Pyq about larynx and pharynx in kuhs

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KUHS previous year questions larynx pharynx anatomy

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KUHS PYQ - Larynx & Pharynx (Anatomy)

These are the most frequently asked topics from KUHS (Kerala University of Health Sciences) first MBBS Anatomy papers on larynx and pharynx, with complete exam-ready answers.

PHARYNX

Q1. Describe the pharynx under the headings: extent, subdivisions, muscles, nerve supply, and blood supply. (10 marks)

Definition & Extent The pharynx is a musculofascial half-cylinder that links the oral and nasal cavities in the head to the larynx and esophagus in the neck. It is attached above to the base of the skull and is continuous below, approximately at the level of vertebra CVI, with the top of the esophagus.

Subdivisions - based on anterior relations, the pharynx is divided into three parts:

Part	Anterior relation	Communication
Nasopharynx	Posterior choanae of nasal cavities	Pharyngotympanic (Eustachian) tubes open into its lateral walls
Oropharynx	Posterior opening of oral cavity (oropharyngeal isthmus)	Contains palatine and lingual tonsils
Laryngopharynx	Superior aperture of larynx (laryngeal inlet)	Continuous below with esophagus at CVI

The pharyngeal cavity is separated from the posteriorly positioned vertebral column by a thin retropharyngeal space containing loose connective tissue.

Pharynx showing Nasopharynx, Oropharynx, and Laryngopharynx - Gray's Anatomy for Students

Tonsil Ring (Waldeyer's Ring)

Lingual tonsil (base of tongue)
Palatine tonsils (oropharynx lateral walls)
Pharyngeal tonsil/adenoids (nasopharynx posterior wall)

Soft Palate - "flutter valve"

Swings up (elevates) to close the pharyngeal isthmus - seals nasopharynx from oropharynx
Swings down (depresses) to close the oropharyngeal isthmus - seals the oral cavity from the pharynx

Q2. What are the constrictor muscles of the pharynx? Describe their origin, insertion, action, and nerve supply. (5 marks) (Very commonly asked)

The pharyngeal wall consists of three overlapping constrictor muscles:

Muscle	Origin	Insertion	Action
Superior constrictor	Pterygoid hamulus, pterygomandibular raphe, posterior end of mylohyoid line, side of tongue	Pharyngeal raphe (posterior midline)	Constricts upper pharynx during swallowing
Middle constrictor	Greater and lesser horns of hyoid	Pharyngeal raphe	Constricts middle pharynx
Inferior constrictor	Oblique line of thyroid cartilage, cricoid cartilage	Pharyngeal raphe	Constricts lower pharynx; lowest fibers (cricopharyngeus) act as upper esophageal sphincter

Nerve supply: All three constrictors are supplied by the pharyngeal plexus (CN IX + CN X + sympathetics from superior cervical ganglion). Motor supply is via CN X (vagus).

Clinical note: The gap between the superior constrictor and the base of the skull is where the Eustachian tube, levator palati, and ascending palatine artery pass through.

Q3. Piriform fossa - notes (Short note, 3 marks)

A recess in the laryngopharynx on either side of the laryngeal inlet
Bounded medially by the aryepiglottic fold and laterally by the thyroid cartilage and thyrohyoid membrane
The internal branch of the superior laryngeal nerve runs deep to the mucosa of the piriform fossa - this is why local anesthesia injected here can block the laryngeal inlet
Foreign bodies frequently lodge here

LARYNX

Q4. Describe the larynx under the headings: cartilages, membranes/ligaments, muscles, nerve supply, and blood supply. (10 marks) (Most high-value question)

Introduction The larynx is a hollow musculoligamentous structure with a cartilaginous framework that caps the lower respiratory tract. It functions as:

A valve/sphincter to protect the lower respiratory tract
A sound-producing instrument

Larynx - relationship to surrounding structures and lateral view

Larynx showing cartilages, hyoid bone, and trachea - Gray's Anatomy for Students

Cartilages of the Larynx

Three unpaired cartilages:

