The skeletal system performs several important functions.

1.It gives support and shape to the body.

2.With the muscles it alows the body to move.

3.It houses and protects many of the body organs.

4.It stores minerals,such as calcium and phosphorus.

5.It helps to filter piosonous substances from the blood.

Charcteristics of a bone

A typical long bone has two wide ends called epihyses(-PHYSIS,growth)and a shaft termed the daphysis. The epihyses are composed primarily of porous,or cancellous(CANCELL/O,lattice,reticular) bone and an outside layer of cmpact bone.The shaft,however,contains a thick layer of compact bone.The medullary(meddull/o,marrow,inner portion)canal runs the length of the shaft.The canal is lined with a menbrane, the endosteum and contais the substance that forms bone marrow.The periosteal menbrane covers theouter srface of the bone;it cntais thebone-forming cells calledosteoblasts that enable bones to grow and repair themselves.Tendons and ligaments bind the muscles to bones or bones to bones by embedding themselves in the periosteum. The bone marrow, which is composed of netlike cells, called reticular(reticul/o,net)cells,prouces red blood cells in the red marrow.This process in known as hemopoiesis.In addition to red blood cells,the hemopoietic tissue of the bone marrow produces platelets(thrombocyes)and white bood cells(leukocytes).

   Besides the typical long bone,several other bone shapes exist.

Like long bone, they are composed of cancellous bone covered with alayer of compact bone;they do not ,however, have a shaft.The three other bone shapes are(1) short,such sa the wirst and anklw bones ,(2)flat,such as the vib nones ,and(3)sesamoid (sesame seed shaped),such as the kneecap.Bones that cannot be classified as long,short,flat,or sesamoid are called irregulat(the vertebrae).

Bones possess several types of markings,holes,and projectins where they join with one another or with muscles or where blood vessels and nerver pass.You should be familiar with the bollowing terms.

a process is th projecting portion of a bone.

a fossa is s shallow depression in a bone.

a foramen is a hole in a bone through which blood vessels and nerves pass.

a condyle is a large process located where tow bones articulate .

an epicondyle is a process on a condyle.

a vrest is a ridge of a bone, such as the liiac crest.

a spine is the pointed projection of a bone.

a trochlea is the smooth surface of a bonee upon which another bone can smoothly move.

a tubercle is a small,round bone process.

a torchanter is either one of the two bony processed of the femur.

a sinus is a hollow or cavity within a bone, such as the sinuses of the skull.

a sulcus is a groove in the bone surface.

epiphysis 骨后 epiphyses

cancellous 网状骨质的

lattice 格子

reticular 网状的

endosteum股内膜

periostea 骨膜的

osteoblast 成骨细胞

ligament 韧带

periosteum 韧带

hemopoiesis 造血 血细胞生成

sesamoid 籽骨

ertebra 脊椎骨

fossa 窝 fossae

foramen   孔

condyle 踝

knuckle 膨出部

epicondyle 上踝

crest 脊

iliac 髂骨的

trochlea 滑车

tubercle 结节

trochanter 转子

femur 股骨 femora

sulcus 沟 gemora femurs

groove 沟