Triangles of the neck US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Triangles of the neck. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Triangles of the neck US Medical PG Question 1: A 4-year-old girl is brought to the physician for a painless lump on her neck. She has no history of serious illness and her vital signs are within normal limits. On examination, there is a firm, 2-cm swelling at the midline just below the level of the hyoid bone. The mass moves cranially when she is asked to protrude her tongue. Which of the following is the most likely diagnosis?
- A. Cystic hygroma
- B. Thyroglossal cyst (Correct Answer)
- C. Ranula
- D. Dermoid cyst
Triangles of the neck Explanation: Thyroglossal cyst
- A midline neck mass that moves cranially with tongue protrusion is the classic presentation of a thyroglossal duct cyst.
- These cysts arise from the remnant of the thyroglossal duct, the embryonic tract along which the thyroid gland descends from the foramen cecum to its final position [1].
Cystic hygroma
- This is a lymphatic malformation typically appearing as a soft, compressible, transilluminant mass, often in the posterior triangle of the neck.
- It does not move with tongue protrusion and is usually not midline.
Ranula
- A ranula is a mucocele that forms in the floor of the mouth, usually due to obstruction of a sublingual salivary gland.
- It presents as a swelling in the oral cavity, below the tongue, and not as an external neck mass.
Dermoid cyst
- A dermoid cyst in the neck is typically a painless, doughy, subcutaneous mass that is also usually midline but does not move with tongue protrusion.
- These cysts are often found above the hyoid bone, unlike the typical position of a thyroglossal cyst.
Triangles of the neck US Medical PG Question 2: A 17-year-old boy comes to the physician because of a 3-month history of pain in his right shoulder. He reports that he has stopped playing for his high school football team because of persistent difficulty lifting his right arm. Physical examination shows impaired active abduction of the right arm from 0 to 15 degrees. After passive abduction of the right arm to 15 degrees, the patient is able to raise his arm above his head. The dysfunctional muscle in this patient is most likely to be innervated by which of the following nerves?
- A. Long thoracic nerve
- B. Suprascapular nerve (Correct Answer)
- C. Upper subscapular nerve
- D. Accessory nerve
- E. Axillary nerve
Triangles of the neck Explanation: ***Suprascapular nerve***
- The patient exhibits impaired active abduction from 0 to 15 degrees but normal abduction after passive assistance, indicating dysfunction of the **supraspinatus muscle**.
- The **supraspinatus muscle** is responsible for **initiating shoulder abduction** from 0 to 15 degrees, after which the deltoid muscle takes over for continued abduction.
- The **suprascapular nerve** innervates both the **supraspinatus** and **infraspinatus muscles**, with the supraspinatus being crucial for the initial phase of abduction.
*Long thoracic nerve*
- This nerve innervates the **serratus anterior muscle**, which is responsible for **scapular protraction** and upward rotation.
- Damage to the long thoracic nerve would typically result in **winged scapula**, not difficulty in initiating abduction.
*Upper subscapular nerve*
- The upper subscapular nerve innervates the **subscapularis muscle**, part of the rotator cuff.
- This muscle is primarily involved in **internal rotation** of the shoulder and contributes to adduction, not abduction.
*Accessory nerve*
- The accessory nerve (cranial nerve XI) innervates the **sternocleidomastoid** and **trapezius muscles**.
- Damage to this nerve would most likely present with weakness in **shrugging the shoulders** or turning the head, not difficulty with shoulder abduction.
*Axillary nerve*
- This nerve innervates the **deltoid muscle** and the **teres minor muscle**, and provides sensory input from the shoulder joint and lateral arm.
- The deltoid is responsible for **shoulder abduction** from 15 to 90 degrees; a deficit here would affect a different range of motion than what is described.
Triangles of the neck US Medical PG Question 3: A 20-year-old man comes to the clinic complaining of shoulder pain for the past week. He is a pitcher for the baseball team at his university and reports that the pain started shortly after a game. The pain is described as achy and dull, intermittent, 7/10, and is concentrated around the right shoulder area. He denies any significant medical history, trauma, fever, recent illness, or sensory changes but endorses some difficulty lifting his right arm. A physical examination demonstrates mild tenderness of the right shoulder. When the patient is instructed to resist arm depression when holding his arms parallel to the floor with the thumbs pointing down, he reports significant pain of the right shoulder. Strength is 4/5 on the right and 5/5 on the left with abduction of the upper extremities. What nerve innervates the injured muscle in this patient?
