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Anatomy of Oral cavity and Pharynx
Dr Mohit GoelJR122 aug. 2012
Oral Cavity2 parts:1] Oral vestibule2]Oral cavity properOral vestibule = slit space between teeth- buccal gingiva and lips-cheek .
>Vestibule communicates with exterior through mouth.
>Size of opening is controlled circumoral muscles such as orbicularis oris, buccinator,depressors and elevators of lips.
ORAL CAVITY PROPER
It is the cavity within the alveolar margins of the maxillae and the mandible
Its Roof is formed by the hard palate anteriorly and the soft palate posteriorly
Its Floor is formed by the mylohyoid muscle. The anterior 2/3rd of the tongue lies on the floor.
hard
soft palate
mylohyoid
FLOOR OF THE MOUTH Covered with mucous
membrane In the midline, a
mucosal fold, the frenulum, connects the tongue to the floor of the mouth
On each side of frenulum a small papilla has the opening of the duct of the submandibular gland
A rounded ridge extending backward & laterally from the papilla is produced by the sublingual gland
NERVE SUPPLY
oSensory Roof: by greater palatine and nasopalatine
nerves (branches of maxillary nerve) Floor: by lingual nerve (branch of
mandibular nerve) Cheek: by buccal nerve (branch of
mandibular nerve)
oMotor Muscle in the cheek (buccinator) and the lip
(orbicularis oris) are supplied by the branches of the facial nerve
MUSCLES
The tongue is composed of two types of muscles:• Intrinsic• Extrinsic
Mylohyoid
The main muscle forming the floor of the mouth is mylohyoid.
GENIOHYOID
Geniohyoid is a narrow muscle which lies above the medial part of . Itarises from the inferior mental spine (genial tubercle) on the back of thesymphysis menti, and runs backwards and slightly downwards to attach to the anterior surface of the body of the hyoid bone.
GenioglossusIt arises from a short tendon attached to the superior genial tubercle behind the mandibular symphysis, above the origin of geniohyoid. From this point itfans out backwards and upwards.
Hyoglossus Hyoglossus is thin and quadrilateral, and arises from the whole length of the greater cornu and the front of the body of the hyoid bone. It passes vertically up to enter the side of the tongue between styloglossus laterally and the inferior longitudinal muscle medially.
Styloglossus
It arises from the anterolateral aspect of the styloid process near its apex
Passing downwards and forwards, it divides at the side of the tongue into a longitudinal part, which enters the tongue dorsolaterally to blend with the inferior longitudinal muscle in front of hyoglossus, and an oblique part, overlapping hyoglossus and decussating with it.
Tip:Submental nodes bilaterally & then deep cervical nodes
Anterior two third:Submandibular unilaterally & then deep cervical nodes
Posterior third:Deep cervical nodes (jugulodigastric mainly)
Lymphatic Drainage
Classification of Neck Nodes According to Levels
Level I
Level II
Level III
Level IV
Level V
Level VI
Level VII
Submental (IA)
Submandibular (IB)
Upper jugular
middle jugular
Lower jugular
Posterior triangle group(Spinal accessory andtransverse cervicalchains)
Prelaryngeal
Pretracheal
Paratrachal
Nodes of upper mediastinum
PHARYNX
Extends from the base of the skull to the lower border of the cricoid cartilage (at which point it border of the cricoid cartilage (at which point it becomes the oesophagus).
Portions of the pharynx lie posterior :• nasal cavity (nasopharynx)• oral cavity (oropharynx)• larynx (laryngopharynx)
NasopharynxRoof : body of sphenoid, basilar part of occipital, bone pharyngeal tonsil Floor: soft palate,pharyngeal isthmus
Anterior wall : post. nasal apertures
Posterior wall: ant. arch of atlas
Lateral wall : auditory tube , tubal elevation , salpingo pharyngeal fold and tubal tonsil
Oropharynx
Roof : soft palate, pharyngeal isthmus
Floor : post. 1/3 tongue, epiglottis, lingual tonsil, median glossoepiglottic fold, 2 lateral glosso epiglottic Fold and vallecula.
