Neck Practice Questions

Q: What is the nerve supply to the platysma muscle?

Facial nerve. **Explanation:** The **platysma** is a broad, thin sheet of muscle located in the subcutaneous tissue of the neck. It is classified as a muscle of facial expression. **1. Why Facial Nerve is Correct:** The platysma develops from the **second pharyngeal arch**. All muscles derived from this arch are innervated by the **Facial nerve (CN VII)**. Specifically, the platysma is supplied by the **cervical branch** of the facial nerve, which descends behind the angle of the mandible to enter the deep surface of the muscle. **2. Why Other Options are Incorrect:** * **Ansa cervicalis:** This nerve loop (C1-C3) supplies the infrahyoid "strap" muscles (omohyoid, sternohyoid, and sternothyroid), not the superficial muscles of the neck. * **Hypoglossal nerve (CN XII):** This is the motor nerve for all intrinsic and extrinsic modules of the tongue (except the palatoglossus). * **Mandibular nerve (V3):** This nerve supplies muscles derived from the first pharyngeal arch, such as the muscles of mastication, the anterior belly of the digastric, and the mylohyoid. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** It lies within the **superficial fascia** of the neck (not the deep fascia). * **Function:** It depresses the mandible and the angle of the mouth, conveying expressions of horror or fright. * **Surgical Significance:** During neck surgeries, the platysma must be identified and sutured separately to ensure a cosmetic scar and prevent "tenting" of the skin. * **Clinical Sign:** In facial nerve palsy (Bell’s palsy), the patient may lose the ability to voluntarily contract the platysma on the affected side.

Q: Which of the following muscles is supplied by two nerves?

Digastric. **Explanation:** The **Digastric muscle** is a classic example of a "hybrid" or "composite" muscle because its two bellies are derived from different embryological branchial arches, each carrying its own nerve supply. * **Anterior Belly:** Derived from the **1st branchial arch**, it is supplied by the **nerve to mylohyoid** (a branch of the mandibular nerve, $V_3$). * **Posterior Belly:** Derived from the **2nd branchial arch**, it is supplied by the **digastric branch of the facial nerve** (CN VII). **Analysis of Incorrect Options:** * **Quadriceps:** Supplied solely by the **femoral nerve** ($L_2-L_4$). * **Triceps:** All three heads are supplied by the **radial nerve** ($C_6-C_8$). Note: Occasionally, the medial head receives a branch from the ulnar nerve, but this is an anatomical variation, not the standard supply. * **Flexor Digitorum Superficialis (FDS):** Entirely supplied by the **median nerve**. It is the Flexor Digitorum *Profundus* (FDP) that has a dual supply (median and ulnar nerves). **High-Yield Clinical Pearls for NEET-PG:** * **Other Hybrid Muscles:** Memorize these for exams: * **Pectineus:** Femoral and Obturator nerves. * **Adductor Magnus:** Obturator and Sciatic (tibial part) nerves. * **Flexor Digitorum Profundus:** Median (AIN) and Ulnar nerves. * **Brachialis:** Musculocutaneous and Radial nerves. * **Embryology Link:** Whenever a muscle has a dual nerve supply, it usually signifies a dual embryological origin. For the digastric, the intermediate tendon connects the two developmentally distinct bellies.

Q: Which of the following arteries supplies the lower two-thirds of the thyroid lobe, trachea, and thymus?

Inferior thyroid artery. The **Inferior Thyroid Artery (ITA)** is a branch of the **thyrocervical trunk**, which arises from the first part of the subclavian artery. It is the primary blood supply to the posterior and inferior aspects of the thyroid gland. 1. **Why Option A is Correct:** The ITA provides extensive vascularization beyond just the thyroid gland. It supplies the **lower two-thirds of the thyroid lobe**, the posterior surface of the gland (including the parathyroid glands), and gives off esophageal, **tracheal**, and **thymic branches** [1]. Its distribution makes it the most comprehensive answer for the structures mentioned. 2. **Why Option B is Incorrect:** The **Superior Thyroid Artery (STA)** is the first branch of the External Carotid Artery. It primarily supplies the upper one-third and the anterior surface of the thyroid lobe. While it has a cricothyroid branch, it does not typically supply the trachea or thymus. 3. **Why Option C is Incorrect:** The **External Carotid Artery** is the parent vessel of the STA, but it does not directly supply the lower thyroid, trachea, or thymus. 4. **Why Option D is Incorrect:** Since the vascular territories of the STA and ITA are distinct and specific, "All of the above" is inaccurate. **High-Yield NEET-PG Pearls:** * **Surgical Anatomy:** During thyroidectomy, the **Inferior Thyroid Artery** is closely related to the **Recurrent Laryngeal Nerve (RLN)** [1], [2]. To avoid nerve injury, the artery should be ligated **far from the gland** (where the nerve is usually posterior to it). * **Parathyroid Supply:** The ITA is the main source of blood for both the superior and inferior parathyroid glands [1]. * **Thyroidea Ima Artery:** In 3-10% of individuals, an accessory artery (Thyroidea Ima) arises from the brachiocephalic trunk or aortic arch to supply the thyroid isthmus.

