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The danger triangle of the face.

The dangerous triangle of the face or maxillofacial death pyramid (MDP) consists of the area from the corners of the mouth to the bridge of the nose, including the nose and maxilla.^[1] 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, but not all, people have valves in the veins of the face.^[2]

An example of disease that may be caused by this process is meningitis, an inflammation of the meninges, the coverings of the brain. Such bacterial infections can be caused by pus entering the brain's blood supply if pimples in the danger triangle are picked.^[3]

Inflammation of cavernous sinus

Furthermore if the cavernous sinus gets inflamed it will constrict the structures that are going through it or surround it. Inside cavernous sinus we can find constriction of the following nerves: CN3Oculomotor nerve, CN4 Trochlear nerve, CN6Abducens nerve, CN5trigeminal nerve, specifically V1Ophthalmic nerve and V2maxillary 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 CN3). In addition following structures will be compressed: Optic Chiasm (resulting in vision problems), Pituitary gland.

Failure of the CN3 Oculomotor nerve will result in loss of function of the following muscles: Medial Rectus (look medially, towards nose), Superior Rectus (look up when eye is looking laterally, outside), Inferior Rectus (look down when eye is looking laterally, outside), Inferior Rectus. As well as muscles that are responsible for raising an eyelid: Levator palpebrae superioris muscle (voluntary muscles, keeps eye open for short period of time) and Superior tarsal muscle (Muller’s muscle).(involuntary under sympathetic innervation, is the one to keep eye open for a long time). (The first muscle(LPS) raises an eyelid but it does not have much stamina, quickly becoming tired and in absence of sympathetic innervation to Superior tarsal muscle (Muller’s muscle), the eyelid is slowly drooping down. Eye is half closed and the patient need to stimulate Levator palpebrae superioris again to open eyelid). The Superior tarsal (Muller’s) muscle is the one that keeps the eye open throughout the day.

References

1. ^ Anatomy in Cutaneous Surgery
2. ^ 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. 
3. ^ http://www.doctorspiller.com/cavernoussinus.htm

External links

• "Cavernous sinus thrombosis: Introduction". National Health Service. 2006-02-10. http://www.nhs.uk/conditions/Cavernous-sinus-thrombosis/Pages/Introduction.aspx?url=Pages/what-is-it.aspx. 
• "Nasal Abscess in Danger Area of Face". http://www.drpaulose.com/ear/ent-pediatric-children/nasal-abscess-in-danger-area-of-face. Retrieved 2011-04-08. 

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