Cunningham's textbook of anatomy - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1818 Excerpt: ...propria of the cornea; the latter, the stroma of the iris and anterior part of the vascular tunic of the lens. The fissure represents-the future camera oculi anterior, and its lining cells form the eudothelium of this chamber. The eyelids arise as two integumentary folds above and below the cornea, each being covered on both its surfaces by the ectoderm. By the third month the folds meet and unite with each other at their edges, the eyelids being only permanently opened shortly before birth; in many animals they are not opened until after birth. The ectoderm forms the epithelium of the conjunctiva and the epithelium corneae. It is also invaginated at the lid margins to form the hair follicles and the lining cells of the tarsal glands and glands of Moll, and, at the fornix conjunctiva; superior, to form the lining of the alveoli and ducts of the lacrimal gland. The naso-lacrimal duct, lacrimal sac, and ducts represent the remains of the furrow between the maxillary and lateral nasal processes (p. 49). It is at first filled with a solid rod of cells, which becomes hollowed out to form the sac and ducts. ORGANON AUDITUS. The ear or auditory organ (Fig. 703) consists of three portions--external, middle, and internal--the last constituting its essential part, since the peripheral terminations of the acoustic nerve are distributed within it. EXTERNAL EAE. The external earl includes--(a) the auricula, attached to and projecting from the side of the head; and (6) the external acoustic meatus leading inwards from the most depressed part of the auricula to the tympanic membrane. Aukicula. The auricle (O.T. pinna) (Fig. 704) presents two surfaces, lateral and medial, the latter forming an angle (cephalo-auricular angle) of about 30 with the side of the head. The later...