Oral cavity: lecture 3 Flashcards
Oral cavity consists of two parts:
- oral vestibulum
- true oral cavity
- Oral Vestibulum
- A slit like opening between lips and gums/teeth – Lips
- m orbicularis oris – Cheeks
- m buccinator, fat
– Gingiva
– Labial Frenulum
– Opening of parotid salivary gland
- True oral cavity
Situated on inside of the dental arches
* Roof- hard palate
* Gums, rugae, raphe
* tongue
* salivary gland openings (mandibular and sublingual)
* Lingual frenulum – sup. Aspect of the tongue to the floor of the mouth and on either side of it we get the openings to the sublingual salivary gland ducts (on sublingual fold)
* sublingual caruncle – where mandibular salivary glands open
* Deep lingual vein
– Osteology: Foramina, incisivum, palatina
Tongue:
- consists of a root and a body
- Ant and post part of the tongue develop from 2 separate pharyngeal arches (origins), therefore have different nerve supply
Anterior part of the tongue:
- loose, oral part
- 2/3rds of the tongue
= body of tongue - sulcus terminalis – separates ant and post part, V shaped
- foramen caecum - where V shaped groove/point of sulcus terminalis ends, it is an embryological remnant
Foramen caecum and sulcus terminalis = separation of ant and post part of tongue - median sulcus – middle of tongue
Posterior part of the tongue:
- root of tongue
- posterior 1/3rd
- lingual tonsils- embedded in lingual tissue = uneven surface
- palatine tonsils – can be removed
- Situated between two folds (mucosal folds, which are muscles which are covered with mucosa)
The glossopharyngeal fold – pharynx to tongue
Palatopharyngeal fold – soft palate to pharynx
Papillae:
- Covers tongue
- filiform – straight up and down papillae
- fungiform – mushroom shaped
- (circum)vallate – fungiform is surrounded by an extra ridge which forms a grove around it
>arranged in a v- shape anterior to sulcus terminalis - foliate – folds of tongue, just anterior to the palatopharyngeal fold
Nerve supply to tongue
– Motor supply:
* N hypoglossus (CN 12)
– Sensory supply: General sensation:
* Vagus(CNX) - Posterior part of tongue
* Glossopharyngeus (CN IX) – Posterior part of tongue
* Lingual nerve (Branch of mandibular CN (V) - ant 2/3 of tongue
Taste sensation:
* Posterior 1/3 Glossopharyngeus (CN IX)
* Anterior 2/3 Branch of facial (CN VII) via corda tympany
Bitter sensation more towards back, rest more ant.
blood supply of tongue
Lingual artery and vein
Intrinsic muscles of the tongue:
Arranged in different directions to
give mobility in all directions for speaking
Function of intrinsic muscles:
Lengthening and shortening, curling and uncurling the apex, flattening and rounding the surface
Don’t need to know intrinsic muscles – only know that these muscles are arranged in all sorts of different directions = gives mobility to the tongue
Extrinsic muscles of the tongue:
move tongue in relation to other structures in the head
- genioglossus
- hyoglossus
- styloglossus
- palatoglossus
m genioglossus
(depresses with bilateral contraction, deviates to contralateral side with unilateral contraction
- Comes from inside of chin and fans out to inf part of tongue
m hyoglossus
(depresses and shortens tongue
- Comes from inf part of tongue and attaches to hyoid bone
m styloglossus
(retracts and curls tongue
- Comes from styloid process and attaches to post, inf part of tongue
m palatoglossus
(elevates posterior tongue, depress soft palate) supplied by pharyngeal plexus (accessory nerve)
- Goes from palate to tongue (palatine tonsils just posterior to it)
Muscles of mouth floor
M mylohyoid
m geniohyoid
These muscles help to lift up and stabilise the tongue – especially the root of the tongue
M mylohyoid
- attaches to mylohyoid line on inside of mandible and hyoid bone
- Forms sling for tongue to lie on
m geniohyoid
- On top of mylohyoid mm
- Goes from inside of chin to hyoid bone
innervation of muscles surrounding tongue
– n hypoglossus XII
(All except m palato- glossus mm)
Blood supply of muscles surrounding tongue
– A. lingualis - dorsalis, profunda
- V comitantes profunda
