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Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
Many authors of recent textbooks in neuroscience, both basic and clinical, do not mention “Muller’s muscle” at all. Authors who do mention it agree that it is a smooth muscle, with motor innervation supplied by the sympathetic nervous system; but their descriptions of its location vary considerably. Most describe it as being the “superior tarsal muscle,” located in each upper eyelid (e.g., W&W, p. 1179; N&D, p. 207 [Fig. 5–34], 212; DSR&W, p. 350; Walt, p. 153; C&M, p. 21–22). Others, however, describe it as being the “orbital(is) muscle” (C&S, p. 228; CH&L, p. 526; DeJ, p. 129, 497), which lies posterior in each orbit and “bridges the inferior orbital fissure” (W&W, p. 1178). Still others describe it as being the “superior and inferior tarsal muscles,” located in each upper and lower eyelid, respectively rr&D, p. 87; Marg, p. 269); and one even states that it (= the “orbitalis” “invests the eyeball and enters both lids” (FitzG, p. 218 [including Fig. 31–2]).
Head, neck and vertebral column
Published in David Heylings, Stephen Carmichael, Samuel Leinster, Janak Saada, Bari M. Logan, Ralph T. Hutchings, McMinn’s Concise Human Anatomy, 2017
David Heylings, Stephen Carmichael, Samuel Leinster, Janak Saada, Bari M. Logan, Ralph T. Hutchings
The upper lid has an extra muscle to elevate it, the levator palpebrae superioris (Figs.3.26, 3.28), unusual in that it contains some smooth muscle fibres as well as skeletal fibres. The smooth muscle portion may have a separate designation as the superior tarsal muscle (of Muller). The gap between the lids when the eye is open is the palpebral fissure and located medially lie the puncta (openings) for the nasolacrimal duct. The edges of the lids contain the eyelashes and the tarsal (meibomian) glands, which are modified sebaceous glands.
An overview of the pharmacotherapeutics for dystonia: advances over the past decade
Published in Expert Opinion on Pharmacotherapy, 2022
O. Abu-hadid, J. Jimenez-Shahed
Apraclonidine is a less lipophilic version of clonidine with the same mechanism of action and is administered as an eye drop. Apraclonidine is shown to help reduce adverse events, such as ptosis and Horner syndrome, due to botulinum toxin injections for BS [105]. The presumed mechanism is activation of the superior tarsal muscle. A prospective observational study used apraclonidine in seven patients with BS who experienced early wearing off with botulinumtoxin [106]. Patients were not blinded and all received apraclonidine, however, the video raters were blinded [106]. All the patients noted subjective improvement, and there was a significant difference in rating (p < 0.025) by the blinded raters before (3.4/4.0) and after (2.3/4.0) administration, with a higher rating indicating more severe blepharospasm [106].