Applied Surgical Anatomy

8/13/2019 Applied Surgical Anatomy

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Applied Surgical Anatomy

- Dr. Gnanasagar



Contents

• Trigeminal Nerve

•Maxillary bone

• Mandibular bone

• Muscles of mastication



Trigeminal nerve

• Largest cranial nerve

• Composed of

– 1 small motor root– 1 large sensory root.

• 3 branches

• supply the skin of the ENTIRE FACE &Oral mucosa

• EXCEPT the pharynx & base of thetongue



Motor root

• Originate within the pons & medulla oblongata

• Unites with the sensory root of mandibulardivision to form a single nerve trunk, just

after their exit from the skull

• Supply

1. Muscles of mastication,

2. Mylohyoid,3. Anterior belly of digastric,

4. Tensor tympani,

5. Tensor veli palatini



Sensory root

• Comprise the major portion of the trigeminal(semilunar or gasserian) ganglion

• Ophthalmic division (V1) travels– in the lateral wall of the cavernous sinus– medial part of the superior orbital fissure– enters the orbit

• Maxillary division (V2)– Exits the cranium through F. rotundum– Enters the upper part of pterygopalatine fossa

• Mandibular division (V3)– Exits the skull with motor root through F. ovale– Enters the infratemporal fossa



Ophthalmic division (v 1)

Purely sensory

Smallest of the 3 divisions

3 branches inside the orbit

Nasociliary - 6 branches

Frontal – largest - 2 branches

Lacrimal – smallest - no branches!



Nasociliary

1. Long ciliary – iris, cornea

2. Short ciliary – sensory to ciliary ganglion

3. Infratrochlear –lacrimal sac & caruncle

4. Anterior ethmoidal - mucosa of the– anterior part of the nasal septum

– lateral wall of the nasal cavity

5. Posterior ethmoidal - ethmoidal andsphenoidal sinuses

6. External nasal - skin over nasal tip & ala.



Frontal & Lacrimal

1. Supratrochlear

- conjunctiva + skin of the medial aspect ofthe upper eyelid

- the skin over the lower + mesial aspectsof the forehead

2. Supraorbital- upper eyelid,

- scalp as far as the parietal bone

Lacrimal

- lateral part of the upper eyelid &

• - adjacent area of skin



Maxillary division

• Purely sensory

• Give branches in 4 places :

Within the cranium – 1 branch

In pterygopalatine fossa - 3 branches

In the Infraorbital canal - 2 branches

On the face - 3 branches



Maxillary Division

Within the cranium – Middle meningeal nerve

In pterygopalatine fossa1. Zygomatic nerve – 2 branches

2. Pterygopalatine nerve - 4 branches

3. Posterior superior alveolar nerve - 2 branches

In the Infraorbital canal - Infraorbital nerve1. Middle superior alveolar (MSA) nerve

2. Anterior superior alveolar (ASA) nerveOn the face

1. Inferior palpebral branches

2. External nasal branches

3. Superior labial branches



Maxillary division

Within the cranium

– Middle meningeal - sensory to duramater

In pterygopalatine fossa

1. Zygomatic nerve - enter orbit thro’

inferior orbital fissure & divides into

i.zygomaticotemporal- skin on the side of the forehead

ii. zygomaticofacial

- skin on the prominence of the cheek



2. Pterygopalatine nerve

1. Orbital branch - orbital periosteum

2. Nasal branch - mucosa of the

– superior & middle conchae,

– lining of the posterior ethmoidal sinuses– posterior part of nasal septum

– Nasopalatine nerve - ant part of nasalseptum & floor of the nose & palatalmucosa in the region of the premaxilla(canines to central incisors)



3. Palatine branchi. Greater palatine nerve - sensory to the

palatal soft tissues & bone anterior tothe first premolar

ii. Lesser palatine nerve - mucosa over thesoft palate

4. Pharyngeal branch - mucosa of thenasopharynx posterior to the auditory(eustachian) tube.



3. Posterior superior alveolar nerve

Usually 2 branches reach the inferior

temporal surface of the maxilla

1st Supply the buccal gingiva in the maxillarymolar region

2nd enters the post sup alveolar canal & -supply mucosa of sinus,

- 3rd,2nd, and 1st molars (alveoli, PDL, pulp)

- EXCEPT the m-b root of the 1st molarin 28% of cases



In the Infraorbital canal

Here max nerve is called infraorbital nerve,

1. Middle superior alveolar (MSA) nerve– 2 maxillary PM

– mesiobuccal root of the 1st molar

– PDL, buccal mucosa, bone in PM region

2. Anterior superior alveolar (ASA) nerve

– central & lateral incisors and thecanine

– PDL, buccal bone, and mucousmembranes of these teeth



Dental Plexus

Individual roots of all teeth, bone & PDL in both

Mx+Md are innervated by the terminal branches oflarger nerves in that region. These nerve networksare termed the dental plexus.

• Superior dental plexus for maxilla.

• Inferior dental plexus for mandible.

• 3 types of nerves emerge from these plexuses& are accompanied by a corresponding artery

1. Dental nerves,

2. Interdental branches

3. Interradicular



• Dental nerve – enters the tooththrough the apical foramen, supplying

the pulp

• Interdental br.- provide sensoryinnervation to the PDL of adjacentteeth, the interdental papillae andbuccal gingiva.