Anterior wall : mouth, tongue
Posterior wall : C2,C3
Lateral wall : palatoglossal , palatopharyngeal arches/folds and palatine tonsils
Laryngo pharynx
• Walls:
Ant. – inlet of pharynx Post. – C3 – C6 Lat. – thyroid cartilage
The pharyngeal muscles are a group of muscles that act upon the pharynx.They include:
Inferior constrictor muscle
Middle constrictor muscle
Superior constrictor muscle
Stylopharyngeus muscle
Salpingopharyngeus muscle
Palatopharyngeus muscle
MRI
BUCCINATORMASSETER
INTRINSIC MUSCLE OF TONGUE
GENIOGLOSSUS MYLOHOID
LINGUAL SEPTUMGENIOHYOIDDIGASTRICPLATYSMA
HARD PALATE
TONGUEHYOGLOSSUS M.LINGUAL TONSILSUBMANDIBULAR GLAND
GLOSSOEPIGLOTIC FOLDDIGASTRIC M.PLATYSMA
NASOPHARYNX
PAROTID GLAND
UVULA
PALATINE TONSILDIGASTRIC MUSCLE
SUBMANDIBULAR GLANDPLATYSMA
LATERALPTERYGOIDMEDIAL PTERYGOID
HARD PALATENASOPHARYNX
SUPERIOR CONSTRIC. MSOFT PALATE
INTRINSIC MUSCLE OF TONGUE
MIDDLE CONSTRIC. M.GENIOGLOSSUS
MYLOHOID
OROPHARYNXEPIGLOTIS
HYPOPHARYNXINFERIOR CONSTRICTOR
M.
Buccinator m.Hard palate
Masseter muscleLateral & medial pterygoid
m.Nasopharynx
Longus capitis muscle
Buccinator m.Tongue(genioglossus m.)
Masseter muscleMedial pterygoid m.
Palatine tonsilOropharynx
Longus capitis muscle
Orbicularis orisHyoglossus
GenioglossusMylohoid
OropharynxSubmandibular glandPalatopharyngeus m.
Superior constrictor m.
Orbicularis orisHyoglossus
GenioglossusMylohoidEpiglotis
HypopharynxSubmandibular glandPalatopharyngeus m.Middle constrictor m.
MandibleDigastric m.MylohyoidGeniohyoidHyoid bone
Submandibular glandEpiglotis
HypopharynxPiriform recess
Inferior constrictor m.
SUBLINGUAL SPACEPaired non-fascial lined spaces of oral cavity in deep oral tongue above floor of mouth superomedial to mylohyoid muscle
Communication between sublingual spaces occurs in midline anteriorly as a narrow isthmus beneath frenulum
o SLS communicates with SMS(submandibular space) and inferior para pharyngeal space (PPS) at posterior margin of mylohyoid muscle
• There is no fascia dividing posterior SLS from adjacent SMS.Therefore there is direct communication with SMS and PPS in this location.
Posterior aspect of SLS is divided into medial and lateral compartments by hyoglossal muscle.Clinical Importance• Since neurovascular bundle to tongue travels in SLS,oral cavity SCCa involving posterior SLS is challenging to treat.• If SCCa crosses lingual septum to contralateral SLS, lesion becomes unresectable for cure.
SUBMANDIBULAR SPACE
Fascial-lined space inferolateral to mylohyoid muscle containing submandibular gland, nodes and anterior belly of digastric muscles.SMS is defined as a superficial space above hyoid bone deep to platysma and superficial to mylohyoid sling . Continues inferiorly into infrahyoid neck as anterior cervical space.
Inferolateral to mylohyoid muscle of floor of mouth• Deep to platysma muscle• Cephalad to hyoid bone• "Vertical horseshoe-shaped" space between hyoid bone below and mylohyoid sling above.
• SMS communicates posteriorly with sublingual space and inferior para pharyngeal space at posterior margin of mylohyoid muscle.
• Continues inferiorly into infrahyoid neck as anterior cervical space.
RETROMOLAR TRIGONE
Triangle-shaped area of mucosa posterior to last mandibular molar that covers anterior surface of lower ascending ramus of mandible.
Pterygomandibular raphe (PMR)- Thick fascial band that extends between posterior border of mandibular mylohyoid ridge and hamulus of medial pterygoid plate.It represents thickening of middle layer of deep cervical fascia condensed between posterior margin of buccinator muscle and anterior margin of superior constrictor muscle.
Clinical Importance
• SCCa (squamous cell ca.) of RMT may spread along PMR (Pterygomandibular raphe ).
o Cephalad spread along PMR takes tumor up to inferolateral pterygoid plate- Anteromedial masticator space.
• Tumor is seen at level of inferior pterygoid Plate involving posterior buccinator muscle and anterior superior constrictor muscle.
• Enlarging tumor involves maxillary sinus, Buccal and masticator spaces.
o Caudal spread along PMR takes tumor inferiorly to posterior margin of mylohyoid m.
• Enlarging tumor in this location involves floor of mouth of oral cavity.
THANK U