Case: A patient with a mediastinal tumor has persistent hoarseness. Imaging shows a tumor compressing a nerve as it loops under the arch of the aorta. Which nerve is affected and which muscle still functions?
Answer: Left Recurrent Laryngeal Nerve. The Cricothyroid muscle still functions. Explanation: The left recurrent laryngeal nerve loops under the aortic arch. All intrinsic muscles are paralyzed except the cricothyroid, which is supplied by the external laryngeal nerve.
Case: A singer cannot reach high notes or tighten their vocal cords after a neck injury. Which muscle is likely paralyzed?
Answer: Cricothyroid muscle. Explanation: The cricothyroid muscle increases the distance between the thyroid angle and arytenoid processes. This action stretches and increases the tension of the vocal cords to produce high-pitched sounds.
Case: During neck surgery, the Internal Laryngeal Nerve is accidentally cut as it pierces the Thyrohyoid membrane. What sensory deficit will the patient experience?
Answer: Loss of sensory innervation above the vocal cords. Explanation: This nerve provides sensory supply to the laryngeal mucosa from the inlet down to the level of the vocal folds. Damage abolishes the cough reflex in this area.
Case: A patient is unable to abduct (open) their vocal cords during deep inspiration. Which pair of muscles is dysfunctional?
Answer: Posterior cricoarytenoid muscles. Explanation: These are the ONLY muscles responsible for abducting the vocal folds (opening the rima glottidis). They are known as the 'safety muscles' of the larynx.
Case: A laryngoscopic exam shows the posterior part of the rima glottidis (between the arytenoid cartilages) fails to close during phonation. Which muscle is responsible?
Answer: Transverse arytenoid muscle. Explanation: This muscle bridges the two arytenoid cartilages. Its contraction pulls the cartilages together, closing the posterior part of the rima glottidis.
Case: A clinician is explaining the use of the Cricoid cartilage as a landmark. What is its unique structural characteristic?
Answer: It is the only complete ring in the respiratory skeleton. Explanation: Unlike the C-shaped tracheal cartilages or the open thyroid cartilage, the cricoid forms a full circle consisting of an anterior arch and a broad posterior lamina.
Case: A patient has difficulty narrowing the laryngeal inlet during swallowing, leading to aspiration. Which muscle is primarily responsible for narrowing the inlet?
Answer: Oblique arytenoid muscle. Explanation: The oblique arytenoid (along with aryepiglottic muscles) acts as a sphincter for the laryngeal inlet to protect the airway during swallowing.
Case: A foreign object is lodged at the level of the Sternal Angle (Angle of Louis). What major anatomical event occurs here?
Answer: Bifurcation of the trachea. Explanation: The trachea is a fibro-cartilaginous tube that ends at the level of the sternal angle (T4 vertebra), where it divides into the right and left main bronchi.
Case: Why is a foreign body more likely to enter the Right Main Bronchus than the left?
Answer: Because the right bronchus is wider, shorter, and more vertical. Explanation: The right main bronchus is more in line with the trachea (more vertical), making it the common path for aspirated objects.
Case: A tumor is found in the Superior Lingular segment. Which lung and lobe is affected?
Answer: Superior lobe of the Left lung. Explanation: The left lung lacks a middle lobe. The lingular segments (superior and inferior) are part of the superior lobe of the left lung.
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