**2. Anatomy**

Nasal bleeding can conveniently be divided into anterior and posterior epistaxis. Anterior bleeds come out the front of the nose, whereas posterior bleeds run down the back of the nose into the pharynx. Roughly 90% of cases of epistaxis can be classified as anterior. The common sites of anterior bleeding include the anterior aspect of the nasal septum, anterior edge of the inferior turbinate and the anterior ethmoid sinus. Among them, the anterior aspect of the nasal septum is the single most common site, where sometimes referred to as Kisselbach's plexus (Little's area). Kisselbach's plexus contains a rich capillary blood supply that is at the confluence of four different arterial blood supplies, which are sphenopalatine artery, greater palatine artery, superior labial artery, and anterior ethmoid artery (Figure 1).

Posterior epistaxis typically arises from vessels on the posterior septum, on the floor of the nose in the posterior choana, or from the back of the middle or inferior turbinate. The area at the back of the inferior turbinate is specified as Woodruff's plexus (Figure 2). Recently, it is known that the Woodruff plexus is a venous plexus located at the back of the inferior meatus, not an arterial plexus.
