1.pdf(1).PDF

Symphysis It consists body, and two perpendicular portions( the rami) which unite with the ends of the body form right angles. The Body: curved somewhat like a horseshoe and has two surfaces and two borders. The outer surface : is marked in the median line by a faint ridge called the symphysis or...

Symphysis It consists body, and two perpendicular portions( the rami) which unite with the ends of the body form right angles. The Body: curved somewhat like a horseshoe and has two surfaces and two borders. The outer surface : is marked in the median line by a faint ridge called the symphysis or line of junction of the two pieces of mandibular body. Below This ridge a triangular eminence, called mental protuberance, contain mental tubercle. Midway between the upper and lower borders 12 of the body, is the mental foramen, for the passage of the mental vessels and nerve. Running backward and upward from each mental tubercle is a faint ridge, the oblique line, which is continuous with the anterior border of the ramus. The internal surface: is concave from side to side. Near the lower part of the symphysis is a pair of laterally placed spines, termed (superior and inferior genial tubercle). Below the mental spines, on either side of the middle line, is an oval depression called digastric fossa.there is line below alveolar arch called mylohyoid line. there is 2 fossa superior fossa called sublingual fossa, submandibular fossa. Borders.—The superior or alveolar border, wider behind than in front, is hollowed into cavities, for the reception of the teeth; The inferior border is rounded, longer than the superior, and thicker in front than behind. 13 Condylod process The Ramus (has two surfaces, four borders, and two processes. Surfaces.—The lateral surface is flat and smooth surface, The medial surface at its center mandibular foramen, for the entrance of the inferior alveolar vessels and nerve. The margin of this opening is called the lingula, below it groove called mylohyoid groove runs obliquely downward and forward, and lodges the mylohyoid vessels and nerve. The mandibular canal runs obliquely downward and forward in the ramus, and then in the body. On arriving at the incisor teeth, it with the mental foramen. The upper border is thin, and is surmounted by two processes, the coronoid in front and the condyloid behind, separated by a deep concavity, the mandibular notch. The Condyloid Process is thicker than the coronoid, and consists of two portions: the condyle, and the constricted portion which supports it, the neck. The Paranasal Sinuses: 14  The paranasal sinuses are four in number. They are cavities within the skull bones lined by mucous membrane and all open into the nasal cavity. The help in decreasing weight of the head, act as boxes for voice, act as air conditioning and ventilate the entering air. They are: 1. The maxillary air sinus: It occupies the greater part of the body of the maxilla. It lies below the orbit and open into the middle meatus of the nasal cavity. 2. The sphenoidal air sinus: It occupies the body of the sphenoid. It lies below the hypophyseal fossa. It opens into the nasal cavity. 3. The frontal air sinus: It lies in the frontal bone above the orbit and nose. It opens into the nasal cavity. 4. The ethmoidal sinus: It lies in between the nasal cavity and the orbit. It opens into the nasal cavity. Maxillary air sinus: 15  The maxillary sinus is the largest paranasal sinus situated in the body of the maxilla. The maxillary sinus is connected with the middle nasal meatus via the maxillary ostium. The maxillary sinus is bordered by three main walls: The roof – is a thin bony plate shared with the inferior wall of the orbit The floor – is composed by the alveolar process of the maxilla. It hosts a couple of elevations formed by the roots of the maxillary teeth. This can be a potential pathway for infection of the sinus, mainly during a complicated dentist procedure. The base – makes the inferior portion of the lateral wall of the nasal cavity THE ORBIT The orbit is a pyramidal cavity with its base anterior and its apex posterior. The orbital margin: is formed above by the frontal bone the lateral margin is formed by the processes of the frontal and zygomatic bones the inferior margin is formed by the zygomatic bone and the maxilla the medial margin is formed by the processes of the maxilla and the frontal bone. Roof: Formed by the orbital plate of the frontal bone, which separates the orbital cavity from the anterior cranialfossa and the frontal lobe of the cerebral hemisphere Lateral wall: Formed by the zygomatic bone and the greater wing of the sphenoid. Floor: Formed by the orbital plate of the maxilla, which separates the orbital cavity from the maxillary sinus Medial wall: Formed from before backward by the frontal process of the maxilla, the lacrimal bone, the orbital plate of the ethmoid and the body of the sphenoid 16  The Nasal Cavity - It is divided into right & left halves separated by nasal septum. - It opens in front by anterior nasal apertures (nares) & behind by posterior nasal apertures(choanae). - Each half of the nasal cavity has the following boundaries: Roof: composed of 3 parts: a) Anterior sloping part formed by frontal & nasal bones. b) Middle horizontal part formed by cribriform plate of ethmoid. c) Posterior sloping part formed by body of sphenoid. Floor: is formed by bony palate. The incisive canals open into the anterior part of the floor close to the nasal septum. Medial wall (nasal septum): is formed by: a) Perpendicular plate of the ethmoid posterosuperior. b) Vomer posteroinferior. The anterior deficiency of the septum is occupied by the septal cartilage. Lateral wall: is formed by: a) Nasal surface of maxilla (anteroinferior). b) Perpendicular plate of palatine bone (posterior). c) Nasal surface of ethmoidal labyrinth (superior). 17  The FACE Face is the part of the front of the head between the auricle and chin to the hair line. Muscles Of Facial Expressions: The facial muscles, also called craniofacial muscles, muscles lying underneath the skin of the face and scalp. The facial muscles are positioned around facial openings (mouth, eye, nose and ear). 18