Final answer:
The submandibular duct crosses superior to the lingual nerve in the oral cavity, which is an important anatomical relationship in the context of surgical interventions and dental procedures.
Step-by-step explanation:
The structure that crosses superior to the lingual nerve in the oral cavity is the submandibular duct (also known as Wharton's duct). The submandibular duct emerges from the submandibular gland and runs anteriorly to open at the sublingual caruncle beside the lingual frenulum, which is situated at the floor of the mouth.
Above the lingual nerve, the duct courses horizontally crossing it from lateral to medial direction. The lingual nerve itself runs beneath and somewhat parallel to the duct, providing sensory innervation to the anterior two-thirds of the tongue and the floor of the mouth.
Anatomically, the submandibular duct crosses over the lingual nerve just after the nerve has looped around the submandibular ganglion and before it continues forward beneath the mucous membrane of the tongue.
This anatomical relationship is critical for surgical procedures and interventions in this area, such as removal of stones from the submandibular duct or nerve blocks for dental anesthesia.