Maxilla is the second largest bone of the face, the iirst being the mandible. The two maxillae form the whole of the upper jaw, and each maxilla enters into the formation of face, nose, mouth, orbit, the infratemporal and pterygopalatine fossae.
1. Anterior surface ends medially into a deeply concave border, called the nasal notch. Posterior surface is convex.
2. Alveolar border with sockets for upper teeth faces downwards with its convexity directed outwards. Frontal process is the longest process which is directed upwards.
3. Medial surface is marked by a large irregular opening, the maxillary hiatus.
Each maxilla has a body and four processes, the frontal, zygomatic, alveolar and palatine.
Body of Maxilla
The body of maxilla is pyramidal in shape, with its base directed medially at the nasal surface, and the apex directed laterally at the zygomatic process. It has four surfaces and encloses a large cavity; the maxillary sinus. The surfaces are : (1) Anterior or facial; (2) posterior or infratemporal; (3) superior or orbital; and (4) medial or nasal.
1. Anterior surface is directed forwards and laterally.
2. Above the incisor teeth there is a slight depression, the incisive fossa, which gives origin to depressor septt Incisivus arises from the alveolar margin below the fossa, and the nasalis superolateral to the fossa along the nasal notch.
3. Lateral to canine eminence there is a larger and deeper depression, the canine fossa, which gives origin to levator anguli oris.
4. Above the canine fossa there is infraorbital foramen, which transmits infraorbital nerve and vessels.
5. Levator labii superioris arises between the infraorbital margin and infraorbital foramen.
6. Medially, the anterior surface ends in a deeply concave border, the nasal notch, which terminates below into process which with the corresponding process of opposite maxilla forms the anterior nasal spine. Anterior surface bordering the nasal notch gives origin to nasalis and depressor septi.
1. Posterior surface is convex and directed backwards and laterally.
2. It forms the anterior wall of infratemporal fossa, and is separated from anterior surface by the zygomatic process and a rounded ridge which descends from the process to the first molar tooth.
3. Near the centre of the surface open two or three alveolar canals for posterior superior alveolar nerve and vessels.
4. Posteroinferiorly, there is a rounded eminence, the maxillary tuberosity, which articulates superomedially with pyramidal process of palatine bone, and gives origin laterally to the superficial head of medial pterygoid muscle.
5. Above the maxillary tuberosity the smooth surface forms anterior wall of pterygopalatine fossa, and is grooved by maxillary nerve.
3. Above the hiatus, there are parts of air sinuses which are completed by the ethmoid and lacrimal bones.
4. Below the hiatus, the smooth concave surface forms a part of inferior meatus of nose.
5. Behind the hiatus, the surface articulates with perpendicular plate of palatine bone, enclosing the greater palatine canal which runs downwards and forwards, and transmits greater palatine vessels and the anterior, middle and posterior palatine nerves.
6. In front of the hiatus, there is nasolacrimal groove, which is converted into the nasolacrimal canal by articulation with the descending process of lacrimal bone and the lacrimal process of inferior nasal concha The canal transmits nasolacrimal duct to the inferior meatus of nose.
7. More anteriorly, an oblique ridge forms the conchal crest for articulation with the inferior nasal concha.
8. Above the conchal crest, the shallow depression forms a part of the atrium of middle meatus of nose.
Side Determination
1. Anterior surface ends medially into a deeply concave border, called the nasal notch. Posterior surface is convex.
2. Alveolar border with sockets for upper teeth faces downwards with its convexity directed outwards. Frontal process is the longest process which is directed upwards.
3. Medial surface is marked by a large irregular opening, the maxillary hiatus.
Features
Each maxilla has a body and four processes, the frontal, zygomatic, alveolar and palatine.
Body of Maxilla
The body of maxilla is pyramidal in shape, with its base directed medially at the nasal surface, and the apex directed laterally at the zygomatic process. It has four surfaces and encloses a large cavity; the maxillary sinus. The surfaces are : (1) Anterior or facial; (2) posterior or infratemporal; (3) superior or orbital; and (4) medial or nasal.
Anterior or Facial Surface
1. Anterior surface is directed forwards and laterally.
2. Above the incisor teeth there is a slight depression, the incisive fossa, which gives origin to depressor septt Incisivus arises from the alveolar margin below the fossa, and the nasalis superolateral to the fossa along the nasal notch.
3. Lateral to canine eminence there is a larger and deeper depression, the canine fossa, which gives origin to levator anguli oris.
4. Above the canine fossa there is infraorbital foramen, which transmits infraorbital nerve and vessels.
5. Levator labii superioris arises between the infraorbital margin and infraorbital foramen.
6. Medially, the anterior surface ends in a deeply concave border, the nasal notch, which terminates below into process which with the corresponding process of opposite maxilla forms the anterior nasal spine. Anterior surface bordering the nasal notch gives origin to nasalis and depressor septi.
Posterior or Infratemporal Surface
1. Posterior surface is convex and directed backwards and laterally.
2. It forms the anterior wall of infratemporal fossa, and is separated from anterior surface by the zygomatic process and a rounded ridge which descends from the process to the first molar tooth.
3. Near the centre of the surface open two or three alveolar canals for posterior superior alveolar nerve and vessels.
4. Posteroinferiorly, there is a rounded eminence, the maxillary tuberosity, which articulates superomedially with pyramidal process of palatine bone, and gives origin laterally to the superficial head of medial pterygoid muscle.
5. Above the maxillary tuberosity the smooth surface forms anterior wall of pterygopalatine fossa, and is grooved by maxillary nerve.
3. Above the hiatus, there are parts of air sinuses which are completed by the ethmoid and lacrimal bones.
4. Below the hiatus, the smooth concave surface forms a part of inferior meatus of nose.
5. Behind the hiatus, the surface articulates with perpendicular plate of palatine bone, enclosing the greater palatine canal which runs downwards and forwards, and transmits greater palatine vessels and the anterior, middle and posterior palatine nerves.
6. In front of the hiatus, there is nasolacrimal groove, which is converted into the nasolacrimal canal by articulation with the descending process of lacrimal bone and the lacrimal process of inferior nasal concha The canal transmits nasolacrimal duct to the inferior meatus of nose.
7. More anteriorly, an oblique ridge forms the conchal crest for articulation with the inferior nasal concha.
8. Above the conchal crest, the shallow depression forms a part of the atrium of middle meatus of nose.
No comments:
Post a Comment