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Surgical Anatomy
Face (midface is the region from spraorbital rims to maxillary alveolar process.
Maxilla • It is the second largest bone of the face • It forms the upper jaw with
the fellow of the opposite side • It also contributes to the formation of 1. Floor of
the nose and the orbit 2. Roof of the mouth 3. Lateral wall of the nose 4.
Pterigopalatine and infratemporal fossae 5. Pterigomaxillary and infraorbital
fissures
Anatomy of the maxilla • The anatomy of the maxilla has two main parts: 1.
Body(pyramidal shape) – Anterior surface – Posterior surface – Orbital surface –
Nasal surface 2. Processes – Zygomatic – Frontal – Alveolar – Palatine
Anterior Surface: • Incisive Fossa: – Depressor septi nasi – Orbicularis oris •
Canine fossa: – Levator anguli oris • Infraorbital foramen (above canine fossa) –
Infraorbital nerves and vessels • Above sharp border between anterior and orbital
surface: – Levator labi superioris • Nasal notch: Dilator Naris • Ant Nasal Spine
Posterior Surface • It is directed backwards and laterally • It forms anterior wall
of the infratemporal fossa • Anterior and posterior surfaces are seperated by ridge
which leads to the socket of 1st molar tooth • Near the centre of posterior surface 2
to 3 openings of dental canal for posterior superior alveolar vessels and nerves • At
the lower end there is a raised maxillary tubrosity which is rough in the upper part
of its medial end for tubercle of the palatine bone which has the attachment of
superficial fibres of themedial pterigoid muscles • Above this smooth surface which
forms the boundry of the ptrigopalatine fossa is grooved for the maxillary nerve,
this groove is contineous with the infra orbital groove
Orbital surface Smooth and triangular • Medial border – Notch: lacrimal notch –
Behind this it articulates with the • Lacrimal • Orbital plate of ethmoid • Orbital
process of palatine • Posterior border: Smooth, rounded and it forms greater part of
infraorbital fissure in middle infraorbital groove • Anterior border: forms orbital
margin ,infraorbital groove and canal; a little lateral to this is canalis sinuosus
which passes in the anterior wall of the maxillary sinus and reaches in the nasal
cavity and opens in the side of the nasal septum in front of incisive canal • A little
lateral to the lacrimal groove there is attachment of inferior oblique muscle of
eveball
Nasal Surface • In its upper posterior part there is a large maxillary hiatus which
leads into the maxillary sinus In articulated skull this hiatus is completed by
ethmoid and lacrimal bones • Behind this there is a rough impression for the
perpendicular plate of palatine bone • Infront of maxillary hiatus there is a lacrimal
groove • More anteriorly concal crest for articulation with inferior nasal concha
Maxillary Sinus • Large pyramidal cavity with its apex directed laterally towards
the zygomatic process • Base is towards the lateral wall of the nose • In articulated
skull it is reduced by Above • Uncinate process of ethmoid • Desending part of
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lacrimal bone Below: inferior nasal concha Behind: perpendicular plate of palatine •
It opens into the middle meatus of the nose usually by two openings one of which is
closed by mucous membrane in living state • Occasionally there are projections in
the maxillary sinus from roof to anterior wall
Processes • Zygomatic: it is rough and pyramidal – Front:it is contineous with the
anterior surface of body – Behind(concave):in continuity of the posterior surface –
Above: articulates with zygomatic bone – Below(arched border) which anterior and
posterior surface of the body
• Frontal Process: – Lateral Surface: • Vertical ridge (Lacrimal crest) • Groove
for the lacrimal sac – Medial surface: It is rough and uneven and articulates with the
ethmoid and also closes the anterior ethmoidal sinus below ethmoidal crest • Upper
end: Articulates with the frontal bone • Anterior border with the nasal bone •
Posterior border with the lacrimal bone
• Alveolar processes: It has thick arched border behind and contains sockets to
receive roots of teeth which vary in size and depth – Canine deepest – Molar widest
and subdivided into 3 minor sockets by septae – Incisors and premolars single –
Occasionally incisors are divided into 2 sockes
• Palatine Process: Thick strong horizontal – Inferior surface is concave and
presents numerous foramina for passage of nutrient vessels and contains
depressions for lodgement of glands – Groove for grater palatine Vessels and
nerves – Incisive fossa leads into the incisive canal – Sometimes anterior and
posterior incisive foramen for long sphenopalatine nerve which communicates with
the greater palatine nerve – Upper surface: forms the floor of the nasal cavity –
Lateral Border fuses with rest of the bone – Posterior border fuses with the
horizontal plate of the palatine.
Maxillary sinus: large pyramidal cavity with its apex directed laterally towards the
zygomatic process, base is towards the lateral wall of the nose. In articulated skull
is reduced by uncinate process of ethmoid bone and sesending part of lacrimal bone
from above, inferior nasal concha from below, and perpendicular plate of palatine
bone from below. It opens into the middle meatus of the nose usually by two
openings one of which is closed by mucous membrane in living state. Occasionally
there are projections in the maxillary sinus from roof to anterior wall.
The floor of the sinus related to the root of upper teeth from canine to the molars.
Muscles attached to maxilla: the muscles of facial expression related to upper lip as
levatore lapii superiors, levatore lapii superiors aleque nase, levator angli oris,
zygomatico major, zygomatico miner, and orbicularis oris.
Arterial supply: the blood supply of maxilla by maxillary artery through its
branches the anterior, middle, posterior superior alveolar artery, inrfaorbital artery,
and greater palatine artery.
Venous drainage as distribution of artery to maxillary vein that join with
infratemporal vein forming retromandibular vein.
