Lesson 2 - Skeletal System

skeletal system

The bodily system that consists of the bones, their associated cartilages, and the joints, and supports and protects the body, produces blood cells, and stores minerals.


the bony skeleton of the head of vertebrates; consists of the eight bones that form the cranium, 14 bones that form the face, and six bones in the middle ear

rib cage

bones that protect the heart and lungs


scientific name for fats


substances that the body cannot manufacture but that are needed for forming healthy bones and teeth and regulating many vital body processes


A mineral that is essential for bone growth, teeth development, blood coagulation, and many other functions

calcium salts

ground substance; crystalline matrix of bone; very rigid structure ~ gives bone excellent support & protection


abnormal loss of bony tissue resulting in fragile porous bones attributable to a lack of calcium

Vitamin D

a fat-soluble vitamin that prevents rickets; promotes growth and health of bones; works with calcium and phosphorus to build bones and teeth


disease caused by deficiency of vitamin D and sunlight associated with impaired metabolism of calcium and phosphorus


condition caused by a diet lacking one or more essential nutrients


mineral substance found in bones in combination with calcium


places where bones connect: hinge, pivot, gliding, ball and socket


membrane surrounding bones; rich in blood vessels and nerve tissue; serves as an attachment for tendons and muscles


process that ensures bone maintenance through simultaneous bone resorption and formation

compact bone

dense, hard layers of bone tissue beneath the periosteum


major protein of connective tissue, cartilage, and bone

spongy bone

layer of bone tissue having many small spaces and found just inside the layer of compact bone

bone marrow

the fatty network of connective tissue that fills the cavities of bones

red bone marrow

involved in blood cell formation; located in the cavities between the spicules in spongy bone

yellow bone marrow

gradually replaces red bone marrow in adult bones; functions as storage for fat tissue and is inactive in the formation of blood cells


refers to the bones


bone forming cells


bone-destroying cells


tough elastic tissue

joint cartilage

works like a shock absorber; keeps your bones from hurting when they rub against one another


this is what occurs when two smaller bones are joined together to form one bone


bony tissue formed during the healing of a fractured bone


thigh bone; the longest and thickest bone of the human skeleton


first of the three bones of the middle ear; shaped like a hammer


second of the three bones of the middle ear; shaped like anvil


third of the three bones of the middle ear; shaped like stirrups

long bones

longer than they are wide; Humerous, Radius, Ulna, Femur, Fibula and Tibia

short bones

bones that are generally small and cube shaped and contain multiple articulating surfaces; examples are the carpals and tarsals.

flat bones

thin, flattened, and usually curved, two thin layers of compact sandwiching spongy bone (skull, ribs, sternum)

sesamoid bones

small, round bones that are embedded in certain tendons; often found in the hands and feet; the largest is the patella


kneecap; largest sesamoid bone in the body

irregular bone

bone that doesn't fit in any other category;
mostly spongy bone with thin compacty outer layer; e.g. vertebrae, facial bones


a U-shaped bone at the base of the tongue that supports the tongue muscles


tissue that connects bone to bone


the tailbone, made up of the four fused vertebrae at the base of the spinal column


the portion of the skull that encloses the brain


immovable joints between skull bones

facial bones

Bones that make up the face that dont surround the cranial cavtiy


lower jawbone


air-filled spaces in the skull that open into the nasal cavity


a slimy substance produced in the nose and throat to moisten and protect them


animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium


bones of the spinal column

spinal / vertebral column

the group of bones that extends from the base of the skull to the hips and surrounds the spinal cord

cervical vertebrae

the first set of seven vertebrae that form the neck; also known as C1 through C7

thoracic vertebrae

the second set of 12 vertebrae; form the outward curve of the spine and are known as T1 through T12

lumbar vertebrae

third set of five larger vertebrae, which forms the inward curve of the spine

spinal cord

column of nervous tissue from the brainstem through the vertebrae, responsible for nerve conduction to and from the brain and the body

costal cartilage

the cartilages that connect the sternum and the ends of the ribs

true ribs

first 7 pairs of ribs; attach directly to sternum

false ribs

last 5 pairs of ribs; attach indirectly to sternum

floating ribs

last two pairs of ribs; do not attach to sternum

pectoral girdle

consists of the clavicle and scapula; functions to attach the upper extremity to the axial skeleton


called the shoulder blade; flat, triangular bone


collar bones


upper arm bone


bone of the lower arm (thumb side)


bone of the lower arm (pinky side)


bones of the wrist


bones of the hand


fingers and toes


finger and toe bones

pelvic girdle

pelvis; anchors the lower limbs


hip bones


thigh bone; the longest and thickest bone of the human skeleton


shin bone; the inner and thicker of the two bones of the human leg between the knee and ankle


calf bone; the outer and thinner of the two bones in the leg between the knee and ankle


ankle bones


bones of the foot between ankle and toes


heel bone

synovial fluid

viscid lubricating fluid secreted by the membrane lining joints and tendon sheaths etc.


inflammation of a joint or joints

hinge joints

joints that move back and forth like the movement of a door hinge; these joints are located at your fingers, toes, elbows, and knees.

ball-and-socket joints

most movable joint, ball shaped head of one bone fits in another concave depression; shoulder and hip

saddle joints

permit one bone to slide in two directions; only one pair exists and it is between the thumb and wrist

sliding joints

allow bones in the hand to glide over one another, giving flexibility

pivot joints

Rotate around each other like in the neck

ellipsoidal joints

attach fingers and toes to hands and feet; the joints that connect your phalanges to your metacarpals; like flattened ball-and-socket joints

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording