Traction suture for canalicular lacerations.

Maintaining good wound closure in canalicular lacerations is difficult because of the horizontal tension exerted by the orbicularis muscle on the wound. A method of placing a deep medial canthal traction suture through the medial orbital periosteum to aid in maintaining good wound approximation is presented.

Horner's muscle and the lacrimal system.

Anatomical dissections were performed on eight fixed cadavar orbits to observe the relationship of the pretarsal, preseptal, and Horner's muscle to the canaliculus. The attachments of Horner's muscle and the deep preseptal muscle to the lacrimal diaphragm reflected their important role in the lacrimal diaphragm's function. In addition, the muscles involved in lacrimal drainage were mechanically pulled with a forceps to induce canalicular pressures. Shortening and compression of the canaliculus by the pretarsal, preseptal, and lateral Horner's muscle increased canalicular pressure, whereas Horner's muscle and the deep preseptal muscle induced negative lacrimal pressures. A positive-to-negative pressure gradient in the lacrimal drainage system was proposed as the main force in lacrimal tear transport.

Margins of safety in lateral orbitotomy.

Five adult cadaver half skulls were used to study the bone cuts of the lateral orbital wall in performing the lateral orbitotomy. Measurements were taken of the anterior vertical opening, the anteroposterior opening, and the distance to the middle cranial fossa. The vertical opening at the anterior aspect of the lateral orbital wall ranged from 18 to 22 mm. The anteroposterior exposure averaged 18 mm when the thick and thin portions of the bone were removed. The distance from the anterior rim to the middle cranial fossa averaged 31 mm on both the superior and inferior cuts. Hence a distance of approximately 12 to 13 mm separated the posterior aspect of the orbitotomy from the middle cranial fossa.