Head and Neck Anatomy Flashcards Preview

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Flashcards in Head and Neck Anatomy Deck (32):
1

Which of the following is the most common origin of the superior thyroid artery?

A) Bifurcation of the carotid artery
B) Common carotid artery
C) External carotid artery
D) Internal carotid artery

The correct response is Option C.

The origin of the superior thyroid artery is predictable and most commonly it arises from the external carotid artery. It has, however, been described to arise from all three of the other options, just less frequently.

 

2

A 6-year-old girl with cerebral palsy is evaluated for sialorrhea. Medical treatment has been unsuccessful. Surgical intervention for drooling control is planned. Which of the following glands contributes the most to basal salivary production?

A) Lacrimal
B) Minor salivary
C) Parotid
D) Sublingual
E) Submandibular

The correct response is Option E.

Daily saliva production is on the scale of 500 to 2000 mL per day. Excessive drooling in patients with cerebral palsy or other severe neurologic impairment is caused by inefficient swallowing. The submandibular glands contribute the most to basal salivary production, approximately 60%. The parotid gland contributes approximately 20% to basal salivary production. Sublingual glands and minor salivary glands each contribute 10%. The lacrimal gland is responsible for production of the aqueous layer of the tear film.

 

3

Which of the following tooth types is most commonly the last one to erupt when the primary teeth are replaced by permanent teeth?

A) Maxillary canine
B) Maxillary central incisor
C) Maxillary first molar
D) Maxillary first premolar
E) Maxillary lateral incisor

The correct response is Option A.

Aside from the third molars, the maxillary canines are typically the last teeth to erupt of the available options (around 11 to 12 years of age). It is important to give the tooth a large area of viable bone to traverse and become supported by, and alveolar bone grafting is typically performed well in advance of the eruption of the maxillary canine in order to preserve the native tooth.

The maxillary central incisor is often the second permanent tooth a child will erupt, typically at age 7 to 8 years.

The maxillary lateral incisor is often the third permanent tooth a child will erupt, typically at age 8 to 9 years.

The maxillary first premolar is often the fourth permanent tooth a child will erupt, typically at age 10 to 12 years.

The maxillary first molar is often the first permanent tooth a child will erupt, typically at age 6 to 7 years.

 

4

Which of the following surgeries addresses the most common anatomic site of obstruction in patients with obstructive sleep apnea?

A) Bilateral sagittal split osteotomy
B) Geniohyoid advancement
C) Septoplasty
D) Tracheostomy
E) Uvulopalatopharyngoplasty

The correct response is Option E.

The answer is uvulopalatopharyngoplasty (UP3). The mainstay of UP3 surgery is to remove the uvula and lateral oropharyngeal tissues. The most common site of obstruction in obstructive sleep apnea (OSA) patients is the retropalatal area, including the lateral pharyngeal walls. This latter anatomic area is even more important if the patient has never had a tonsillectomy; in this case, the tonsils are removed in continuity with UP3. UP3 generally decreases the various indexes documented during a sleep study, such as the apnea-hypopnea index, by about 50%. Thus, those at the border of severe and moderate sleep apnea can see their reported indexes go to a level that can be managed by lifestyle changes without the need for a continuous positive airway pressure (CPAP) machine. On the other hand, in patients with very high indexes, these procedures merely make the disease less severe and may allow for a lower setting on the CPAP machine. Although the CPAP machine which applies positive pressure transnasally to patients can “cure” OSA, their compliance rates are low.

There are other procedures that can help with OSA, such as a septoplasty or those that deal with the tongue base (e.g., geniohyoid advancement), but neither directly treats the most common site of obstruction. A tracheostomy is a curative treatment for OSA, but it completely bypasses all of the obstructive points without addressing them. A tracheostomy has much morbidity, including a measurable mortality rate, and is reserved for life-threatening cases of OSA. A sagittal split operation of the mandible is used for occlusion, not OSA.

 

5

A 50-year-old man who underwent superficial parotidectomy for a benign tumor 9 months ago comes to the office because of a 6-month history of gustatory sweating. Which of the following nerves carries the parasympathetic postganglionic nerve fibers to the parotid gland in a healthy patient?

A) Auriculotemporal
B) External carotid plexus
C) Facial (VII)
D) Great auricular
E) Marginal mandibular

The correct response is Option A.

