Chapter 3: The Skeletal System

- MED TERM

ossification

process of bone formation specifically in newborns which continues through adolescence.

periosteum

the tough fibrous tissue that forms the outermost covering of bone.

compact bone

The dense, hard, and very strong bone that forms the protective outer layer of bones.

spongy bone

porous ("sponge-like") which makes it lighter and weaker than compact bone.

medullary cavity

the central cavity located in the shaft of long bones, where it is surrounded by compact bone. The red and yellow bone marrow are stored here.

endosteum

the tissue that lines the medullary cavity.

red bone marrow

located within the spongy bone, hemopoietic tissue manufacturing red blood cells, hemoglobin, white blood cells, and thrombocytes. Plus it is partially replaced by yellow bone marrow during adolescence.

hematopoietic

pertaining to the formation of blood cells.

yellow bone marrow

functions as a fat storage area. Composed of mainly fat cells and is located in the medullary cavity of long bones.

cartilage

smooth, rubbery, blue-white connective tissue that acts as a shock absorber between bones. It is more flexible than bone.

articular cartilage

covers the surfaces of bones where they articulate, or come together to form joints. Makes smooth joint movement possible and protects the bones from rubbing against each other.

meniscus

the curved, fibrous cartilage found in some joints like the knee and the joint of the jaw.

diaphysis

the shaft of a long bone.

epiphyses

the wider ends of long bones such as the femurs of the legs.

proximal epiphysis

end of the bone located nearest to the midline of the body.

distal epiphysis

the end of the bone located farthest away from the midline of the body.

foramen

an opening in a bone through which blood vessels, nerves, and ligaments pass.

process

a normal projection on the surface of a bone that most commonly serves as an attachment for a muscle or tendon.

joints (articulations)

The place of union between two or more bones. They are classified according to their construction or based on the degree of movement they allow.

fibrous joints (sutures)

inflexible layers of dense connective tissue that hold the bones tightly together. They allow little or no movement. In newborns and very young children some of these joints are movable before they have solidified.

cartilaginous joints

allow only slight movement and consist of bones connected entirely by cartilage. For example, where the ribs connect to the sternum.

pubic symphysis

allows some movement to facilitate childbirth.

synovial joints

created where two bones articulate to permit a variety of motions. These joints are described based on their type of motion.

ball and socket joints

such as the hips and shoulders allow a wide range of movement in many directions. (type of synovial joint)

hinge joints

such as the knees and elbows, are synovial joints that allow movement primarily in one direction or plane.

synovial capsule

the outermost layer of strong fibrous tissue that resembles a sleeve as it surrounds the joint.

synovial membrane

lines the capsule and secretes synovial fluid

synovial fluid

flows within the synovial cavity, acts as a lubricant to make the smooth movement of the joint possible.

ligaments

bands of fibrous tissue that form joints by connecting one bone to another bone or by joining a bone to cartilage.

bursa

a fibrous sac that acts as a cushion to ease movement in areas that are subject to friction such as in the shoulder, elbow, and knee joints where a tendon passes over a bone.

axial skeleton

protects the major organs if the nervous, respiratory, and circulatory systems. Organized into five parts: bones of the skull, ossicles of the middle ear, the hyoid bone (between the chin and thyroid) , rib cage, vertebral column.

appendicular skeleton

makes body movement possible and protects the organs of digestion, excretion, and reproduction. Organized into: upper extremities (shoulders, arms, forearms, wrists, and hands). lower extremities (hips, thighs, legs, ankles, and feet).

bones of the skull

Cranium: 8 bones, Face: 14 bones, Middle ear: 6 bones

frontal bone

anterior portion of the cranium that forms the forehead.

parietal bones

two of the largest bones of the skull (Paired) They form most of the roof and upper sides of the cranium.

occipital bone

forms the back part of the skull and the base of the cranium.

temporal bones

form the sides and base of the cranium.

external auditory meatus

the opening of the external auditory canal of the outer ear. Located within the temporal bone of each side of the skull.

sphenoid bone

an irregular, wedge-shaped bone at the based of the skull. Makes contact with all of the other cranial bones and helps form the based on the cranium, the sides of the skull, and the floors and sides of the eye sockets.

ethmoid bone

light, spongy bone located at the roof and sides of the nose. It separates the nasal cavity from the brain, and it forms a portion of each orbit.

auditory ossicles

the three tiny bones located in each middle ear. These bones are known as the malleus, incus, and stapes.

two nasal bones

form the upper part of the bridge of the nose.

two zygomatic bones (cheekbones)

They articulate with the frontal bone that makes up the forehead.

two maxillary bones (maxillae)

forms most of the upper jaw.

two palatine bones

forms the anterior part of the hard palate of the mouth and the floor of the nose.

two lacrimal bones

make up part of the orbit (socket of the eye) at the inner angle.

two inferior conchae

the thin, scroll-like bones that form part of the interior of the nose.

vomer bone

forms the base for the nasal spectrum. (The nasal spectrum is the cartilage wall that divides the two nasal cavities)

mandible (jawbone)

The only moveable bone of the skull. The mandible is attached to the skull at the temporomandibular joint (TMJ)

thoracic cavity (rib cage)

The bony structure that protects the heart and lungs. It consists of the ribs, sternum, and upper portion of the spinal column extending from the neck to the diaphragm, but not including the arms.

How many pairs of ribs (costals) are there?

12 pairs.

true ribs

first seven pairs of ribs that attach anteriorly to the sternum.

false ribs

the next three pairs of ribs that attach anteriorly to cartilage the connects them to the sternum.

floating ribs

the last two pairs of ribs that are only attached posteriorly to the vertebrae but are not attached anteriorly.

sternum (breast bone)

A flat dagger shaped bone located in the middle of the chest. By joining with the ribs, it forms the front of the rib cage. It is divided into three parts.

manubrium

the bony structure that forms the upper portion of the sternum.

body of the sternum (gladiolus)

the bony structure that forms the middle portion of the sternum.

xiphoid process

The structure made of cartilage that forms the lower portion of the sternum.

pectoral girdle (shoulder girdle)

the shoulders form this which supports the arms and hands.

clavicle (collarbone)

A slender bone that connects the manubrium of the sternum to the scapula.

scapula (shoulder blade)

The shoulder bone.

acromion

an extension of the scapula that forms the high point of the shoulder.

humerus

the bone of the upper arm

radius

the smaller and shorter bone in the forearm. (the radius runs up the thumb side of the forearm.

ulna

The larger and longer bone of the forearm. The proximal end of the ulna articulates with the distal end of the humerus to form the elbow joint.

olecranon (funny bone)

The large, proximal tip of the ulna. This forms the point of the elbow and exposes a nerve that tingles when struck.

eight carpals

The bones that form the wrist. They also form a narrow bony passage known as the carpal tunnel The median nerve and the tendons of the finger pass through this tunnel to reach the hand.

the five metacarpals

The five bones that form the palms of the hand.

phalanges

They are the 14 bones of the fingers. The bones of the toes are also known as phalanges.

distal (outermost), middle, proximal (nearest the hand) phalanges

The three bones of each of the four fingers.

distal and proximal phalanges

These are the thumb’s two bones.