Head and Neck Anatomy 11-17, 19-22 Flashcards
The periodontal ligament anchors the teeth to the surrounding alveolar bone through attachment to which of the following structures?
A) Cementum
B) Dentin
C) Enamel
D) Gingiva
E) Neurovascular bundle
The correct response is Option A.
The dental root is covered by a mineralized layer called cementum. This is anchored to the surrounding alveolar bone by the periodontal ligament (periodontal membrane), which includes Sharpey fibers, to firmly anchor the tooth to the bone as well as sensory fibers. This facilitates the periodontal ligament’s functions of stabilizing the tooth, serving as a shock absorber, and allowing proprioception.
The bulk of the dental root is composed of dentin, but it does not directly attach to the surrounding bone.
The neurovascular bundles enter the tooth at the root apex and provide sensation and blood supply, but they are not a strong mechanical source of attachment.
The enamel is the mineralized cover of the dental crown. It is not attached to the free gingiva, which attaches to the periodontal ligament at the cementoenamel junction.
The gingiva does not directly attach to the bone.
During recipient vessel dissection in preparation for a head and neck free flap reconstruction, a nerve that runs deep and roughly parallel to the posterior belly of the digastric muscle is accidentally divided. This patient is most likely to have which of the following dysfunctions as a result?
A) Impaired shoulder elevation
B) Loss of depressor anguli oris movement
C) Paralysis of the hemidiaphragm
D) Tongue deviation
E) Vocal cord paralysis
The correct response is Option D.
The hypoglossal (XII) nerve emerges from the hypoglossal canal in the skull base and runs deep and roughly parallel to the posterior belly of the digastric in the upper neck, eventually innervating the intrinsic and extrinsic muscles of the tongue (except for the palatoglossus, which is innervated by the vagus [X] nerve). Division of the nerve results in ipsilateral tongue paralysis. The posterior belly of the digastric muscle is known as the “resident’s friend” because it acts as a useful anatomic landmark for several critical structures in the neck. It lies directly superficial to the branches of the external carotid artery, the internal carotid artery, jugular vein, and hypoglossal (XII) nerve.
The marginal mandibular nerve, a branch of the facial (VII) nerve, innervates the depressor anguli oris and depressor labii inferioris, which are the facial mimetic muscles responsible for frowning. It runs superficial to the posterior belly of the digastric muscle but deep to the platysma muscle. It is often injured in surgery of the neck region.
The vagus (X) nerve exits the cranium via the jugular foramen and courses from superior to inferior within the carotid sheath between the internal jugular vein and common carotid artery. It has diverse functions including supplying the larynx, pharynx, heart, esophagus, stomach, and small and large intestines. Transection of the vagus (X) nerve in the neck can result in vocal cord paralysis, among other dysfunctions.
The spinal accessory (XI) nerve innervates the sternocleidomastoid and trapezius muscles. Therefore, its division results in impaired shoulder mobility. Although it lies deep to the posterior belly of the digastric muscle, it courses inferiorly and posteriorly, crossing the internal jugular vein, rather than parallel to the muscle, to enter the posterior triangle of the neck. The phrenic nerve originates from cervical spinal nerves (C3-C5) and is found in the floor of the posterior triangle of the neck and is not found deep to the posterior belly of the digastric.
An 8-year-old boy is brought to the clinic for evaluation of a congenital ear deformity characterized by an unfolded antihelix. During the embryological period, which of the following structures failed to develop appropriately?
A) First pharyngeal cleft
B) First pharyngeal pouch
C) Second pharyngeal arch
D) Third pharyngeal arch
E) Third pharyngeal pouch
The correct response is Option C.
The ear development starts during the third month of gestation from six hillocks that arise on the first and second arches.
The first pharyngeal cleft develops into the external auditory meatus. The second through fourth pharyngeal clefts are usually obliterated due to the expansion of the second pharyngeal arch.
The first pharyngeal pouch develops into the auditory tube and middle ear cavity. The second through fourth pharyngeal pouches are not related to ear development, nor is the third pharyngeal arch. The second pouch becomes the palatine tonsils’ crypts, while the third pouch forms parathyroid glands and thymus. The fourth pouch differentiates into parathyroid glands and parafollicular cells of the thyroid gland. The cartilaginous component of the third pharyngeal arch gives rise to part of the hyoid bone.
