Lecture 5 - Chewing and swallowing Flashcards
TMJ: what is it, where is it found, and what parts does it have?
Tempromandibular joint - synovial joint with
It is located between the condyle (located just in front of the ear, can feel it move when opening the mouth) of the mandible and the mandibular fossa and articular tubercle of the temporal bone
- Modified hinge joint (more movement)
- Fibrocartilage - can handle more stress
- Capsule - the zygomatic process of the bone, attaches to the neck of the mandible
- Ligaments - lateral temporomandibular, stylomandibular, and sphenomandibular ligaments
- Synovial membrane - covers the internal aspect of the capsule and non-articulating surfaces
- Articular disc
Temporomandibular ligament: what movements, what does it do?
Facilitate movements of the lower jaw
This joint allows a range of movements of the lower jaw, namely translational movements (protrusion/retraction and lateral deviation) and rotational movements (elevation/depression)
Stylomandibular ligament: what movements, what does it do?
Acts to limit excessive protrusion of the jaw
Sphenomandibular ligament: what movements, what does it do?
Primarily acts to protect the TMJ from excessive translation of the condyle after the mouth is opened more than 10 degrees
Articular disc: what is it, what does it do, what movements does it allow?
A plate of fibrocartilage dividing the joint into upper and lower synovial compartments
Allows for basic movements of the jaw
- Hinge - allows for condyle rotation around a transverse axis in the lower compartment
- Gliding/translation - allows forward movement in the upper compartment by having the condyle and disc move into the articular tubercle from the mandibular fossa
Functional movements of the jaw
- Depression
- Elevation
- Protrusion/protraction
- Retrusion/retraction
- Lateral excursion/deviation/swing
Teeth: the four types in the mouth, the function, the four divisions, how many divisions humans have
I - incisors: biting
C - canines: puncturing and shredding
PM - premolars: crushing and grinding
M - molars: crushing and grinding
- Chewing/mechanical digestion
- Talking
- Protection - biting
Upper/lower right/left
Two sets of teeth: deciduous and permanent
Deciduous teeth: when do they appear, how many teeth are there, which teeth are present, and when are they replaced?
6-30 months of age
20
Per quadrant: 2I, 1C, 2M
6-25 years of age
Permanent teeth: when do they appear, how many teeth are there, which teeth are present, and when are they replaced?
6-25 years of age
32
Per quadrant: 2I, 1C, 2PM, 3M
Never
Mastication: what is it, what muscles allow it to occur, and what innervates these muscles?
The process of food being crushed and destroyed - chewing
- Masseter
- Temporalis
- Lateral pterygoid
- Medial pterygoid
Innervated by the mandibular division of the trigeminal nerve (CN V₃)
Masseter muscle: origin, insertion, and function
Zygomatic arch
The lateral side of the body and the angle of the mandible
Elevates the mandible and closes the mouth
Temporalis muscle: origin, insertion, and function
Temporal fossa
Coronoid process of the mandible
Elevates and retracts the mandible - closing the mouth
Medial pterygoid muscle: origin, insertion, and function
Sphenoid bone
The medial side of the angle of the mandible
Elevates the mandible - closes the mouth
Lateral pterygoid muscle: origin, insertion, and function
Sphenoid bone
TMJ and mandibular neck
When both sides are contracting - it protrudes the mandible to allow depression of the jaw
When only one side is contracting - laterally deviates the mandible
Tongue: what is it, what type of epithelium is present, what parts of it are there, and what functions does it have?
Highly mobile structure – consisting of a bag of muscle
Covered with stratified squamous epithelium
Dorsal surface:
- foramen caecum
- sulcus terminalis
- Pallae:
* circumvallate
* fungiform
* filiform
Ventral surface
- Lingual tonsils underlie the epithelium of
posterior third – lymphoid tissue
- lingual frenulum
- Sensation
- Taste
- General sensation
- Articulation
- Chewing
- Swallowing
- Immunological defence
Dorsal surface of the tongue - foramen caecum: what is it and what does it do?
The back part of the tongue
The point of attachment of the thyroglossal duct
Dorsal surface of the tongue - sulcus terminalis: what is it, where is it located, and what does it do?
V-shaped groove in the tongue located just anterior to the foramen caecum and posterior to the papillae
Divides the tongue into an anterior 2/3 and a posterior 1/3
Dorsal surface of the tongue - circumvallate: what is it, where is it located, and what does it do?
