32 TOPOGRAPHICAL ANATO:\IY OF THE 



more than one row, and that they are implanted in the skin at 

 different angles in the several rows. On the inner margin of the 

 border of the lid are the small openings of the ducts of the tarsal 

 glands. 



The two eyelids are joined at the extremities of the palpebral 

 fissure (the lateral and medial angles) by the lateral and medial 

 commissures^ (commissurie palpebrarum lateralis et medialis). Both 

 commissures are acute ; but the lateral becomes rounded when the 

 eye is widely opened, and in the neighbourhood of the medial com- 

 missure the lids circumscribe a space, the lacus^ lacriinalis, in which 

 is a rounded body, the lachrymal caruncle^ (caruncula lacrimalis), 

 covered with pigmented skin on which are a few small hairs. On 

 the borders of the lids near the medial commissure are the small 

 puncta ^ lacrivialia, upper and lower, leading into the lachrymal 

 ducts (ductus lacrimales) by which the tears are drained from the 

 eye. 



Each eyelid contains a framework of fibrous tissue, the tarsus,^ 

 much better developed in the upper than in the lower lid. A 

 sphincter muscle (m. orbicularis oculi) is associated with the lids, 

 and can be exposed b}^ the removal of the skin over them. In 

 addition, the upper lid and the region of the eyebrow contain 

 muscular fibres that corrugate the eyebrow (m. corrugator super- 

 cilii), and a very thin and variable muscle (m. malaris) passes into 

 the lower lid from the fascia in front of the orbit. 



The third eyelid consists of a pigmented semilunar fold of con- 

 junctiva, the membrana nictitans,^ easily demonstrated near the 

 medial commissure, and a piece of cartilage (cartilago palpebrse 

 tertise) that will be examined with the other contents of the orbit. 



Dissection. — Remove the skin from the whole of the face except 

 about the nostrils and over the lips. This must be done with care 

 and especially so over the eyelids, where removal is rendered difficult 

 by close adhesion to the underlying orbicular muscle. 



M. CUTANEUS (faciei). — The cutaneous muscle of the face is 

 difficult to demonstrate satisfactorily except over the border of the 

 mandible and in the region of the angle of the mouth. The most 

 definite part of it constitutes the risorius'' muscle (m. risorius) that 



^ Commissura [L.], a joining together. In anatomy, a commissure joins like jaarts. 



2 Lacus [L.], a lake. Lacrima [L.], a tear. 



3 Caruncula (dim. of cam, flesh) [L.], a small fleshy mass. 

 * Punctum [L.], a point, a minute round spot. 



^ Tarsus [L.], rapaos (tarsos) [Gr.], a frame of wicker-work ; a mat of reeds, such 

 as was built into brick-work to bind it together. 

 " Nictitarc [L.], to wink. 

 ^ Risor [L.], a laugher. 