A 65-year-old man presents with facial flushing and sweating with eating 4 weeks after undergoing parotidectomy. Which of the following tests will be most likely to establish the diagnosis?
A) Cottle maneuver
B) Ice pack test
C) Jones test
D) Minor iodine-starch test
E) Schirmer test
The correct response is Option D.
Auriculotemporal syndrome, or Frey syndrome, can occur after parotidectomy and less commonly after trauma, other facial surgeries (e.g., rhytidectomy), and neck dissection. It results from abnormal innervation (synkinesis) of sweat glands from the postganglionic parasympathetic fibers in the parotid. Symptoms include flushing, sweating, neuralgia, burning, and itching in response to gustatory stimulus. Diagnosis of Frey syndrome is based on clinical history, but the diagnosis can be confirmed with the Minor iodine-starch test: the ipsilateral face is painted with iodine and the patient is challenged with a sialogogue (e.g., lemon juice). Areas of gustatory sweating will turn blue.
The Jones test assesses patency of the lacrimal drainage system. The Cottle maneuver assesses the internal nasal valve. The ice pack test is used to assess myasthenic ptosis. The Schirmer test is a tear production test that can be used to assess dry eyes before blepharoplasty.
A 7-year-old boy sustains a deep laceration over the right side of the face. A photograph is shown. Injury to the parotid (Stensen) duct is suspected. At the anterior edge of the parotid gland, the duct should lie immediately superficial to which of the following structures?
A) Deep subcutaneous fat
B) Masseteric fascia
C) Submuscular aponeurotic system (SMAS)
D) Superficial parotid fascia
E) Temporoparietal fascia
The correct response is Option B.
The parotid gland is the largest of the three paired salivary glands (parotid, submandibular, and sublingual). It has two lobes, the deep and superficial, each of which is enveloped in a fascial sheath (parotid sheath) and between which passes the facial vein and nerve. The superficial lobe lies lateral (superficial) to the masseter muscle, and the deep lobe lies between the mastoid process and the mandibular ramus. The parotid, or Stensen, duct arises from the deep lobe of the parotid gland and receives contributions from the superficial lobe as it travels anteriorly. After exiting the anterior edge of the superficial lobe, the duct passes directly over the masseter muscle, crosses over the anterior edge of the masseter, extends medially and anteriorly over and through the buccinator muscle, and enters into the mouth via the parotid papilla, typically located opposite the second maxillary molar. The course of the duct has classically been described as following a line connecting the tragus and the midportion of the upper lip, but there is significant variation, and some studies report that this line should end in the lower half of the upper lip. The laceration shown in the photograph is just at the anterior border of the parotid and, at this level, the duct should be passing over the masseter muscle and its fascia. The course of the duct is below the superficial lobe of the parotid and, therefore, well below the subcutaneous tissue and the submuscular aponeurotic system (SMAS), which is confluent with the platysma inferiorly and the temporoparietal fascial superiorly. Superficial parotid fascia defines the layer of fascia that invests the superficial lobe of the parotid gland.
A 7-year-old girl presents with a tender and erythematous right pretragal abscess. Upon inquiring about the pit inferior to it, her parents report only recent drainage, despite presence since birth. They deny hearing deficits but report a family history of a similar defect. Facial cellulitis and excess granulation tissue are also noted on physical examination. Photographs are shown. Malformation of which of the following embryological structures most likely accounts for these findings?
A) Hillocks
B) Meatal plug
C) Otic capsule
D) Otic vesicle
E) Tubotympanic recess
The correct response is Option A.
Auricular hillocks are ectodermal derivatives of the first pharyngeal groove and are responsible for the formation of external ear structures (e.g., auricle and external auditory canal [EAC]). Incomplete fusion of the auricular hillocks (defective closure of the dorsal 1st pharyngeal groove) results in preauricular sinus. This is the only answer choice that contributes to the development of the external ear.
The meatal plug is an ectodermal derivative of the first pharyngeal groove (extends from the medial end of the EAC), which largely degenerates/canalizes, but is responsible for formation of the surface layer of the tympanic membrane. Persistence of the meatal plug results in conductive congenital deafness.
