Orbital Muscles

Kocabıyık, Necdet

doi:10.1002/9781118430309.ch22

Cited by 9 publications

(11 citation statements)

References 27 publications

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“…Likewise, we did not find the well-known insertion anomaly of the LR, (i.e., a retractor bulbi that is an additional slip of the LR and provides a muscular funnel around the optic nerve's exit from the eye ball). 8 This aplasia or dysplasia is considered to be caused by a failure of innervation during early development (reviewed by Tawfik and Dutton 19 ). Determination of the normal muscle insertions of a fetus seems to depend on the timing and sequence of developing muscles and the rotating eye ball.…”

Section: Discussionmentioning

confidence: 99%

“…7 Bergman's textbook summarized these variations. 8 These variations tend to involve the upper muscles, such as the SR, the levator palpebrae superioris (LPS), and the superior oblique (SO). 1,9 To better understand these variations and abnormalities, it is necessary to further analyze the annular tendon (annulus of Zinn) as a common origin of extraocular muscles, because morphologic variations may involve muscle origins from this tendon.…”

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confidence: 99%

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Examination of the Annular Tendon (Annulus of Zinn) as a Common Origin of the Extraocular Rectus Muscles: 2. Embryological Basis of Extraocular Muscles Anomalies

Kim

Hayashi

Yamamoto

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Many reports have described anomalous connections of the superior rectus (SR) with other extraocular rectus muscles, in which additional heads of the other three rectus muscles likely provided the connections. We examined how these connections are established during fetal development. METHODS. We analyzed paraffin-embedded horizontal sections from 25 late-stage fetuses. Horizontal sections are best suited for understanding the mediolateral relationships of muscle origins. RESULTS. We confirmed a common tendinous origin of the lateral rectus (LR), inferior rectus (IR) and medial rectus (MR) muscles that was separated from the SR origin. Notably, eight fetuses (32%) had tendinous or muscular connections between the SR and other rectus muscles that had one of four morphologies: (a) a thin tendon from the SR to the common tendon of the three rectus muscles (2 fetuses), (b) a thin tendon to the LR (one fetus), (c) a thin tendon to the inferior rectus muscle origin (two fetuses), and (d) SR muscle fibers arising from an additional head of the LR (three fetuses). CONCLUSIONS. The SR seemed to issue a thin tendon that passed along the inferior or lateral side of the oculomotor nerve. Conversely, the LR and inferior rectus muscle were likely to carry a supernumerary bundle that reached the SR. The accessory head of the medial rectus muscle showed a stable morphology in that it seemed to also provide an anomalous double head. However, the presence of an accessory head in the LR was rare. In contrast with our previously published diagram of the orbital apex, the accessory head of the medial rectus muscle passed along the lateral side of the superior oblique.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Examination of the Annular Tendon (Annulus of Zinn) as a Common Origin of the Extraocular Rectus Muscles: 2. Embryological Basis of Extraocular Muscles Anomalies

Kim

Hayashi

Yamamoto

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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“…Certain nerves (including optic, oculomotor and abducens nerves) and vessels, ciliary ganglion, orbital pad of fat, as well as greater part of the eyeball lie within the cone. Anatomical variations of EOMs, however rare, include: absence of certain muscles, duplication or occurrence of additional bellies, occurrence of slips or bridges between selected muscles, as well as anomalies of innervation or insertions [1, 10]. Such variations may cause a number of changes in morphology and spatial organization of structures located within the orbit.…”

Section: Introductionmentioning

confidence: 99%

Bilateral muscular slips between superior and inferior rectus muscles: case report with discussion on classification of accessory rectus muscles within the orbit

et al. 2018

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Accessory rectus muscles have rarely been reported as muscular ‘bands’ or ‘slips’ originating from the common tendinous ring (annulus of Zinn) and inserting in atypical location. This group of muscles is innervated by the inferior branch of the oculomotor nerve, lies on lateral side of the optic nerve and inserts in rectus muscles. Since there are only few descriptions of such unusual findings in the medical literature, the anatomical data on accessory rectus muscles is limited. Furthermore, existing reports vary in terms of studied objects (cadavers or living subjects), medical history (absence or presence of ocular movement disorders or eye movement abnormalities) and details of anatomical description. This report complements earlier publications and provides complete anatomical description of the accessory rectus muscle observed bilaterally during the dissection of a 68-year-old male cadaver with no eye movement abnormalities reported in the medical history. The accessory rectus muscle was divided into two ‘slips’ or ‘heads’—superior and inferior—running in the sagittal plane (laterally to the optic nerve and the main trunk of the ophthalmic artery) and attached to the superior and inferior rectus muscles. Noticeable thickening of both superior and inferior rectus muscles at the insertion point of the accessory muscle heads was observed only in the sagittal plane. On both sides, the inferior head of the accessory rectus muscle was innervated by one of sub-branches derived from the inferior branch of the oculomotor nerve. No sub-branches to the superior head were macroscopically observed during the dissection. The classification, embryological background and clinical relevance of this variation have been discussed.

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“…It is also important to keep in mind the variations of the ocular muscles which may sometimes be absent, double, or supernumerary bellied and may also have insertion anomalies or insertion variations. They may also have muscular bridges, slips or neuromuscular bundles between them which makes the operation difficult (Kocabiyik, ).…”

Section: Discussionmentioning

confidence: 99%

“…It should be also noted that the trochlear nerve has close relation with the ethmoidal branches of the ophthalmic artery (Villain et al, ). The variations related to superior oblique muscle was seldomly reported (Kocabiyik, ).…”

Section: Discussionmentioning

confidence: 99%

The Anatomical Relationships of the Ocular Motor Nerves with an Emphasis on Surgical Anatomy of the Orbit

Apaydın

Kendir

Karahan

2018

The Anatomical Record

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The surgical procedures directed to the orbit are invariably reported to be one of the most challenging procedures of the neurosurgery and it is very important to take measures to protect the ocular nerves. Many researchers have tried to identify safe approaches or safe regions in the orbit but the suggestions and results vary among published studies. The ocular motor nerves are under risk of injury during various approaches to the orbit. Simple but careful attention to potential variations in the origin and anatomical course of the ocular nerves and their relationships to the orbit may help to define "safe zones" during various approaches, thus, help to enhance clinical outcomes. The objective of this review, therefore, is to discuss the surgical anatomy of the orbit with special emphasis on oculomotor, trochlear, and abducens nerves and further emphasize their relationships with a surgical point of view during various approaches directed to the orbit. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

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Orbital Muscles

Cited by 9 publications

References 27 publications

Examination of the Annular Tendon (Annulus of Zinn) as a Common Origin of the Extraocular Rectus Muscles: 2. Embryological Basis of Extraocular Muscles Anomalies

Examination of the Annular Tendon (Annulus of Zinn) as a Common Origin of the Extraocular Rectus Muscles: 2. Embryological Basis of Extraocular Muscles Anomalies

Bilateral muscular slips between superior and inferior rectus muscles: case report with discussion on classification of accessory rectus muscles within the orbit

The Anatomical Relationships of the Ocular Motor Nerves with an Emphasis on Surgical Anatomy of the Orbit

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