- A. Axillary nerve
- B. Long thoracic nerve
- C. Subscapular nerve
- D. Accessory nerve
- E. Suprascapular nerve (Correct Answer)
Triangles of the neck Explanation: ***Suprascapular nerve***
- The patient's symptoms, including shoulder pain exacerbated by the <b>"empty can" test</b> (resisted arm depression with thumbs down), are highly suggestive of a <b>rotator cuff injury</b>, specifically involving the <b>supraspinatus muscle</b>.
- The <b>suprascapular nerve</b> innervates both the <b>supraspinatus</b> and <b>infraspinatus muscles</b>, which are critical for shoulder abduction and external rotation.
*Axillary nerve*
- The <b>axillary nerve</b> innervates the <b>deltoid muscle</b> and the <b>teres minor muscle</b>.
- Injury to the axillary nerve or these muscles would primarily affect <b>shoulder abduction</b> beyond the initial 15 degrees and external rotation, but the "empty can" test specifically targets the supraspinatus.
*Long thoracic nerve*
- The <b>long thoracic nerve</b> innervates the <b>serratus anterior muscle</b>, which is responsible for scapular protraction and upward rotation.
- Damage to this nerve typically presents with "<b>winged scapula</b>," which is not indicated in this case.
*Subscapular nerve*
- The <b>subscapular nerve</b> innervates the <b>subscapularis muscle</b> (upper and lower subscapular nerves), which is a key internal rotator of the shoulder.
- While it's a rotator cuff muscle, injury to the subscapularis would primarily manifest as difficulty with internal rotation, not typically identified by the "empty can" test.
*Accessory nerve*
- The <b>accessory nerve (cranial nerve XI)</b> innervates the <b>sternocleidomastoid</b> and <b>trapezius muscles</b>.
- Injury to this nerve would result in difficulty shrugging the shoulders or turning the head, not pain related to rotator cuff function.
Triangles of the neck US Medical PG Question 4: During a thyroidectomy, a surgeon must carefully identify and preserve the parathyroid glands. These glands are most commonly located posterior to which part of the thyroid gland?
- A. Superior poles
- B. Inferior poles (Correct Answer)
- C. Pyramidal lobe
- D. Middle third
Triangles of the neck Explanation: Detailed anatomical knowledge is crucial during thyroidectomy to ensure preservation of vital structures [1].
***Inferior poles***
- The **inferior parathyroid glands** (parathyroid IV) are most commonly located posterior to the **inferior poles** of the thyroid gland [1].
- While they are more variable in position than superior glands and can descend into the thymus or mediastinum, the **most common location** is still posterior to the inferior poles [1].
- During thyroidectomy, these glands are frequently encountered in the inferior pole region and must be carefully preserved [1].
*Superior poles*
- The **superior parathyroid glands** (parathyroid III) are typically found at the **middle-to-upper third** of the thyroid, near the cricothyroid junction, rather than directly at the superior poles.
- While their position is more constant than inferior glands, they are not specifically located at the superior poles themselves.
*Pyramidal lobe*
- The **pyramidal lobe** is an embryological remnant extending superiorly from the thyroid isthmus.
- It is not associated with parathyroid gland location, as parathyroids are distinct endocrine structures located on the posterior thyroid surface.
*Middle third*
- The **superior parathyroid glands** are often found near the middle third of the thyroid posteriorly.
- However, when considering all four parathyroid glands (both superior and inferior pairs), the **inferior glands** at the inferior poles represent the most common overall location pattern.
Triangles of the neck US Medical PG Question 5: A 40-year-old male presents to the physician's office complaining of an inability to push doors open. He has had this problem since he was playing football with his children and was tackled underneath his right arm on his lateral chest. On examination, he has a winged scapula on the right side. Which of the following nerves is most likely the cause of this presentation?
- A. Phrenic nerve
- B. Spinal accessory nerve
- C. Long thoracic nerve (Correct Answer)
- D. Greater auricular nerve
- E. Musculocutaneous nerve
Triangles of the neck Explanation: ***Long thoracic nerve***
- The **long thoracic nerve** innervates the **serratus anterior muscle**, which is responsible for scapular protraction and upward rotation.
- Damage to this nerve, often from trauma to the lateral chest wall (tackled underneath the arm), leads to paralysis of the serratus anterior and a characteristic **winged scapula** with lateral and inferior prominence.
- Patients have difficulty with **pushing movements** (protraction) and overhead activities.
*Phrenic nerve*
- The **phrenic nerve** primarily innervates the **diaphragm** and is crucial for respiration.
- Damage to the phrenic nerve would cause respiratory compromise, not a winged scapula or difficulty pushing doors.
*Spinal accessory nerve*
- The **spinal accessory nerve (cranial nerve XI)** innervates the **sternocleidomastoid** and **trapezius muscles**.