The otic vesicle is an ectodermal derivative of the developing brain that is responsible for formation of inner ear structures (e.g., saccule, utricle, semicircular and cochlear ducts, and membranous cochlea including the spiral organ of Corti). Abnormal development of the membranous labyrinth results in sensorineural congenital deafness.
The otic capsule is derived from mesenchyme of the first and second pharyngeal arches, surrounds/is induced by the otic vesicle, and is responsible for formation of inner ear structures (e.g., bony labyrinth). Abnormal development of the bony labyrinth results in sensorineural congenital deafness.
The tubotympanic recess is an endodermal derivative of the first pharyngeal pouch, responsible for the formation of middle ear structures (e.g., auditory tube, tympanic cavity, etc.). Abnormal/under-development of the middle ear structures increases the risk for chronic otitis media and can have an effect on conductive hearing.
A 4-year-old boy is seen following a pitbull bite to his face. The periorbital findings are shown in the photograph. A stent is placed and the ends of the stent are advanced across the canaliculus. The ends of the stent will enter the nasal cavity in which of the following locations?
A) Above the superior turbinate
B) Below the superior turbinate
C) Above the middle turbinate
D) Below the middle turbinate
E) Above the inferior turbinate
F) Below the inferior turbinate
The correct response is Option F.
Reconstruction of the lacrimal apparatus is a critical step in addressing this patient’s periorbital wounds. Failure to properly manage this aspect of the injury will lead to epiphora and the inevitable need for a secondary procedure to manage tear drainage. Delayed reconstruction of this injury would likely require a conjunctivodacryocystorhinostomy, a surgically created conduit between the eyelid and the nose. The best initial management of this lacrimal apparatus disruption is as described—placement of a stent through the canaliculi, into the lacrimal duct (contained within the maxillary bone), and into the nose. The exit point of the nasolacrimal duct is via the valve of Hasner, below the inferior turbinate. It is here that the ends of the stent can be identified and retrieved, although this is often quite challenging.
The frontal, maxillary, and anterior ethmoid sinus cells drain into the middle meatus, just below the middle turbinate. The sphenoid sinus and posterior ethmoid sinuses drain into the sphenoethmoid recess, between the nasal septum and the superior turbinate.
A 20-year-old man is brought to the emergency department after sustaining a stab wound to the neck during a violent assault. Physical examination shows an expanding neck hematoma and stridor. Intraoperative exploration shows a deep laceration to the anterior lateral neck at the level of thyroid cartilage and profuse extravasation of blood from the carotid sheath. According to anatomical zone-based classification of penetrating neck injuries, which of the following zones is involved?
A) Zone 1
B) Zone 2
C) Zone 3
D) Zone 4
The correct response is Option B.
“Penetrating neck injury represents 5-10% of all trauma cases. It is important for clinicians to be familiar with management principles, as mortality rates can be as high as 10%.”
Penetrating neck injury describes trauma to the neck that has breached the platysma muscle. The most common mechanism of injury worldwide is a stab wound from violent assault, followed by gunshot wounds, self harm, road traffic accidents, and other high velocity objects. The neck is a complex anatomical region containing important vascular, aerodigestive, and neurological structures that are relatively unprotected. Arterial injury occurs in approximately 25% of penetrating neck injuries; carotid artery involvement is seen in approximately 80% and vertebral artery in 43%.
Hard signs indicating immediate explorative surgery in penetrating neck injury:
Shock
Pulsatile bleeding or expanding hematoma
Audible bruit or palpable thrill
Airway compromise
Wound bubbling
Subcutaneous emphysema
Stridor
Hoarseness
Difficulty or pain when swallowing secretions
Neurological deficits
The assessment and management of penetrating trauma to the neck has traditionally centered on the anatomical zone-based classification first described by Monson et al. in 1969
Zone 1 extends from clavicles to cricoid, zone 2 from cricoid to angle of mandible, and zone 3 from angle of mandible to skull base.
There are only 3 zones in penetrating neck injuries.
