**2. Anatomy of the maxilla**

The maxillae are the largest bones of the face, after the mandible. Each assists in forming the boundaries of three cavities: the roof of the mouth, the floor and lateral wall of the nose, and the floor of the orbit. They also enter into the formation of the fossae infratempo‐ ral and fossae pterygopalatine, and two fissures, the inferior orbital and pterygomaxil‐ lary. [1] The body of the maxilla is somewhat pyramidal in shape, and contains a large cavity, the maxillary sinus (antrum of Highmore). [1]

#### **2.1. Blood supply and venous drainage of the maxillary teeth**

The arteria (a.) maxillaris arises from the a. carotis externa, which supplies the maxillary teeth. The maxillary arch is supplied by a plexus of three arterial branches: the a. alveolares superi‐ ores anteriores, a. alveolares superiores medialis, and a. alveolares superiores posteriores. The a. alveolares superiores posteriores arises from the third division of the a. maxillaris before the a. maxillaris enters the fossa pterygopalatine (Figure 1). It continues on and enters the infratemporal surface of the maxilla to supply the maxillary sinus, the premolars, and the molars (Figure 1).

**Figure 1.** A. maxillaries and a. alveolares superiores posteriores.

During operations performed in this area there may be spontaneous bleeding from these vessels during surgery and sometimes serious bleeding in the postoperative period after local anesthetics lose activity. This situation may put the patient in a dangerous situation at two time points: immediately after the operation, because of bleeding, and later, after the operation, because of infection of formed clots. Careful CT examinations before the operation and appropriate surgical management will help to avoid all intraoperative and post-operative bleeding complications.

**2. Anatomy of the maxilla**

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molars (Figure 1).

cavity, the maxillary sinus (antrum of Highmore). [1]

**Figure 1.** A. maxillaries and a. alveolares superiores posteriores.

**2.1. Blood supply and venous drainage of the maxillary teeth**

The maxillae are the largest bones of the face, after the mandible. Each assists in forming the boundaries of three cavities: the roof of the mouth, the floor and lateral wall of the nose, and the floor of the orbit. They also enter into the formation of the fossae infratempo‐ ral and fossae pterygopalatine, and two fissures, the inferior orbital and pterygomaxil‐ lary. [1] The body of the maxilla is somewhat pyramidal in shape, and contains a large

The arteria (a.) maxillaris arises from the a. carotis externa, which supplies the maxillary teeth. The maxillary arch is supplied by a plexus of three arterial branches: the a. alveolares superi‐ ores anteriores, a. alveolares superiores medialis, and a. alveolares superiores posteriores. The a. alveolares superiores posteriores arises from the third division of the a. maxillaris before the a. maxillaris enters the fossa pterygopalatine (Figure 1). It continues on and enters the infratemporal surface of the maxilla to supply the maxillary sinus, the premolars, and the

During operations performed in this area there may be spontaneous bleeding from these vessels during surgery and sometimes serious bleeding in the postoperative period after local The a. alveolares superiores medialis arises from the a. infraorbitalis as does the a. alveolares superiores anteriores. It arises within the infraorbital canal where it descends to supply the maxillary sinus and plexus at the level of the canine. The a. alveolares superiores anteriores also arises at the level of the middle superior alveolar artery and runs with it to supply the anterior portion of the maxillary arch, maxillary sinus, and anterior teeth.

The venous (v.) drainage of v. alveolares superiores posteriores, v. alveolares superiores medialis, and v. alveolares superiores anteriores drain into the plexus venosus pterygoideus. [3] Some of the most important points during operations in the maxillary part of the body are first, during the design of the flap, to protect the plexus venosus pterygoideus and lymphatic drainage and, second, to be gentle during the retraction of soft tissues.

#### **2.2. Innervation of the maxilla and of the maxillary teeth**

The nervus trigeminus (the fifth cranial nerve) is a mixed nerve (n.) responsible for sensation in the face and certain motor functions, such as biting and chewing. It has three major branches: the n. ophthalmicus, n. maxillaris, and the n. mandibularis. The n. ophthalmicus and n. maxillaris are purely sensory. The n. mandibularis has both sensory and motor functions (Figure 2). [1]

**Figure 2.** The nervus trigeminus


**Figure 3.** N.infraorbitalis, c. infraorbitalis and f.infraorbitalis

**Figure 2.** The nervus trigeminus

and parts of the meninges.

238 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**•** The n. ophthalmicus carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose, the nasal mucosa, the frontal sinuses,

**•** The n. maxillaris carries sensory information from the lower eyelid and cheek, the nares and upper lip, the upper teeth and gums, the nasal mucosa, the palate and the roof of the pharynx, the maxillary, ethmoid and sphenoid sinuses, and parts of the meninges. It leaves the ganglion trigeminale between the n. ophthalmicus and the n. mandibularis lateral to the sinus cavernosus. The nerve leaves the cranium forward, through the foramen rotundum and enters the fossa pterygopalatina where it divides into three main branches: the n.

**•** The n. infraorbitalis is a direct extension of the n. maxillaris. It leaves the fossa pterygopa‐ latina and enters the orbit through the fissura orbitalis inferior, together with a. infraorbi‐ talis. The nerve runs forward on the floor of the orbita in one fulcrum, which turns anteriorly to the canalis infraorbitalis. Going forward it leaves the maxilla through the foramen infraorbitale (Figure 3), positioned on the anterior wall of the maxilla under the sutura

zygomaticus, n. infraorbitalis, and truncus pterygopalatinus.

zygomaticomaxillaris, and gives rise to terminal branches.

