This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
In the foetus, the frontonasal process comes from above downward to join the maxillary processes on each side. This leaves an orbitonasal cleft to form the orbit. Owing to defects in the development of this cleft, dermoid tumors may occur in its course. They are seen either at the outer or inner angle of the eye. They are more common at the outer angle near the external angular process, and may have a prolongation to the dura mater. They also occur at the inner angle at the frontonasal suture (Fig. 89). At this point, also, meningoceles are liable to occur. As pointed out by J. Bland Sutton the question of diagnosis is of importance, as an attempt to remove a meningocele by operation is apt to be followed by death, whereas a dermoid, though it may have a fibrous prolongation to the dura mater, can be more safely removed.
Suppuration may either originate within the orbit or extend into it from the neighboring tissues. If the former is the case, it may occur from caries of the bones of the orbit, as in syphilis. It may originate from erysipelas involving the orbit. General inflammation and suppuration of the eye may break through the eye and spread in the orbital tissues (panophthalmitis). If pus enters the orbit from the outside, it is usually from suppuration and caries of the frontal sinus and ethmoidal cells. In this case, the swelling shows itself at the upper portion of the inner angle of the eye. Pus in the maxillary sinus is most apt to discharge into the nose, and not break through the roof into the orbit above. Pus within the orbit tends to push the eyeball forward and even distend the lids. As the orbitotarsal ligament runs from the bony edge of the orbit to the lids, pus does not find an easy exit. The abscess should be opened by elevating the upper lid, and incising the conjunctiva in the sulcus between the globe of the eye and the lid. Pus from suppuration of the lachrymal sac does not tend to invade the orbit but works its way forward to the skin.
Fig. 89. - Dermoid of orbit. Boy, 15 years of age. It extended back to the body of the sphenoid bone. Case of Dr. Wm. Zentmayer.
Owing to the considerable space which exists between the eye and orbital walls, large foreign bodies may find a lodgment there, often producing serious symptoms for a considerable length of time. The tang of a gun barrel has been so found. This should lead one to search for foreign bodies carefully when this portion of the orbital contents has been wounded.
Fig. 91. - The rim of the orbit has been divided and the piece of the bone turned outward; an incision is then made through the periosteal lining. (Kronlein's operation for obtaining access to the retrobulbar region).