 

6

A 17-year-old boy is brought to the emergency department because of profuse bleeding from a stab wound to the neck above the angle of the mandible anterior to the sternocleidomastoid muscle. After airway stabilization is established, vascular repair of a laceration of the jugular vein is performed. Where is this injury located?

A) Posterior triangle
B) Zone I
C) Zone II
D) Zone III

The correct response is Option D.

Effective treatment of penetrating neck injuries depends on a thorough understanding of neck anatomy. The neck houses vital structures from six organ systems: The vascular system includes the innominate, subclavian, axillary, carotid, jugular, and vertebral vessels. The respiratory system includes the larynx, trachea, and the lung. The digestive system includes the pharynx and esophagus. The neurologic system includes the spinal cord, brachial plexus, cranial nerves, and the sympathetic chain. The endocrine system includes the thyroid and parathyroid. The skeletal system includes the cervical spine.

Anatomy of the neck may be considered using two anatomical paradigms: the concept of “triangles” and the concept of “zones.” The triangles are divided into anterior and posterior, while the zones are divided in a cranial/caudal orientation anterior to the sternocleidomastoid muscle. An understanding of both is important when considering penetrating injuries.

The neck may be divided into two triangles, anterior and posterior to the sternocleidomastoid muscle. The anterior triangle is bordered anteriorly by the midline, posteriorly by the sternocleidomastoid muscle, and superiorly by the lower edge of the mandible. Most vital structures are located in the anterior triangle. The posterior triangle is located within the boundaries of the sternocleidomastoid muscle anteriorly, inferiorly by the clavicle, and the anterior border of the trapezius muscle posteriorly. Trauma to the posterior triangle, excluding the spine, carries a much lower likelihood of significant injury.

Zone I is in the inferior neck and includes the base of the neck and thoracic inlet. It extends from the sternal notch and clavicles to the cricoid cartilage. Zone I contains the thoracic outlet vasculature, vertebral and proximal carotid arteries, apices of the lungs, trachea, esophagus, spinal cord, and thoracic duct.

Zone II is in the mid-neck and continues cephalad from the cricoid cartilage to the angle of the mandible, and contains the jugular veins, vertebral and common carotid arteries, and internal and external branches of the carotid arteries. It also includes nonvascular structures including the trachea, esophagus, larynx, and spinal cord.

Zone III (upper neck) includes the region above the angle of the mandible up to the base of the skull and contains the pharynx along with the jugular veins, vertebral arteries, and the distal portion of the internal carotid arteries. Its caudal border is distal to the common carotid arteries.

Portions of the jugular vein are located in all three zones. Only Zone III is located above the angle of the mandible.

 

7

A 60-year-old man undergoes microvascular anastomosis. The proximal facial artery off the external carotid artery is to be dissected and used as a recipient vessel. During the procedure, a large, overlying, nerve-like structure is inadvertently transected. Which of the following is the most likely consequence?

A) Dysarthria
B) Lip elevation
C) Shoulder drop
D) Tongue numbness
E) Vocal cord paralysis

The correct response is Option A.

The facial artery generally starts as part of the lingual-facial trunk, then travels below the hypoglossal nerve before it enters into the submandibular gland and along the lateral border of the mandible. Failure to recognize this structure could cause injury and subsequent loss of motor function of the ipsilateral tongue. Ipsilateral hypoglossal (XII) nerve injury causes the tongue to move toward the side of damage, resulting in dysarthria, and problems moving solid food to the oropharynx.

Vocal cord paralysis is related to a recurrent laryngeal or vagus (X) nerve injury, which could happen after superior laryngeal artery or common carotid dissection, respectively.

Shoulder drop is related to accessory (XI) nerve injury, which has anatomic relation to the occipital artery.

Tongue numbness is from an injury to the lingual nerve (related mostly to the laryngeal artery and submandibular duct).

Lip elevation is related to a marginal mandibular (V3) nerve injury—this nerve runs with the facial artery lateral to the mandible, but not below the margin of the mandible.

 

8

An 11-month-old male infant is noted by his parents to have a painless, progressive, right maxillary growth. At an outside facility, an incisional biopsy is performed. The pathology shows sinonasal myxoma. Postoperative MRI shows residual tumor with surrounding inflammation. Which of the following is the most appropriate treatment plan?

