Case 1 - Oeosphageal cancer Flashcards
What 3 ligaments stabilise the TMJ?
Lateral (temperomandibular) ligament
Stylomandibular ligament
Sphenomandibular ligament
What are the attachments of the temporalis?
O = Temporal fossa
I= coronoid process of mandible
What are the attachments of the masseter?
O: zygomatic arch and bone
I: lateral surface of mandible, including the ramus
What are the attachments of the lateral pterygoid?
O: superior head= roof of temporal fossa, inferior head =lateral pterygoid plate of sphenoid
I: Neck of mandible
What are the attachments of the medial pterygoid?
O: superficial head= maxillary tuberosity and palatine bone, deep head= lateral pterygoid plate of sphenoid
I: ramus of mandible (near angle) on medial side
What are the 2 groups of pharyngeal muscles and their role?
Circular muscles: contract sequentially from superior to inferior to propel food into the oeosphagus
Longitudinal muscles: act to shorten and widen the pharynx and elevate larynx during swallowing
Give the names of the circular pharyngeal muscles
Superior, middle and inferior pharyngeal constrictors
Give the names of the longitudinal pharyngeal muscles
Stylopharyngeus
Palatopharyngeus
Salpingopharyngeus
What is the oesophagus lined by and why?
Non-keratinised stratified squamous epithelium = resists abrasion
Where are the 2 plexuses found in the oesophagus? Give their roles
Meissner’s (submucosal) plexus: found in the submucosa, controls the size of blood vessels and secretion of gastric juice
Myenteric plexus: found between circular (inner) and longitudinal (outer) layers of muscle in muscularis propria, when activated it casuses relaxation
What muscle type is found in the oesophagus?
First 1/3 = skeletal
Middle 1/3 = skeletal and smooth
last 1/3 = smooth
Compare the roles of different teeth for eating
Incisors = slice and cut
Canines = tear and rip
Premolars = grind and crush
Molars = mostly grinding (some crush)
What muscles predominantly produce the protrusion and retraction of jaw during chewing?
Protraction = lateral pterygoid, some by medial pterygoid
Retraction = temporalis
What muscles act as the depressors of the mandible? Give their innervation
- Lateral pterygoid = V3
- Anterior belly of digastric = V3
- Mylohyoid = V3
- Geniohyoid = cervical plexus
Describe the chewing reflex of the jaw
Presence of a bolus pushing against the roof and back of the mouth initiates a reflex inhibition of the muscles of mastication to open the mouth.
In turn, depression of the mandible activates muscle spindles (stretch receptors) which sends afferent signal via trigeminal nerve
This activates the elevators of the mandible to close the mouth
Which muscles act as the elevators of the mandible?
- Temporalis
- Masseter
- Medial pterygoid
What are the 3 phases of swallowing?
Phase 1 = oral phase
Phase 2 = pharyngeal phase
Phase 3 = oesophageal phase
Describe what happens in the oral phase of swallowing
1: mastication
2: salivation for chemical digestion of food to increase SA and to lubricate bolus
3: Tongue forms a downward slope by elevating the tip (extrinsic muscles) and forming a central tunnel (intrinsic muscles) to push food into the oropharynx
Describe briefly what happens in the pharyngeal phase of swallowing
- Stimulation of afferent CN IX fibres (palatopharyngeal and palatoglossal arches) by bolus to activate nucleus solitarius and CN X
- Ensure bolus doesnt enter nasopharynx or larynx
- Push bolus into pharynx
- UES relaxes
What mechanisms are in place to ensure the bolus doesnt enter the nasopharynx?
- Contraction of the uvula (CN IX)
- Levator levi palatini contracts to lift the soft palate (CN X)
- Tensor veli palatini tenses the soft palate and attenuates LLP’s action (CN V)
What mechanisms are in place to ensure the bolus doesnt enter the larynx?