Oral structures also supplied by branches of the
facial, lingual
and maxillary arteries (all branches from the external carotid artery)
Three groups of tonsil tissue:
- Nasopharynx
- pharyngeal tonsil (adenoids)
found at post aspect of the nasopharynx - Oropharynx
- lingual tonsil
- palatine tonsil (‘tonsils’) between palatoglossus and palatopharyngeal arches
* Waldeyer’s ring = 1st line of defence
Salivary glands
- Parotid
- Submandibular
- sublingual
- minor glands
Parotid gland
- (serous= has a watery secretion)
– largest - opens in oral vestibule at level of 2nd upper molar
Responsible for majority of lubrication in mouth
Has a single duct that runs across the masseter muscle
Submandibular gland
(Mixed but mainly serous)
- opens on sublingual caruncle or papilla (duct in relation to n lingualis)
Sublingual gland
(Mixed but mainly mucous)
- 10-12 openings on floor of mouth on sublingual fold
Minor glands
scattered in mouth all open on floor of mouth in proper oral cavity
Submandibular gland has two parts:
Note submandibular salivary gland “hooks”around free border of mylohyiod. Lingual nerve and submandibular duct “twist”around each other on floor of mouth
Watch GIT lec 3A oral structures - LAST 2:39 MIN
Soft palate
- Uvula (kleintongetjie)
- Palatoglossus m – covered by mucosa
- Palatopharyngeus m
- tonsils
Muscles of the soft palate
- m uvula
- m levator veli palatini
- m tensor veli palatini * m palatoglossus
- m palatopharyngeus
blood supply of the soft palate
a maxillaris
Junction of oral cavity and pharynx
- Orifice between oral cavity proper and oropharynx has 2 pairs of muscular folds forming the:
- Tonsillar bed
- arcus palatoglossus
- arcus palatopharyngeal
Pharynx
Nasopharynx
* tuba auditiva
Oropharynx
* uvula, epiglottis
Laryngopharynx
* Piriform recess-n laryng int
Pharynx innervation
- pharyngeal plexus
- vagus-accessorius
Constrictor muscles: of pharynx
- superior, middle, inferior constrictors
Longitudinal Pharyngeal muscles
- open pharynx up
- m stylopharyngeus
- m salpingopharyngeus
- m palatopharyngeus
Facial nerve = 7th cranial nerve
- very closely associated with the parotid salivary gland
- It originates from the stylomastoid foramen
- It the immediately runs anteriorly and becomes very intrinsically involved in the parotid salivary gland
Parotid duct
runs across masseter muscle – opens in oral vestibule
The 5 branches of the facial nerve
Muscles of facial expression around mouth:
- Orbicularis oris
- Risorius
- Zygomatic maj and min
- Superior labial levator
- Depressor anguli oris
- Inferior labial depressor
If have facial paralysis, motor supply affected, not sensory, so can still feel, just cant move.
Motor supply by
CNVII (facial nerve)
Sensory supply is by
5th cranial nerve – trigeminal nerve
Branches of trigeminal nerve
Muscles of mastication
masseter, temporalis, medial pterygoid, and lateral pterygoid.
muscles of mastication nerve supply
CN V
masseter muscle:
Prox: zygomatic arch
Dist: the angle and lateral surface of the mandibular ramus
Action: elevation of the mandible and some protraction of the mandible.
temporalis muscle
prox: temporal bone
Dist: coronoid process of mandible
Action: produce the movements of the mandible at the temporomandibular joint and thus facilitate the act of mastication.
medial pterygoid muscle
consists of two heads; superficial and deep.
prox:
Superficial part: Tuberosity of maxilla, Pyramidal process of palatine bone; Deep part: Medial surface of lateral pterygoid plate of sphenoid bone
Dist: both heads insert on the inner surface of mandible
Action: elevate the mandible and laterally deviate it to the opposite side.
Lateral pterygoid muscle
prox:
Superior head: Infratemporal crest of greater wing of sphenoid bone Inferior head: Lateral surface of lateral pterygoid plate of sphenoid bone
Dist:
Superior head: Joint capsule of temporomandibular joint
Inferior head: Pterygoid fovea on neck of condyloid process of mandible
Action: depresses the mandible and opens the mouth when assisted by the anterior belly of the digastric muscle and the mylohyoid muscle
