skeletal systems (tendons and ligaments)

how many bones are in the human skeleton

about 206 (depends on if sesamoid bones are counted)

what are the two main divisions of the skeleton

axial and appendicular

primary functions of the skeletal system

support/structure, muscle and tendon attachment, protection, storage of minerals, hemotopoiesis (blood formation), and movement

types of bones

long, short, flat, irregular, and sesamoid

function of long bones and example

serve as levers, less articulation area; ex: femur, humerus

function of short bones, and example

cube-shaped, shock absorption, large articulation area; ex: carpals, tarsals

function of flat bones and example

protection; ex: sternum, ribs, scapula

function of irregular bones and example

various functions; ex: vertebrae, hyoid

function of sesamoid bones and example

located in tendons, increase mechanical advantage; ex: patella, sesamoids of thumb and big toe

what type of cartilage covers the epiphysis of long bones

hyaline (articular) cartilage

two types of bone growth

longitudinal (length) and appositional (thickness/width)

where does longitudinal bone growth occur

epiphyseal plate (growth plate), which ossifies into bone

how does appositional growth occur

periosteum adds concentric layers, medullary cavity remodels outward

what percent of the skeleton is remodeled annually

5-10%

cortical bone

dense, outer bone

cancellous bone

spongy, inner bone

basic composition of bone

60-70% calcium salts, 25-30% water, and collagen for flexibility

Wolff's law

states that bone adapts to stress placed on it

stress in bone biomechanics

force per area

strain in bone biomechanics

change in length divided by resting length

elastic region of bone

deformation that can return to original shape (reversible)

plastic region of bone

deformation that cannot return to original shape (permanent)

why are children's bones more ductile and tough

less mineralized, so they can bend more without fracturing

how does rate of loading affect bone strength

bone can handle greater stress if loading is faster

joint

articulation of two or more bones

three functional classifications of joints

synarthrodial (immovable), amphiarthrodial (slightly movable), and diarthrodial (freely movable)

suture joint

immovable fibrous joint (in cranial bones)

gomphosis joint

socket joint (teeth in the jaw)

syndesmosis joint and example

ligamentous joint; ex: inferior tibiofibular joint

symphysis joint and example

fibrocartilage pad; ex: pubic symphysis, vertebral disks

synchondrosis joint and example

hyaline cartilage joint; ex: ribs with sternum

what structures surround most diarthrodial joints

sleevelike capsule with synovial fluid, ligaments for support

six types of diarthrodial joints and examples

arthrodial (gliding): carpals

condyloidal (ellipsoid): wrist, MCP joints

enarthrodial (ball+socket): shoulder, hip

ginglymus (hinge): elbow, knee

sellar (saddle): thumb CMC joint

trochoidal (pivot): radius and ulna

tendon

dense connective tissue attaching muscle to bone; transmits muscle force to skeleton

ligament

dense connective tissue attaching bone to bone; provides joint stability

which provides greater elasticity: tendon or ligament?

tendon is slightly more elastic; ligaments are more stabilizing

what role do ligaments like the ACL play in the skeletal system

reinforce synovial joints and limit excessive movement