A 2-year-old boy is evaluated because of a soft, nontender, noncompressible glabellar mass that has progressively grown since birth. A photograph is shown. Which of the following is the most appropriate next step in management before scheduling surgery?
A) Corticosteroid injections
B) MRI
C) Plain film x-ray study
D) Propranolol trial
E) Observation
The correct response is Option B.
The differential diagnosis for a lesion in this location with the findings described include dermoid cyst, hemangioma, and encephalocele. Osteoma, which is a benign bony tumor, is unlikely because of patient age and examination findings. The noncompressible quality of the lesion makes hemangioma and encephalocele less likely. Propranolol therapy after 12 months of age is unlikely to help, even if the lesion is a hemangioma. If the lesion is a hemangioma, then observation would be appropriate, but because the lesion is still growing, this diagnosis is questionable. Corticosteroid injections are only moderately helpful in treating a hemangioma, but they are contraindicated for dermoid cysts and encephalocele. Diagnosis is the next step with a goal of ruling out intracranial communication, as it will impact the surgical approach. MRI is the best option. Plain x-rays films would not provide adequate information for management.
A 12-year-old boy with a thyroglossal duct cyst undergoes a Sistrunk procedure. Which of the following structures are resected during this procedure?
A) Cyst and cyst tract only
B) Cyst, cyst tract, and middle third of the cricothyroid cartilage
C) Cyst, cyst tract, and middle third of the hyoid bone
D) Cyst, cyst tract, and middle third of the thyroid cartilage
E) Cyst, cyst tract, and the pyramidal lobe of the thyroid
The correct response is Option C.
The Sistrunk procedure is the operation of choice for thyroglossal duct cysts. This operation involves resection of the cyst, the cyst tract, and the middle third of the hyoid bone. In the Sistrunk procedure, the thyroid cartilage is not removed, nor is the cricothyroid cartilage. If, upon exploration, the distal tract is found to be in communication with the pyramidal lobe of the thyroid, then the communication should be excised. Despite this, resection of the pyramidal lobe of the thyroid is not a standard component of the Sistrunk procedure.
Which of the following cranial nerves develops within the first branchial arch?
A) Facial (VII)
B) Glossopharyngeal (IX)
C) Hypoglossal (XII)
D) Trigeminal (V)
E) Vagus (X)
The correct response is Option D.
The trigeminal nerve (cranial nerve V) develops from the first branchial arch and gives rise to the malleus and incus. The ligaments associated with the first branchial arch are the anterior ligament of the malleus and the sphenomandibular ligament. The muscles of the first branchial arch include the muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid), tensor veli palatini, tensor tympani, mylohyoid, and the anterior belly of the digastric. The first pouch is associated with the external auditory canal and middle ear space.
The facial nerve (cranial nerve VII) develops from the second branchial arch and gives rise to the stapes, styloid, and the upper body of the hyoid. It includes the stylohyoid ligament. The associated muscles are facial expression muscles, stapedius, stylohyoid, and the posterior belly of the digastric. The second pouch is associated with the tonsillar fossa.
The glossopharyngeal nerve (cranial nerve IX) develops from the the third branchial arch and gives rise to the lower body of the hyoid. Its muscle is the stylopharyngeus, and the pouch is associated with the inferior parathyroid gland and the thymus.
The fourth branchial arch is associated with the larynx. The muscles associated with this arch are the laryngeal, pharyngeal, and soft palate. The pouch is associated with the superior parathyroid gland and the thyroid gland.
A newborn female presents with a large intraoral mass arising from alveolar mucosa of the lower jaw that does not cause any airway obstruction. Photographs are shown. Which of the following is the most likely pathology of the lesion?
A) Congenital epulis
B) Hemangiopericytoma
C) Odontogenic keratocyst
D) Rhabdomyosarcoma
E) Teratoma
The correct response is Option A.
Congenital epulis is a rare, benign tumor of the oral cavity that is found in newborns. They are considered a form of granular cell tumor that can lead to mechanical obstruction, resulting in respiratory distress or difficulty eating. Surgical excision is the treatment of choice and recurrence after excision is rare. The female-to-male ratio is 10:1. It is observed three times more frequently on the maxilla than the mandible. They are solitary in most cases, but can be large and multiple.