A) Chemotherapy and radiation therapy
B) Chemotherapy only
C) Curettage debulking of the tumor
D) Surgical resection with clear margin
E) Observation

The correct response is Option D.

Myxomas are slow-growing benign tumors. When they present in the infant face, they are most common in the maxilla or mandible. They present as a painless, progressive facial swelling and should be surgically removed with a clear margin. These tumors should have a clear margin to prevent incomplete resection and continued growth. They are not always well circumscribed, so a normal margin or tissue plane should be resected with the tumor.

 

9

A 20-year-old woman with a history of bruxism is evaluated because of a 3-year history of gradual widening of the lower third of the face. Physical examination shows rectangular appearance of the face; occlusion shows no abnormalities. Anteroposterior x-ray study discloses bone spurs at both angles of the mandible. Which of the following is the most appropriate next step in management?

A) Excision of the submandibular gland
B) Injection of botulinum toxin type A to the masseter muscle
C) Marginal mandibulectomy
D) Suction-assisted lipectomy of the cheek
E) Superficial parotidectomy

The correct response is Option B.

The patient described has bilateral masseter hypertrophy. Treatment options for this condition include muscle relaxants, injection of botulinum toxin type A, or resection of the internal layer of the masseter muscle.

Superficial parotidectomy is indicated for benign and malignant tumors of the parotid gland.

Resection of the submandibular gland is indicated for recurrent sialadenitis (infection) or obstructive sialodocholithiasis (salivary stones), as well as for benign tumors such as pleomorphic adenomas.

Marginal mandibulectomy may be indicated for certain benign and malignant tumors of the intraoral cavity.

Suction-assisted lipectomy will not treat masseter hypertrophy.

 

10

A 22-year-old man is brought to the emergency department after sustaining a stab wound to the face. The patient is hemodynamically stable, and physical examination shows a laceration that extends from the tragus of the right ear to the right oral commissure. Which of the following is the most likely primary complication of saliva extravasating into the wound because of parotid duct injury?

A) Parotid gland atrophy
B) Salivary fistula
C) Sialocele
D) Wound infection
E) Xerostomia

The correct response is Option C.

If parotid duct injury is not repaired immediately, saliva can leak into the surrounding soft tissues. This leakage most commonly increases the risk for sialocele (pseudocapsule), followed by salivary fistula formation. Wound infection, parotid gland atrophy, and xerostomia (dry mouth) are uncommon. Studies have shown that correction of the more common complications may require surgical or medical treatments such as use of anti-sialogogues, radiation therapy, parasympathetic denervation (tympanic denervation), cauterization of the fistulous tract, reconstruction of the duct, or superficial or total parotidectomy.

 

11

An otherwise healthy term 6-month-old male infant is evaluated for a mobile, firm, well-circumscribed mass at the right lateral brow in the area of the zygomaticofrontal suture. Which of the following procedures is the most appropriate next step in management?

A) CT scan
B) Fine-needle aspiration of the mass
C) MRI
D) Surgical excision of the mass
E) Ultrasonography

The correct response is Option D.

Dermoid cysts are common in the lateral brow. They present as firm, well-circumscribed, slow-growing masses that have the potential for infection or continued growth. Surgical excision is recommended and no imaging is required. CT scan or MRI require sedation and are unnecessary risks for this patient with a lateral dermoid. Midline masses do require imaging because of the risk for intracranial excision.

12

A 24-year-old man with a history of left facial trauma and condylar fracture of the mandible is evaluated because of redness and perspiration of the left cheek and ear after ingesting certain foods. Aberrant regeneration of which of the following nerves is the most likely cause of this patient’s symptoms?

A) Auriculotemporal
B) Facial
C) Great auricular
D) Inferior alveolar
E) Lingual

The correct response is Option A.

Although it is most commonly seen after parotidectomy, Frey syndrome has also been encountered after condylar fracture of the mandible and treatment. The syndrome is thought to result from damage to auriculotemporal parasympathetic nerve fibers with subsequent aberrant regeneration and innervation of sympathetic fibers to the sweat glands.

The facial, inferior alveolar, greater auricular, and lingual nerves are not thought to be the underlying cause of Frey syndrome.

 

13

A 12-hour-old male newborn has cyanosis that improves with crying. Which of the following is the most likely diagnosis?

