20 - Oral cavity Flashcards
What are the borders of the oral cavity?
Roof - hard and soft palate
Floor - tongue, floor of mouth
Lateral walls - cheeks
Anterior - oral fissure, lips
Posterior - oropharyngeal isthmus
What is the oral vestibule?
Area between teeth and cheeks
What is the oral cavity proper?
Area from the teeth to the oropharyngeal isthmus
Describe the lips.
- mobile musculo-fibrous folds
- lined externally by skin and internally by oral mucosa
- orbicularis oris is the main muscular contribution
What is the philtrum?
Depression in the midline above the upper lip
What is the blood supply of the lips?
Labial arteries are branches of the facial artery, which anastomose together to form an arterial ring
What is the sensory innervation of the lips?
Upper - CN V2 (infraorbital)
Lower - CN V3 (mental)
What is the lymphatic drainage of the lips?
- submandibular nodes
- except for lower middle lip which drains to the submental nodes
Describe the cheeks.
- lateral moveable walls of oral cavity
- continuous anteriorly with lips
- composed of muscle and fascia, lined externally with skin and internally with oral mucosa
What is the main muscular component of the cheeks?
Buccinator
Where is the buccal fat pad located?
Superficial to buccinator
What is the blood supply of the cheeks?
Maxillary artery
What is the sensory innervation of the cheeks?
Buccal branches of CN V3
What is the motor innervation of the cheeks?
Buccal branch of CN VII
What are key features of the oral vestibule?
- labial frenulum (connects gingiva to lips) in midline
- buccal frenulum laterally
- papilla of parotid duct (near maxillary 2nd molar)
What forms the floor of the mouth?
- muscular diaphragm by paired mylohyoid muscles
- mylohyoid muscles attach from the mylohyoid line on mandible to body of hyoid and into each other, forming the raphe in the midline
- paired geniohyoid muscles sit superior to the mylohyoid raphe
What separates the anterior 2/3 and posterior 1/3 of the tongue?
Terminal sulcus and valate papilllae
What are the different types of tastebuds?
- fungiform
- foliate
- vallate
- filiform
Describe fungiform papillae.
- mushroom like
- appear as red spots
- numerous at apex and margins
Describe foliate papillae.
Folds of mucosa lining posterior and lateral superior surface of tongue
Describe vallate papillae.
- largest papillae
- arranged in V shape anterior to terminal sulcus
- surrounded by circular trenches
- tastebuds are within the trenches
- serous glands empty into trenches
Describe filiform papillae.
- only papillae without tastebuds
- conical projections with efferent nerve endings
What is the function of the papillae on the surface of the tongue?
Grip food and house tastebuds
Describe the inferior surface of the tongue.
- thin transparent mucosa is continuous with that of the floor of the mouth
- midline marked by frenulum of the tongue
- deep lingual vein can be seen either side of frenulum
- sublingual caruncle houses submandibular duct
- sublingual ducts open laterally to sublingual caruncle
What is the function of intrinsic tongue muscles?
Change the shape and size of tongue
What are the intrinsic tongue muscles?
- superior longitudinal
- inferior longitudinal
- vertical
- transverse
What is the function of the extrinsic tongue muscles?
- originate from outside the tongue
- protrude, retract, elevate and depress the tongue
What are the extrinsic tongue muscles?
- palatoglossus
- styloglossus
- hyoglossus
- genioglossus
Describe the muscles of the tongue.
- 4 intrinsic and 4 extrinsic
- all paired
- paired muscles are separated by sagittal septum (continuous with lingual aperoneurosis)
- intrinsic muscles are entirely within tongue, do not attach to bone
- extrinsic muscles originate from outwith the tongue
What is the origin and insertion of genioglossus?
Origin - superior mental spines of mandible
Insertion - inferior fibres attach to hyoid bone, superior fibres blend with intrinsic muscles of tongue
What is the origin and insertion of hyoglossus?
Origin - greater horn of hyoid bone
Insertion - fibres blend with intrinsic muscles on lateral aspects
What is the origin and insertion of palatoglossus?
Origin - palatine aponeurosis
Insertion - fibres blend with intrinsic muscles on lateral surface
What is the origin and insertion of styloglossus?
Origin - styloid process of temporal bone
Insertion - fibres blend with intrinsic muscles and superior fibres of hyoglossus
What is the function of genioglossus?
Protruding the tongue
What is the function of hyoglossus?
Depresses sides of the tongue
What is the function of styloglossus?
Elevating and retracting tongue
What is the function of palatoglossus?
- depresses soft palate
- elevate posterior tongue
What neurovascular structures surround the muscles of the tongue?
- lingual artery enters tongue between hyoglossus and genioglossus
- hypoglossal and lingual nerve enter tongue o the internal surface of the hyoglossus
What is the motor innervation of the tongue?
- all muscles are supplied by hypoglossal nerve
- except palatoglossus by vagus nerve
What is the general sensation innervation of the tongue?
Anterior 2/3 - CN V3
Posterior 1/3 - glossopharyngeal nerve
What is the special sensation innervation of the tongue?
Anterior 2/3 - facial nerve via chorda tympani
Posterior 1/3 (and valate papillae) - glossopharyngeal nerve
What nerve supplies parasympathetic secreto-motor innervation to the tongue?
Vagus nerve to the serous glands of the tongue
What is the blood supply of the tongue?
Lingual artery from the ECA
What is the venous drainage of the tongue?
Deep lingual and dorsal lingual veins drain the tongue, beginning at the apex, draining into the IJV
