Dimensions, Function and Applications of the Auricular Muscle in Facial Plastic Surgery

The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study

OBJECTIVE

Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery.

METHODS

The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured.

RESULTS

The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus.

CONCLUSIONS

Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

Applicability of a sheep model for training in plastic surgery of eyelids and orbit

OBJECTIVE

To test the applicability of a fresh tissue model for teaching facial plastic techniques and approaches to the eyelids and orbit.

DESIGN

Observational animal experiments.

SUBJECTS

Ten prepubescent sheep heads harvested following humane euthanasia at the completion of unrelated live animal research.

METHODS

Young sheep were saline perfused at the end of an in vivo protocol. Head and neck tissues were harvested and refrigerated for 3-7 days. An experienced oculoplastic surgeon and an otolaryngologist explored the feasibility of common oculoplastic procedures in the ovine model.

RESULTS

The model has potential for teaching basic principles in eyelid surgery including upper lid blepharoplasty, aponeurotic ptosis repair, upper lid gold weight lid loading for facial paralysis, lateral canthotomy and inferior limb cantholysis, lower lid tightening, and transconjunctival approach to the orbital floor. Eye muscle advancement, optic nerve sheath fenestration, and enucleation also accurately simulated human surgery. Anatomic variations limit the sheep model for orbital floor reconstruction and lacrimal drainage procedures.

CONCLUSIONS

The sheep head and neck provide an inexpensive, safe model for developing skills in several oculoplastic procedures. Formal simulation testing is needed to confirm these expert opinions.