L8: Oral cavity and submandibular gland Flashcards
Clinical relevance of oral cavity
ORAL ULCER - more than 7 days, in 95% is cancer Tonsillitis Tumours Trauma (e.g. piercings) Congenital disorders
Surface anatomy
- Lingual v running with lingual a and n
- Sublingual fold overlying sublingual gland (2 openings of gland along fold)
- Submandibular duct either side of frenulum with 1 opening
- Sublingual caruncles (prominences)
- Frenulum = membrane attaching tongue to base of oral cavity (can be tongue tied if extends too far forward)
Clinical: piercing
Piercing of tongue may damage lingual n causing loss of taste and sensation to ant 2/3 of tongue
Back of oral cavity surface anatomy
Soft palate and uvula (extension of soft palate)
Either side is palatine tonsil between palatopharyngeal arch and palatoglossal arch
Surface of tongue
- (Front) fungiform papillae
- Filiform papillae
- Vallate papillae (V shaped, ant to terminal sulcus)
- Pharyngeal part of tongue post to terminal sulcus
- Foramen cecum: where pharyngeal tonsils meet at midline (thyroid first develops here in embryology)
Oral cavity boundaries
Roof: hard and soft palates (palatine process of maxilla - ant 3/4, horizontal plates of palatine - post 1/4)
Floor: muscular diaphragm and tongue
Lateral walls: oral mucosa, fascia, buccinator
Opens anteriorly to oral fissure, posteriorly to oropharyngeal isthmus
It is below nasal cavity, above larynx
Lateral walls - cheeks
Buccinator
- Attached posteriorly to pterygomandibular raphe
- In same plane as sup constrictor muscle of pharynx
= continuity between walls of oral and pharyngeal cavities
- Holds cheeks against alveolar arches and keeps food between teeth when chewing
- Innervated by facial n [VII]
Floor of oral cavity
Paired mylohyoid muscles joined at midline by raphe
- Has free posterior margin
- Attached anteriorly to mandible at mylohyoid line
- Posteriorly to hyoid bone
- Innervated by mandibular n [V3]
Geniohyoid is deep to mylohyoid, originates from inferior mental spines
- Innervated by C1
Gateway into oral cavity
Triangular aperture/oropharyngeal triangle
- Between mylohyoid, sup constrictor, middle constrictor
- Structures enter and leave oral cavity: lingual n, hypoglossal n, glossopharyngeal n and arteries get into oral cavity
Muscles of tongue - intrinsic
ALL innervated by hypoglossal n [XII] (Origin and insertion within tongue) 1. Superior longitudinal 2. Vertical 3. Transverse 4. Inferior longitudinal 5. Septum (at midline)
Muscles of tongue - extrinsic
ALL innervated by hypoglossal n [XII] EXCEPT palatoglossus is by vagus [X] (all structures from palatine bone incl. soft palate are innervated by vagus nerve)
1. Palatoglossus
2. Styloglossus
3. Hyoglossus (hyoid bone to tongue)
4. Genioglossus (sup mental spines to tongue)
(important for moving tongue so we can speak)
Muscles from superficial to deep
Skin - mylohyoid - geniohyoid - genioglossus
2 potential spaces and their contents
First: between mylohyoid and hyoglossus
- Lingual n (from V3)
- Chorda tympani (from VII): ant 2/3 taste
- Hypoglossal n [XII]
- Deep lingual v
Second: between hyoglossus and genioglossus
- Glossopharyngeal n [IX]: post 1/3 taste
- Lingual a
- Dorsal lingual v
Course of hypoglossal nerve
+ relation to lingual nerve
Crosses lateral to internal and external carotid arteries (with deep lingual vein) and goes deep to mylohyoid via triangular aperture to enter potential space between mylohyoid and hyoglossus
Lingual and hypoglossal in same lateral to medial plane but lingual is more superior than hypoglossal
Course of glossopharyngeal nerve
Runs between internal and external carotid into triangle aperture, then enters second potential space between hyoglossus and genioglossus
Submandibular gland features
Submandibular duct
Has superficial and deep parts
Wraps around free edge of mylohyoid muscle
To reach gland must dissect through: skin, subcutaneous fat, platysma and investing layer of deep cervical fascia
Submandibular (Wharton) duct originates from superficial part of gland but emerges from deep part and terminates next to sublingual papilla next to base of frenulum of tongue
Muscles associated with submandibular gland
Structures running across gland
Muscles: mylohyoid, hyoglossus and posterior belly of digastric (all important structures under post belly)
Structures running across: facial v, facial a and lymph nodes
Nerves at risk in submandibular excision
Marginal mandibular branch of facial nerve, hypoglossal nerve, lingual nerve
Where would you site incision for submandibular gland excision?
About 4cm below and parallel to lower border of mandible to avoid injury to marginal mandibular branch of facial nerve
What structures running across submandibular gland must be ligated and divided in submandibular gland excision?
Facial vein lies over surface of gland
Facial artery arches over and grooves the post part of gland as it passes forward between it and mandible. As it hooks under lower border of mandible it is closely related to marginal mandibular branch of VII and gives off submental artery at this point.
Lymph nodes may be adherent to surface of gland
Marginal mandibular nerve path
+ damage
Lies between investing layer of deep cervical fascia and platysma (superficially).
Passes downward from parotid and lies up to 2.5cm below border of mandible.
Passes forward to cross facial artery, facial vein and lower border of mandible to supply lower lip
DAMAGE: flattening and inversion of ipsilateral lower lip
Lingual nerve path
+ damage
Lingual n (and submandibular ganglion) lies above deep portion of submandibular gland and loops under duct from lateral to medial deep to mylohyoid on surface of hyoglossus
DAMAGE: loss of sensation and taste to anterior 2/3 of ipsilateral tongue and floor of mouth
(taste supplied by chorda tympani)
Hypoglossal nerve path
+ damage
Runs below deep part of gland medial to posterior belly of digastric and passes forwards deep to mylohyoid. Purely motor to ipsilateral tongue
DAMAGE: may cause dysarthria
Roof of oral cavity
Hard and soft palate
(Maxilla and palatine bones)
Anterior hard palate and posterior soft palate
Hard palate: - Palatine process of maxillae (ant 3/4) - Horizontal plates of palatine bone (post 1/4) - Anteriorly palatine rugae, incisive papilla overlying incisive foramen
Soft palate: - Ends at uvula - (post nasal spine where 2 horizontal plates of palatine bone meet) - Palatopharyngeal arch (more post) and palatoglossal arch
Innervation and arterial supply of soft palate
Innervation: lesser and greater palatine nerves through lesser and greater palatine foramen (V3)
Arterial: lesser and greater palatine arteries from infratemporal and pterygopalatine fossa (branches of maxillary), ascending palatine artery from facial artery
Lymphatic drainage of oral cavity
To regions 1 and 2 in the neck
Muscles of soft palate
- Tensor veli palatini
- Levator veli palatini
- Palatopharyngeus
Palatine tonsil –> - Palatoglossus
- Musculus uvulae
1 is supplied by [V3] and rest by pharyngeal plexus of [X]
