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

PURPOSE: To determine the dimensions and function of the auricular muscle and to consider applications of this muscle in facial plastic surgery. METHODS: Nonpreserved fresh frozen human cadaver dissections from the (HOSPITAL-Blinded) Body Donation program were dissected. The length and width of the superior auricular muscle were measured. One surgeon performed all dissections and measurements. RESULTS: A total of seven left and five right hemifaces were studied. The average central height of the superior auricular muscle was 4.7 cm, and an average width was 5.0 cm. There was no significant difference between the average values of the left versus the right hemiface measurements. The muscle originated in the fibers of the galea and temporal fascia and inserted into the conchal cartilage in each specimen. Engaging the muscle in its line of action yielded slight elevation of the forehead and prevented movement of the galea along the vertex of the scalp. CONCLUSIONS: The auricular muscle acts as an occipitofrontalis stabilizer and a weak brow elevator. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors - www.springer.com/00266 .

Histologic Evaluation of Nonvisual Afferent Sensory Upper Eyelid Proprioception.

PURPOSE: Recent research has suggested a possible role for proprioception in ipsilateral frontalis activation in the setting of ptosis; however, there has not been any robust histologic or anatomic evidence to support this theory. To further elucidate proprioceptive structures in the eyelid, this investigation uses validated histologic techniques to explore the presence of proprioceptive structures or afferent neural networks in the Levator Palpebrae Superioris (LPS) and Müller muscle. METHODS: Müller muscle and LPS samples were evaluated by a laboratory with extensive experience with the histology of extraocular muscle proprioception. Immunofluorescence and confocal laser scanning microscopy were used to analyze the tissue samples. RESULTS: Thirty-four Müller muscle samples and 10 LPS samples were analyzed. Golgi tendon bodies and muscle spindles were not identified in the Müller muscle and LPS samples. This result is expected in the Müller muscle given that these structures are not typically present in smooth muscle, but noteworthy in the skeletal muscle of the LPS. Previously undescribed synaptophysin-positive free nerve terminals within the intermuscular connective tissue of the Müller muscle were identified. CONCLUSIONS: The nerve terminals identified are anatomically consistent with free nerve endings present in the extraocular muscles that have been implicated in proprioception. These findings advance our current knowledge of the ultrastructure of Müller muscle and the LPS and suggest a possible mechanism for proprioception in the upper eyelid that may have a role in ipsilateral brow elevation in the setting of ptosis.The authors describe proprioception in the upper eyelid: A histologic analysis.