os investientium

(plural ossa investientia))

membrane bone (a bone which arises directly from connective tissue membranes without cartilaginous precursors. Includes dermal bones, as opposed to cartilage ones. Membrane bones are thin, laminar and located near the surface of the body. When the connective mesenchyme transforms into bone it does not differ histologically from bone which arose from cartilage. Also called achondral, dermal (q.v.), covering and investing bone)