ENT - Wk 5 Pharynx & Layrnx

ENT - Wk 5 Pharynx & Layrnx

1. PHARYNX: Crossroads of air and food passages

   • Each passage can be closed by a sphincter
     • Pharyngeal Wall: Made up of mucous membrane, pharyngobasilar fascia & muscle layer (inner longitudinal outer circular)
       • LONGITUDINAL MUSCLES: Elevate and shorten the pharynx. INCLUDE: Stylopharyngeus, palatopharyngeus, salpingopharyngeus - all small thin, ribbon-like muscles suspending pharynx from skull base
       • CIRCULAR MUSCLES: Close space behind nose, mouth and larynx and are open at the front. INCLUDE: Superior constrictor, middle constrictor and inferior constrictor (Thyropharyngeus and cricopharyngeus)
         • Inf. contrictor includes 'killian's dehiscence' mid line meeting of muscle fibres
         • SWALLOWING: 3 STAGES
           • 1. ORAL: Preparatory stage - chewing, lubrication to form soft bolus. SOFT PALATE RELAXED, NASAL AIRWAY OPEN
           • 2. PHARYNGEAL: (Involuntary / reflex stage) usually very rapid (1-1.5 sec). Respiration momentarily inhibited, NASAL AND LARYNGEAL AIRWAY CLOSED to prevent nasal regurgitation, choking or aspiration
             • SOFT PALATE RAISED, TONGUE BASE RETRACTED, LARYNX PULLED UP AND FORWARDS UNDER TONGUE BASE, EPIGLOTTIS FOLDS BACKWARDS, FALSE CORDS CLOSE, CRICOPHARYNGEUS RELAXES AND OPENS - Food into oesophagus
           • 3. OESOPHAGEAL: (Also involuntary) PERISTALSIS - sequential muscular squeezing. LARYNX RELAXES AND LOWERS, CRICO PHARYNGEUS passively CLOSES to push down bolus, VOCAL F's OPEN, RESPIRATION RESUMES
       • PHARYNGEAL POUCH: Lining mucosa extrudes from 'killian's dehiscence' because of weakness in the muscle. This forms a little pouch which can collect food and cause regurgitation, choking or aspiration. (Common in elderly men). Has to be fixed with endoscopic stapling.
       • PHARYNGEAL NERVES: CN IX (Glossopharyngeal) and CN X (Vagus). Glossoph. is sensory, except for motor sup. to stylopharyngeus. Stimulation of Vagus can instigate a sympathetic response to contract cricopharyngeus sphincter
         • PHARYNGEAL ARTERIES: Extend from branches of facial and maxillary arteris, which come from external carotid artery in neck. Blood drains into internal jugular veins
           • MUCOUS MEMBRANE is continuous with pharynx and trachea.
             • SUPRAGLOTTIC LARYNX (above V.F.) = low, stratefied squamous epithelium
               • FALSE AND TRUE V.F.'s = thick stratified squamous epithelium
               • SUBGLOTTIS (below V.F.'s) ciliated columnar (respiratory) epithelium
   • OROPHARYNX: Lower edge soft palate to tip epiglottis
     • Opens into buccal cavity (mouth) and includes post. 1/3rd tongue (vallecula)
     • SOFT PALATE: Fibrous tissue from tendons of tensor palati muscles.
       • Contains mucous glands and lymphoid tissue - mostly on inferior aspect. Stratified squamous epithelium
       • Superior surface (back of nose) columnar epithelium
       • Flap valve - shuts off oropharynx to allow breathing while chewing.
         • Shuts off nasopharynx to prevent food entering while swallowing
       • MUSCLES of S.P
         • Tensor palati: tightens S.P, opens Eus. tube
         • Levator palati: raises soft palate, helps open Eus. tube after age 7
         • Palatoglossus: closes oropharyngeal isthmus by approximating palatoglossal arches and lifting base of tongue
         • Palatopharyngeus: lifts pharynx and larynx during swallowing, directing food into lower part of oropharynx
         • Uvular muscle: shortens uvula adding bulk to dorsal surface of soft palate& assisting closure of nasopharyngeal opening
   • HYPOPHARYNX: Behind and to sides of larynx (inc. pyriform fossae) down to crico-arytenoid joint
     • Below this is the pharyngo-oesophageal junction - with oes. sphincter

