Skeletal System Part 1
Long bone: examples
femur, tibia, fibula, humerus, radius, ulna, phalanges
Compact bone
- 80% of skeleton - few spaces - make up external layer of all bones - bulk of diaphysis - provides protection, support, resists stresses of weight and movement
Types of cells in Bone Tissue
- osteoblasts - osteocytes - osteoclasts
Diaphysis
- growing between - bone shaft or body - long cylindrical main portion
Epiphyses
- growing over - distal and proximal ends
Microscopic structure of bones
- abundant matrix, widely-spaced cells - 25% water, 25% collagen fibers, 50% mineralized salts - hardness depends on crystallized inorganic salts - flexibility depends on collagen fibers (rods in concrete)
Storage ex.
- bones contain a matrix that contains calcium phosphate - fat stored in yellow bone marrow
Effects of Aging
- cartilage/bone deteriorate - cartilage calcifies (hard/brittle) - articular cartilage may no longer function (osteoarthritis)
Irregular bone: definition
- complex shape (hard to fit into other categories) - varied shapes that permit connections with other bones
Projections for muscle attachment
- crest - spine - trochanter - tubercle - tuberosity
Depressons and Openings
- foamen - fossa - meatus - sinus
Flat bone: definition
- generally thin - 2 parallel surfaces - gives protection and surface area for muscle attachment
Long bone: definition
- longer in length than width - consists of a shaft and a variable number of ends - somewhat curved for strength
Support ex.
- lower limbs support entire body - pelvic girdle supports abdominal cavity
Medullary cavity
- marrow cavity - space within the diaphysis for marrow storage - primarily fatty yellow bone marrow in adults
Short bone: definition
- nearly equally in length and width - somewhat cube shaped
Remodeling...
- old bone replaced by new bone - thickness of bone changes over time - caused by physical use, stress, and strain
Compact bone elements
- osteons - lamellae - central canals - osteocytes - lacunae - canaliculi
In newborns, all marrow is...
- red bone marrow and involved in hemopoiesis - changes from red to yellow as age increases
Metaphyses
- regions on a mature bone where diaphysis joins the epiphyses - growing bones contain an epiphyseal plate - as growth stops, cartilage is replaced by bone (epiphyseal line/disc)
Protection ex.
- skull protects brain - ribs protect heart/lungs
Mineral homeostasis of the skeleton...
- stores minerals (calcium/phosphorus) - release minerals into blood stream on demand to maintain and distribute to certain organs
Endosteum
- thin membrane lining medullary cavity - contains a single layer of bone forming cells
Articular cartilage
- thin, hyaline cartilage covering epiphysis where bones fom joints with other bones - reduces friction/absorbs shock - no perichondium - damage repair limited
Periosteum
- tough sheath of dense irregular connective tissue surrounding bone surface - contains bone forming cells to enable bone to grow in diameter - protects bone, assists in fracture repair, nourishes bone tissue, attachment point for ligaments and tendons
Basic bone anatomy
1. diaphysis 2. epiphyses 3. metaphyses 4. articular cartilage 5. periosteum 6. medullary cavity 7. endosteum
Repair
1. hematoma 2. fibrocatilage callus 3. bony callus 4. remodeling
Types of bone
1. long 2. short 3. flat 4. irregular 5. round
Bone Growth/Development
1. middle of the bone 2. osteoblasts deposit bone 3. bone is reabosrbed by osteoclasts to form a medullary cavity 4. secondary ossification center form in the epiphyses 5. eventually disk ossifies
Functions of the skeleton
1. support for the body 2. protection of soft body parts 3. production of red blood cells 4. storage of minerals and fats 5. permission for flexible body movement
___ bones in the adult human body
206
What is bone length dependent on?
How long the epiphyseal disk remains in active division
Where is the primary ossification center?