Part of the papillae
Posterior part of the pallae, anterior to the sulcus terminalis
Involved in (bitter) taste and gag reflex
Dorsal surface of the tongue - fungiform: what is it, where is it located, and what does it do?
Part of the papillae
The central anterior part of the tongue
Involved in taste, touch and temperature modalities
Dorsal surface of the tongue - filiform: what is it, where is it located, and what does it do?
Part of the papillae
On the lateral anterior side of the tongue
Responsible for giving the tongue its texture and are responsible for the sensation of touch
Ventral surface of the tongue - lingual tonsils: what is it, where is it located, and what does it do?
Underlie the epithelium of the posterior third of lymphoid tissue
Consists of lymphoid tissue located at the base of the tongue
Provide protection against harmful substances and pathogens that may enter the body through the nose or mouth
Ventral surface of the tongue - lingual frenulum: what is it, where is it located, and what does it do?
Fold of mucous membrane found underneath the tongue
Extends from the midline of the ventral surface of the tongue to the floor of the mouth but not reaching the tip
Helps the tongue to move and perform its functions in swallowing, feeding, and speech
Tongue muscles: what types are there and what do they do?
Intrinsic:
* Originate and insert within the tongue, can be superior & inferior longitudinal, transverse and vertical fibres
* Alter the shape of the tongue
Extrinsic:
* Originate outside and insert within the tongue
* Alter the position of the tongue
* Examples include the styloglossus, palatoglossus, Hygolossus, and Genioglossus
Styloglossus: where is located and what does it do?
Extends from the styloid process of the temporal bone to the posterolateral aspect of the tongue (connects to the ear-ish)
Acts to lift the lateral edges and to retract the tongue
Palatoglossus: where is located and what does it do?
Extends from the palatine aponeurosis to the posterolateral aspect of the tongue (upper side of the cheek-ish)
Elevates the posterior part of the tongue
Hyoglossus: where is located and what does it do?
Extends from the hyoid bone to the posterior aspect of the tongue (connects to the neck-ish)
Retracts and depresses of the tongue
Genioglossus: where is located and what does it do?
Extends from the genial tubercles of the mandible to the tip and body of the tongue (lower part of the mouth-ish)
Protrudes the tongue
Tongue neurovascular supply
Nerves:
Motor – hypoglossal (CN XII)
Sensory – taste (CN VII facial & CN IX glossopharyngeal) & general sensation (CN IX glossopharyngeal & CN V trigeminal)
GOOGLE/ watch leccy WHERE EACH NERVE GOES ETCETCETC
Arterial supply – lingual branch of external carotid artery
Venous drainage – lingual vein → internal jugular vein
Salivary glands: what are the three main types, what are the minor glands, and what do they do?
Parotid, sublingual, and submandibular
Labial, buccal, palatal, lingual
Produce saliva:
* serous fluid - wash oral cavity
* mucin - lubrication
* amylase - carbohydrate digestion
* lysozyme – antibacterial
* immunoglobulin A – defence
* high pH to reduce acidity/tooth decay
Parotid gland: what is it, where is it located, where does it open, what does it do, and what nerve innervates it?
The largest, wedge-shaped gland posterior to the
mandible
The duct opens into the mouth opposite 2nd upper molar
- Allows facial nerves and vessels to pass through it
- Produces serous saliva
PNS – glossopharyngeal nerve
Submandibular glands: what is it, where is it located, where does it open, what does it do, and what nerve innervates it?
Gland that wraps around the mylohyoid
The duct opens into the mouth at the sublingual papilla
Produces mixed seromucous saliva (3:2)
PNS – facial nerve
Sublingual glands: what is it, where is it located, where does it open, what does it do, and what nerve innervates it?
A gland located in the sublingual fold (floor of mouth)
Many ducts - open onto the sublingual fold
Produces mixed seromucous saliva (1:3)
PNS – facial nerve
Videos to watch
4.4.2 The Mandible (3.55 min):
https://aclandanatomy.com/MultimediaPlayer.aspx?multimediaId=10528413
4.4.3 The Temporomandibular Joint (2.55 min)
https://aclandanatomy.com/MultimediaPlayer.aspx?multimediaId=10528415
4.4.4 Muscles of Mastication: Pterygoid Muscles (2.19 min)
https://aclandanatomy.com/MultimediaPlayer.aspx?multimediaId=10528417
4.4.5 Muscles of Mastication: Temporalis and Masseter (3.35 min)
https://aclandanatomy.com/MultimediaPlayer.aspx?multimediaId=10528419