Teratomas and rhabdomyosarcomas of the mandible are even more rare and are usually seen in the older patient population; they are not seen in the neonatal population.
Hemangiopericytomas are rare, vascular neoplasms that originate from vascular pericytes. They can occur anywhere in the body, including the mandible. They are slow-growing and present in the older patient population. The likelihood of presentation in a neonate is exceedingly low.
Odontogenic keratocysts are rare and benign, but locally aggressive lesions of the posterior mandible. They most commonly present in the third decade of life. They make up 19% of jaw cysts.
The inferior oblique muscle of the orbit is innervated by which of the following cranial nerves?
A) Oculomotor (III)
B) Trochlear (IV)
C) Trigeminal (V)
D) Abducens (VI)
E) Facial (VII)
The correct response is Option A.
The inferior oblique muscle receives its nerve supply from the oculomotor nerve, or cranial nerve III. The other voluntary muscles within the orbit that receive their innervation from the oculomotor nerve are the levator palpebrae superioris, superior rectus, medial rectus, and inferior medial rectus muscles. The superior oblique muscle is innervated by the trochlear nerve (cranial nerve IV). The lateral rectus muscle is innervated by the abducens nerve (cranial nerve VI).
The inferior oblique is the only one of these muscles that does not arise from the apex of the orbit. It originates from the medial floor of the orbit just posterior to the infraorbital rim. It runs laterally, posteriorly, and upward, crossing inferior to the inferior rectus, and inserting on the posterior half of the globe beneath the lateral rectus insertion. Its action is to elevate the globe, producing upward gaze of the pupil. Risk of iatrogenic injury to the inferior oblique is greatest with transconjunctival surgical approach to the orbit. Therefore, with this procedure, care must be exercised to place the periosteal incision along the anterior aspect of the infraorbital rim.
A patient undergoes extraction of a fully impacted mandibular third molar. During corticotomy of the mandible, protection of the adjacent soft tissue is necessary to avoid injury to which of the following nerves?
A) Facial
B) Hypoglossal
C) Inferior alveolar
D) Infraorbital
E) Lingual
The correct response is Option E.
Protection of the lingual border of the mandible during extraction of mandible wisdom teeth is critically necessary because of the close proximity of the lingual nerve to the lingual border of the mandible. This nerve can be inadvertently injured if not routinely protected during third molar extractions.
During embryological development, which of the following structures is derived from the same pharyngeal arch as the antihelix?
A) Mandible
B) Maxilla
C) Mylohyoid
D) Stapes
E) Tensor veli palatini
The correct response is Option D.
The pharyngeal arches are created during embryological development by the migration of the neural crest cells and the surrounding pharyngeal endoderm and mesoderm. The first four pharyngeal arches are the most prominent and have unique nervous, arterial, muscular, and bony components. The muscular components of the first pharyngeal arch are innervated by the trigeminal nerve (cranial nerve V) and include the muscles of mastication, as well as the anterior digastric, mylohyoid, tensor tympani, and tensor veli palatini. The maxillary artery supplies blood to the components of the first pharyngeal arch. The greater wing of the sphenoid, as well as the incus, the malleus, maxilla, zygomatic, mandible, and temporal bones comprise the bony components of the first pharyngeal arch. The second pharyngeal arch is innervated by the facial nerve (cranial nerve VII) and receives blood supply from the stapedial artery. The bony components of the second pharyngeal arch include the stapes, styloid process, stylohyoid ligament, lesser horn, and upper body of the hyoid. The muscular components of the second pharyngeal arch include the muscles of facial expression, as well as the posterior digastric, stylohyoid, and stapedius.
During embryological development of the external ear, the antihelix, antitragus, and lobule are derived from the three posterior hillocks of the second pharyngeal arch, while the tragus, the root of the helix, and the superior helix are derived from the three anterior hillocks of the first pharyngeal arch.
A 12-month-old boy presents for evaluation of a soft, fixed lateral brow mass that has been enlarging since it was first noted at 2 months of age. A photograph is shown. The parents report that the mass does not change in size during crying or activity, nor did it change in size during recurrent pink eye infections. Which of the following is the most likely diagnosis?
