The Skeletal System Flashcards
What is the skeleton composed of
- Connective tissue
*Bone; compact & spongy bone,
*Cartilage; hyaline, elastic & fibrocartilage
Cartilage
- Embedded in chondroitin sulphate, composed of chondrocytes
- Occur singly or in groups (lacunae), matrix contains translucent proteins
- No nerves, blood or lymphatic vessels
- Collagen & elastin fibres
- “CHONDRO..” - refers to cartilage
Bone
- Mainly CaPO4 & CaCO3
- Contains nerves, blood & lymphatic vessels
- Compact & spongy bone
Composes all connective tissue
Mesenchymal, cells & fibres in ground substance
Functions of bone
- Shape
- movement
- protection
- blood cell production - bone marrow in some bones produce RBCs & WBCs
- mineral reservation
List the 5 major types of bone based on shape
- Long bones
- Short bones
- Flat bones
- Irregular bones
- Sesamoid bones
Long bones
- greater in length than width
- e.g. femur, radius
Short bones
- approx. equal in length & width
- e.g. carpal & tarsal
Flat bones
-flat & thin, greater area for muscle attachment protection
-e.g. scapula, cranial bones, ribs
Functions of Cartilage
- forms embryonic skeleton
- covers ends of bones for protection
- cushions joints
- joins some bones for support & flexibility
Irregular bones
- Complex shapes
- e.g. vertebrae, some facial bones
Sesamoid bones
- Bones within ligaments or tendons
- E.g patella
- Bones that develop in tendon from stress - protect tendons
Bone that develops within tendons or ligaments due to stress
sesamoid bone
What forms the embryonic skeleton
Cartilage
What provides cushioning & flexibility in joints
cartilage
List the three types of cartilage
hyaline, elastic, fibrocartilage
where is the strongest type of cartilage present
- high stress points of the body
where is cartilage present
lacuna/lacunae
Cell types in bone
- Ostogenesis cells
- Osteoblasts
- Osteocytes
- Osteoclasts
Ostogenesis cells
- Specializes/divides & replaces itself to become osteoblasts to begin the formation of bone matrix
Osteoblasts
- Produced by osteogenesis cells to form matrix & collagen fibres (extracellular matrix)
- Also produces CaCO & CaPO4, secretes osteoid
- Does not divide
Osteocytes
- Developed from osteoblasts
- Mature “living” bone cells that no longer secrete matrix & do not divide
- maintains bone tissue
- Involved in metabolic activity
- Resides in pockets of calcified bone matrix (lacunae)
Osteoclasts
- resorption = breaks down bone extraceullar matrix
- secrets acids & protein digesting enzymes to dissolve bone matrix & release stored minerals
“CHONDRO-“
Cartilage
“OSTEO-“
Bone
“genesis-“
creation
“Osteo-“ + “Genesis” = osteogenesis
Osteoclast resorption
breaks down bone matrix by secreting acids & protein digesting enzymes to dissolve bone matrix & release stored minerals
Osteoid
- Unmineralized portion of bone
- Secreted by osteoblasts
- Form foundation for new bone tissue
Structure of long bone
- head = proximal epiphysis
- Between both epiphysis ends & shaft = metaphysis
- shaft = diaphysis
- end = distal epiphysis
Diaphysis
- Shaft of long bone
Epiphysis/epiphysial line
- Long bone
- Region where bone grew in length
- Between proximal epiphysis & metaphysis
Metaphysis
- Long bone between shaft & proximal epiphysis & between shaft & distal epiphysis
Articular cartilage
- covers & protects end of bone
*in proximal epiphysis
Periosteum
- tough membrane that covers outer surface of the long bone
- contains cells involved in bone formation & maintenance & blood vessels for bone nourishment
- osteogenic inner layer & fibrous outer layer
Medullary cavity
- Cavity shaft of long bone
- Contains blood vessels & a storage area for fat = yellow bone marrow
endosteum
- Thin membrane that lines medullary cavity
- Contains cells involved in bone formation & maintenance
- In diaphysis (shaft)
Two types of bone
spongy & compact
Compact bone - structure
- Organized & strong
- Forms hard layer of bone in shaft of long bones & external layer of bones
- Contains yellow bone marrow for storage of fat (triglycerides)
- Contains osteons (Haversian system)
Osteon
- Concentric rings (lamellae) of calcified matrix
- Surrounds vertically oriented blood vessel (Haversian system)
- Contains lacunae & canaliculi
canacliculi
osteocytes use communicate, filled with extracellular fluid that connect one cell to another
Spongy bone - structure
- Less organized compared the compact bone
- Thick plates of bone (trabeculae) oriented along lines of stress
- Spaces in trabeculae filled with red bone marrow (formations of red bloods cells)
- Found in ends of long bones & inside flat bones
Two types of ossification (bone formation)
- Intramembranous ossification
- Endochondrol ossification
Intramembranous ossification
- Bone formed directly on or within fibrous membranes
- Simpler, forms flat bones of skull, parts of mandible & clavicle
Endochondral ossification
- Bone is formed in cartilage which is covered by perichondrium membrane, invaded by blood vessels, osteoblasts are formed starting the process of formation of compact bone
- More complex, most bones in the body
- “ENDO” - Inside
- “CHONDRO” - cartilage
The process of intramembranous ossification
- Development of ossification centre
- Calcification
- Formation of trabeculae (spongy bone)
- Development of periosteum
Intramembranous ossification - development of ossification
