1348 



CLINICAL AND TOPOGRAPHICAL ANATOMY 



These conjunctival vessels, derived from the lacrimal and palpebral arteries, become very 

 visible in conjunctivitis. In deep inflammation affecting the iris and ciHary body, the episcleral 

 branches of the anterior ciliary arteries (which are derived from the muscular and lacrimal 

 arteries) become engorged and are visible as a pink circumcorneal zone of congestion, deeply 

 situated under the conjunctiva. These branches take a large share in the nutrition of the cornea, 

 and are responsible for the vascularity of pannus and the 'salmon patches' of interstitial 

 keratitis. 



The conjunctival nerves for the upper lid and bulbar part of the membrane, and the nerves 

 to the cornea, are supplied by the ophthalmic division of the trigeminal. The maxillary divi- 

 sion of this nerve supphes the lower palpebral conjunctiva. 



The differing structure of the palpebral and ocular portions has important bearings. Thus 

 the palpebral conjunctiva is thick, highly vascular and sensitive. To this vascularity we owe the 

 chemosis, or hot, red, tense swelling of purulent ophthalmia. The exquisite suffering of the same 

 disease, or that caused by a foreign body, is explained by the numerous nerve-papillae and end- 

 bulbs. To the thickness and abundance of the connective tissue are due the contraction and 

 permanent thickening which may occur in granular lids. The so-called granulations, met with 

 in this disease on the palpebral conjunctiva, are really little nodules of hypertrophied lymphoid 

 foUicles, or mucous glands, which abound here. 



Immediately under the bulbar conjunctiva, between it and the sclerotic, lies the anterior 

 part of the fascia bulbi (of Tenon). This fibrous membrane forms a sheath for the posterior 



Fig. 1095. — The Lacrimal Apparatus and Naso-lacrimal Duct. (Bellamy.) 

 (Bristles are introduced into the puncta lacrimalia.) 



Lacrimal sac 

 Medial palpebral ligament 



' J- Valvular folds in naso-lacrimal duct 



Medial wall of maxillary sinus 



Lower uaaal concha Orifice of naso-lacrimal duct 



five-sixths of the eyeball, and is intimately connected with the sheaths of the extrinsic muscles 

 and tlxrough the check ligaments with the orbital walls. Together with the conjunctiva it 

 must be opened in the operation of tenotomy for strabismus, and after division of a rectus tendon 

 the muscle retains some control over the eye through its connection with the fascia bulbi. In 

 enucleation of the eyeball both conjunctiva and fascia bulbi are divided around the cornea, 

 where they are intimately blended. In removal of the upper jaw the attachment of the sus- 

 pensory ligament of this fascia must always be left if i)ossible, for otherwise the eyeball will tend 

 to fall forward and the cornea suffer from its exposure (Lockwood). Finally the cavity between 

 the two layers of the caj^sule is continuous with the extensions of the cerebral membranes along 

 the optic nerve, i. e., with the subarachnoid space. 



For an account of the intrinsic and extrinsic muscles of the eye the reader is referred to the 

 section on the Kyi:. ]{efereiice may be made here, however, to the part played by certain fibres 

 of the cervical sympathetic system. I'^merging from the cord at the first and second thoracic 

 segments, tlie communicjiting fibres i)ass uj) the sympathetic chain in the neck to cell stations 

 in tlie HU|)erior cervical ganglion. Thence continuing onward tlu-ough the carotid canal and 

 superior orbital fissure, they supply (1) the dilator nuiscle of the iris, (2) the unstriped muscle 

 element in theeyelid.s, and {',i) smooth nuiscle fibres, decribed by 8ai)pey, in the check ligaments 

 and fascia bulbi. Paralysis of the cervical sympathetic nerve in the neck, usually in its lowest 

 part, by trauma or the i)rcssure of a malignant growth, causes therefore (1) narrowing of the 

 pupil, (2) narrowing of the palpebral fissure (pscudo-ptosis), and (3) enophthalmos. 



The lacrimal gland lies in a lioUow at the supero-Iateral angle of the orbit, 

 protected by the zyfi;oinatic proce.ss of the frontal bone. It is not palpable nor- 

 mally. Its lower or j)alpebral portion rests on the lateral third of the fornix 



