Sternum, ribs, thoracic vertebrae and intercostal space

Question 1

what rib articulates with the sternal angle

Answer 1

rib 2

Question 2

what is the mid clavicular line

Answer 2

line that is halfway through the clavicle

Question 3

what provides attachment for large and powerful muscles in the posterior thorax

Answer 3

the spinous processes of the thoracic vertebrae

Question 4

what is thoracic cage made out of

Answer 4

12 thoracic vertebrae and 12 pairs of ribs

Question 5

what joins the three parts of the sternum

Answer 5

cartilaginous joints

Question 6

describe the structure of the sternum

Answer 6

• manubrium sterni - has facets for articulation with the clavicle and with the first rib on each side via costal cartialges
• this second costal cartilages particulate partially with the manubrium and partially with the body of the sternum
• body - articulates with the manubrium at the sternal angle - it is a flat bone that has notched for ribs 2-7
• xiphoid process - this is the inferior part of the sternum

Question 7

describe the joints of the ribs

Answer 7

• posteriorly each rib has two facets for articulation with the bodies of the adjacent vertebrae
• costal cartilages joins it to the sternum

Question 8

describe the structure of thoracic vertebrae

Answer 8

• solid body of the vertebrae is heart shaped
• each vertebral is separated by an intervertebral disc
• the transverse process articulates with the ribs and serves as attachments for muscles and ligaments at the ribcage and back
• spinous processes project inferiorly and posteriorly and are flat beneath the skin in a living person
• spinous processes also serve as muscle and ligament attachments

Question 9

what is the thorax divide into

Answer 9

The thorax is divided into the mediastinum in the centre and the 2 pleural cavities either side.

Question 10

what are the layers of muscles within the ribs

Answer 10

1. The outermost layer consists of the external intercostal muscles. The fibres of these muscles run anteroinferiorly (downward and forwards, the hands in the pockets direction) from the lower surface of each rib to the one below. These muscles elevate the ribs in deep inspiration.
2. The middle layer consists of the internal intercostal muscles the fibres of which run at right angles to the external intercostals.
3. The internal layer consists of the innermost intercostal muscles which run in the same direction as the internal intercostals.

Question 11

what runs between the internal and innermost intercostals

Answer 11

• in each intercostal space run the intercostal vein, artery and nerve