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Nerve Supply: the sensory enervation of maxilla from maxillary division of
trigeminal nerve as arteries distribution.
Lymphatic drainage of maxilla through lymphatic vessels to the periaricular, parotid
and submandibular lymph nodes.
Age changes in Maxilla: at birth:
1. Transverse and anterioposterior diameter less than vertical diameter.
2. Well marked frontal process.
3. Body consists of little more than alveolar process.
4. Tooth sockets close to orbit.
5. Maxillary sinus is a more furrow on the lateral wall of nose.
In adults the vertical diameter is more due to:
1. Developed alveolar process.
2. Increased size of maxillary sinus.
Mandible • Largest and strongest bone of the face • Curved horizontal body;
convex forwards • It has two rami which project upward from posterior end of the
body • The body is horse shoe shaped
External Surface • Faint ridge: symphisis menti • Mental protuberance in the
triangular area below sympisis menti • Mental tubercle on each side of mental
protruberance • Mental foramen between premolar teeth • Oblique line
Internal Surface • Myelohyoid line • Sub mandibular fossa • Sub lingual fossa •
Genial tubercle • Myelohyoid groove
Borders • Upper boder: – Sockets for the mandibular teeth are present • Lower
border(Base) presents a digastric fossa • Ramus – Lateral Surface – Medial Surface
• Mandibular foramen canal • Lingula- mylohyoid groove • Inferior border is
continuous with the angle of mandible • Upper Border: Mandibular Notch.
Arterial Supply of Mandible from maxillsy artery by inferior alveolar artery along
the inferior alveolar canal and mental artery through mental foramen. And lingual
artery to the ligual gingival and anterior two third of the tongue.
Veinous drainage of Mandible through inferior alveolar vein and lingual vein which
drained to the facial vein or internal jugular vein.
Nerve supply of Mandible through mandibular division of trigeminal nerve
branches as inferior alveolar nerve, lingual nerve, and long buccal nerve.
• Processes: – Condylar – Coronoid • Mandibular canal
Age changes in mandible:
Extensive changes occur in the mandible from birth until old age. The two halves of
the mandible are connected at the symphysis menti by fibrous tissue until the age of
one year, when bony union occurs. The mandible shows striking changes associated
with the growth and eruption of the teeth. At birth the alveolar process of the
mandible is larger and contains not only the crowns and roots of the primary teeth,
but also the rudiments of the permanent teeth. The part of the mandible below the
alveolar process is poorly developed so that the mental foramen is relatively close
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to the lower margin of the bone. During the eruption of the teeth the body of the
mandible elongates and there is a simultaneous absorption and addition of bone on
the anterior and posterior borders of the ramus respectively. At birth the ramus of
the mandible projects only a little above the level of the alveolar margin and the
angle is very obtuse (175°); in old age this angle becomes less obtuse (140°) owing
to the absorption of the alveolar margin after the teeth have been shed or extracted.
Applied Anatomy Muscle injuries: Its cause and effects • Incisivus labii
Superioris: – During the exposure of the bone of premaxilla between the canines ,a
mucoperiosteal flap reflection may detach the muscle and if the muscle gets
damaged the the drooping of the septum and ala of the nose may occur
• Mylohyoid muscle – Surgical manupulation of the floor of the mouth may
result in edematous swelling of the sublingual space (above the mylohyoid muscle
)and submandibular space(below the mylohyoid muscle) – Cellulitis of this
sublingual space in quiet common however excessive bilateral cellulitis of the
sublingual spaces may push the tongue backwards and compress the pharynx and
may result in airway obstruction
• Genoiglossus muscle – During the elevationof the lingual mucosa before
making an impression for a subperiosteal implant a portion of the muscle may be
reflected from te genial tubercle, however if the muscle is completly detached from
the tubercle it may lead to retrusion of the tongue and airway obstruction
• Medial pterigoid – The medial pterigoid muscle binds the pterigomandibular
space medially ,during surgical procedures involving the area of pterigomandibular
space infection may occour and may be dangerous due to its closed proximity to the
pharyngeal space – Surgical exposure of the tissue posterior to the maxillary
tubrosity may also involve the medial pterigoid muscle as a part of the muscle
originates from the maxillary tubrosity
• Lateral pterigoid muscle – The lateral pterigoid muscle fibres are placed in an
angulated manner and because of this there may be pain in patients with a full
arched subperiosteal implant or prosthetic splint
• Mentalis muscle: – Complete reflection of the mentalis muscle for the purpose
of extension of a subperiosteal implant may result in a condition known as witch’s
chin There is failure of the mentalis muscle reattachment following the
implantation. An external bandage is applied for four days to help in the
reattachment of the muscle
• Buccinator muscle: – Myositis of the detached buccinator muscle in patients
with subperiosteal implants may cause swelling and pain at the site of origin of the
muscle
Nerve injuries • Inferior alveolar nerve: – The nerve may be damaged easily
when making an incision or reflection of the mucosa in its area therefore position of
the inferior dental canal in vertical and buccolingual dimension is of great
importance during site preprations for implants
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• Lingual nerve – The position of the nerve is lateral to the retromolar pad the
incision should remain lateral to the pad and the mucosal reflection should be done
with a periosteal elevator in constant contact with the bone to prevent injury to the
nerve
• Nerve to mylohyoid: – The nerve lies in closed relation to the ramus of
mandible hence it is prone to get damaged during surgical intervention
• Long buccal nerve: – When the ramus is accessed for the purpose of a block
graft excision great care must be take to protect this nerve from injury
Injury to vessels • Maxillary vessels: – During the surgical orthognathic
procedures the major nutrient artery of the maxilla are sometimes damaged, but the
blood supply is maintained by anastamosis present in the soft palate
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