HEAD AND ANTERIOR CERVICAL STRUCTURES. 15 



The Eyeball and its Surroundings : 



Upper eyelid, tarsus (superior palpebral fold). 



Lower eyelid (inferior palpebral fold). 



Edges of eyelids (a), (b). (Meibomian follicles.) 

 Lachrymal papilla. 



Palpebral conjunctiva, fornix. 



Lachrymal caruncle. Semilunar fold of conjunctiva, 878. (858) 



Ocular conjunctiva, 876. (856) 



Scleral sulcus. 



Zones of iris ; ciliary, pupillary. 



An examination of the living eye should be made with the aid of the ophthalmoscope, and the follow- 

 ing mentioned structures identified : 



Optic disc or papilla. Lamina cribrosa. 

 Yellow spot. Fovea centralis. 



Dissection of the Orbital Region and Face. 



Moderately distend the cheeks with tow and stitch the margins of the lips together. Treat the eyelids 

 in the same manner. Continue the incision in the median line of the face to the chin. Beginning at 

 the root of the nose, make a semicircular incision outward along the lower border of the orbit to the 

 outer angle of the eye. Also, make an incision downward in front of the ear, and forward along the 

 lower border of the inferior maxilla or mandible to the median line. Beginning in front of the ear, 

 turn the skin forward to the median line, and remove it. Care must be exercised to remove the skin 

 only, especially over the ala of the nose and the chin, where it is closely adherent to the subjacent struc- 

 tures. The skin of the eyelids should then be removed, by carefully reflecting it to the margin of the lids 

 from above and below. The structures of the external orbital region will be first considered. 



Superficial fascia, 452. (447) 



Structure of the lids, 1119-20. Fig. 666. (1097) 902. (881) 



Skin. Areolar tissue. 

 Muscles of the eyelids and eyebrows. Upper tarsal cartilage, 455. (450) 



Carefully expose the orbicularis palpebrarum. Preserve the branches of the facial nerve which enter 

 its deep surface, on the outer side. 



Orbicularis muscle, musculus ciliaris Riolini, 902. (881) 

 Orbicularis palpebrarum, 455-6 ; Fig. 309. (450-1) 

 Internal tarsal ligament or tendo-oculi. 

 External tarsal ligament. 

 Orbital portion : 



Origin and Insertion. 

 Palpebral portion : 



Origin. Insertion. 



Structure. Nerve-supply. Action. Relations. 

 Orbicularis, 1120. (1097) 



The dissectors of the opposite sides will now work together, and continue the dissection of the external 

 orbital structures on the left side, in the manner indicated. Discontinue further dissection of the right 

 eye at this point, and preserve it for dissection later, with the internal orbital structures. 

 On the left side, beginning at the outer edge, raise the orbicularis and reflect it inward. Care must be 

 exercised not to injure the palpebral structures underneath. The corrugator supercilii and tensor tarsi 

 will be demonstrated as the orbicularis is raised. 



Corrugator supercilii, 457-8; Fig. 310. (452) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. 

 Tensor tarsi, 457; Fig. 310. (451) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. 

 Central connective tissue, 903. (881) Palpebral ligament, 1120. (1097) 

 Blood-vessels. Nerves : (a) Sensory ; (b) Motor, 904. (883) 

 Tarsus, superior palpebral muscle, 903. (881-2) 



To expose the insertion of the superior palpebral muscle, divide the superior palpebral ligament along 

 the border of the orbit and reflect it downward to the tarsus. 



Palpebral conjunctiva, 903. (882) 

 Lymphatic vessels of the lids, 904. (883) 

 Glands of the eyelids, 903. (822-3) 



Meibomian glands, lashes, and sebaceous follicles, 1120. (1097) 



