Changes

=Costae=

=Costae=

[[Image:Thorax skeleton.png|thumb|right|150px|Canine thorax showing placement of mitral valve - Wikimedia Commons 2008]]

[[Image:Thorax skeleton.png|thumb|right|150px|Canine thorax showing placement of mitral valve - Wikimedia Commons 2008]]

*Arranged in pairs and articulate with two successive vertebrae

Costae are arranged in pairs and articulate with two successive vertebrae. Inidividual ribs have a bony dorsal part, a body of rib, and ventral costal cartilage. They increase in length, curvature and amount of cartilage craniocaudally. The cartilage of last rib may fail to join that of its neighbor and is said to be a '''floating''' rib. Costae join ventrally on the midline at the '''Sternum''', which is comprised of three parts, the '''manubrium''', '''sternebrae''' and '''xiphoid cartilage'''. The '''manubrium''' is the most cranial and projects beyond the first set of ribs and can be palpated in most species. The '''sternebrae''' is joined by cartilage in young animals that is later replaced by bone and is the main body joining the ribs on the midline. The '''xiphoid Cartilage''' is caudal and projects between lower ends of costal arches, providing attachment for the '''linea alba'''.

*Bony dorsal part, body of rib, and ventral costal cartilage

*Increase in length, curvature and amount of cartilage craniocaudally

*Cartilage of last rib may fail to join that of its neighbor: said to be '''floating'''

There are a number of costal joints and costosternal joints. The costal joints include the '''costovertebral joint''', where the head of rib articulates with vertebral column via a ball and socket with very restricted mobility and the '''costotransverse joint''' where a tubercle articulates with the vertebra via a sliding joint. The costosternal joints include the '''interchondral joint''' that is within the rib itself and is an elastic syndesmoses and the '''intersternal joint''' which is an impermanent synchondroses between the rib and the sternum.

*Join ventrally on the midline at the '''Sternum''', which is comprised of three parts

**'''Manubrium''': most cranial, projects beyond the first set of ribs and can be palpated

**Body: segmented '''sternebrae''' joined by cartilage in young animals that is later replaced by bone

**'''Xiphoid Cartilage''': caudal end that projects between lower ends of costal arches, providing attachment for the '''linea alba'''

**Costovertebral joint: head of rib articulates with vertebral column, ball and socket with very restricted mobility

**Costotransverse joint: tubercle articulates with vertebra, sliding joint

**Costosternal joints:

***Interchondral joints: asternal ribs, elastic syndesmoses

***Intersternal joints: impermanent synchondroses

=Thoracic Musculature=

=Thoracic Musculature=