Week 1: Gross Anatomy of Oral Cavity, Pharynx & Oesophagus Flashcards
Oral Cavity Functions
Ingestion, masication, taste, speech, breathing
Mixing of food and saliva
Initiation of digestion: mechanical and chemical
First steps of swallowing
Secretions from oral cavity and salivary glands contribute to many of the above functions (water, mucous, ions, small molecules, enzymes etc)
Point at which oropharynx continues posteriorly from oral cavity
Palatoglossal Arch
Muscle contained within palatoglossal arch
Palotoglossal muscle
Major Muscles involved in chewing (mastication)
Innervation of these muscles
Temporalis, Masseter
Lateral and Medial Pterygoids
CNV3: Mandibular Division of Trigeminal Nerve
Also intrinsic and extrinsic muscles of the tongue. Innervated by CNXII Hypoglossal n. Except Palatoglossus which is innervated by CNX Vagus n.
Joint at which movement of mandible occurs, relative to the rest of the skull (i.e. jaw movements).
Type of joint, and the movements allowed by this joint.
Specific position of the joint
Temporomandibular Joint (TMJ)
Synovial Hinge Joint
Elevation/ depression of jaw (opening/closing of mouth)
Protrusion and retraction of mandible
Side to side grinding (ab/adduction of mandible)
Mandible portion moves within the mandibular fossa of the temporal bone
Muscles of mastication (chewing) - actions occurring at the TMJ
Temporalis: Anterior portion closes jaw, and posterior fibers retract jaw
Masseter: closes and protracts jaw
Lateral Pterygoid: Projects jaw, and allows ab/adduction of jaw from side to side
Medial Pterygoid: Elevates jaw, and allows ab/adduction of jaw from side to side
Name the permanent teeth from anterior to posterior
Total of 4 quadrants x 8 teeth: incisors, canines (cuspids), premolars (bicuspids), molars.
2 Incisors
1 canine/cuspid
2 premolars/bicuspids
3 molars
Total = 32 teeth
Name the deciduous teeth from anterior to posterior
Aka Primary teeth: there are 4 quadrants x 5 teeth (total of 20)
2 incisors
1 canine/cuspid
2 molars
Joints of the teeth to skull/jaw bones, and the specific locations involved
The teeth are secured by gomphoses: fibrous ‘peg in socket’ joints.
Secured to the superior alveolar process of the maxilla and inferior alveolar process of the mandible
Innervation of maxillary and mandible teeth
Maxillary teeth: Superior Alveolar nerve. CNV2 - 2nd (maxillary) division of Trigeminal nerve (CNV)
Mandibular teeth: Inferior Alveolar nerve. CNV3 - 3rd (mandibular) division of the trigeminal nerve (CNV)
Functions of the tongue
Mechanical Digestion (moving bolus of food around mouth, mashing it against roof of mouth)
Speech
Taste
Initial phase of swallowing
Immune protection (MALT of lingual tonsils on posterior 1/3 of tongue)
Muscular innervation of the tongue
Most muscles innervated by Hypoglossal nerve (CNXII)
Exception: Palatoglossus innervated by Vagus nerve (CNX)
This makes sense as palatoglossus is also a palate muscle and most palate muscles are innervated by vagus
General Sensory innervation of the tongue
Anterior 2/3 innervated by Mandibular division of Trigeminal nerve (CNV3)
Posterior 1/3 innervated by Glossopharyngeal nerve (CNIX)
Taste Innervation of the Tongue
Anterior 2/3 innervated by Facial Nerve (CNVII)
Poster 1/3 innervated by Glossopharyngeal nerve (CNIX)
Intrinsic muscles of the tongue. Names and type of muscle.
All skeletal.
Longitudinal, Transverse and Vertical mm
Extrinsic muscles of the tongue: names, attachments, actions
Genioglossus = attached to deep surface of mandible. Positioned inferoanterior relative to body of tongue. Depresses and projects tongue.
Hyoglossus = attached to hyoid bone. Depresses and slightly retracts tongue.
Styloglossus = attached to Styloid process of Temporal bone. Raises and retracts tongue.
Palatoglossus = attached to palatine aponeurosis. Also a muscle of the palate. Moves tongue posteriorly and depresses palate.
Name the salivary glands. How much saliva produced daily?
Parotid, submandibular and sublingual.
