Overview of the skeletal system

long bones

most of bones in extremities , appendicular skeleton minus small bones in wrist and ankles, Phalanges, metatarsals, humerus

irregular bones

have all sorts of projection, ex: vertebrae

flat bones

really thin, lightweight, seen in areas of a lot of movement or where we don't want bones to be super heavy.

ex: Sternum, scapula, ribs , and many bones of the skull

short bones

square-shaped bones of the wrists and ankles

sesamoid bones

floating bones, more round

ex: patella

what cartilage makes up the skeleton?

1. hyaline

2. elastic

3. fibrocartilage

4. perichondrium

hyaline cartilage

Most common type of cartilage; it is found on the ends of long bones, ribs, and nose

elastic cartilage

cartilage with abundant elastic fibers; more flexible than hyaline cartilage

fibrocartilage

cartilage that contains fibrous bundles of collagen, for shock absorption and seen between major bones that have to absorb forces

Perichondrium

Dense irregular connective tissue membrane covering cartilage

appositional growth of cartilage

cells in the perichondrium secrete matrix against the external face of existing cartilage

interstitial growth of cartilage

Chondrocytes divide and secrete new matrix, expanding cartilage from within

compact bone

external layer, creates smooth surface to bones

spongy bone

internal layer, filled with trabeculae

yellow bone marrow

fatty tissue found in the medullary cavity of most adult long bones

red bone marrow

produces blood cells, are everywhere in children and in adults are found in flat and irregular bones, heads of femur and humerus

structure of short, irregular, flat bones

1. compact

2. spongy

3. compact

structure of long bones

1. Proximal Epiphysis

2. Diaphysis

3. Distal Epiphysis

proximal and distal epiphysis

have the structure of compact bone then spongy

diaphysis

is compact bone

Epiphyseal line

separation point between diaphysis and epiphysis , only present when bones are done growing in length (adult bones)

epiphyseal plates

Plates which allow for growth of long bone during childhood

Periosteum

Glistening double layered membrane surrounding bone

outer layer of periosteum contains…

dense irregular collagenous connective tissue

inner layer of periosteum contains…

bone cells

endosteum

delicate membrane lining the hollow cavity of the bone, contains same cells are inner periosteum

blood and nerves

Nutrient a. - Travels through the diaphysis and branches to supply bone

Epiphyseal aa. work in a similar way

Nerves travel with aa. (neurovascular bundle)

osteoprogenitor cells

bone stem cells

Osteoblasts

responsible for bone growth, matrix synthesizing cell

osteocyte

mature bone cell, monitors and maintains the mineralized bone matrix

osteoclast

Bone-destroying cells

Osteon

functional unit of compact bone, create "pillars"

where are osteons located ?

only in compact bone and parallel to long axis of bone

within the osteon what is there?

openings in the center where vein artery and nerve travel through

Lamellae

Concentric rings made up of groups of hollow tubes of bone matrix, resists twisting and stretching forces

lacunae

small cavities in bone that contain osteocytes

Canaliculi

little channels that connect lacunae

Central (Haversian) Canal

right in center, run parallel with length of osteon

Perforating (Volkmann's) canals (compact bone)

how osteons communicate and how info travels through

architecture of spongy bone

• appear poorly organized (actually develop due to stress lines)

• irregular arrangement of lamella and osteocytes

• nutrients reach the spongy bone by diffusing through the canaliculi

spicules

spikes or branches that are connecting the trabeculae to each other, perpendicular to long axis of bone

Trabeculae

Tend to run in thicker groupings in parallel ish to long axis of the bone , Provide internal support

organic substances of bone

bone cells and osteoid

what do organic substances do?

help with tension and twisting forces on bone

inorganic substances of bone

mineral salts, calcium phosphate (85%) and calcium carbonate (10%)

what do inorganic substances in bone do?

help resist compression forces