Friday, February 8, 2013

Bones of the thorax


1. CLAVICLE - the collar bone. a slender bone, ventrally, one on each side, connecting the breastbone to each shoulder blade

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2. SCAPULA - the shoulder blades. two flat, triangular bones, one on each dorsal side of the thorax. The extension of the scapula that joins with the clavicle to form a joint above the shoulder is called acromion (acr/o means extremity, om/o means shoulder). The joint formed by these two bones is known as the acromioclavicular (AC) joint. 

3. STERNUM - the breastbone. a flat bone extending down the midline of the chest. the uppermost part of the sternum articulates on the sides with the clavicle and ribs, and the lower, narrower portion is attached to the diaphragm and abdominal muscels. The lower part of the strernum is the xiphoid process (xiph/o means sword). The upper portion is the manubrium (from a latin term meaning handle). 

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4. RIBS - There are 12 pairs of ribs. The 1st 7 pairs join the sternum anteriorly through cartilaginous attachments called costal cartilages. Ribs 1-7 are called true ribs. They join with the sternum anteriorly and with the vertebral column in the back. Ribs 8 to 10 are called false ribs. They join with the vertebral column in the back but join the 7th rib anteriorly instead of attaching to the sternum. Ribs 11 and 12 are the floating ribs because they are completely free at their anterior ends. ­

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