- Injury to this nerve can cause scapular winging due to **trapezius paralysis**, but the winging is typically **medial** with the inferior angle moving medially, unlike the lateral winging from serratus anterior paralysis.
- The mechanism of injury (lateral chest trauma during tackling) and inability to push are classic for **long thoracic nerve** injury, not spinal accessory nerve.
*Greater auricular nerve*
- The **greater auricular nerve** is a cutaneous nerve that provides sensation to the skin over the parotid gland, mastoid process, and auricle.
- Damage to this nerve would result in sensory loss in these areas and is unrelated to muscle weakness or a winged scapula.
*Musculocutaneous nerve*
- The **musculocutaneous nerve** innervates the **biceps brachii**, **brachialis**, and **coracobrachialis muscles**, responsible for elbow flexion and forearm supination.
- Damage to this nerve would primarily affect these movements and sensation in the lateral forearm, not leading to a winged scapula.
Triangles of the neck US Medical PG Question 6: A 47-year-old man presents to you with gradual loss of voice and difficulty swallowing for the past couple of months. The difficulty of swallowing is for both solid and liquid foods. His past medical history is insignificant except for occasional mild headaches. Physical exam also reveals loss of taste sensation on the posterior third of his tongue and palate, weakness in shrugging his shoulders, an absent gag reflex, and deviation of the uvula away from the midline. MRI scanning was suggested which revealed a meningioma that was compressing some cranial nerves leaving the skull. Which of the following openings in the skull transmit the affected cranial nerves?
- A. Jugular foramen (Correct Answer)
- B. Foramen rotundum
- C. Foramen spinosum
- D. Foramen ovale
- E. Foramen lacerum
Triangles of the neck Explanation: ***Jugular foramen***
- The symptoms described—loss of voice, difficulty swallowing, loss of taste on the posterior third of the tongue, absent gag reflex, and uvula deviation—point to impairment of **cranial nerves IX (glossopharyngeal), X (vagus), XI (accessory)**, which all exit the skull via the **jugular foramen**.
- The **vagus nerve** (CN X) is responsible for voice and swallowing (via innervation of the pharynx and larynx), the **glossopharyngeal nerve** (CN IX) for taste from the posterior third of the tongue and the gag reflex, and the **accessory nerve** (CN XI) for shoulder shrugging (trapezius and sternocleidomastoid muscles).
- Note: Loss of taste on the palate may involve CN VII (facial nerve) fibers, but the dominant clinical picture with absent gag reflex, uvula deviation, dysphagia, and dysphonia clearly indicates jugular foramen pathology.
*Foramen rotundum*
- The **foramen rotundum** transmits the **maxillary nerve (V2)**, a branch of the trigeminal nerve.
- Damage to V2 would primarily cause sensory deficits in the midface and upper teeth, which are not described in this patient.
*Foramen spinosum*
- The **foramen spinosum** transmits the **middle meningeal artery** and the **meningeal branch of the mandibular nerve (V3)**.
- Injury here would not explain the constellation of symptoms related to voice, swallowing, taste, or shoulder movement.
*Foramen ovale*
- The **foramen ovale** transmits the **mandibular nerve (V3)**, the **accessory meningeal artery**, and occasionally the superficial petrosal nerve.
- Damage to V3 would result in sensory loss to the lower face and motor deficits in the muscles of mastication, which are not reported.
*Foramen lacerum*
- The **foramen lacerum** is filled with cartilage in vivo and does not typically transmit major neurovascular structures directly through its aperture.
- The **internal carotid artery** passes superior to it, and some small nerves may traverse its vicinity, but not the specific cranial nerves indicated by the patient's symptoms.
Triangles of the neck US Medical PG Question 7: A 72-year-old woman is brought to the emergency department for right hip pain 1 hour after she fell while walking around in her house. She has been unable to stand or walk since the fall. She has hypertension and gout. Her sister died of multiple myeloma at the age of 55 years. Current medications include amlodipine and febuxostat. She does not smoke cigarettes. She drinks a glass of wine daily. Her temperature is 37.3°C (99.1°F), pulse is 101/min, and blood pressure is 128/86 mm Hg. Examination shows right groin tenderness. Range of motion of the right hip is limited by pain. The remainder of the examination shows no abnormalities. A complete blood count and serum creatinine concentration are within the reference range. An x-ray of the hip shows a linear fracture of the right femoral neck. She is scheduled for surgery. Which of the following is the most likely underlying cause of this patient's fracture?