Q: Which of the following muscles adducts the vocal cords?

Lateral cricoarytenoid. The intrinsic muscles of the larynx are responsible for controlling the tension and position of the vocal cords, thereby regulating phonation and the airway. ### **Explanation of Options** * **A. Lateral cricoarytenoid (Correct):** This muscle originates from the arch of the cricoid cartilage and inserts into the muscular process of the arytenoid. Its contraction pulls the muscular process anteriorly, causing **medial rotation** of the arytenoid cartilages. This action brings the vocal folds together, resulting in **adduction**. * **B. Posterior cricoarytenoid:** This is the **only abductor** of the vocal cords. It rotates the arytenoids laterally, opening the rima glottidis. It is often referred to as the "safety muscle of the larynx" because it maintains the airway. * **C. Cricothyroid:** This muscle tilts the thyroid cartilage forward, which increases the distance between the thyroid and arytenoid cartilages. This action **tenses and elongates** the vocal cords, raising the pitch of the voice. * **D. Vocalis:** This muscle (the medial part of the thyroarytenoid) runs parallel to the vocal ligament. Its primary role is to **relax** the vocal cords by shortening them, which lowers the pitch. ### **NEET-PG High-Yield Pearls** * **Nerve Supply:** All intrinsic muscles of the larynx are supplied by the **Recurrent Laryngeal Nerve (RLN)**, EXCEPT the **Cricothyroid**, which is supplied by the **External Laryngeal Nerve**. * **Key Actions Summary**: * **Abductor:** Posterior cricoarytenoid (Safety muscle). * **Adductors:** Lateral cricoarytenoid, Transverse arytenoid. * **Tensors:** Cricothyroid. * **Relaxers:** Thyroarytenoid and Vocalis. * **Clinical Correlation:** Bilateral RLN injury leads to the vocal cords being fixed in a paramedian position, causing respiratory distress (stridor) because the "safety muscle" (abductor) is paralyzed.

Q: Which of the following arteries supplies the parathyroid glands?

Inferior thyroid artery. The blood supply to the parathyroid glands is a high-yield topic in neuroanatomy and endocrine surgery. **Explanation of the Correct Answer:** The **inferior thyroid artery (ITA)**, a branch of the thyrocervical trunk (from the subclavian artery), is the primary blood supply to **both** the superior and inferior parathyroid glands in approximately 80–90% of individuals [1]. This occurs via small parathyroid branches that arise from the ITA before it enters the thyroid gland. Identifying these vessels is crucial during thyroidectomy to avoid accidental devascularization of the parathyroids, which can lead to postoperative hypocalcemia [1]. **Analysis of Incorrect Options:** * **A. Superior thyroid artery:** While it supplies the upper pole of the thyroid gland, it only contributes to the superior parathyroid glands in a minority of cases (about 10–15%). It is not the primary source. * **C. Common carotid artery:** This is a major trunk that does not give off direct branches to the parathyroid glands. It bifurcates into the internal and external carotid arteries. * **D. Middle thyroid artery:** This is an **anatomical misnomer**. There is a middle thyroid *vein*, but there is no standard middle thyroid artery. (Note: The *Arteria Thyroidea Ima* is an occasional vessel from the brachiocephalic trunk or aorta, but it is not the "middle" thyroid artery). **High-Yield Clinical Pearls for NEET-PG:** 1. **Recurrent Laryngeal Nerve (RLN):** The ITA has a close relationship with the RLN [1]. During surgery, the nerve is usually found posterior to the artery on the right and anterior/posterior on the left. 2. **Ectopic Glands:** Inferior parathyroids (derived from the 3rd pharyngeal pouch) are more prone to ectopic locations (e.g., thymus) but usually still retain their blood supply from the ITA [1]. 3. **Venous Drainage:** Parathyroid veins drain into the thyroid venous plexus (superior, middle, and inferior thyroid veins).

Q: Which nerve pierces the thyroid gland?

Recurrent laryngeal nerve. The **Recurrent Laryngeal Nerve (RLN)** is the correct answer because of its intimate anatomical relationship with the thyroid gland and the inferior thyroid artery. As the RLN ascends in or near the tracheoesophageal groove, it passes deep to the pretracheal fascia [1]. Before entering the larynx behind the cricothyroid joint, it frequently passes through the **suspensory ligament of Berry** (which connects the thyroid gland to the trachea) [2]. In many individuals, the nerve may actually pierce the posterior part of the thyroid gland's capsule or be embedded within the glandular tissue itself, making it highly vulnerable during thyroidectomy [1]. **Analysis of Incorrect Options:** * **Superior Laryngeal Nerve (SLN):** This nerve divides into internal and external branches. The internal branch pierces the thyrohyoid membrane, and the external branch supplies the cricothyroid muscle [3]. Neither branch pierces the thyroid gland. * **Inferior Laryngeal Nerve:** This is simply the terminal continuation of the Recurrent Laryngeal Nerve after it passes the lower border of the inferior constrictor muscle. While technically the same nerve, "Recurrent Laryngeal Nerve" is the standard anatomical term for the segment related to the gland. * **Posterior Laryngeal Nerve:** This is not a standard anatomical term in human neuroanatomy regarding the thyroid region. **NEET-PG High-Yield Pearls:** 1. **Ligament of Berry:** The RLN is most commonly injured here during surgery [2]. 2. **Arterial Relation:** The RLN is closely related to the **Inferior Thyroid Artery**, while the External Laryngeal Nerve is related to the **Superior Thyroid Artery** [1, 4]. 3. **Function:** The RLN supplies all intrinsic muscles of the larynx *except* the cricothyroid (supplied by the External Laryngeal Nerve). 4. **Injury:** Unilateral RLN injury causes hoarseness; bilateral injury causes stridor and airway emergency.