• Interradicular br.- provide sensorysupply to the PDL of adjacent roots.

– Terminate in the PDL @ furcations.



On the face: 3 branches

1. Inferior palpebral branches - the skinof the lower eyelid

2. External nasal branches - skin on thelateral aspect of the nose

3. Superior labial branches -skin andmucous membranes of the upper lip



Mandibular division (v 3)

• Largest branch of trigeminal nerve

• Mixed nerve – larger sensory root &smaller motor root

• They unite just outside the skull andform the main trunk of the 3rd division.

This trunk remains undivided for only 2to 3 mm before it splits into a smallanterior and a large posterior division



Mandibular Nerve

Give off branches in 3 areas:

From undivided nerve trunk – 2 br.

Anterior division branches – 4 br.

Posterior division branches – 3 br.



From the main trunk:-

1. Nervus spinosus (meningeal branch ofthe mandibular nerve)- duramater

- mastoid air cells

2. Medial pterygoid nerve

- motor nerve to the medial pterygoidmuscle

- tensor veli palatini

- tensor tympani



Anterior division branches:

1. Nerve to masseter

2. Nerve to temporalis3. Nerve to lateral pterygoid

4. Buccal or long buccal or buccinator nerve

- Crosses in front of anterior border oframus @ the occlusal level opposite tothe md II or III molar

- Enters cheek through the buccinator

muscle

- Supply buccal gingiva of the md molars &the mucobuccal fold in that region



Buccal nerve



Posterior division branches:

1. Auriculotemporal nerve – TMJ

2. Lingual nerve – run anteromedial to Infr. AlvNerve,

– general sensation for anterior 2/3rd oftongue

– mucosa of the floor of the mouth

– lingual gingiva

3. Inferior alveolar nerve – largest branch

– enters mandibular canal thro’ md foramen

– Along with inferior alveolar artery & vein

– Supply pulp & buccal PD tissues of md Ms



Auriculotemporal nerve



• IAN divides into 2 @ the mental forameni. Incisive nerve – remain within the canal &

supply the mandibular PM, canine & incisors

ii. Mental nerve – buccal mucosa anterior tomental foramen till the midline & skin of thelower lip & chin of that side.

4. Mylohyoid nerve- branches from the inferior alveolar nerve

before it enters the mandibular canal,- a mixed nerve

- motor to the mylohyoid muscle & anteriorbelly of the digastric,

- sensory to the skin on the inferior & anteriorsurfaces of the mental protuberance &mandibular incisors.



Inferior alveolar nerve



Lingual nerve



Maxillary bone

• Porous cancellous bone permits infiltration

anesthesia

• In many areas, bone over the apices of the

maxillary teeth either is paper-thin / absent

(dehiscence).

• Posterior superior alveolar nerves & blood vessels

enter the infratemporal surface of the maxilla

through several alveolar canals.

• The maxillary tuberosity is a rounded eminence

posterior to the III molar.



• Maxillary nerve passes on the superiorsurface of the maxilla in a groove,

directed laterally and slightlysuperiorly, continuous with the infra-orbital groove.

• The palatal processes of the maxillaare thick horizontal projections thatform a large portion of the floor of

the nose and the roof of the mouth

• Makes the anterior three fourths ofthe hard palate



Mandibular bone

Bone is• Thicker on the external surface of the

mandible.

• Thinner along the labial alveolar processes

in the anterior region (incisors)permitting infiltration anesthesia.

Mental foramen is in the region of the 2nd

premolar on each side, midway betweenthe upper & lower borders of the body.

• The mental nerve, artery & vein exit the

mandibular canal through this.



di l f f dibl



Medial surface of Mandible

• Ramus contains mandibular foramen

– halfway between the superior and inferiorborders &

– 2/3rd to 3/4th distance between anterior -posterior border of the ramus

– 6-10mm above the level of mandibularocclusal plane

• Coronoid notch on the anterior border oframus represents a landmark tordetermining the height of needlepenetration for inferior alveolar nerve

block.



• The ramus at the level of themandibular foramen is thicker in itsanterior region than posteriorly.

•This is of clinical importance duringthe inferior alveolar nerve block.

• The thickness of soft tissues betweenneedle penetration and the bone of theramus at the level of the mandibularforamen averages about 20 to 25 mm

M l f ti ti



Muscles of mastication

Muscle Origin Attachment Action

Masseter 1. Zygomatic processof maxilla2. Medial & infrsurface of zyg bone

1. Angle of md2. Ramus3. Latl surface of

coronoid process

1. Closes mandible,2. Clenches teeth

Temporalis Temporal fossa 1. Coronoid process

2. Anterior borderof ramus

1. Closes mandible,

2. Clenches teeth

MedialPterygoid

1. Medial surface oflatl pterygoid plate2. Palatine bone &maxillary tuberosity

1. Medial surfaceof ramus

2. Angle ofmandible

1. Elevate themandible

2. Side to side jawmovement

LateralPterygoid

Supr head – lat sideof gr wing of sphenoidInfr head – lat side oflatl pterygoid plate

Superior head – discof TMJ

Inferior head –neck of condyle

1. Open jaw2. Protrudes md3. Moves mandible

sidewards



Muscles of mastication

Temporalis

Masseter



Medial pterygoid



Lateral pterygoid



Summary

Applied Surgical Anatomy

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