The n. alveolares superiores arises from the n. maxillaris in the fossa pterygopalatina just before n. infraorbitalis enters the orbita or arises from the n. infraorbitalis in the sulcus infraorbitalis. The upper alveolar nerves are divided in three groups: the n. alveolaris superior posterior, the n. alveolaris superior medius, and the n. alveolaris superior anterior. [4] Working 5 mm above the roots of the teeth in the maxilla will avoid damage to the neurovascular plexus. [5] This is one of the most important points during surgical procedures performed in the maxillary sinuses when the teeth are vital (Figure 4). A second important point is to avoid damage to the n. infraorbitalis, which is commonly damaged during elevation and retraction of mucoper‐ iosteal flaps.

**Figure 4.** N. infraorbitalis, c. infraorbitalis and f. infraorbitalis (part of figure adapted from Netter).

The n. mandibularis carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw, parts of the external ear, and parts of the meninges. The mandibular nerve carries touch/position and pain/temperature sensation from the mouth. It does not carry the taste sensation; the chorda tympani is responsible for taste. However, one of its branches, the lingual nerve, carries somatic sensation from the tongue.

## **3. History and anatomy of the maxillary sinus**

The maxillary sinus was first discovered and illustrated by Leonardo da Vinci (1452-1519), but the earliest scientific description is attributed to the British surgeon Nathaniel Highmore (1613-1685). [2] The sinus maxillaris is located behind the anterior wall of the os. maxillaris, under the orbital cavities and above the alveolar bone of the teeth. It has the shape of a pyramid, with a volume of ~15 cc, inferosuperior length of 33 mm, a mediolateral length of 23 mm, and anteroposterior length of 34 mm (Figure 5). The deepest point of the maxillary sinus is normally located in the area of the molar roots; the next deepest area is at the premolar roots. Thus, the risk of exposing the maxillary sinus intraoperatively is greatest when molar teeth are extracted (Figure 6). [6-10]

Kiliç et al. [8] evaluated the maxillary sinus regions from 92 patients, using dental cone-beam CT. This study showed that ~10.5% of molar roots were located in the maxillary sinus. Jung and Cho [9] in their study showed that 28.1% of molar roots were located in the maxillary sinus. Hirata et al. [10] investigated 1337 patients after 2038 molar extractions and found 3.8% maxillary sinus perforations. In addition to the relationship between the roots and the maxillary sinus floor, exposing the maxillary sinus intraoperatively when molar teeth are extracted depends on the shape and distance of the roots from each other, extraction technique, skill and experience. Knowledge of the anatomical shape of the maxillary sinus and the relationship between the sinus floor and tooth apices, careful planning, and good extraction technique will avoid maxillary sinus perforations.

The paranasal sinuses and the majority of the nasal cavity itself are lined with pseudostratified columnar ciliated epithelium (respiratory type). The cilia suspend a mucous blanket, which is secreted by goblet cells in the mucous membrane. [11] The sinus maxillaris has an opening for drainage, the ostium, located on the medial wall into the hiatus semilunaris. The position of the ostium does not help draining of sinus contents when the head is in an upright position. Before operation, this opening should be checked in CT scans for any obstruction. Ordinarily, it has a diameter of 5-7 mm and a length of 1-2 mm.

**Figure 6.** Maxillary sinus exposed after second molar tooth extraction.

**Figure 4.** N. infraorbitalis, c. infraorbitalis and f. infraorbitalis (part of figure adapted from Netter).

lingual nerve, carries somatic sensation from the tongue.

240 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**3. History and anatomy of the maxillary sinus**

(Figure 6). [6-10]

The n. mandibularis carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw, parts of the external ear, and parts of the meninges. The mandibular nerve carries touch/position and pain/temperature sensation from the mouth. It does not carry the taste sensation; the chorda tympani is responsible for taste. However, one of its branches, the

The maxillary sinus was first discovered and illustrated by Leonardo da Vinci (1452-1519), but the earliest scientific description is attributed to the British surgeon Nathaniel Highmore (1613-1685). [2] The sinus maxillaris is located behind the anterior wall of the os. maxillaris, under the orbital cavities and above the alveolar bone of the teeth. It has the shape of a pyramid, with a volume of ~15 cc, inferosuperior length of 33 mm, a mediolateral length of 23 mm, and anteroposterior length of 34 mm (Figure 5). The deepest point of the maxillary sinus is normally located in the area of the molar roots; the next deepest area is at the premolar roots. Thus, the risk of exposing the maxillary sinus intraoperatively is greatest when molar teeth are extracted

Kiliç et al. [8] evaluated the maxillary sinus regions from 92 patients, using dental cone-beam CT. This study showed that ~10.5% of molar roots were located in the maxillary sinus. Jung Janner et al. [12] reported that the thickness of the Schneiderian membrane showed a wide range, with a minimum value of 0.16 mm and a maximum value of 3.461 mm. The highest mean values, ranging from 2.16 to 3.11 mm, were found for the mucosa located in the midsagittal regions of the maxillary sinus. Dagassan-Berndt et al. [13] stated that in the molar regions with periodontal destruction, Schneiderian membrane thickening occurred, particu‐ larly in combination with small bone layers above the root tips or periapical lesions.

**Figure 5.** The sinus maxillaries. Volume ~15 cc and pyramidal shape. 1. inferosuperior length 33 mm, 2. Mediolateral length 23 mm, 3. Anteroposterior length 34 mm.
