Axial Skeleton- Thoracic Cage

Question 1

What is the thoracic cage?

Answer 1

• The bony framework of the chest
• Consists of the thoracic vertebrae posteriorly, the ribs laterally and the sternum anteriorly
• Acts as a protective framework around vital organs
• Provides attachment points for many muscles supporting the pectoral girdles, the chest, the neck, the shoulders, the back and the muscles that are involved in respiration

Question 2

What is the sternum?

Answer 2

• Also called the breast-bone
• Flat bone that forms the anterior midline of the thoracic wall
• Shape similar to a sword
• Composed of 3 parts: manubrium, body and xiphoid process

Question 3

What is the manubrium? (sternum)

Answer 3

• The widest and most superior portion of the sternum
• “handle” of the sword
• 2 clavicular notches articulate the sternum with the left and right clavicles (collarbones)

Question 4

What is the body? (sternum)

Answer 4

• The longest part of the sternum
• “Blade” of the sword
• Individual costal cartilages from ribs 2-7 are attached to the body at indented articular costal notches

Question 5

What is the sternal angle? (sternum)

Answer 5

• Where the body and manubrium articulate
• A horizontal ridge that can be felt under the skin
• Important landmark of where the second ribs attach (important for counting ribs)

Question 6

What is the xiphoid process? (sternum)

Answer 6

• Represents the very tip of the “sword”

- A small, inferiorly pointed projection that is cartilaginous

Question 7

What are ribs?

Answer 7

• Elongated, curved, flat bones that articulate with the thoracic vertebrae and end in the anterior wall of the thorax
• Males and females both have 12 pairs of ribs

Question 8

What are true ribs?

Answer 8

• Pairs 1-7
• At the anterior body wall, the true ribs articulate individually to the sternum by separate cartilaginous extensions called costal cartilages
• The first pair of true rib are the smallest

Question 9

What are false ribs?

Answer 9

• Pairs 8-12
• Their costal cartilages do not attach directly to the sternum, making them “false”
• Costal cartilages of ribs 8-10 fuse to the costal cartilage of rib 7, so they are indirectly connected to the sternum
• Last 2 pairs (ribs 11 and 12), are called floating ribs because they have absolutely no connection to the sternum

Question 10

What is the head of the rib?

Answer 10

• The vertebral end of a typical rib articulates with the vertebral column at the head
• The articular surface of the head is divided into superior and inferior articular facets by an interarticular crest
• These facets articulate with the costal facets on the bodies of the thoracic vertebrae

Question 11

What is the neck of the rib?

Answer 11

• Lies between the head and tubercle of the rib

Question 12

What is the tubercle of the rib?

Answer 12

• Has an articular facet for the costal facet on the transverse process of the thoracic vertebra

Question 13

What ribs articulate to what thoracic vertebrae?

Answer 13

• Rib 1 articulates with T1
• Ribs 2-9 articulate with T2-T9
• Ribs 10-12 articulate with T10-T12

Question 14

What is the angle of the rib?

Answer 14

• The border of the rib that indicates the site where the tubular shaft (longest part of the rib) begins
• Curves anteriorly toward the sternum

Question 15

What is the costal groove of the rib?

Answer 15

• Along the shaft

- Along its inferior internal border, it marks the path of intercostal nerves and blood vessels to the thoracic wall