A) Branchial cleft cyst
B) Dermoid cyst
C) Hemangioma
D) Lacrimal gland
E) Lymphatic malformation
The correct response is Option B.
Dermoid cyst is the correct answer and the most common cause of a lateral brow mass in an infant. If it were a hemangioma, its size would change during crying or any activity that increases blood flow. Lacrimal gland ptosis is unlikely in a child but can be seen in the adult population, and can be ruled out if the mass is above the orbital rim, as seen in the photograph. The mass is not in the distribution of any of the different types of branchial cleft cysts. Lymphatic malformations typically change in size during infections.
A 24-month-old infant is evaluated because of a mass on the lower lip that her parents first noticed 1 month ago. Physical examination shows a mucosal lesion of the right lower lip that is round, clear, translucent, soft, and measures approximately 0.5 cm in diameter. Which of the following is the most appropriate next step in management?
A) CT scan of the face without contrast
B) Excisional biopsy
C) Fine-needle aspiration
D) MRI of the face with contrast
E) Ultrasonography of the lesion
The correct response is Option B.
The lesion described is a mucocele, which is a type of cyst likely caused by minor salivary gland mucin seepage. They are most frequently on the lower lip mucosa away from the midline, but they can present anywhere there is oral mucosa. A minority of these resolve on their own, therefore, the majority of the time an excisional biopsy is recommended.
Imaging is not indicated for this type of lesion. Fine-needle aspiration is not indicated.
A 23-year-old African-American man presents with a raised thickened scar on his anterior chest that he complains is pruritic and unattractive. It was removed by another provider 4 years earlier and has slowly recurred over the past year. On examination, the lesion extends beyond the initial borders of the scar and is firm and hyper-pigmented. On review of his prior pathology report, which of the following histologic characteristics is most likely?
A) Greater ratio of type III to type I collagen
B) Multitude of myofibroblasts and smooth muscle actin
C) Parallel collagen bundles
D) Thick, wavy, and randomly oriented collagen fibers
The correct response is Option D.
In patients with abnormal or excessive scar tissue formation, treatment and prognosis will be driven by the correct diagnosis of a keloid versus a hypertrophic scar. This patient presents with a recurrent keloid of the chest. His clinical history supports this diagnosis by recurrence after resection, growth extending beyond the original border of the lesion, late recurrence after several years, and continued growth over several years without regression or improvement. Hypertrophic scars are less likely to recur, contained within the original boundaries of the lesion, often regress somewhat within a year, and recur earlier in the postoperative period if they are to recur. Both hypertrophic scars and keloid scars can be pruritic.
Pathologic analysis of keloids reveals more type I collagen than type III collagen, similar to normal skin. Hypertrophic scars will exhibit increased type III collagen and pro-fibrotic collagen cross-linking. Keloid growth is thought to be impacted by cell-signaling between keratinocytes and fibroblasts, but hypertrophic scar production requires an abundance of myofibroblasts expressing smooth muscle actin. While hypertrophic scars have parallel collagen fibrils and bundles, keloids are characterized histologically by thick, randomly oriented collagen fibrils that are not organized into bundles.
Which of the following structures contributes to the formation of the mandibular body and ramus?
A) First branchial arch
B) First branchial cleft
C) Second branchial arch
D) Second branchial cleft
The correct response is Option A.
The first branchial arch contributes to the formation of the mandible, the tragus, and the anterior helix.
The first branchial cleft gives rise to the external auditory canal. The second branchial arch contributes to the formation of the majority of the external ear–the antitragus, remainder of the helix, antihelix, and crura all arise from the second branchial arch. The second branchial cleft is typically obliterated during development, but may persist in the form of a second branchial cleft cyst.
Which of the following cranial nerves develops with the first branchial arch?
A) Facial (VII)
B) Glossopharyngeal (IX)
C) Hypoglossal (XII)
D) Trigeminal (V)
E) Vagus (X)
The correct response is Option D.
The first branchial arch is associated with the trigeminal nerve (V), second branchial arch with the facial nerve (VII), third branchial arch with the glossopharyngeal (IX), fourth branchial arch with the superior laryngeal (X), and sixth branchial arch with the recurrent laryngeal (X).
The stylopharyngeus muscle is innervated by which of the following nerves?
