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Organ of sight

In the centre there is a head with the lateral wall of the orbit demolished, and the skull opened in order to show the nerves of the orbit in their full lenght. The optic nerve enters the cranial cavity through the optic foramen of the sphenoid bone and joins the optic chiasma from which originates the optic tract that winds round the cerebral peduncle. The three motor nerves for the ocular muscles can be seen; they go to the orbit through the superior orbital fissure of the sphenoid bone (open); the oculomotor which starts from the intrapeduncolar fossa of the mesencephalon; the trochlear (or pathetic) that appears from below the inferior colliculus and goes forward along the border between the pons and the cerebral peduncle; the abducent, which can only be seen briefly as it is covered by the ophthalmic nerve.

The orbital branches of the trigeminal nerve is clearly visible. Originating from the trigeminal (Gasser’s) ganglion which is left on site inside the open trigeminal (Meckel’s) cave, the ophthalmic nerve can be seen. The ophthalmic nerve divides into its three branches just before the superior orbital fissure: the nasociliary nerve which hides behind the superior rectus where it emits the long ciliary nerves; the frontal nerve that goes along the vault of the orbit and then ascends upon the forehead; the lacrimal nerve which joins the lacrimal gland (here it is pushed inferiorly). From the trigeminal ganglion the origin of the maxillary nerve which leaves the skull through the foramen rotund um of the sphenoid bone and enters the orbit through the inferior orbital fissure, can be seen.

Finally there is a model of the ciliary ganglion with its long sensory root that detaches from the nasociliary nerve when enters the orbit and short ciliary nerves that go into the eye. At the sides are two models showing the arteries and the veins of the orbit and part of the lacrimal apparatus. On the latter, on the medial canthus of eyelids, the lacrimal lake with the demi lunar fold and the lacrimal canaliculi and the lacrimal sac. At the top there is a fragment of the superior eyelid as seen from its conjunctiva! surface: on its inferior (tarsal) part, the longitudinal ridges originating from the tarsal (Meibomian) gland can be seen. At the bottom is a row of eyeballs. In the first three of them the cornea and the sclera have been removed to show the vascular tunic (uvea).

These models show, on the uvea, the ciliary arteries, the ciliary nerves and the roots of the vorticose veins. The fourth eyeball has not been dissected in order to show the cornea and the sclera; on the sclera the insertions of the two oblique muscles are visible. The fifth eyeball demonstrates the retina, the sixth (a feta I eye) shows the vitreous:body transversed by the hyaloid artery. The last two eyeballs show the ciliary body; one with the lens on site and the other one without it.

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