HoyaDocs · HNSS Block 5 · Head & Neck AnatomyUpdated 28 Sep 2026 · Rev 1.0

Lab 6 Exam-Day Review — The Larynx

Dissection of the Larynx — laryngeal skeleton, membranes, interior spaces and folds, intrinsic muscles, nerves, blood supply, lymph and the laryngopharynx.

1. Rules & top traps 2. Laryngeal skeleton 3. Membranes & interior 4. Laryngoscopic view 5. Muscles 6. Nerves & lesions 7. Vessels & lymph 8. Laryngopharynx & swallowing 9. Airway procedures 10. Self-check

1 · Exam-Day Rules & Top Traps

✍️ Wording

Full names. Spelling counts: arytenoid · corniculate · cuneiform · cricoid · cricothyroid · thyrohyoid · quadrangular membrane · conus elasticus · rima glottidis · infraglottic · piriform recess · vallecula · posterior cricoarytenoid.
“Vocal fold” = true cord; “vestibular fold” = false cord.

★ High-yield traps

Posterior cricoarytenoid = the ONLY abductor of the vocal folds (“PCA = Pulls Cords Apart”) — recurrent laryngeal nerve.
Cricothyroid = the only intrinsic muscle NOT supplied by the recurrent laryngeal nerve → external laryngeal nerve; tilts the thyroid cartilage → tenses the folds → raises pitch.
The vocal fold is the dividing line: above = internal laryngeal nerve (sensory, cough reflex) + superior laryngeal artery + superior deep cervical nodes; below = recurrent laryngeal nerve + inferior laryngeal artery + inferior deep cervical / pretracheal / paratracheal nodes.
Internal laryngeal nerve + superior laryngeal artery pierce the thyrohyoid membrane.
Ventricle = space between the vestibular (false) and vocal (true) folds.
Vocal fold = vocal ligament (upper edge of the conus elasticus) + vocalis + mucosa. Vestibular fold covers the vestibular ligament (lower edge of the quadrangular membrane).
Epiglottis = elastic cartilage. Vallecula = oropharynx (anterior to epiglottis); piriform recess = laryngopharynx (lateral to the inlet).
Cricothyroidotomy = through the cricothyroid ligament; tracheostomy = between tracheal rings.

2 · Laryngeal Skeleton

Hyoid bone↓Thyrohyoid membrane↓Thyroid cartilage↓Cricothyroid ligament↓Cricoid cartilage↓1st tracheal ring → trachea

Superior → inferior in the anterior midline — palpable from the chin down.

Cartilage / structure	Key features	High-yield
Thyroid cartilage	Two laminae meet anteriorly → laryngeal prominence (Adam’s apple); V-shaped thyroid notch above (palpable)	Common carotid bifurcates at its superior border
Thyrohyoid membrane	Hyoid → thyroid cartilage	Pierced by the internal laryngeal nerve + superior laryngeal artery
Cricothyroid ligament	Thyroid cartilage → cricoid cartilage (anterior part of the conus elasticus)	Cricothyroidotomy site
Cricoid cartilage	Signet-ring shaped: narrow arch anteriorly, tall lamina posteriorly; only complete ring	Arytenoids sit on its posterior lamina
Epiglottis	Elastic cartilage; attached to the hyoid (hyo-epiglottic ligament) and thyroid cartilage (thyro-epiglottic ligament)	Folds down over the laryngeal inlet in swallowing → prevents aspiration
Arytenoid cartilages	Paired pyramids on top of the cricoid; vocal process (anterior) + muscular process (lateral)	Rotate/slide to open and close the rima glottidis
Corniculate cartilages	Little “hats” on the arytenoid apices	—
Cuneiform cartilages	In the aryepiglottic (AE) fold	AE fold: arytenoid → epiglottis
Trachea	C-shaped rings	Tracheostomy between rings

Functions of the larynx

Breathing · phonation · swallowing (airway protection).

Extrinsic muscles move the whole larynx

Act via the hyoid: suprahyoid elevate, infrahyoid depress the hyoid + larynx (swallowing).

3 · Membranes, Folds & Interior Spaces

Two tiers: quadrangular membrane (vestibular fold) above, conus elasticus (vocal fold) below, ventricle between them. The dashed line at the vocal folds divides sensory supply, blood supply and lymph drainage.