A) Facial (VII)
B) Glossopharyngeal (IX)
C) Hypoglossal (XII)
D) Trigeminal (V)
E) Vagus (X)
The correct response is Option B.
The pharyngeal muscles are all innervated by the vagus (X) nerve, except the stylopharyngeus muscle, which is innervated by the glossopharyngeal nerve (IX).
The trigeminal nerve (V) is responsible for facial and oral sensation. The maxillary branch (V2) is responsible for sensation of the upper teeth, upper lip, hard palate, cheeks, and nasopharyngeal mucosa. The mandibular branch (V2) provides sensory fibers for the lower teeth, lower mucosa of the mouth and the anterior two-thirds of the tongue. The facial nerve (VII) provides motor innervation of the muscles of facial expression and the posterior bellies of the stylohyoid and digastric muscles. The vagus nerve (X) provides motor innervation to all of the pharyngeal muscles except the stylopharyngeus muscle. The hypoglossal nerve (XII) provides motor innervation to the intrinsic and extrinsic tongue muscles and also provides motor innervation to the geniohyoid muscle through the ansa cervicalis.
Which of the following structures is formed from the same branchial arch as the vagus (X) nerve?
A) Inferior parathyroid glands
B) Lesser horn of hyoid
C) Levator veli palatini
D) Maxillary artery
E) Styloid process
The correct response is Option C.
Each of the six branchial arches gives rise to a branch of the aortic arch, a cranial nerve, muscular structures, and skeletal structures. The fourth branchial arch gives rise to the right proximal subclavian artery, the aortic arch, the vagus (X) nerve, the superior laryngeal nerve, the intrinsic muscles of the levator veli palatini, cricothyroid muscles, laryngeal cartilages, and the superior parathyroid glands.
The styloid process is derived from the second branchial arch, along with the stapedial and hyoid arteries, the facial (VII) nerve, the muscles of facial expression, the stapes, the lesser horn of the hyoid bone, and the crypts of the palatine tonsils.
The maxillary artery is derived from the first branchial arch, along with the trigeminal (V) nerve, the muscles of mastication, anterior belly of the digastric muscle, tensor tympani, tensor veli palatini, mylohyoid, mandible, incus and malleus, maxilla, vomer, zygoma, and temporal bone.
The inferior parathyroid glands are derived from the third branchial arch, along with the common carotid artery, internal carotid artery, glossopharyngeal (IX) nerve, stylopharyngeus muscle, greater horn of the hyoid bone, and thymus.
The lesser horn of the hyoid bone is derived from the second branchial arch.
A 9-year-old boy is brought to the office for evaluation of a nodule on the neck that appeared 1 week ago. The nodule measures 2 cm and is slightly to the right of midline. A photograph is shown. The lesion is slightly tender. Which of the following is the most appropriate management of this lesion?
A) Excision of lesion with any tract and a section of hyoid bone
B) Excision of lesion with any tract and a section of thyroid cartilage
C) Excision of lesion with any tract only
D) Fine-needle aspiration with cytology
E) Intralesional sclerotherapy under image guidance
The correct response is Option A.
Thyroglossal duct cysts are neck lesions that usually present during childhood, often after a localized inflammation or infection. They are usually neck lesions near the midline. Some may move with swallowing if they are close to the base of the tongue, but not all exhibit this finding. The congenital thyroglossal duct is the remnant of the descent of the developing thyroid gland, and it runs from the foramen cecum of the base of the tongue, down to the thyroid. Imaging is typically by ultrasound, but other modalities, including radioisotope scans to rule out ectopic thyroid tissue or confirm the location of the normal thyroid gland, have been suggested to avoid excising ectopic thyroid gland.
The Sistrunk procedure shows less recurrence and is a complete excision, including any associated tract, and about a 1-cm section of hyoid bone. Although proposed in 1928, this is still the most commonly recommended approach for thyroglossal duct cysts.
Fine-needle aspiration is appropriate for thyroid nodules, which are unlikely to present in an acute manner in this population.
Sclerotherapy is used for vascular anomalies and likely would have presented earlier on in childhood.
A newborn has a pretragal cystic mass with a sinus tract visible in the external auditory meatus. Which of the following is the most likely diagnosis?
