Chapter 6: Skeletal System, Bones + Joints

Hematopoiesis

occurs in the read marrow of some bones

Osteocalcin

helps to regulate insulin secretion, regulates glucose homeostasis, energy expenditure

Long Bones

Longer than they are wide

Short Bones

Cube shaped

Sesamoid bones

special type of short bones that form in a tendon (kneecap)

Flat Bones

thin, flattened, bit curved

Irregular bones

complicated shapes

Osseous tissue

bone tissue

Compact bone

dense outer layer, looks smooth + solid

Spongy bone

internal layer, red or yellow bone marrow fills in the open spaces

Trabeculae

honeycomb of small needle-like or flat pieces

diaphysis

tubular shaft that forms the long axis of the bone

Medullary cavity

central area that contains no bone tissue but contains yellow marrow (fat)

epiphyses

bone ends

periosteum

white, double-layered membrane that covers the external surface of the entire bone except the joints

Osteoclasts

bone destroying cells

Osteoblasts

bone forming cells

endosteum

delicate connective tissue membrane that covers internal bone surface

nutrient foramen

opening in the wall of the diaphysis in which the nutrient artery and nutrient veins go through

Nutrient artery

runs inward to supply blood to bone marrow and spongy bone and branches outward to supply the compact bone

Hematopoietic tissue

blood forming

red marrow

in adults is found in the cavities between trabeculae of spongy bones in flat bones and head of femur and humerus, in infants is found in the medullary cavity of the diaphysis and all areas of spongy bone

bone markings

marks on the external surface of the bone that vies information about how the bone, its muscles, and the ligaments work together 

osteoprogenitor cell

stem cells that are actively dividing (mitosis), found in periosteum and endosteum membranes

osteoid

initial unmineralized bone (collagen and calcium-binding proteins)

bone matrix

part of the bone tissue and forms most of the mass of the bone and is made up of organic and inorganic substances

osteocytes

mature bone cells that occupy spaces (lacunaue), monitor and maintain the bone matrix

bone remodeling

breaking down and depositing bone which is carried out by osteoblasts and osteoclast cells

bone lining cells

flat celss on bone surfaces, helps to maintain the matrix

osteon

structural unit of compact bone

lamella

each matrix tube

central canal

runs through the core of each osteon and contains small blood vessels and nerve fibers

perforating canals 

lie at right angles to the long axis of the bone

lacunae

space in which the osteocytes are located at the junctions of the lamellae

canaliculi

hairlike canals that come from the lacunae and connect them to each other and to the central canal

interstitial lamellae

lie between intact osteons

circumerential lamellae

extend around the entire circumference of the diaphysis and resist twisting of long bones

soft organic components

allow it to resist tension (tension)

hard inorganic components

allow it to resist compression

hydroxyapatites

calcium phosphates

Fractures

breaks in the bone

Nondisplaced fractures

both ends retain their normal position

Displaced Fractures

bone ends are out of normal alignment 

Complete fracture

bone is broken through

Incomplete fracture

bone is no broken through

Open

penetrates through the skin

closed

doesn’t penetrate through the skin

Hematoma 

clotted blood at the break

Fibrocartilaginous callus forms

mass of cartilaginous matrix and repair tissues connects the broken bone ends

Bony callus forms

immature bone that replaces the fibrocartilaginous callus

Osteomalacia

number of disorders in which the bones are poorly mineralized

Rickets

similar to osteomalacia but in children

Osteoporosis

group of diseases in which bone resorption outpaces bone deposit

Paget’s Disease

excessive and haphazard bone deposit and resorption

Pagetic bone

newly form bone has high ratio of spongy bone to compact bone 

Axial skeleton

structured from 80 bones in three categories (skull, vertebral column, and thoracic cage)

skull

body’s most complex bony structure and is formed by cranial and facial bones (22 bones)

cranium

protects the brain and is the attachment site for the head and neck muscles

facial bones

types of bones making up the skull, mostly flat bones except for the mandible

sutures

united interlocking joints that hold the flat bones together and have serrated appearance

vertebral column

26 irregular bones connected in a way that is flexible and curved

cervical vertebrae

7 vertebrae of the neck

thoracic vertebrae

12 vertebrae of thoracic cavity

lumbar vertebrae

5 vertebrae supporting the lower back

sacrum

5 fused vertebrae that articulates with the hip bones

coccyx

4 fused vertebrae at the end of the vertebral column

intervertebral disc

cushion like pad that are sandwiched between vertebrae and acts as shock absorbers

thoracic cage

forms a protective cage around the heart and lungs, supports the shoulders and limbs, and provides muscle attachment points

Appendicular skeleton

bones of the limbs that are appended to the axial skeleton

pectoral girdle

consists of the clavicle and scapula

clavicle

slender, s-shaped bones

scapulae

thin triangular flat bones

humerus

long bone

radius

thin at proximal end and wide at the distal end

ulna

slightly longer than the radius, wide at the proximal end and thin at the distal end

carpus

consists of 8 marbled sized short bones (carpals) united by ligaments

metacarpals

five long bones

femur

largest, longest, strongest bone in the body

patella

kneecap: triangular, sesamoid bone that protects the knee joints

tibia

second largest bone, receives the weight from the femur

fibula

sticklike bone with slightly expanded ends, doesn’t bear weight, muscles attached

tarsus

ankle: made of 7 bones

metatarsus

5 small bones

phalanges

14 small bones

hallux

great toe has two phalanges

pelvic girdle

formed by the sacrum and a pair of hip bones (coxal bone)