Human Rib cage
Definition:
A protective structure in the chest region formed by the vertebral column, ribs, coastal cartilages
and sternum.
More about Rib cage:
The rib cage is also known as thoracic cage or the thoracic basket.
It is more or less triangular and conical in shape.
Its main function is protection of the heart and lungs in the chest area and upper abdomen.
It supports the skeletal frame work of the body.
Also, the rib cage plays a vital role in the breathing mechanism, as it can expand and contract with
the help of respiratory muscles and diaphragm.
The lower end of the rib cage is attached to the diaphragm
The bones that form the rib cage are
-
Sternum - a flat and dagger shaped bone, made up of three bones namely manubrium,
body and xiphoid process. It is approximately 15cm long situated on the midline of thorax.
It is longer in males than in female.
Thoracic vertebrae - they are 12 in number and are attached to the ribs from the dorsal
side.
Ribs –They are “C” shaped bones joining the sternum on the ventral side and the thoracic
vertebra on the dorsal side.
There are 24 ribs, 12 on either side of the sternum and vertebrae.
The ribs from 1-7 are attached to the sternum by coastal cartilage and hence are known as
“true ribs”.
The 8th, 9th and 10th ribs are not attached directly to the sternum but are attached to the
coastal cartilage of the 7th rib, and hence are known as “false ribs”.
The 11th and 12th ribs are attached to the vertebrae but not to the sternum and hence are
known as “floating ribs”. They protect the kidneys.
Diagram:
http://www.123rf.com/photo_16755649_rib-cage.html
Video Link:
http://www.youtube.com/watch?v=PNo5HJIY5w4
http://www.youtube.com/watch?v=3IlbLTMNer8
http://www.youtube.com/watch?v=ZJzJIO4AH3w
http://www.youtube.com/watch?v=tiaOZmu5Vq0
Questions based on the Rib cage:
1) Which among the following pairs are known as “false ribs”.
a) 1st -7th
b) 7th - 10th
c) 8th – 10th
d) 11th and 12th
Solution: (c) The ribs from 8th to 10th are not attached directly to the sternum but to the
coastal cartilage of the 7th rib and hence are known as false ribs.
2) How many ribs together are involved in the formation of rib cage?
a) 22
b) 24
c) 12
d) 28
Solution: (b) 24 ribs are involved in the formation of rib cage, 12 on either side of the
sternum and vertebrae.
3) What is the function of the coastal cartilage in the rib cage?
Solution: The coastal cartilage connects the ribs from 1-7 to the sternum.
4) What are floating ribs?
The 11th and 12th ribs of the rib cage are not attached to the sternum, but are attached to
vertebrae only . These ribs are known as floating ribs.