Q: Which of the following does not occur at the level of the C6 vertebra?

The trachea bifurcates.. The **C6 vertebra** is a critical anatomical landmark in the neck, representing the transition point between several respiratory and gastrointestinal structures. ### 1. Why the Correct Answer is Right **Option A: The trachea bifurcates.** The trachea begins at the lower border of the cricoid cartilage (C6) but does **not** bifurcate there. Tracheal bifurcation (the carina) occurs at the level of the **T4-T5 vertebrae** (the Sternal Angle of Louis). In a living subject in the erect position, this bifurcation can descend as low as T6 due to gravity and respiration. ### 2. Analysis of Incorrect Options (Events at C6) The following events occur at the level of the lower border of the cricoid cartilage, which corresponds to the **C6 vertebra**: * **Option B & C: The pharynx ends and the esophagus begins.** The muscular tube of the pharynx transitions into the esophagus at this level. This is also the site of the cricopharyngeal sphincter (the narrowest part of the esophagus). * **Option D: The larynx ends.** The larynx transitions into the trachea at the lower border of the C6 vertebra. ### 3. High-Yield Clinical Pearls for NEET-PG * **Palpation:** The **Carotid Tubercle** (Chassaignac’s tubercle) is the prominent anterior tubercle of the transverse process of C6. It is used as a landmark to compress the carotid artery to control bleeding. * **Middle Cervical Ganglion:** Located at the level of C6. * **Vertebral Artery:** Usually enters the foramen transversarium at the level of **C6** (not C7). * **Omohyoid:** The intermediate tendon of the omohyoid muscle crosses the carotid sheath at the level of C6.

Question 1

A 50-year-old female patient presented with a chief complaint of a painless thyroid nodule. Further examination is insignificant. TSH levels are normal. FNAC reveals papillary changes with nuclear atypia. Total thyroidectomy is planned. During surgery, a nearby nerve is injured while ligating the superior thyroid artery. Which of the following laryngeal muscles is likely to be affected?

Accepted Answer

Thyroarytenoid muscle

Answer

Cricothyroid muscle

Answer

Posterior cricoarytenoid muscle

Answer

Lateral cricoarytenoid muscle

Question 2

What is the nerve supply to the platysma muscle?

Accepted Answer

Facial nerve

Answer

Ansa cervicalis

Answer

Hypoglossal nerve

Answer

Mandibular nerve

Question 3

Which of the following muscles is supplied by two nerves?

Accepted Answer

Digastric

Answer

Quadriceps

Answer

Triceps

Answer

Flexor digitorum superficialis

Question 4

Which of the following is NOT a branch of the cervical part of the facial artery?

Accepted Answer

Ascending pharyngeal artery

Answer

Ascending palatine artery

Answer

Tonsillar branch

Answer

Submental artery

Question 5

Which cranial nerve is present around the origin of the occipital artery at the lower end of the sternocleidomastoid muscle?

Accepted Answer

Hypoglossal nerve

Answer

Spinal accessory cranial nerve

Answer

Superior laryngeal nerve

Answer

Petrosal nerve

Question 6

Which of the following arteries supplies the lower two-thirds of the thyroid lobe, trachea, and thymus?

Accepted Answer

Inferior thyroid artery

Answer

Superior thyroid artery

Answer

External carotid artery

Answer

All of the above

Question 7

Which of the following muscles adducts the vocal cords?

Accepted Answer

Lateral cricoarytenoid

Answer

Posterior cricoarytenoid

Answer

Cricothyroid

Answer

Vocalis

Question 8

Which of the following arteries supplies the parathyroid glands?

Accepted Answer

Inferior thyroid artery

Answer

Superior thyroid artery

Answer

Common carotid artery

Answer

Middle thyroid artery

Question 9

Which nerve pierces the thyroid gland?

Accepted Answer

Recurrent laryngeal nerve

Answer

Superior laryngeal nerve

Answer

Inferior laryngeal nerve

Answer

Posterior laryngeal nerve

Question 10

Which of the following does not occur at the level of the C6 vertebra?

Accepted Answer

The trachea bifurcates.

Answer

The pharynx ends.

Answer

The esophagus begins.

Answer

The larynx ends.

Neck — MCQs

Neck — MCQs

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