The skeletal system

made up of osteons

the basic structural unit; long cylinders that act as tiny weight-bearing pillars in the bone

have trabeculae- tiny bone struts that are key for helping the bone to resist stress

also where bone marrow is

Intramembranous ossification- a type of ossification, bone that develops from a fibrous membrane and creates a membranous bone, Ex

the clavicle and skull

Endochondral ossification- bone develops by replacing cartilage and creates endochondral bone Ex

all other bones

Clavicle

act as a brace when we hold our arms out, anchors muscles, and attaches to the sternum medially and the scapula laterally

Scapula

attaches to the rib cage and vertebral column by the muscle, allows for more mobility and flexibility, and allows the arms to move laterally

Axil skeleton

center of the body

Appendicular skeleton

appendages

Cartilage

flexible connective tissue

Ligaments

short bands of tough, yet flexible, dense connective tissue that can connect 2 bones and stabilize joints

Tendons

Cords of dense connective tissue, connect muscle to bone

Joints

articulations or junctions between 2 or more bones and include all other components, aid in movement and flexibility

Thumb

is opposable, has a special joint with metacarpal 1 and 2 phalanges

Spongy bone

small needle-like pieces of bone and open space, in most bones, makes blood cells and stores fat, lessens bone weight

Epiphyseal line

where the plate used to be once it is fused by osseous tissue, in adults after growth is finished

Periosteum

fibrous connective tissue, covers shaft of long bones

Compact bone

dense, smooth, and homogeneous, in all bones, hard external layer of bones, surrounds the medullary cavity, provides protection and strength

Medullary cavity

full of yellow marrow, cavity in the shaft of a long bone, stores adipose tissue

Diaphysis

made entirely of compact bone

Distal epiphysis

Endosteum

membrane lining the inner surface of the long bone bony wall, helps bones grow, repair, and remodel

Yellow bone marrow

inner cavity of long bones, made of adipose tissue, in children forms blood cells

Perforating (sharpey's) fibers

Nutrient arteries

narrow cavity of long bones through nutrient canals, forms the central arteries

Articular cartilage

covers the epiphyses of long bones, made of glassy hyaline cartilage, provides a smooth surface that decreases friction at joints

Epiphyses

ends of long bones, a thin layer of compact bone, encloses spongy bone, allows long bone to move in joints

Diaphysis

the shaft on the of the bone that makes up the majority of the long bones

Red bone marrow

in cavities in spongy bone of flat bones and epiphyses of some long bones, contain blood stem cells that can become red blood cells, white blood cells or platelets

Nerves in the bone

found along blood vessels, in periosteum, volkmann's canals, marrow, osteochondral, growth plate, and synovial membrane, connection to the nervous system, spatial orientation pain temperature and painful stimuli

Organic matrix

gives the bones strength and flexibility, calcium and collagen

Nutrient route through a bone

periosteum, osteon, central canal, lamellae, lacum, osteocyte

Canaliculi

Central canal

Lacuna

Phalanges (T)

Connective tissue

the majority is bone (osseous) tissue but cartilage and dense connective tissue cover the bone’s external surface

Nervous tissue

tissue in bone, has nerves

Epithelial tissue

in the bone blood vessels, provides nourishment

Muscle tissue

skeletal muscle tissue, attached to the bone

Skeleton

a framework holding up the entire body, protects the most vital organs, bones used as levers to produce movements, stores minerals and energy, forms hormones and blood cells

Hematopoiesis

blood cell formation, occurs in the red bone marrow of certain bones

Nutrients in bones

calcium and phosphate (released into the blood when needed), energy stored in the form of fat in yellow bone marrow

Long bones

longer than they are wide, tend to have a long shaft with either end being a bit wider, arm bones, hand bones, leg bones, and footbones

Short bones

more cube-shaped, tend to be as wide as they are long, provide support and stability with little movement, carpals and tarsals

sesamoid bone

a type of short bone, patella, a special type of short bone, means to be shaped like a sesame seed, embedded within tendons

Flat bones

thin and flat, often with a little curve, have a large surface area for attaching to muscles, sternum, shoulder blades, ribs, and cranial bones

Irregular bones

every other bone, have a highly specialized shape and structure, coxal and vertebrae

Structure of bone

dense and smooth layer of compact (cortical) bone tissue on the outside surrounding the more porous spongy bone tissue on the inside, bones usually have distinct markings due to ligaments and muscles

Compact bone

made up of osteons, lamella with tiny slats and collagen, and haversian canals

Osteons

the basic structural unit, long cylinders that act as tiny weight-bearing pillars in the bone

Lamella

hollow tubes grouped together to make compact bone, filled with tiny salts and collagen fibers that allow the bone to resist torsion and stress, the salt is hard, the collagen is rubbery and durable

Haversian canal

runs through the middle of each osteon and contains small blood vessels for nourishment and nerve fibers for signaling

Spongy bone

less organized than compact bone, no osteons, have trabeculae

Trabeculae

in spongey bone, tiny bone struts that are key for helping the bone to resist stress: also where bone marrow is

Projections

a type of bone marking, where muscles and ligaments attach

Surfaces

a type of bone marking, forms joints

Depressions and openings

a bone marking, for blood vessels and nerves to run through

Osteocytes

maintain healthy bone structure, housed in the lacunae- gaps between the lamellae, monitor and maintain quality in response to stimuli

Osteoblasts

build and construct bones by calcifying bone as it forms

Osteoclasts

critical in the regeneration of the bone through bone remodeling by absorbing bone tissue wherever it is not needed or is degenerating

Ossification (osteogenesis)

the process of bone tissue formation, the key to forming your skeleton as an embryo, essential for bone growth from childhood up to early adulthood, used for bone remodeling and repair later in life, articular cartilage and epiphyseal plates don't go through this

Intramembranous ossification

a type of ossification, the bone that develops from a fibrous membrane and creates a membranous bone, Ex: the clavicle and skull

Endochondral ossification

bone develops by replacing cartilage and creates endochondral bone Ex: all other bones, process: glassy dense collagen hyaline cartilage and chondrocyte cells become dense collagen and calcium osseous tissue and osteocyte cells

Bone remodeling

1. osteocytes release chemical signals to tell osteoclasts to go to the damage
2. osteoclasts release enzymes there that allow them to digest the calcium phosphate, putting the calcium and phosphate back into the blood (restoration)
3. macrophages promote bone tissue remodeling
4. osteoblasts come in and build new bone before thru undergo apoptosis

Fracture

a break in a bone, treated with reduction or realignment and immobilization

Hematoma

forms due to hemorrhaged blood clots (from where blood vessels in the bone were torn during the break), first step in bone repair

Fibrocartilage callus

forms that span the break of bones and connect broken ends of a bone, the second step in bone repair

3rd step in bone repair

osteoblasts begin forming spongy bone and replacing the cartilaginous callus

Joints (articulations)

the meeting places between 2 or more bones, classified by structure or function, give the skeleton mobility and hold it together

Connective tissue

ligament and joints, connections in joints

Synarthroses

a functional classification of joints, non-moving joints, the part of the skull that protects the brain, the cranium

Amphiarthroses

a functional classification of joints, slightly-moving joint, where pubic bones meet in the pelvis

Diarthroses- a freely moving joints

knee and elbow joints, in our limbs