect lacunae to each other and the central canal (cracks)
Anatomy of spongy bone
Trabeculae
- Align along lines of stress
- No osteons
- Contain irregularly arranged lamellae, osteocytes, and canaliculi
- Capillaries in endosteum supply nutrients
Chemical Composition of Bone: Organic
Osteogenic cells, osteoblasts, osteocytes, osteoclasts
Osteoid—organic bone matrix secreted by osteoblasts
- Ground substance (proteoglycans, glycoproteins)
- Collagen fibers
- Provide tensile strength and flexibility
Chemical Composition of Bone: Inorganic
Hydroxyapatites (mineral salts)
- 65% of bone by mass
- Mainly calcium phosphate crystals
- Responsible for hardness and resistance to compression
Bone Development
Osteogenesis (ossification)—bone tissue formation
Stages
- Bone formation—begins in the 2nd month of development
- Postnatal bone growth—until early adulthood
- Bone remodeling and repair—lifelong
Two Types of Ossification
Intramembranous ossification
- Membrane bone develops from fibrous membrane
- Forms flat bones, e.g. clavicles and cranial bones
Endochondral ossification
- Cartilage (endochondral) bone forms by replacing hyaline cartilage
- Forms most of the rest of the skeleton
Endochondral Ossification
Uses hyaline cartilage models
Requires breakdown of hyaline cartilage prior to ossification
Postnatal Bone Growth
Interstitial growth: increase length of long bones
Appositional growth: increase thickness and remodeling of all bones by osteoblasts and osteoclasts on bone surfaces
Growth in Length of Long Bones
Epiphyseal plate cartilage organizes into four important functional zones:
- Proliferation (growth)
- Hypertrophic
- Calcification
- Ossification (osteogenic)
Hormonal Regulation of Bone Growth
Growth hormone stimulates epiphyseal plate activity
Thyroid hormone modulates activity of growth hormone
Testosterone and estrogens (at puberty)
- Promote adolescent growth spurts
- End growth by inducing epiphyseal plate closure
Bone Deposit
- Occurs where bone is injured or added strength is needed
- Requires a diet rich in protein; vitamins C, D, and A; calcium; phosphorus; magnesium; and manganese
Sites of new matrix deposit are revealed by the:
Osteoid seam
Unmineralized band of matrix
Calcification front
The abrupt transition zone between the osteoid seam and the older mineralized bone
Bone Resorption
Osteoclasts secrete
- Lysosomal enzymes (digest organic matrix)
- Acids (convert calcium salts into soluble forms)
Dissolved matrix is transcytosed across osteoclast, enters interstitial fluid and then blood
What 2 things control the continual remodeling of bone?
- Hormonal mechanisms that maintain calcium homeostasis in the blood
- Mechanical and gravitational forces
Hormonal Control of Blood Ca2+
Calcium is necessary for:
- Transmission of nerve impulses
- Muscle contraction
- Blood coagulation
- Secretion by glands and nerve cells
- Cell division
Primarily controlled by parathyroid hormone (PTH) ->Paul Revere that rounds up osteoclasts
Decrease in Blood Ca2+ levels leads to:
- Parathyroid glands release PTH
- PTH stimulates osteoclasts to degrade bone matrix and release Ca2+
- RESULT: Increase Blood Ca2+ levels
May be affected to a lesser extent by calcitonin (Tone down calcium levels)
Increase in Blood Ca2+ levels leads to:
- Parafollicular cells of thyroid release calcitonin
- Osteoblasts deposit calcium salts
- Decrease Blood Ca2+ levels
- Leptin has also been shown to influence bone density by inhibiting osteoblasts
Response to Mechanical Stress (The Grey)
Wolff’s law: A bone grows or remodels in response to forces or demands placed upon it
Observations supporting Wolff’s law:
- Handedness (right or left handed) results in bone of one upper limb being thicker and stronger
- Curved bones are thickest where they are most likely to buckle
- Trabeculae form along lines of stress
- Large, bony projections occur where heavy, active muscles attach
4 either/or Classifications of Bone Fractures
Bone fractures may be classified by four “either/or” classifications:
1) Position of bone ends after fracture:
- Nondisplaced—ends retain normal position
- Displaced—ends out of normal alignment
2) Completeness of the break
- Complete—broken all the way through
- Incomplete—not broken all the way through
3) Orientation of the break to the long axis of the bone:
- Linear—parallel to long axis of the bone
- Transverse—perpendicular to long axis of the bone
4) Whether or not the bone ends penetrate the skin:
- Compound (open)—bone ends penetrate the skin
- Simple (closed)—bone ends do not penetrate the skin
Common Types of Fractures
All fractures can be described in terms of:
- Location
- External appearance
- Nature of the break
Stages in the Healing of a Bone Fracture
1) Hematoma forms
- Torn blood vessels hemorrhage
- Clot (hematoma) forms
- Site becomes swollen, painful, and inflamed
2) Fibrocartilaginous callus forms
- Phagocytic cells clear debris
- Osteoblasts begin forming spongy bone within 1 week
- Fibroblasts secrete collagen fibers to connect bone ends
- Mass of repair tissue now called fibrocartilaginous callus
3) Bony callus formation
- New trabeculae form a bony (hard) callus
- Bony callus formation continues until firm union is formed in ~2 months
4) Bone remodeling
- In response to mechanical stressors over several months
- Final structure resembles original
Homeostatic Imbalances
Osteomalacia and rickets
- Calcium salts not deposited
- Rickets (childhood disease) causes bowed legs and other bone deformities
- Cause: vitamin D deficiency or insufficient dietary calcium
Osteoporosis (Holey bone disease)
- Loss of bone mass—bone resorption outpaces deposit
- Spongy bone of spine and neck of femur become most susceptible to fracture
Risk factors
- Lack of estrogen, calcium or vitamin D; petite body form; immobility; low levels of TSH; diabetes mellitus
Osteoporosis: Treatment and Prevention
- Calcium, vitamin D, and fluoride supplements
- Increase Weight-bearing exercise throughout life
- Hormone (estrogen) replacement therapy (HRT) slows bone loss
- Some drugs (Fosamax, SERMs, statins) increase bone mineral density
Paget’s Disease
Excessive and haphazard bone formation and breakdown, usually in:
- spine, pelvis, femur, or skull
Pagetic bone has very high ratio of spongy to compact bone and reduced mineralization
- Unknown cause (possibly viral)
- Treatment includes calcitonin and biphosphonates
The Axial Skeleton
- Consists of 80 bones
Three major regions:
- Skull
- Vertebral column
- Thoracic cage
Appendicular Skeleton
Bones of the limbs and their girdles
- Pectoral girdle attaches the upper limbs to the body trunk
- Pelvic girdle secures the lower limbs
Pectoral Girdle (Shoulder Girdle)
Clavicles and the scapulae
- Attach the upper limbs to the axial skeleton
- Provide attachment sites for muscles that move the upper limbs
Pelvic (Hip) Girdle
Two hip bones (each also called coxal bone or os coxae)
- Attach the lower limbs to the axial skeleton with strong ligaments
- Transmit weight of upper body to lower limbs
- Support pelvic organs
Each hip bone consists of three fused bones:
- ilium
- ischium
- pubis
Together with the sacrum and the coccyx, these bones form the bony pelvis