Space / fold	Definition
Laryngeal inlet (aditus)	Opening from the laryngopharynx into the larynx. Anterior = superior epiglottis; lateral = AE folds; posterior = interarytenoid notch
Vestibule (supraglottis)	Upper chamber: inlet → vestibular folds
Vestibular fold (false cord)	Mucosa over the vestibular ligament (lower thickened edge of the quadrangular membrane)
Ventricle	Gap between vestibular and vocal folds; saccule = glandular pouch → mucus lubricates the vocal folds
Vocal fold (true cord)	Vocal ligament (upper edge of conus elasticus) + vocalis muscle + mucosa
Rima glottidis	Triangular opening between the vocal folds; glottis = rima + vocal folds
Infraglottic space	Below the vocal folds → trachea

4 · Laryngoscopic (Superior) View

View from above, as in laryngoscopy. The piriform recesses flank the aryepiglottic folds and funnel food around the inlet toward the esophagus.

Vallecula vs. piriform recess

Epiglottic vallecula	Between tongue base + epiglottis · oropharynx · laryngoscope blade sits here
Piriform recess	Lateral to the inlet/AE folds · laryngopharynx · food “gutters”; fish bones lodge here → internal laryngeal nerve at risk (under the mucosa)

Vocal fold position

Phonation: folds closed (adducted)
Respiration: folds open (abducted); wider in forced breathing

5 · Intrinsic Laryngeal Muscles

Muscle	Attachments	Action	Nerve
Cricothyroid	Cricoid arch → inferior border + inferior horn of thyroid lamina (outside the larynx)	Tilts thyroid cartilage forward/down → tenses/lengthens vocal folds → raises pitch	External laryngeal (SLN)
Posterior cricoarytenoid	Posterior cricoid lamina → muscular process of arytenoid	ABDUCTS — widens the rima glottidis (sole abductor)	Recurrent laryngeal
Lateral cricoarytenoid	Cricoid arch → muscular process of arytenoid	Adducts (rotates arytenoids medially) → narrows rima	Recurrent laryngeal
Transverse arytenoid	Between the two arytenoids (posterior)	Adducts — closes posterior glottis	Recurrent laryngeal
Oblique arytenoid	Muscular process → opposite arytenoid apex; continues into AE fold	Adducts; narrows the laryngeal inlet	Recurrent laryngeal
Thyroarytenoid	Inner thyroid angle → arytenoid	Relaxes/shortens vocal folds → lowers pitch	Recurrent laryngeal
Vocalis	Medial part of thyroarytenoid, along the vocal ligament	Fine-tunes fold tension/thickness	Recurrent laryngeal

Open

Posterior cricoarytenoid only.

“PCA = Pulls Cords Apart.”

Close

Lateral cricoarytenoid, transverse + oblique arytenoids.

Pitch

Up: cricothyroid (tenses).
Down: thyroarytenoid (relaxes).

6 · Nerves of the Larynx & Lesions

CN X→Superior laryngeal nerve→Internal branch: pierces thyrohyoid membrane (sensory above folds)+External branch: cricothyroid

CN X→Recurrent laryngeal nerve (R: around subclavian a.; L: around aortic arch)→All other intrinsic muscles + sensory below folds

	Internal laryngeal	External laryngeal	Recurrent laryngeal
Supplies	Mucosa above vocal folds	Cricothyroid	All other intrinsic muscles; mucosa below vocal folds
Travels with	Superior laryngeal artery	Superior thyroid artery	Inferior thyroid / inferior laryngeal artery
Lesion	Loss of cough reflex (afferent limb) → aspiration risk	↓ vocal range — can’t raise pitch, no hoarseness (“opera singer”)	Unilateral: hoarseness. PCA lost → folds can’t open → stridor/airway obstruction (esp. bilateral)
At risk from	Piriform recess foreign body (fish bone)	Thyroidectomy (superior pole)	Thyroidectomy (inferior thyroid a.); left side also by thoracic lesions near the aortic arch

