Sacrum
A benzisoxazole is a bicyclic heterocycle consisting of a benzene ring fused to that of isoxazole.
A benzoxazole is a bicyclic heterocycle consisting of a benzene ring fused to that of oxazole.
A benzothiopyran is a bicyclic heterocycle consisting of a benzene ring fused to that of thiopyran.
A benzotriazole is a bicyclic heterocycle consisting of a benzene ring fused to that of triazole.
A benzothiazole is a bicyclic heterocycle consisting of a benzene ring fused to that of thiazole.
A benzothiazine is a bicyclic heterocycle consisting of a benzene ring fused to that of thiazine.
A benzofurane is another term for a benzofuran - any of a class of bicyclic heterocycles consisting of a benzene ring fused with one of furan.
A benzothiazoline is a bicyclic heterocycle consisting of a benzene ring fused to one of thiazoline.
Assuming your question relates to the human spine -From the top -8 Cervical vertibrae - C1-C812 Thoracic vertibrae - T1-T125 Lumbar vertibrae - L1-L55 Sacral vertibrae - S1-S5 some of which are fused together.Hope this helps.
Sacrum
A benzazepine is any of the class of heterocyclic compounds consisting of a benzene ring fused to an azepine ring.
A benzodioxole is any of several isomeric tricyclic heterocycles consisting of a benzene ring fused to a dioxole.