“Extensor pollicis longus. 1 tendon, 1 sheath make up which extensor compartment?” June 19, 2017 mfadmin Biology Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review. “Extensor pollicis longus. 1 tendon, 1 sheath make up which extensor compartment?” Compartment 3