7 · Blood Supply, Veins & Lymph

	Above the vocal folds	Below the vocal folds
Artery	Superior laryngeal a. ← superior thyroid a. ← ECA (1st branch); enters via the thyrohyoid membrane	Inferior laryngeal a. ← inferior thyroid a. ← thyrocervical trunk ← subclavian
Vein	Superior laryngeal v. → superior thyroid v. → internal jugular v.	Inferior laryngeal v. → inferior thyroid v. → brachiocephalic v.
Sensory nerve	Internal laryngeal	Recurrent laryngeal
Lymph	Superior deep cervical nodes (along IJV)	Inferior deep cervical, pretracheal, paratracheal nodes

★ Vocal fold cancer

Lymphatics in the vocal folds are sparse → vocal fold cancers rarely metastasize to lymph nodes.

8 · Laryngopharynx (Hypopharynx) & Swallowing

Laryngopharynx

Most inferior part of the pharynx; opens into the larynx via the laryngeal inlet; continues into the esophagus
Wall: middle + inferior constrictors, stylopharyngeus, palatopharyngeus
Piriform recesses = gutters guiding food around the inlet into the esophagus
All pharyngeal muscles = CN X except stylopharyngeus (CN IX)

Zenker’s diverticulum

Inferior constrictor = thyropharyngeus + cricopharyngeus. Weak area between them = Killian’s triangle → herniation. Food enters the sac → dysphagia, halitosis, regurgitation, aspiration.

Swallowing phase	What happens
Oral	Tongue pushes the bolus posteriorly
Oropharyngeal	Soft palate seals the nasopharynx; larynx elevated; pharynx widened
Pharyngeal	Constrictor peristalsis; epiglottis flips down over the inlet; piriform recesses channel food
Esophageal	Peristalsis to the stomach

9 · Airway Procedures

Procedure	Where	Notes
Orotracheal intubation	Mouth → between the vocal folds → trachea	Laryngoscope blade in the vallecula lifts the epiglottis; high Mallampati → plan video laryngoscopy
Cricothyroidotomy	Through the cricothyroid ligament (thyroid ↔ cricoid)	Emergency if intubation fails; prolonged use can damage the vocal folds/larynx
Tracheostomy	Between tracheal rings	Longer-term airway

10 · Self-Check

1. Which muscle is the only abductor of the vocal folds, and what nerve supplies it?

Posterior cricoarytenoid — recurrent laryngeal nerve.

2. Which intrinsic laryngeal muscle is not supplied by the recurrent laryngeal nerve?

Cricothyroid — external branch of the superior laryngeal nerve.

3. What pierces the thyrohyoid membrane?

Internal laryngeal nerve and superior laryngeal artery.

4. A fish bone lodged lateral to the laryngeal inlet damages which nerve? What is lost?

Internal laryngeal nerve (under the piriform recess mucosa) → loss of sensation above the vocal folds and the cough reflex.

5. What is the space between the vestibular and vocal folds?

The laryngeal ventricle (with the saccule producing mucus).

6. The vocal ligament is the upper border of which membrane?

Conus elasticus. (Vestibular ligament = lower border of the quadrangular membrane.)

7. After thyroid surgery a patient is hoarse. Which nerve, and which artery does it accompany?

Recurrent laryngeal nerve; inferior thyroid artery.

8. Bilateral recurrent laryngeal nerve injury is dangerous because…?

Both posterior cricoarytenoids are lost → folds can’t abduct → stridor/airway obstruction.

9. Where do lymphatics drain from below the vocal folds?

Inferior deep cervical, pretracheal and paratracheal nodes.

10. Why do vocal fold cancers rarely spread to nodes?

The vocal folds have sparse lymphatics.

11. What is the shape of the cricoid cartilage, and what sits on it?

Signet ring (tall posterior lamina); the arytenoid cartilages sit on its posterior lamina.

12. Name the borders of the laryngeal inlet.

Anterior: epiglottis; lateral: aryepiglottic folds; posterior: interarytenoid notch.

13. Which muscle lowers pitch?

Thyroarytenoid (relaxes/shortens the vocal folds).

14. Where is Killian’s triangle, and what forms there?

Between thyropharyngeus and cricopharyngeus (inferior constrictor); Zenker’s diverticulum.

HoyaDocs · HNSS Lab 6 Larynx Exam-Day ReviewUpdated 28 Sep 2026 · Rev 1.0