- A. Defective osteoclast function
- B. Impaired bone mineralization
- C. Monoclonal antibody production
- D. Interrupted vascular supply
- E. Reduced osteoblastic activity (Correct Answer)
Triangles of the neck Explanation: ***Reduced osteoblastic activity***
- In a 72-year-old woman, a **femoral neck fracture** following a fall typically indicates underlying **osteoporosis**, which is characterized by reduced **osteoblastic activity** and overall bone density loss.
- As women age, particularly after menopause, **estrogen deficiency** leads to an imbalance in bone remodeling, with bone resorption outpacing bone formation, thus leading to weaker bones.
*Defective osteoclast function*
- **Defective osteoclast function** is primarily associated with conditions like **osteopetrosis**, where bones become dense and brittle due to impaired bone resorption, making them prone to fracture, which is not consistent with the typical presentation of a hip fracture in an elderly woman.
- This condition is rare and usually presents earlier in life, often with symptoms such as **anemia**, **hepatosplenomegaly**, and **cranial nerve compression**.
*Impaired bone mineralization*
- **Impaired bone mineralization** is characteristic of **osteomalacia** (in adults) or **rickets** (in children), usually due to **vitamin D deficiency** or phosphate imbalances.
- While it can lead to bone pain and increased fracture risk, osteoporosis due to aging is a much more common cause of hip fractures in this demographic, and there are no signs of osteomalacia such as **pseudofractures** or specific biochemical abnormalities like **hypophosphatemia** or **elevated alkaline phosphatase** without other causes.
*Monoclonal antibody production*
- **Monoclonal antibody production** is associated with **multiple myeloma**, a plasma cell malignancy that causes **lytic bone lesions** and diffuse osteopenia.
- While the patient's sister died of multiple myeloma, her normal complete blood count and creatinine, and the absence of specific myeloma-related symptoms (e.g., **hypercalcemia**, **renal failure**, **anemia**, or **CRAB criteria**) make this diagnosis less likely for her acute hip fracture.
*Interrupted vascular supply*
- **Interrupted vascular supply** can lead to **avascular necrosis (AVN)**, which weakens the bone and can cause collapse, eventually leading to a fracture.
- However, for an acute traumatic hip fracture, especially in the femoral neck, the primary underlying cause in an elderly person is generally **osteoporosis**, and AVN would typically present with chronic pain and characteristic imaging findings prior to an acute traumatic event.
Triangles of the neck US Medical PG Question 8: A 25-year-old man presents to the clinic with a midline swelling in his neck. He is unsure about when it appeared. He denies any difficulty with swallowing or hoarseness. His past medical history is insignificant. On physical examination, there is a 1 cm x 2 cm firm mildly tender nodule on the anterior midline aspect of the neck which moves with deglutition and elevates with protrusion of the tongue. Which of the following is the most likely embryologic origin of the nodule in this patient?
- A. Midline endoderm of the pharynx (Correct Answer)
- B. 1st and 2nd pharyngeal arch
- C. The branchial cleft
- D. 4th pharyngeal arch
- E. 4th pharyngeal pouch
Triangles of the neck Explanation: ***Midline endoderm of the pharynx***
- The symptoms described, particularly a midline neck swelling that **moves with deglutition** and **elevates with tongue protrusion**, are classic for a **thyroglossal duct cyst**.
- Thyroglossal duct cysts arise from remnants of the **thyroglossal duct**, an embryonic structure that forms from the **midline endoderm of the pharyngeal floor** and descends to form the thyroid gland.
*1st and 2nd pharyngeal arch*
- The 1st and 2nd pharyngeal arches primarily contribute to the formation of structures in the **mandible**, **maxilla**, **middle ear**, and **hyoid bone**.
- Abnormalities in these arches typically lead to conditions like **Treacher Collins syndrome** or **Pierre Robin sequence**, not midline neck cysts with these specific movement characteristics.
*The branchial cleft*
- **Branchial cleft cysts** typically present as **lateral neck masses**, often anterior to the sternocleidomastoid muscle, and usually do not move with deglutition or tongue protrusion.
- They arise from incomplete obliteration of **pharyngeal clefts**, which are ectodermal structures.
*4th pharyngeal arch*
- The 4th pharyngeal arch contributes to the formation of the **cricothyroid muscle**, part of the **pharynx**, and the **laryngeal cartilages**.
- Anomalies of the 4th pharyngeal arch are rare and typically involve **vascular structures** or **recurrent laryngeal nerve** abnormalities, not midline neck cysts.
*4th pharyngeal pouch*
- The 4th pharyngeal pouch contributes to the development of the **superior parathyroid glands** and the **ultimobranchial body** (which gives rise to parafollicular C cells of the thyroid).
