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Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.
 
  Whitnall 1 has pointed out that the upper part of the sheath of the Levator palpebræ becomes thickened in front and forms, above the anterior part of the muscle, a transverse ligamentous band which is attached to the sides of the orbital cavity. On the medial side it is mainly fixed to the pulley of the Obliquus superior, but some fibers are attached to the bone behind the pulley and a slip passes forward and bridges over the supraorbital notch; on the lateral side it is fixed to the capsule of the lacrimal gland and to the frontal bone. In front of the transverse ligamentous band the sheath is continued over the aponeurosis of the Levator palpebræ, as a thin connective-tissue layer which is fixed to the upper orbital margin immediatly behind the attachment of the orbital septum. When the Levator palpebræ contracts, the lateral and medial parts of the ligamentous band are stretched and check the action of the muscle; the retraction of the upper eyelid is checked also by the orbital septum coming into contact with the transverse part of the ligamentous band.


FIG. 889– Muscles of the right orbit. (See enlarged image)

  The four Recti (Fig. 889) arise from a fibrous ring (annulus tendineus communis) which surrounds the upper, medial, and lower margins of the optic foramen and encircles the optic nerve (Fig. 890). The ring is completed by a tendinous bridge prolonged over the lower and medial part of the superior orbital fissure and attached to a tubercle on the margin of the great wing of the sphenoid, bounding the fissure. Two specialized parts of this fibrous ring may be made out: a lower, the ligament or tendon of Zinn, which gives origin to the Rectus inferior, part of the Rectus internus, and the lower head of origin of the Rectus lateralis; and an upper, which gives origin to the Rectus superior, the rest of the Rectus medialis, and the upper head of the Rectus lateralis. This upper band is sometimes termed the superior tendon of Lockwood. Each muscle passes forward in the position implied by its name, to be inserted by a tendinous expansion into the sclera, about 6 mm. from the margin of the cornea. Between the two heads of the Rectus lateralis is a narrow interval, through which pass the two divisions of the oculomotor nerve, the nasociliary nerve, the abducent nerve, and the ophthalmic vein. Although these muscles present a common origin and are inserted in a similar manner into the sclera, there are certain differences to be observed in them as regards their length and breadth. The Rectus medialis is the broadest, the Rectus lateralis the longest, and the Rectus superior the thinnest and narrowest.
  The Obliquus oculi superior (superior oblique) is a fusiform muscle, placed at the upper and medial side of the orbit. It arises immediately above the margin of the optic foramen, above and medial to the origin of the Rectus superior, and, passing forward, ends in a rounded tendon, which plays in a fibrocartilaginous ring or pulley attached to the trochlear fovea of the frontal bone. The contiguous surfaces of the tendon and ring are lined by a delicate mucous sheath, and enclosed in a thin
Note 1.  C. B. Lockwood, Journal of Anatomy and Physiology, vol. xx. [back]

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