Skeletal System Flashcards
What are the functions of the skeletal system?
Support, movement, protection, mineral storage (calcium) , Hematopoesis (Blood cell formation)
What does the axial skeleton consist of?
80 bones that make up central axis along midline (skull, vertebrae, thoracic cage)
How many bones in the skull?
29
How many vertebrae?
26
How many bones make up the thoracic cage?
24 ribs and 1 sternum
What does the Appendicular skeleton consist of?
126 bones that make up the limbs and girdles that attach the limbs to the axial skeleton (pectoral girdle and pelvic girdle)
Long bone
Expanded ends called epiphysis, central shaft called diaphysis. Examples include humerus, tibia, fibula, ulna, phalanges, etc
Short bone
box shaped (carpals and tarsals)
Flat bone
broad surface (scapula, clavicle, frontal, ribs, sternum, etc)
Sesamoid bone
bones embedded within tendons (patella is largest example, most are small bones in palmar and plantar regions)
Irregular Bone
Complex shape not long, short or flat (vertebrae, hyoid, temporal, maxillae, mandible, etc)
What makes up the matrix of osseous tissue?
Osteoid and hydroxyapetite
Osteoid
Provides flexibility and tensile strength to resist stretching (osseous tissue)
Hydroxyapetite
Gives bones its hardness and ability to resist compression
What cells can you find in osseous tissue?
Osteogenic cells, osteoblasts, osteocytes, and osteoclasts
Osteogenic cells
Stem cells that produce osteoblasts
Osteoblast
Bone-forming cells found on inner and outer surfaces
Osteocytes
Mature bone cells found in lacunae connected by canaliculi
Osteoclast
Bone-destroying cells, break down the matrix to release minerals
Compact bone
Superficial layer of bones, dense, appears smooth and solid, consists of multiple osteon
Osteon
Consists of concentric lamellae surrounding central canal that runs parallel to the axis of a long bone is lined with endosteum and contains blood vessels and nerves
Lamellae
Plates of osseous tissue
Concentric lamellae
surround the central canal forming osteons
Interstitial lamellae
wedged between osteons
Circumferential lamellae
surrounding the outer and inner edges of compact bone
Perforating canal (Volkmann’s)
runs perpendicular to axis of long bone connecting central canals to the periosteum and medullary cavity. Lined with endosteum, contains blood vessels and nerves.
Spongy Bone (trabecular)
Deep layer of bone, surrounds medullary cavity in the diaphysis of long bones and fills epiphysis of long bones, consists of trabeculae with many open spaces (trabecular cavities)
Trabeculae
Mesh of small branching plates
Epiphysis
Expanded end of long bone, composed mostly of spongy bone, contains red marrow
Diaphysis
tube-shaped central shaft of long bone, contains thick outer layer of compact bone
Epiphyseal plate
disc of hyaline cartilage at the epiphysis-diaphysis junction, allows bone to grow in length, ossifies at end of puberty to become epiphyseal line (compact bone)
Articular cartilage
Covers external surface of epiphyses, structure similar to hyaline cartilage, decreases friction at joint surfaces
Medullary cavity
Deep within the diaphysis, contains, red (blood cell formation more in infants than adults) and yellow bone marrow (mostly fat)
Periosteum
Outside membrane covering diaphysis, richly supplied w blood vessels, contains outer layer of fibrous CT and inner cellular layer of osteogenic cells
Endosteum
Membrane lining the medullary cavity, the trabeculae of spongy bone, and canals of compact bone, sontains osteogenic cells and osteoclasts.
What is ossification?
The formation of bone from another tissue
Intramembranous ossification
Bone develops within a fibrous membrane *Examples- parietal, frontal, part of occipital, part of mandible, part of clavicles, patella
Endochondral ossification
Hyaline cartilage is replace by bone *Examples- All other bones includes all long bones, short bones, most irregular, some flat bones (ribs, sternum, scapula,coxal)
Interstitial/longitudinal growth
increase in length of long bone *chondrocytes on epiphyseal side divide (zone of proliferation), older chondrocytes closer to diaphysis calcify and die, osteoclasts breakdown calcified matrix, osteoblasts deposit new bone from diaphysis side (zone of ossification)
Closure of epiphyseal plate
At maturity chondrocyte division slows and osteoblasts catch up, plate completely ossifies and becomes epiphyseal line
Appositional growth
growth in thickness (width) *Osteoblasts deposit bone to the outer surface below the periosteum, osteoclasts remove bone from the inner surface, enlarging the medullary cavity
Bone remodeling
occurs throughout one’s life, involves both new bone formation (osteoblast activity) and bone reabsorption (osteoclast activity)
Why does bone remodeling occur?
Maintain proper proportions, repair injured bone or increase bone strength, mechanical stress( bones adapts to loads under which it is placed) and hormonal control (PTH is released from parathyroid glands when calcium is too low, PTH activates osetoclasts to breakdown bone matrix releasing calcium)
Osteoporosis
Disease characterized by a decrease in bone mass that occurs when the rate of bone reabsorption exceeds the rate of bone formation as the body ages *osteoclast activity out paces osteoblast activity, results in porous bones that are light and fragile
Closed (simple) fracture
A fracture in which the skin remains intact
Compound (open) fracture
A fracture in which at least one end of the broken bone tears through the skin (carries high risk of infection)
Transverse fracture
Occurs straight across the long axis of the bone
Oblique fracture
Occurs at an angle that is not 90 degrees
Spiral fracture
Bone segments are pulled apart as a result of a twisting motion
Comminuted fracture
Several breaks result in many small pieces between two large segments
Impacted fracture
One fragment is driven into another, usually as a result of compression
Greenstick fracture
A partial fracture in which only one side of the bone is broken
What are the four steps of bone regeneration?
- Formation of fracture hematoma
- Formation of internal and external calli/callus
- Ossification of cartilage
- Remodeling
Process
Bump or projection of the bone (zygomatic process of temporal)
Trochanter
Large rough projection (greater trochanter of femur)
Tubercle
Small rounded projection (Greater and lesser tubercle of humerus)
Crest
Prominent ridge (iliac crest)
Spine
Sharp, slender or pointed process (anterior superior iliac spine)
Head
Prominent rounded articular surface (head of humerus or femur)
Condyle
Smooth rounded articular process
Facet
small, flat articular surface (patellar facet of femur)
Fossa
Shallow depression
Sulcus
Groove
Meatus
Tube shaped canal or passageway
Fissure
Slit like opening, crack
Foramen
Rounded opening for nerves/vessels
Sinus
Cavity within a bone
Neck
Narrowing of the bone below the head