2. LARYNX: Opposite 36rd - 6th cervical vertebrae. FORMED OF 3 Cartilages - EPIGLOTTIS, THYROID & CRICOID CARTILAGES

   • Below cricoid cart. and superficial to it is the thyroid gland
   • Cartilages connected together by fibrous tissue membranes and joined to U shaped hyoid bone above
     • Hyoid bone is attached to tongue base
   • VOCAL FOLDS: 3 Layers - EPITHELIUM, LAMINA PROPRIA (Superficial and intermediate layer) and BODY of V.F. / VOCALIS MUSCLE
     • Only close for phonation, coughing, sneezing or straining physically
     • 23mm male 16mm female
     • Sit 8mm apart at rest
   • FUNCTIONS to PROTECT AIRWAY (epiglottis, false and true cords) COUGH REFLEX (CNX in larynx, trachea and bronchi) and VOICE PRODUCTION
   • LARYNX MEMBRANES: THYROHYOID, CRICOTHYROID - WHOSE UPPER EDGE IS VOCAL FOLD and QUADRATE MEMBRANE - Inside thyroid cart - LOWER EDGE IS FALSE V.F. (Vestibular fold), UPPER EDGE IS ARY-EPIGLOTTIC FOLD.
     • Thyrohyoid membrane is pierced from outside by internal laryngeal nerve and artery
       • 2 X Sphincter muscles: ARYEPIGLOTTIC (with X cross over) - pulls epiglottis down to protect airway and THYRO-EPIGLOTTIC Muscle (Outside quadrate membrane) contraction squeezes laryngeal inlet closed.
         • 3 x vocal fold muscles: POSTERIOR CRICO-ARYTENOID opens V.F.'s by pulling and rotating arytenoids. ESSENTIAL FOR LIFE AS KEEPS AIRWAY OPEN!!!!
           • LATERAL CRICOARYTENOID pulls arytenoid carts. forward and rotates folds together
             • INTER-ARYTENOID (between arytenoids) TILT ARYTENOIDS BACK TOWARDS SLOPING CRICOID. PULL FOLDS TOGETHER - no rotation
               • CRICOTHYROID MUSC. pulls and rotates thy. down therby STRECHES AND TIGHTENS V.F.'s within larynx
                 • SUPERIOR LARYNGEAL NERVE - CN X (Vagus)
                   • Internal branch above: Pierces thyrohyoid, gives sensation to larynx above F.V.'s - cough, heat, pain etc...
                   • External branch below: Runs down over larynx, supplies cricotyroid muscle, lenghtens & tensions V.F.'s
                     • CAN BE DAMAGED IN THYROID SURGERY!!!!! This paralyses cricothyroid musc. on that side causing floppy V. fold. But cord still technically mobile
                   • RECURRENT LARYNGEAL NERVE - CN X (Vagus) MOTOR MUSCLE MOVEMENT and sensation below the V.F.'s
                     • ALL INTRINSIC MUSCLES for phonation supplied by recurrent laryngeal nerve (Vagus X) except cricothyroid which is SUPERIOR LARYNGEAL NERVE – EXTERNAL BRANCH
                 • THYROARYTENOID: (Inside adam's apple to ary. cartl) Opposes cricothyroid action, CONTRACTS AND SHORTENS V.F.'s
                   • VOCALIS: (Arytenoid to edge of vocal ligament) THICKENS VERTICAL EDGE OF CORD and provides FINE CONTROL of voice for SINGING!
                   • Length of cord is determined by opposing action of crico-thyroid & thyro-arytenoid muscles Tension of cord is determined by thyroarytenoid / vocalis tension
     • PYRIFORM FOSSA = thryohyoid memb. and thyroid cart. Medial wall = ary-epiglottic fold
     • CRICOTHYROID membrane also called CORNUS ELASTICUS
   • MUSCLES which DEPRESS LARYNX: STERNOHYOID, STERNOTHYROID, THYROHYOID OMOHYOID (clavicels to hyoid bone)
   • MUSCLES which STABILISE & ELEVATE LARYNX: STYLOPHARYNGEUS, STYLOHYOID AND PALATO PHARYNGEUS 9From skull base) and HYOID bone attachments to jaw GENIOHYOID AND MYLO HYOID
   • INTRINSIC LARYNGEAL MUSCLES: Sphincter action to protect airway and V.F. adduction or abduction plus lengthening and shortening for cord tension
     • POSTERIOR CRICO-ARYTENOID MUSC. = ABDUCTION
       • LATERAL CRICO-ARYTENOID MUSC. = ADDUCTION
         • INTERARYTENOID MUSC. = ADDUCTION

3. NASOPHARYNX: Behind nasal cavities, above soft palate

   • Eustachian tubes open into lateral walls
   • Adenoids lie above in roof (lymphoid tissue)

4. Palatine TONSILS

   • Medial surface has crypts
   • Deep surface covered fibrous capsule
   • Upper part has deep intra-tonsillar cleft
   • Can get acute tonsillitis or Quinsy (peritonsillar abscess) - Freakin gross
   • WALDEYER'S RING: ADENOIDS, TUBAL TONSILS, LINGUAL TONSILS, PALATINE TONSILS

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