anatomy: bones(functions and classification) and overview of skeletal system

primary functions of bone

support, protection, movement(anchorage), storage, hematopoiesis, hormone production

support

anchorage for the body(lower extremity(pillars), thoracic cage(walls), skull(enclosed room))

protection

vital organs lie deep to bones(skull(brain), thoracic cage(lung and heart), vertebrae(spinal cord))

movement

attachment for skeletal muscle(via tendons), types of movement is determined by joint types

storage

triglyceride(fat) - yellow bone marrow, minerals(calcium an phosphate)

hematopoiesis

production of blood cells and platelets, occurs in red bone marrow

hormone production

production of osteocalcin which regulates: insulin secretion, glucose homeostasis, energy expenditure)

2 primary classifications

appendicular, axial

appendicular

limbs(upper and lower), limb girdle(scapula and clavicle, pelvis)

axial

core; protection of organs, skull, vertebrae, ribs

long bone

most bones in the extremities

flat bone

lot of movement/dont want bones to be heavy; sternum, scapula, ribs, skull

irregular bone

have projections; vertebrae and pelvis

short bone

square shaped; carpels and tarsals

sesamoid bone

floating bones; short bones; encapsulated within patella; movement in joints

cartilage of the skeleton

hyaline, elastic, and fibrocartilage

hyaline cartilage

articular, most common in skeletal, in most join intersections

elastic cartilage

ear, structure

fibrocartilage

shock absorption, menisci, pubic symphysis

perichondrium

layer of dense irregular CT that surrounds all cartilage

cartilage development

responsible for the embryonic skeleton; 2 types of growth appositional and interstitial

appositional

cells in the perichondrium secrete new matrix; adds new layers from the outside

interstitial

cells within lacunae split and expand from the inside

compact bone

external layer; smooth surface; attachments

spongy

internal layer; filled with trabeculae; gaps and air pockets; spaces have bone marrow

yellow bone marrow

most bones of extremities

red bone marrow

hematopoiesis; children(basically everywhere), adults(flat and irregular bones, heads of femur and humerus)

structure of short, irregular, and flat bones

compact bone on both sides, spongy bone in the middle

structure of long bones

epiphysis on both sides, diaphysis in the middle

structure of long bones

articular(hyaline) cartilage, epiphyseal line, marrow cavity in the middle

periosteum

glistening, double layered membrane surrounding bone

outer layer(dense irregular CT), inner later(bone cells), nerves and blood vessels

endosteum

delicate membrane covering the internal bone surfaces; contains same cells as inner periosteum; covers all trabeculae and canals

blood and nerves

nutrient artery(travels through the diaphysis and branches to supply bone), epiphyseal arteries(similar); nerves(travel with arteries)

osteoprogenitor cell

stem cell

osteoblast

matrix-synthesizing cell; responsible for bone growth

osteocyte

mature bone cell; monitors and maintains the mineralized bone matrix

osteoclast

bone-resorbing cell

osteon

functional unit of bone; in compacted bone(parallel to long axis, weight bearing pillars)

haversian system

lamellae, lacunae, canaliculi, central(haversian) canal, perforating(volkmanns) canal

lamellae

Collagen fibers running in opposite directions, create rings in microscopic images

Concentric rings, collagen and bone salts, resists torsional/tensile forces

lacunae

osteocytes; in between lamellae

between rings of lamellae, home for osteocytes

canaliculi

rings in between lamellae

connect lacunae to each other and canals

central(haversian) canal

run in parallel with osteons

perforating (volkmanns) canal

how artieries travel through osteons

inside canal

neurovascular bundle

architecture of spongy bone

appear poorly organized but develop due to stress lines; irregular arrangement of lamella and osteocytes; nutrients reach the spongy bone by diffusion through the canaliculi

spicules

in spongy bone; little spikes connecting trabecular to each other; provide internal support

trabeculae

in spongy bone; run in thicker groups in parallel access to the bone; provide internal support

chemical composition of bone

organic substances and inorganic substances

organic substances

cells, osteoid(ground substance and collagen); tension, twisting forces on bone

inorganic substances

mineral salts(mostly calcium phosphate and some carbonate); resist compression forces; bone after death

bone markings

not smooth; change in the surface allows for attachment of: other bones, ligaments, muscles(tendons)

4 categories of bony markings

projections, surfaces, depressions, openings