A human embryo at approximately the fifth to sixth week of intrauterine life undergoes initial ossification of one skeleton element earlier than all others. Which bone is this?
- A Frontal bone
- B Mandible
- C Clavicle ✓
- D Humerus
Correct answer: C. Clavicle
Explanation
The clavicle begins to ossify before any other bone in the body, starting during the fifth to sixth week of intrauterine life from two primary centres lying side by side in the shaft. It is also unusual because although largely membranous in origin, it contains a small cartilaginous component at both ends, making its ossification mixed. The frontal bone and mandible are membranous but begin later, and the humerus starts as a cartilage model that chondrifies early but ossifies much later.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.