372 THE MUSCLES AND FASCIA 



In performing enudeation of the eyeball the conjunctiva is clipped with scissors near the cornea 

 and the capsule of Tenon is divided with it. One Rectus muscle after another is caught up 

 on a blunt hook and divided. The scissors are now pushed well in along the outer orbital wall 

 and the optic nerve is divided. Finally, the Oblique muscles, the ciliary vessels and nerves, and 

 fragments of tissue helping to retain the globe are cut and the eyeball is enucleated. 



An orbital abscess is evacuated by making an incision close to the border of the orbit, above 

 or below the eyeball. 



Exophthalmos, or abnormal protrusion of the eyeball, is believed to be due to hypersecretion 

 of the thyroid (as in goitre), which, through the cervicocephalic division of the sympathetic, 

 stimulates the nonstriated tarsal muscles to sustained contraction. These muscles are arranged 

 like a cuff, and may be regarded as having their origin in the orbital septum and their insertion 

 at the equator of the eyeball. In their action they are antagonists of the Recti, and of the 

 Levator palpebrae superioris, and open wide the palpebral fissure and draw the eyeball forward. 

 (Consult J. Landstrom, Ueber Morbus Basedowii, Thesis, Stockholm, 1907.) 



5. The Nasal Region (Fig. 289). 



Pyramidalis nasi. Dilatator naris anterior. 



Levator labii superioris alaeque nasi. Compressor nasi. 



Dilatator naris posterior. Compressor narium minor. 



Depressor alae nasi. 



The Pyramidalis nasi (m. procerus) is a small pyramidal slip placed over the 

 nasal bone. Its origin is by tendinous fibres from the fascia covering the lower 

 part of the nasal bone and upper part of the cartilage, where it blends with the 

 Compressor nasi, and it is inserted into the skin over the lower part of the forehead 

 between the two eyebrows, its fibres decussating with those of the Occipitofron- 

 talis (see page 364). 



The Levator labii superioris alaeque nasi is a thin triangular muscle placed 

 by the side of the nose, and extending between the inner margin of the orbit 

 and upper lip. It arises by a pointed extremity from the upper part of the nasal 

 process of the maxilla, and, passing obliquely downward and outward, divides into 

 two slips, one of which is inserted into the cartilage of the ala of the nose; the 

 other is prolonged into the upper lip, becoming attached to the under surface of 

 the skin and blended with the Orbicularis oris and Levator labii superioris 

 proprius. 



The Dilatator naris posterior is a small muscle which is placed partly beneath 

 the elevator of the nose and lip. It arises from the margin of the nasal notch 

 of the maxilla and from the sesamoid cartilages, and is inserted into the skin near 

 the margin of the nostril. 



The Dilatator naris anterior is a thin, delicate fasciculus passing from the 

 cartilpo-e of the ala of the nose to the integument near its margin. This muscle is 

 situated in front of the preceding. 



The Compressor naris (m. nasalis) is a small, thin, triangular muscle arising 

 by its apex from the maxilla, above and a little external to the incisive fossa; 

 its fibres proceed upward and inward, expanding into a thin aponeurosis which 

 is attached to the fibrocartilage of the nose and is continuous on the bridge of 

 the nose with that of the muscle of the opposite side and with the aponeurosis of 

 the Pyramidalis nasi. 



The Compressor narium minor is a small muscle attached by one end to the 

 alar cartilage, and by the other to the integument at the end of the nose. 



The Depressor alae nasi (m. depressor septi) is a short radiated muscle arising 

 from the incisive fossa of the maxilla; its fibres ascend to be inserted into the 

 septum and back part of the ala of the nose. This muscle lies between the 

 mucous membrane and muscular structure of the lip. 