- Contraction of lateral cricoarytenoids and oblique/ transverse arytenoids to adduct the vocal cords (so cannot breath at this point)
- Retroversion of epiglottis to block larynx
What mechanisms push the bolus into the pharynx?
- Contraction of the palatopharyngeus and palatoglossus (muscles around the arches) pulls the arches together
- Longitudinal muscles elevate the pharynx and larynx
- Inner circular muscles are responsible for pharyngeal peristalsis
What causes relaxation of the upper esophageal sphincter? (3 factors)
1- relaxation of the cricopharyngeus (most important!!) via CN X
2 - Contraction of suprahyoid and thyrohyoid to pull the hyoid and larynx upwards
3- Pressure of the bolus to distend the UES
Describe what happens in the oesophageal phase of swallowing
1: primary peristalsis: continuation of pharyngeal peristalsis, i.e. relaxes the LES
2: secondary peristalsis: if the bolus gets stuck, it activates stretch receptors so the muscle above the bolus contracts and the muscle below relaxes (local reflex)
Describe the type of secretion of the parotid gland, and where it enters the oral cavity
Serous secretion, enters via the parotid duct around the 2nd upper molar
Describe the type of secretion of the submandibular gland, and where it enters the oral cavity
Mixed secretion, i.e. both serous and mucous. Enters via submandibular duct in the lingual frenulum
Describe the type of secretion of the sublingual gland, and where it enters the oral cavity
Mucous secretion, some serous but minor. Via sublingual ducts (10-20x) into floor of oral cavity
Compare the saliva produced by serous and mucus cells
Serous = watery and enzyme-rich
Mucus = glycoprotein, mucous rich so is thick
Give examples of the intrinsic saliva glands and what they secrete
Buccal, labial, lingual, palatine = primary mucus saliva at a constant rate
Describe the innervation (inc nuclei involved) of the extrinsic salivary glands
PARASYMPATHETIC (inc. saliva production)
Facial nerve: superior salivary nucleus to the submandibular ganglion, then post-symp fibres innervate submandibular and sublingual glands
Glossopharyngeal: inferior salivary nucleus to the otic ganglion, then post-symp fibres innervate the parotid gland
What can increase saliva secretion?
Chemoreceptors (e.g. acidic food) or mechanoreceptors (chewing) = act on superior and inferior salivary nucleus
Sight, smell and thought of food
How does the sympathetic NS influence the saliva?
Sympathetic T1-T4 = deep petrosal nerve, makes a more protein-rich and viscous saliva (thicker)
Compare the osmolality of primary and secondary secretions
Primary = isotonic (same as blood plasma)
Secondary= hypotonic (less than blood plasma)
Describe the main movements of ions that forms the primary secretion in the acinar cells
- Na+/K+ ATPase creates a gradient, so NKCC1 allows Na+, K+, 2Cl- to enter via concentration gradient, but K+ is recycled back after
- Cl- accumulates then leaves via Cl- channels
- Na+ drawn in via paracellular route down electrochemical gradient
- AQP5 expressed on apical + basolateral membranes so H2O enters via osmosis
Describe the modification of primary secretion into secondary secretion by the duct cells
- Na+ reabsorbed by ENaC (passive) and leaves basolaterally by Na+/K+ ATPase
- Positive charge on basolateral side draws Cl- in via Cl- channels
- Apical Cl-/ HCO3- exchangers for the HCO3- generated intracellularly via carbonic anhydrase (so Cl- into blood and HCO3- in lumen)
- Basolateral exchangers swap Na+ for H+ (so H+ enters blood and Na+ back out via ATPase)
= Impermeable to water, so creates a dilute and hypotonic saliva
What may be present in the saliva for the antimicrobial defence?
IgA, lysozymes, cystatins, defensins
What centre is responsible for the neural control of swallowing?
Central Programme Generator (CPG) in the medulla - it excites/ inhibits muscles of swallowing
What nerves are involved in the neural control of swallowing?
CN V, VII, IX, X, XII