- Mesenchymal (stem) cells turn into chondrocytes or osteocytes
- Clusters of osteoblasts secret matrix
Intramembranous ossification - calcification
- Osteoblasts differentiate into osteocytes
- Formation of lacuna & canaliculi
- Deposition of minerals (calcium & phosphorus) in matrix
Intramembranous ossification - Formation of trabeculae (spongy bone)
- Osteoid is laid down between embryonic blood vessels, forming trabeculae
Intramembranous ossification - development of periosteum
- Outer layer of compact bone outside of spongy bone
- spongy layer remains sandwiched between compact bone layers
Process of endochondral ossification
Bones Can’t Pop During Exercise
1. Bone collar formation
2. Cavitation
3. Periosteal Bud invasion
4. Diaphysis Elongation
5. Epiphyseal Offisifation
How is the medullary cavity developed
By bone resorption through osteoclasts
List the primary factors affecting ossification
- Nutrition
- Heredity
- Hormones
Define Ossification
Process of bone formation
Where does bone growth in length occur
Epiphyseal plate
How does the bone growth in length
- Four zones at the epiphyseal plate (RPHC)
1. Zone of resting cartilage
2. Zone of proliferating cartilage
3. Zone of hypertrophic cartilage
4. Zone of calcified cartilage - At the end of growing, epiphyseal plates become ossified
- epiphyseal plate becomes epiphyseal lines
Four zones at the epiphyseal plate in bone growth
- Zone of resting cartilage; no bone growth; functions to anchor cartilage to bone
- Zone of proliferating cartilage; cartilage cells divide & secret extracellular matrix
- Zone of hypertrophic cartilage; mature cartilage cells become enlarged
- Zone of calcified cartilage; dead cartilage cells have been calcified; osteoclasts dissolve cartilage; osteoblasts lay down new bone replacing cartilage
What zone in the epiphyseal plate anchors the cartilage to the bone
Zone of resting cartilage
What zone in the epiphyseal plate includes cells that divide & secrete extracellular matrix
Zone of proliferating cartilage
What zone in the epiphyseal plate includes mature cartilage cells that become enlarged
Zone of hypertrophic cartilage
What zone in the epiphyseal plate includes dead cartilage cells have been calcified
Zone of calcified cartilage
How does the bone grow in width
- Periosteum & Endosteum
- Periosteum cells differentiate into osteoblasts, secreting bone matrix becoming osteocytes resulting in wider bone (outside)
- Osteoclasts erode endosteum, releasing calcium into blood stream causing medullary cavity to enlarge (inside)
Components of Axial skeleton
- Skull
- Hyoid bone
- Vertebrae
- Ribs
- Sternum
- Ear ossicles
Functions of axial skeleton
- Protects brain, spinal cord, heart, lungs
- Attachment site for muscles that move head, neck & back
- Stabilizes parts of appendicular skeleton
List the bones of the skull
- Frontal bone (front)
- Parietal bone (back)
- Temporal bone (centre, temples)
- Occipital bone (bottom back)
- Maxilla (upper jaw)
- Mandible (chin/lower jaw)
- Sphenoid bone (behind ethmoid)
- Ethmoid (behind eye)
Bones in the body
206
Hyoid bone
- U shaped structure in anterior neck
Thorax
- Chest region
- Ribs attached to vertebral column at back & sternum in front by hyaline cartilage
Ribs
- 1-7: true ribs
- 8-10: false ribs; attached together by cartilage before joint 7th rib
- 11-12: floating ribs; are not attached to sternum
Divisons of vertebral column
- Cervival vertebrae (7) neck
- Thoracic vertebrae (12) check
- Lumbar vertebrae (5) lower back
- Sacrum (1) pelvis attach
- Coccyx (1) fused bones
(26 bones)
Function of Vertebral Column
- Strength & flexibility
- Protects spinal cord
- Supports skull
- Provides attachment of ribs & muscles
Components of Appendicular skeleton
- Pectoral (shoulder) girdle
- Upper (fore-) limb
- Pelvic (hip) girdle
- Lower (hind-) limb
Functions of appendicular skeleton
- Facilitate movement of body
- Provides shape to arms & legs
- Maintain mineral homestasis
List the bones of the upper limb
(Anterior view)
1.Clavicle (shoulder)
2. Scapula (shoulder blade)
3. Humerus (long bone above elbow)
4. Radius (right forearm)
5. Ulna (left forearm)
6. Carpals (wrist)
7. Metacarpals (palm)
8. Phalanges (fingers)
List the bones of the lower limb
(Anterior view)
1. Hip bone
2. Sacrum (medial to hip bone)
3. Femur (hip - knee)
4. Patella (anterior knee)
5. Tibia (left shin)
6. Fibula (right shin)
7. Tarsals (ankle)
8. Metatarsals (flat part of foot)
9. Phalanges (toes)
Enlarged tarsal bone which forms heel
calcaneus
C1 & C2 Vertebrae
C1 - Atlas (top of vertebrae)
C2 - Axis
Atlas vs axis complex (vertebrae)
Atlas - supports head, ring shaped bone with no centrum, reduced spinous process
Axis - peg shaped (dens) projected upward, allows for side to side movement, reduced transverse processes, longer spinous process than atlas
Between the atlas & axis of the vertebrae which one has a longer spinous process
Axis
Two bones of pectoral (shoulder) girdle
Clavicle & sacpula
Three fused bones in the hip bone
- Ilium (“butterfly” wings)
- Ischium (posterior)
- Pubis (anterior)
Male vs. female pelvis bones
Male;
- heavier, narrow
- smaller opening, funnel-shaped
- more anterior curvature
- Narrower sciatic notch
Female;
- Broader, lighter, smoother
- larger opening, more circular (child bearing)
- Less anterior curvature
- Broader sciatic notch
