It is supplied by sympathetic nerves , and its function is unknown .
It lies at the back of the orbit and spans the infraorbital fissure It is a thin layer of smooth muscle that bridges the inferior orbital fissure .
layer is supplied by sympathetic nerves , and layer 's function is unknown .
It lies at the back of the orbit and spans the infraorbital fissure It is a thin layer of smooth muscle that bridges the inferior orbital fissure .