Age of closure of sphenooccipital synchondrosis is:

 # Age of closure of sphenooccipital synchondrosis is:

a) 6 years 

b) 12 years

c) 18 years 

d) 25 years

The correct answer is C. 18 years.

The spheno-occipital synchondrosis (also known as the basiocciput or basicranial synchondrosis) is the synchondrosis between the basisphenoid and basiocciput bones, which together when joined form the clivus. When fused, the synchondrosis is often called the spheno-occipital suture - this is a misnomer - as anatomically it is not a suture.

Fusion of the spheno-occipital synchondrosis initiates in girls at 12-13 years, and in boys at 14-15 years and is complete by 17-18 years. Fusion begins superiorly and progresses inferiorly, and also starts at the inner surface of the skull base proceeding towards the ectocranial surface.