Middle of the bone
Foramen
a rounded opening through a bone EX: foramen magnum
Spongy bone
aka cancellous bone - no osteons - have trabeculae (which support/protect bone marrow) - spaces filled with red bone marrow - form most of epiphyses of long bones and narrow rim around medullary cavity of diaphysis - most of bone tissue of short, flat, and irregular bones - lighter weight than compact, moves more easily when pulled by skeletal muscle
Short bone: examples
carpals, tarsals
During prenatal development, most skeleton is...
cartilage
Lacunae
cavities that contain osteocytes around in concentric circles called lamellae
Sinus
cavity or hollow space in the bone EX: frontal sinus
Osteopor. inceases in women due to the reduction of ________ levels in menopause
estrogen
Hematoma
blood escapes from vessels, forms clot; inflamation
Cartilage converts to _____ when mineral salts are added
bone
Comminuted
bone breaks into several fragments
Osteoblasts
bone builders - secrete matrix - don't undergo cell division - trap themselves in their own secretions and become osteocytes
Oblique
bone is broken at an angle
Transverse
bone is broken into two pieces on a tranverse plane
Linear
bone is broken logitudinally but NOT separated into two parts
Processes
bony prominence or knob; often forms a joint with a fossa EX: olecranon process of the ulna
Osteoclasts
break down bone - huge cells from fusion of monocytes - concentrated in the endosteum - release enzymes and acids to digest matrix - called resorption - part of normal development, growth, maturation, and repair of bone
Fracture
break in a bone
Greenstick
break on the outer arc of the bone is incomplete
Simple
broken bone doesn't pierce skin
Compound
broken bone end pierces skin
Impacted
broken ends of bone are wedged into each other
Round bone: definition
circular
Osteons/Haversian systems
circular/cylindrical shaped units of compact bone
Central canals
contain blood vessels and nerves which bring blood to osteocytes
Endochondal ossification
conversion from cartilage to bone
Flat bone: examples
cranial bones, sternum, ribs, scapula
Red bone marrow consists of...
developing blood cells, adipocytes, fibroblasts, and macrophages
Red bone marrow present in...
developing fetuses and some adult bones: pelvis, ribs, sternum, vertebrae, skull, ends of arm and thigh bones
2 main parts of a long bone
diaphysis and epiphysis
Spiral
due to twisting of bone, bone is ragged
Fossa
flattened or shallow surface EX: mandibular fossa
Trabeculae
irregular lattice work of thin columns of bone
Articulation
joining of bones together at a joint, allows movement
Tuberosity
large, roughened process EX: Radial tuberosity of radius
Condyle
large, rounded, articulating knob EX: mandibular condyle
Epiphyseal plate
layer of hyaline cartilage that allows the diaphysis to grow in length
Yellow bone marrow is...
mainly adipose cells with few blood cells
Osteocytes
maintain tissue - maintain daily bone metabolism (exchange of nutrients and waste) - don't undergo cell division
Trochanter
massive process found only on the femur EX: greater/lesser trochanter of femur
Crest
narrow, ridge-like projection EX: Iliac crest of coxal bone
Production of blood cells
occurs in red bone marrow (connective tissue)
Each bone is an ____
organ, composed of bone, cartilage, dense connective, epithelium, adipose, nervous, blood (forming tissue)
By 30, bone reabsorption by osteoclasts exceeds new bone synthesis by ___
osteoblasts
Remodeling
osteoblasts build new compact bone at the periphery; osteoclasts reabsorb the spongy bone and build a new medullary cavity
Bony callus
osteoblasts produce trabeculae of spony bone and convert the fibrocartilage to bone; joins the pieces together
Round bone: example
patella
Head
prominent, rounded, articulating proximal end of a bone EX: head of the femur
Red bone marrow produces...
red blood cells, white blood cells, and platelets through hemopoiesis or hematopoiesis
Production ex.
red bone marrow of fetal bones and certain adult bones produce blood cells
Spine
sharp, slender process EX: Spine of the scapula
Compact/Spongy bone is categorized upon...
size and distribution of spaces
Canaliculi
tiny canals between cells that allow nutrients from the blood to reach all of the cells
Tubercle
small, rounded process EX: Greater Tubercle of humerus
The skeletal system is...
the entire framework of bones and cartilage
Osteology
the study of bone structure and treatment of bone disorders
Lamellae
thin layers (concentric circles around central canals) that form the matrix of osteons
Fibrocartilage callus
tissue repair begins; fibrocartilage fills space between bones; collagen fibers tie the ends of bones together
Perichondrium
tissue that surrounds hyaline and elastic cartilage - has blood vessels in it
Meatus
tubelike passageway through a bone EX: external auditory meatus
Irregular bone: examples
vertebrae, some facial bones
Osteoporosis
weak, thin bone, cause pain and tends to fracture easily - bones more porous, but matrix is harder = brittle - take longer to heal when broken
Articulating surfaces
where bones meet (joints)