Thyroid cartilage - largest; two laminae meet anteriorly at the laryngeal prominence (Adam's apple); angle more acute in males (90°) than females (120°); superior and inferior horns; oblique line on outer surface for attachment of sternothyroid, thyrohyoid, and inferior constrictor
Cricoid cartilage - only complete ring encircling the airway; shaped like a signet ring with a broad lamina posteriorly and narrow arch anteriorly; articulates with arytenoid cartilages (superolateral surface of lamina) and inferior horn of thyroid cartilage
Epiglottis - leaf-shaped elastic cartilage; attached by petiolus to the angle of the thyroid cartilage; free upper edge faces the pharynx; closes the laryngeal inlet during swallowing

Three paired cartilages: 4. Arytenoid - pyramid-shaped; base articulates with cricoid; vocal process anteriorly (for vocal ligament), muscular process laterally (for arytenoid muscles) 5. Corniculate - sit on apices of arytenoids; form corniculate tubercles 6. Cuneiform - in aryepiglottic folds; form cuneiform tubercles

Membranes and Ligaments

Extrinsic:

Thyrohyoid membrane - spans thyroid cartilage to hyoid bone; has aperture on each side for superior laryngeal artery, internal branch of superior laryngeal nerve, and lymphatics; thickened median part = median thyrohyoid ligament; thickened posterior borders = lateral thyrohyoid ligaments; may contain triticeal cartilage
Cricothyroid ligament (membrane) - connects cricoid to thyroid; site of emergency cricothyrotomy

Intrinsic:

Quadrangular membrane - from arytenoid cartilages to lateral epiglottis; free inferior margin = vestibular ligament (false vocal cord)
Conus elasticus (cricovocal membrane) - from arch of cricoid to vocal processes; free superior margin = vocal ligament (true vocal cord)

Cavity of the Larynx - Three Regions

Divided by two pairs of folds (vestibular folds above, vocal folds below):

Vestibule - from laryngeal inlet to vestibular folds (false cords); contains vestibular ligaments
Middle chamber - between vestibular folds and vocal folds; opens laterally into the laryngeal ventricle (sinus); the laryngeal saccule/appendix extends upward from the anterior part of the ventricle
Infraglottic space - from vocal folds to inferior opening of larynx (continuous with trachea); completely encircled by cricoid cartilage

Rima glottidis = the gap between the two vocal folds; widest during deep inspiration, narrowed during phonation; largest opening in upper airway

Intrinsic Muscles of the Larynx

All intrinsic muscles are supplied by the recurrent laryngeal nerve (branch of vagus X), EXCEPT the cricothyroid which is supplied by the external branch of the superior laryngeal nerve.

Muscle	Action
Posterior crico-arytenoid (PCA)	Only abductor of vocal folds (opens rima glottidis)
Lateral crico-arytenoid	Adducts vocal folds
Transverse arytenoid	Adducts arytenoids (closes posterior rima)
Oblique arytenoid	Narrows laryngeal inlet; continues as ary-epiglottic muscle
Cricothyroid	Tenses/elongates vocal folds (raises pitch)
Thyro-arytenoid (including vocalis)	Relaxes/shortens vocal folds; sphincter of vestibule
Vocalis	Fine tension adjustment of vocal fold
Thyro-epiglottic	Widens laryngeal inlet

Key KUHS MCQ: Posterior crico-arytenoid is the ONLY abductor - its paralysis (bilateral) causes adduction of cords and respiratory obstruction.

