Danger triangle of the face
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|Danger triangle of the face|
|The danger triangle of the area from the corners of the mouth to the bridge of the nose|
The danger triangle of the face consists of the area from the corners of the mouth to the bridge of the nose, including the nose and maxilla.[not in citation given] Due to the special nature of the blood supply to the human nose and surrounding area, it is possible (although very rare) for retrograde infections from the nasal area to spread to the brain.
This is possible because of venous communication (via the ophthalmic veins) between the facial vein and the cavernous sinus. The cavernous sinus lies within the cranial cavity, between layers of the meninges and is a major conduit of venous drainage from the brain.
It is a common misconception that the veins of the head do not contain one-way valves like other veins of the circulatory system. In fact, it is not the absence of venous valves but the existence of communications between the facial vein and cavernous sinus and the direction of blood flow that is important in the spread of infection from the face. Most people, but not all, have valves in the veins of the face.
Inflammation of cavernous sinus
If the cavernous sinus turns inflamed, it will constrict the structures that are going through it or surround it. Inside cavernous sinus, constriction of the following nerves can be found: CN III (oculomotor nerve), CN IV (trochlear nerve), CN VI (abducens nerve), CN V (trigeminal nerve), specifically V1 (ophthalmic nerve) and V2 (maxillary nerve) branches. Failure of each of the nerves listed above will manifest in loss of function of the specific muscle, gland or a parasympathetic innervations (from CN III). In addition, it is possible that inflammation of the cavernous sinus will result in compression of the optic chiasm (resulting in vision problems) and/or the pituitary gland.
Failure of CN III will result in loss of function of the following muscles: medial rectus, superior rectus, inferior rectus, as well as muscles that are responsible for opening the eyelid: levator palpebrae superioris muscle and the superior tarsal muscle (Muller’s muscle). CN III damage also results in loss of parasympathetic innervation of the eye (loss of pupillary constriction and lens accommodation).
- Anatomy in Cutaneous Surgery
- Zhang J, Stringer MD (July 2010). "Ophthalmic and facial veins are not valveless". Clin. Experiment. Ophthalmol. 38 (5): 502–10. doi:10.1111/j.1442-9071.2010.02325.x. PMID 20491800.