Which ribs have a single facet and lack a neck or tubercle?

Which ribs have a single facet and lack a neck or tubercle?

• A. Ribs 1, 2, and 3
• B. Ribs 4, 5, and 6
• C. Ribs 10, 11, and 12
• D. Ribs 7, 8, and 9

Answer: (C)

Ribs differ in how their heads articulate with the spine and whether they have a neck or a tubercle for the transverse process. A typical rib has two articular facets on the head, a neck, and a tubercle that connects to the transverse process. The lowest ribs are different: their heads carry a single articular facet, and they lack a distinct neck and a tubercle. Without a tubercle for the transverse process, they don’t form a costotransverse joint and are short, hence described as floating ribs. This combination—one facet on the head and no neck or tubercle—applies to the bottom three ribs, making them the correct group.

Ribs differ in how their heads articulate with the spine and whether they have a neck or a tubercle for the transverse process. A typical rib has two articular facets on the head, a neck, and a tubercle that connects to the transverse process. The lowest ribs are different: their heads carry a single articular facet, and they lack a distinct neck and a tubercle. Without a tubercle for the transverse process, they don’t form a costotransverse joint and are short, hence described as floating ribs. This combination—one facet on the head and no neck or tubercle—applies to the bottom three ribs, making them the correct group.