The World Andwer

Page 89

CHAPTER #3 - THE SKELETAL SYSTEM: THE APPENDICULAR SKELETON

APENDICULAR SKELETON - consists of the bones of the pectoral

(shoulder) and pelvis (hip) girdles and extremities.

I. PECTORAL (SHOULDER) GIRDLE - attach the bones of the upper

extremities to the axial skeleton. They have no articulation

with the vertebral column. The shoulder Joints are not very

stable, but are freely movable and thus allow movement in

many directions. Each of the two pectoral girdles consists

of two bones.

A.) CLAVICLE - (collarbones) - is the anterior component

and articulates with the sternum at the

sternoclavicular joint. They are long, slender bones

with a double curvature. The two bones lie

horizontally in the superior and anterior part of

the thorax, superior to the first rib.

1.) STERNAL EXTREMITY - is the medial end of the

clavicle, it is rounded and articulates with

the sternum.

2.) ACROMIAL EXTEMITY - is the broad, flat, lateral

end and articulates with the acromion of the

scapula.

3.) ACROMIOCLACICULAR JOINT - Is created when the

acromial extremity articulates with the

acromion of the scapula.

4.) CONOID TUBERCLE - is on the inferior surface of

the lateral end of the bones serves as a point

of attachment for a ligament.

5.) COSTAL TUBEROSITY - is on the inferior surface

of the medial end and serves as a point of

attachment for a ligament.

B.) SCAPULA - (shoulder blades) - is the posterior

component of the scapula which is positioned

freely by complex muscle attachments, articulates

with the clavicle and humerus. They are large,

triangular, flat bones situated in the dorsal

part of the thorax between the levels of the

second and seventh ribs. Their medial borders are

located about 5 cm. (2") from the vertebral

column.

1.) SPINE - is a sharp ridge that runs diagonally

across the dorsal surface of the body.

2.) BODY - is the flattened, triangular portion.

3.) ACROMION - is the end of the where the spine

protects as a flattened,...