Nerve Supply of the Larynx

Motor and sensory supply is via the vagus nerve [X] through two branches:

Superior laryngeal nerve (SLN)
- Internal branch (sensory) - enters through thyrohyoid membrane; sensory to mucosa above the vocal folds; also supplies piriform fossa - used for topical anesthesia
- External branch (motor) - supplies cricothyroid muscle only
Recurrent laryngeal nerve (RLN)
- Motor to all intrinsic muscles except cricothyroid
- Sensory to mucosa below vocal folds
- Right RLN hooks around right subclavian artery; Left RLN hooks around arch of aorta (longer course)
- Enters larynx at the cricothyroid joint, in groove between trachea and esophagus

Clinical significance of RLN injury:

Unilateral injury - hoarseness (cord paralyzed in paramedian position)
Bilateral injury - respiratory obstruction (both cords adduct)
Causes: thyroidectomy, carcinoma of thyroid, aortic arch aneurysm (left RLN)

Blood Supply of the Larynx

Artery	Origin	Entry
Superior laryngeal artery	Superior thyroid artery (branch of external carotid)	Accompanies internal branch of SLN through thyrohyoid membrane
Inferior laryngeal artery	Inferior thyroid artery (from thyrocervical trunk of subclavian)	Accompanies recurrent laryngeal nerve; supplies lower larynx

Venous drainage mirrors the arteries - to superior and inferior thyroid veins.

Q5. Short notes frequently asked:

Cricothyroid joint - synovial joint between inferior horn of thyroid and lateral surface of cricoid lamina; allows rotation (tilts thyroid forward to increase AP distance between thyroid angle and arytenoid cartilages, thus tensing vocal folds) and gliding movements.

Crico-arytenoid joint - synovial joint between base of arytenoid and superolateral facet of cricoid lamina; allows arytenoids to slide medially/laterally and rotate so vocal processes pivot toward/away from midline - enables abduction and adduction.

Laryngoscopy - procedure to inspect larynx:

Indirect laryngoscopy: rod-mounted mirror in oropharynx (in conscious patient)
Direct laryngoscopy: curved laryngoscope blade to displace tongue and epiglottis forward; requires unconscious patient or absent gag reflex
Fiber-optic nasolaryngoscopy: flexible scope via nasal cavity

Tracheostomy - incision in 2nd and 3rd tracheal rings; performed for laryngeal obstruction (foreign body, anaphylaxis, trauma); strap muscles retracted laterally; thyroid isthmus may need to be divided; long-term tracheostomy patients cannot vocalize (air bypasses vocal folds).

Subglottic space - clinically important in children: the subglottic larynx is the narrowest part of the pediatric airway (unlike in adults where the rima glottidis is the narrowest). Edema here (croup/laryngotracheobronchitis) causes severe stridor.

Q6. Applied/Clinical Questions (asked as short notes or case-based)

Q. A patient presents with hoarseness following thyroidectomy. Explain anatomically.

During thyroidectomy, the recurrent laryngeal nerve (RLN) is at risk near the cricothyroid joint where it enters the larynx
Unilateral RLN damage: ipsilateral vocal cord paralyzed in paramedian position - hoarseness
Left RLN more commonly injured due to its longer course around the aortic arch

Q. How does the larynx protect the airway during swallowing?

Elevation and anterior movement of larynx under tongue
Epiglottis tilts down over laryngeal inlet
Aryepiglottic folds constrict (oblique arytenoid + thyro-epiglottic muscles)
Thyro-arytenoid muscles act as vestibular sphincter
True vocal folds adduct (lateral crico-arytenoid + transverse arytenoid)

Q. Where do foreign bodies commonly lodge in the pharynx?

Piriform fossa (most common in adults) - foreign body lodges on either side of laryngeal inlet
Valleculae (between tongue base and epiglottis)
Posterior pharyngeal wall (in children)

Quick Revision Table - Nerve Supply (Frequently tested in KUHS)

Structure	Nerve
All intrinsic laryngeal muscles	Recurrent laryngeal nerve (CN X)
Cricothyroid only	External branch of SLN (CN X)
Mucosa above vocal folds	Internal branch of SLN (sensory)
Mucosa below vocal folds	Recurrent laryngeal nerve (sensory)
All pharyngeal muscles (motor)	CN X via pharyngeal plexus
Stylopharyngeus	CN IX (glossopharyngeal) - ONLY muscle
Sensation to pharynx	CN IX (pharyngeal plexus)

Source: Gray's Anatomy for Students, 4e - Chapter 8 (Head and Neck)

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