Development of ossification centres in the squamous portion of the occipital bone in man.

The development of ossification centres in the squamous portion of the human occipital bone is described on the basis of anomalies observed in a large series of skulls. The interparietal part develops from three pairs of centres in membrane--one pair for the lateral plates, one pair for the central piece, and the third pair representing the pre-interparietals. The supraoccipital part develops from five centres in cartilage--two centres for each lateral segment and a single centre for the central segment. The supraoccipital part extends from the posterior margin of the posterior condylar fossae to about 2 cm above the external occipital protuberance and about 0.4 cm above the superior nuchal line near the lambdoid suture.