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Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.
 
  The supratrochlear nerve (n. supratrochlearis), the smaller of the two, passes above the pulley of the Obliquus superior, and gives off a descending filament, to join the infratrochlear branch of the nasociliary nerve. It then escapes from the orbit between the pulley of the Obliquus superior and the supraorbital foramen, curves up on to the forehead close to the bone, ascends beneath the Corrugator and Frontalis, and dividing into branches which pierce these muscles, it supplies the skin of the lower part of the forehead close to the middle line and sends filaments to the conjunctiva and skin of the upper eyelid.
  The supraorbital nerve (n. supraorbitalis) passes through the supraorbital foramen, and gives off, in this situation, palpebral filaments to the upper eyelid. It then ascends upon the forehead, and ends in two branches, a medial and a lateral, which supply the integument of the scalp, reaching nearly as far back as the lambdoidal suture; they are at first situated beneath the Frontalis, the medial branch perforating the muscle, the lateral branch the galea aponeurotica. Both branches supply small twigs to the pericranium.
  The Nasociliary Nerve (n. nasociliaris; nasal nerve) is intermediate in size between the frontal and lacrimal, and is more deeply placed. It enters the orbit between the two heads of the Rectus lateralis, and between the superior and inferior rami of the oculomotor nerve. It passes across the optic nerve and runs obliquely beneath the Rectus superior and Obliquus superior, to the medial wall of the orbital cavity. Here it passes through the anterior ethmoidal foramen, and, entering the cavity of the cranium, traverses a shallow groove on the lateral margin of the front part of the cribriform plate of the ethmoid bone, and runs down, through a slit at the side of the crista galli, into the nasal cavity. It supplies internal nasal branches to the mucous membrane of the front part of the septum and lateral wall of the nasal cavity. Finally, it emerges, as the external nasal branch, between the lower border of the nasal bone and the lateral nasal cartilage, and, passing down beneath the Nasalis muscle, supplies the skin of the ala and apex of the nose.
  The nasociliary nerve gives off the following branches, viz.: the long root of the ciliary ganglion, the long ciliary, and the ethmoidal nerves.
  The long root of the ciliary ganglion (radix longa ganglii ciliaris) usually arises from the nasociliary between the two heads of the Rectus lateralis. It passes forward on the lateral side of the optic nerve, and enters the postero-superior angle of the ciliary ganglion; it is sometimes joined by a filament from the cavernous plexus of the sympathetic, or from the superior ramus of the trochlear nerve.
  The long ciliary nerves (nn. ciliares longi), two or three in number, are given off from the nasociliary, as it crosses the optic nerve. They accompany the short ciliary nerves from the ciliary ganglion, pierce the posterior part of the sclera, and running forward between it and the choroid, are distributed to the iris and cornea. The long ciliary nerves are supposed to contain sympathetic fibers from the superior cervical ganglion to the Dilator pupillæ muscle.
  The infratrochlear nerve (n. infratrochlearis) is given off from the nasociliary just before it enters the anterior ethmoidal foramen. It runs forward along the upper border of the Rectus medialis, and is joined, near the pulley of the Obliquus superior, by a filament from the supratrochlear nerve. It then passes to the medial angle of the eye, and supplies the skin of the eyelids and side of the nose, the conjunctiva, lacrimal sac, and caruncula lacrimalis.
  The ethmoidal branches (nn. ethmoidales) supply the ethmoidal cells; the posterior branch leaves the orbital cavity through the posterior ethmoidal foramen and gives some filaments to the sphenoidal sinus.

The Ciliary Ganglion (ophthalmic or lenticular ganglion) (Figs. 775, 777).—The ciliary ganglion is a small, sympathetic ganglion, of a reddish-gray color, and about the size of a pin’s head; it is situated at the back part of the orbit, in some loose fat between the optic nerve and the Rectus lateralis muscle, lying generally on the lateral side of the ophthalmic artery.

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