There are also many small intrinsic salivary glands
1-1.5 L saliva produced per day
Pharynx and Oesophagus: Functions
Swallowing and propulsion of food to stomach.
Pharynx also involved in breathing (forms part of URT)
Secretions from mucosa have protective function
Lower and upper oesophageal sphincters (LOS and UOS) prevent air entering oesophagus (upper) and prevent reflux of stomach contents into oesophagus (LOS)
Pharynx: its 3 components, vertebral levels, sensory innervation
Naso-, oro- and laryngo- pharynx
Pharynx extends from base of skull to C6/7
Sensory innervation = Mostly Glossopharyngeal nerve (CNIX) and Vagus nerve (CNX)
What are the muscles of the pharynx and their attachment points?
Innervations?
Superior pharyngeal constrictor = attached to mandible
Middle pharyngeal constrictor = attached to Hyoid
Inferior pharyngeal constrictor = attached to thyroid and cricoid
**The inferior constrictor includes the upper oesophageal sphincter (UOS) - the cricopharyngeus muscle
Palatopharyngeus muscle = Palatine Aponeurosis and hard palate to the upper border of the thyroid muscle
Stylopharyngeus muscle = Styloid process of temporal bone to the pharynx
All pharynx muscles innervated by Vagus nerve (CNX) except Stylopharyngeus which is innervated by the Glossopharyngeal nerve (CNIX)
Muscles of the soft palate, their actions and innervations
Lavator veli palatini = “elevator of soft palate” elevates soft palate during swallowing
Tensor veli palatini = ‘tensor of soft palate” tenses the palate, which helps the levator veli palatini to elevate the soft palate during swallowing
*Elevation of palate during swallowing prevents food moving into nasopharynx
Palatoglossus & Palatopharyngeus = both depress the palate and narrow the opening to the oropharynx (at palatoglossal arch)
*Depression of palate and narrowing of opening into oropharynx (at palatoglossal arch) allows simultaneous chewing and breathing
All innervated by Vagus nerve (CNX) except Tensor veli palatini which is innervated by the inferior alveolar nerve - mandibular division of the Trigeminal nerve (CNV3)
Oesophagus: Types of muscle and innervations, and locations of constrictions
Comprised of skeletal (superiorly), then mixed skeletal/smooth, then smooth muscle only (more inferiorly).
All innervated by vagus (CNX)
Constrictions: Origin: UOS Arch of Aorta Diaphragm (as it passes through) LOS
What is the clinical significance of the constrictions of the oesophagus?
Constrictions, due to sphincters (UOS and LOS) and obstruction from adjacent structures (Arch of aorta, diaphragm) are areas often associated with oesophageal injury. These areas are thus at higher risk of meta- or neo-plasia.
Anatomical relationships of oesophagus in neck and superior mediastinum?
Neck: anteriorly = trachea, posteriorly = cervical vertebral bodies
Superior mediastinum: anteriorly = trachea, arch of aorta, brachiocephalic veins, etc. Posteriorly = thoracic vertebral bodies
Anatomical relationships of oesophagus in inferior mediastinum and abdominal cavity?
Inferior mediastinum: anterior = heart, posterior = descending aorta
Abdominal cavity: Passes posteriorly to left lobe of liver before entering stomach
Explain the basic control of swallowing, and the functions of swallowing. What are the phases?
Swallowing moves bolus of food from oral cavity, through the oro- and laryngo-pharynx, into the oesophagus and then into the stomach.
Swallowing is initiated voluntarily.
Pharyngeal and Oesophageal phases are controlled automatically by somatic and somatic + autonomic neurons
1) Buccal phase = voluntary
2) Pharyngeal phase = somatic / somatic + autonomic neural control
3) Oesophageal phase = somatic / somatic + somatic autonomic neural control
Describe buccal phase of swallowing
Voluntary phase (initial)
Tongue moves bolus of food towards oropharynx.