- Malformations of this pouch are associated with parathyroid and thyroid conditions, not midline thyroglossal duct cysts.
Triangles of the neck US Medical PG Question 9: An 87-year-old male presents to his neurologist for a follow-up visit. He is being followed for an inoperable tumor near his skull. He reports that he recently noticed that food has started to lose its taste. He also notes increasing difficulty with swallowing. He has a history of myocardial infarction, diabetes mellitus, hyperlipidemia, hypertension, and presbycusis. He takes aspirin, metoprolol, metformin, glyburide, atorvastatin, lisinopril, and hydrochlorothiazide. On examination, the patient is a frail-appearing male sitting in a wheelchair. He is oriented to person, place, and time. Gag reflex is absent on the right side. A taste evaluation is performed which demonstrates a decreased ability to detect sour and bitter substances on the right posterior tongue. The nerve responsible for this patient’s loss of taste sensation also has which of the following functions?
- A. Somatic sensory innervation to the roof of the pharynx
- B. Parasympathetic innervation to the trachea
- C. Somatic sensory innervation to the lower lip
- D. Parasympathetic innervation to the parotid gland (Correct Answer)
- E. Parasympathetic innervation to the submandibular gland
Triangles of the neck Explanation: ***Parasympathetic innervation to the parotid gland***
- The patient's symptoms, including loss of taste on the **right posterior tongue**, difficulty swallowing, and an absent gag reflex, point to an issue with the **glossopharyngeal nerve (CN IX)**.
- The glossopharyngeal nerve provides **parasympathetic innervation to the parotid gland** via the otic ganglion, stimulating saliva production.
*Somatic sensory innervation to the roof of the pharynx*
- The glossopharyngeal nerve (CN IX) does provide somatic sensory innervation to the pharynx, but specifically the **posterior 1/3 of the tongue**, tonsils, and part of the pharynx, not primarily the roof.
- While related to the pharynx, this option is not the most precise or unique function associated with the primary nerve implicated here.
*Parasympathetic innervation to the trachea*
- **Parasympathetic innervation to the trachea** is primarily mediated by the **vagus nerve (CN X)**, which innervates the smooth muscle and glands of the trachea and bronchi.
- The glossopharyngeal nerve (CN IX) does not have a direct role in tracheal innervation.
*Somatic sensory innervation to the lower lip*
- **Somatic sensory innervation to the lower lip** is primarily provided by the **mental nerve**, a branch of the **trigeminal nerve (CN V)**.
- The glossopharyngeal nerve (CN IX) is not involved in sensory innervation of the lower lip.
*Parasympathetic innervation to the submandibular gland*
- **Parasympathetic innervation to the submandibular and sublingual glands** is provided by the **facial nerve (CN VII)** via the submandibular ganglion.
- This function is distinct from the glossopharyngeal nerve's role in innervating the parotid gland.
Triangles of the neck US Medical PG Question 10: Impaired gag reflex is seen due to a lesion in which cranial nerves?
- A. CN V&VI
- B. CN X & XI
- C. CN IX & X (Correct Answer)
- D. CN VII & VIII
- E. CN XI & XII
Triangles of the neck Explanation: ***Correct: CN IX & X***
The **gag reflex (pharyngeal reflex)** is a protective reflex involving two cranial nerves:
- **Afferent limb**: **CN IX (Glossopharyngeal nerve)** provides sensory innervation to the posterior third of the tongue, oropharynx, and pharyngeal walls
- **Efferent limb**: **CN X (Vagus nerve)** provides motor innervation to the pharyngeal muscles (via the pharyngeal plexus) that contract during the reflex
**Clinical correlation**: Testing the gag reflex helps assess brainstem function and the integrity of CN IX and X. Impairment suggests lesions affecting these nerves or their nuclei in the medulla.
*Incorrect: CN V & VI*
- CN V (Trigeminal) provides facial sensation and motor to muscles of mastication, not involved in gag reflex
- CN VI (Abducens) controls lateral rectus muscle for eye abduction
*Incorrect: CN X & XI*
- While CN X is involved, CN XI (Accessory nerve) innervates sternocleidomastoid and trapezius muscles, not pharyngeal muscles
*Incorrect: CN VII & VIII*
- CN VII (Facial) controls facial expression and taste from anterior 2/3 of tongue
- CN VIII (Vestibulocochlear) is involved in hearing and balance, not the gag reflex
*Incorrect: CN XI & XII*
- CN XI (Accessory) innervates SCM and trapezius
- CN XII (Hypoglossal) provides motor to intrinsic and extrinsic tongue muscles, not pharyngeal muscles involved in gag reflex
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