A) Dermoid cyst
B) First branchial cleft cyst
C) Second branchial cleft cyst
D) Third branchial cleft cyst
E) Vascular cystic lesion
The correct response is Option B.
The first branchial cleft develops into the external auditory canal. The second, third, and fourth branchial clefts merge to form the sinus of His, which will normally become involuted. When a branchial cleft is not properly involuted, a branchial cleft cyst forms. Occasionally, both the branchial pouch and branchial cleft fail to become involuted, and a complete fistula forms between the pharynx and skin.
First branchial cleft cysts are divided into type I and type II. Type I cysts are located near the external auditory canal. Most commonly, they are inferior and posterior to the tragus (base of the ear), but they may also be in the parotid gland. Type II cysts appear at the angle of the mandible and may involve the submandibular gland.
The second branchial cleft accounts for 95% of branchial anomalies, and they are most frequently identified along the anterior border of the upper third of the sternocleidomastoid muscle and adjacent to the muscle. However, these cysts may present anywhere along the course of a second branchial fistula, which proceeds from the skin of the lateral neck, between the internal and external carotid arteries, and into the palatine tonsil. Therefore, a second branchial cleft cyst is part of the differential diagnosis of a parapharyngeal mass.
Third branchial cleft cysts are rare. A third branchial fistula extends from the same skin location as a second branchial fistula (recall that the clefts merge during development); however, a third branchial fistula courses posterior to the carotid arteries and pierces the thyrohyoid membrane to enter the larynx, terminating on the lateral aspect of the pyriform sinus. Third branchial cleft cysts occur anywhere along that course (eg, inside the larynx), but they are characteristically located deep to the sternocleidomastoid muscle.
Congenital dermoid cysts of the face typically occur at the lateral orbit overlying the ZF suture, and vascular cyst lesions can be located anywhere on the face but do not present with sinus tracts into the EAC.
Which of the following structures contributes to the formation of the tragus?
A) First branchial arch
B) First branchial cleft
C) Second branchial arch
D) Second branchial cleft
The correct response is Option A.
The first branchial arch contributes to the formation of the tragus and anterior helix.
The first branchial cleft is incorrect. It gives rise to the external auditory canal.
The second branchial arch is incorrect. It contributes to the formation of the majority of the external ear – the antitragus, remainder of the helix, antihelix, and crura all arise from the second branchial arch.
The second branchial cleft is incorrect. It is typically obliterated during development, but may persist in the form of a second branchial cleft cyst.
The muscles of facial expression, the posterior belly of the digastric muscle, and the stapedius muscle are derived from which of the following pharyngeal arches?
A) First
B) Second
C) Third
D) Fourth
E) Sixth
The correct response is Option B.
The pharyngeal, or branchial, arches are developmental structures derived from all three germ layers and also contain neural crest cells. These arches give rise to bony, cartilaginous, vascular, muscular, and neural structures of the head and neck.
The second pharyngeal arch gives rise to the muscles of facial expression, posterior belly of the digastric muscle, and the stapedius muscle. These muscles are innervated by the facial nerve (VII), which also arises from this arch.
The first pharyngeal arch gives rise to the muscles of mastication, anterior belly of the digastric, mylohyoid, tensor tympani, and tensor veli palatini muscles as well as the trigeminal nerve (V). The third pharyngeal arch gives rise to the stylopharyngeus muscle as well as the glossopharyngeal nerve (IX). The fourth pharyngeal arch gives rise to the cricothyroid muscle and all intrinsic muscles of the soft palate except the tensor veli palatini, as well as the superior laryngeal nerve (X). The sixth pharyngeal arch gives rise to the intrinsic muscles of the larynx except the cricothyroid muscle as well as the recurrent laryngeal nerve (X). The fifth pharyngeal arch does not give rise to structures in humans.
Which of the following structures (A-E) is responsible for anchoring the tooth in its socket?
The correct response is Option D.
The periodontal ligament is responsible for keeping the tooth anchored. Enamel is the outer protective layer of the tooth. Dentine, enamel, cementum, and pulp are the four major components of the tooth but none are responsible for anchoring the tooth.