Describe the Pharyngeal phase of swallowing: major movements and muscles involved
Soft palate elevates to close off nasopharynx
Suprahyoid mm move larynx superiorly and anteriorly, opening the laryngopharynx allowing the passage of the bolus
Stylopharyngeus and Palatopharyngeus mm elevate pharynx
*Larynx protected by contraction of muscles around laryngeal inlet which narrow the inlet and pull the epiglottis posteriorly: via aryepiglottic and thyroepiglottic mm
Vocal and vestibular folds also adduct via lateral cricoarytenoid and transverse arytenoid mm
A wave of of contraction then relaxation of pharyngeal constrictors (sup, mid and inferior) moves bolus inferiorly
UOS relaxes to allow bolus into oesophagus
Describe the control of swallowing and the main muscles and nerves involved
The swallowing reflex is triggers by the bolus of food contacting the palate and the oropharynx
The swallowing centre in the medulla coordinates motor neurons in the pons, medulla and upper cervical spinal cord
Muscle groups involved:
Muscles of tongue = mainly CNXII (hypoglossal)
Muscles of soft palate = mainly CNX (vagus)
Muscles of the pharynx = mainly CNX (vagus)
Suprahyoid muscles = CNV, VII and C1 fibers (Trigeminal, facial nerves, and fibers from C1)
Describe the oesophageal phase of swallowing
Local and central control via?
Wave of peristalsis propels bolus from the superior portion (beginning at UOS) to inferior portion (terminating at LOS) of the oesophagus, into the stomach
Controlled via swallowing centre in the medulla, and locally controlled via enteric nervous system
**The UOS and LOS are naturally (tone) contracted, and thus relax to allow bolus to pass. The rest of the oesophagus contracts to propel the food downwards, then relaxes
**A 2nd wave of peristalsis may occur if some food still left in oesophagus
Describe the passage of a bolus through the oesophagus with relation to the pressures of each section of the oesophagus
The natural pressure (due to tone contraction) of the UOS and LOS are above atmospheric pressure as they are usually contracted. These sphincters must relax to allow the bolus through.
The remainder of the oesophagus has a sub-atmospheric pressure as it is within the thoracic cavity. Thus, these sections of the oesophagus contract to propel the bolus downwards, and then relax
**A 2nd wave of peristalsis may occur if some food still left in oesophagus
What are the pressures of each component of the oesophagus?
What is the average speed of the peristaltic wave?
UOS = ~60mmHg LOS = ~20-40mmHg
everything in-between = subatmospheric (as within thoracic cavity)
Peristaltic wave = ~2-6cm/sec. Varies depending on the consistency of the bolus
List some common oesophageal disorders
Gastro-oesophageal reflux & associated complications
Achalasia: poor relaxation of LOS, and loss of peristalsis throughout oesophagus, leading to simultaneous contraction of full length. Associated with difficulty swallowing/regurgitation, etc.
Scleroderma (autoimmune) causes fibrosis of oesophagus
Tumours
Formative: What are the actions of the extrinsic muscles of the tongue?
Genioglossus = projection and depression of tongue
Hyoglossus = depression and slight retraction of tongue
Styloglossus = Elevation and retraction of tongue
Palatoglossus = Moves tongue posteriorly. (Also depresses soft palate as is also a palate muscle)
Formative: Summarise motor and sensory innervation of the tongue
Motor innervation of tongue: all muscles innervated by hypoglossus (CNXII) except the palatoglossus which is innervated by vagus (CNX)
General sensory innervation: Anterior 2/3 = mandibular division of trigeminal nerve (CNV3). Posterior 1/3 = glossopharyngeal nerve (CNIX)
Taste innervation: Anterior 2/3 = facial nerve (CNVII). Posterior 1/3 = Glossopharyngeal nerve (CNIX)
What trigger the stimulation of salivary gland secretions? What is the mechanism and the nerves/ganglia involved?
Stimulated by thought, sight, smell and presence of food in mouth
This stimulates the PSNS - specifically, the craniosacral division of the ANS - to stimulate saliva production.
Parotids = preganglionic nucleus in medulla. Fibers with CNIX (Glossopharyngeal). Otic Ganglion.
Submandibular and Sublinguals = preganglionic nucleus in pons. Fibers with CNXII (hypoglossal n). Submandibular ganglion.
List the muscles around the mouth and their innervation:
“Muscles of facial expression” are those that move the lips. These also assist in speech.
Sphincter of the lips = orbicularis oris (“orbits the mouth”)
Numerous other muscles levitate, depress the angle of the mouth, and of upper and lower lips
Buccinator muscle = muscle of the cheek. Helps to position bolus between the molars for grinding
All of these muscles are innervated by the facial nerve (CNVII)
What is the sphincter that surrounds the mouth?
The muscle of the cheek?
Orbicularis Oris
Buccinator
