Which ribs are considered to be typical ribs?

• A. 1st
• B. 2nd
• C. 3rd
• D. 10th

Answer: (C)

Typical ribs are defined as ribs that possess certain anatomical features common to most ribs in the thoracic region. These ribs typically include the 3rd through the 9th ribs. The third rib specifically is characterized by having a head with two facets for articulation with the vertebrae, a neck, and a tubercle for the attachment of the costotransverse ligament.

Unlike the first rib, which is broader and has unique features due to its position and muscle attachments, the second rib has characteristics that distinguish it from typical ribs as well, such as a more prominent tubercle for muscle attachments. The 10th rib, while similar in some ways, has a single facet on its head for articulation with the corresponding vertebra, which deviates from the common anatomy found in typical ribs.

Thus, the 3rd rib is an outstanding representative of the typical rib structure, exhibiting all features commonly found in the majority of the ribs, making it the correct answer in this context.