vertebral column has five major regions. They are, the Cervical , Thoracic , Lumbar , Sacrum ( sacral vertebrae found in the infant which are fused to form one bone in the adult) and Coccyx ( coccygeal vertebrae found in the infant which are fused to form one bone in the adult). Each vertebra has a central hollow portion, the neural canal, through which the spinal cord passes. The first vertebra is called as the atlas and the second vertebra is called as the axis .
Atlas is articulated with the occipital condyles. The vertebral column protects the spinal cord, supports the head and serves as the point of attachment for the ribs and musculature of the back. Figure . Structure of the skull Lateral view Anterior view ([WHUQDODXGLWRU\PHDWXV RSHQLQJRIWKHHDU 3DULHWDOERQH )URQWDO ERQH 7HPSRUDO ERQH 6SKHQRLGERQH (WKPRLGERQH /DFULPDOERQH =\JRPDWLFERQH 0D[LOOD 0DQGLEOH 2FFLSLWDOERQH 1DVDOERQH 3DULHWDOERQH 1DVDOERQH 6SKHQRLGERQH 7HPSRUDOERQH (WKPRLGERQH /DFULPDOERQH =\JRPDWLFERQH 0D[LOOD 0DQGLEOH YRPHU &HUYLFDO YHUWHEUDH 7KRUDFLF YHUWHEUDH /XPEDU YHUWHEUDH ,QWHUYHUWHEUDO GLVF 6DFUXP IXVHG &RFF\[ IXVHG Figure .
Vertebral Column (c) The Sternum (Chest bone) Sternum is a flat bone on the mid ventral line of the thorax. It provides space for the attachment of the thoracic ribs and abdominal muscles. (d) The Rib Cage There are pairs of ribs (Figure . ).
Each rib is a thin flat bone connected dorsally to XI Std Biology-Zoology Chapter- the vertebral column and ventrally to the sternum. It has two articulation surfaces on its dorsal end, hence called bicephalic. The first seven pairs of ribs are called ‘ true ribs’ or vertebro–sternal ribs . Dorsally they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilages.
The th , th and th pairs of ribs do not articulate directly with the sternum but joined with the cartilaginous (hyaline cartilage) part of the seventh rib. These are called ‘false ribs’