Bones - Sternum

Question 1

What parts make up the sternum?

Answer 1

1) Manubrium
2) Body
3) Xiphisternum

Question 2

Manubrium

Answer 2

Most superior part. Trapezoid shape.

Superior aspect - jugular notch. On either side is a fossa, lined with cartilage - these articulate with the clavicles, formin the sternoclavicular joint.

Laterally -

Facet - costal cartilage of 1st rib.

Demi-facet - costal cartilage of 2nd rib.

Inferiorly - articulates with the body of sternum - sternal angle (T4), manubriosternal joint.

Question 3

Body of sternum

Answer 3

Superiorly - manubriosternal joint

Inferiorly - xiphisternal joint

Laterally -

4 articular facets (costal cartilages 3-6)

2 demi-facets (costal cartilages 2 and 7)

Question 4

Xiphoid process

Answer 4

Located at the level of T10

Largely cartilaginous.

Ossifies age 40.

Can articulate with costal cartilage of rib 7.

Question 5

Clinical relevance - fractures of the sternum

Answer 5

Severe blunt trauma to the chest, such as an RTA. Relatively uncommon.

Typically breaks into several pieces - comminuted fracture.

Common site of fracture - manubriosternal joint.

Fragments are not displaced due to pectoralis muscle keeping them in place.

Associated with a high mortality rate (25-45%). This is due to potential heart and lung injuries.

Diagnosis - X-ray, CT, USS.