A) Choanal atresia
B) Laryngomalacia
C) Macroglossia
D) Micrognathia
E) Subglottic stenosis

The correct response is Option A.

Choanal atresia is a unilateral or bilateral anatomic abnormality of the posterior nasal passages and choanae, which prevents nasal gas exchange in newborns. The classic presentation of bilateral choanal atresia is cyanosis that improves with crying. Nasal airway obstruction can also become apparent when attempting to breast-feed the baby. On clinical examination, there would be no fogging of a mirror when held under the nares. The remaining abnormalities are other causes of respiratory obstruction in the pediatric patient.

14

A 54-year-old man comes to the office because of swelling of the left side of the face 3 days after cholecystectomy. Physical examination shows erythema and purulent drainage from the parotid duct. Which of the following is the most appropriate initial management?

A) Antibiotic therapy and sialogogues
B) Aspiration of the mass
C) Incision and drainage of the mass
D) Oral cultures and oral cavity antibiotic irrigation
E) Superficial parotidectomy

The correct response is Option A.

Initial treatment of acute suppurative sialadenitis begins with aggressive medical management. This includes prompt fluid and electrolyte replacement, oral hygiene, reversal of salivary stasis, and antimicrobial therapy. Stimulation of salivary flow is done by use of sialogogues such as lemon drops. Warm soaks and massage promote secretion and drainage of the gland.

Oral cultures are typically contaminated by oral flora and therefore do not direct antibiotic treatment. Needle aspiration is more accurate in isolating the cause of suppurative parotitis.

Incision and drainage is reserved for cases resistant to medical management. Surgical removal of the gland is not recommended in the case of an actively infected gland.

 

15

Which of the following cranial nerves provides parasympathetic innervention of the parotid gland?

A) V
B) VII
C) VIII
D) IX
E) X

The correct response is Option D.

Innervation of the parotid gland comes from parasympathetic fibers that travel with the glossopharyngeal nerve (cranial nerve IX). It also receives taste sensation (afferent) from the posterior one-third of the tongue.

The maxillary nerve of cranial nerve V (V2) is a sensory nerve and receives sensation from the mid face.

Parasympathetic fibers (efferent) innervate the submandibular and sublingual glands via the chorda tympani. Afferent fibers, via the chorda tympani, send taste sensation of the anterior two-thirds of the tongue.

The vestibulocochlear nerve (cranial nerve VIII) supplies sound and equilibrium to the brain.

The auricular branch of the vagus nerve (cranial nerve X), innervates the external acoustic meatus. Stimulation of the vagus nerve can lead to reflex coughing (Arnold reflex).

 

16

Which of the following muscles is associated with the hyoid or second branchial arch?

A) Lateral pterygoid
B) Levator veli palatini
C) Posterior digastric
D) Stylopharyngeus
E) Thyroarytenoid

The correct response is Option C.

The first branchial arch, also known as the mandibular arch, has the trigeminal nerve (ophthalmic, maxillary, and mandibular branches) as its neurologic component. The muscles of mastication (i.e., temporalis, masseter, medial, and lateral pterygoids); mylohyoid; anterior digastric; tensor tympanic; and the tensor veli palatini are the muscle components. The cartilaginous bar gives rise to the premaxilla; maxilla, zygomatic bone; part of the temporal bone; incus; malleus; anterior malleolar ligament; and the sphenomandibular ligament. The pharyngeal pouch and groove develop the tubotympanic recess (tympanic cavity, mastoid antrum and pharyngotympanic tube, internal acoustic meatus, tympanic membrane, adenoids). The vascular element largely disappears, but gives rise to the maxillary and external carotid arteries.

The second branchial arch, also known as the hyoid arch, accounts for 95% of all branchial arch anomalies. The cranial nerve is the facial nerve. It supplies the muscles of facial expression; buccinators; stapedius; stylohyoid; posterior digastric; auricular and platysma muscles. The skeletal contributions from Reichert’s cartilage include the stapes, styloid process, stylohyoid ligament, and hyoid (lesser cornu and upper part of body). The pharyngeal pouch and groove shape the crypts of the palatine tonsil and the cervical sinus. The vascular component again primarily disappears but forms the stapedial and hyoid arteries.

Third branchial cleft anomalies are rare. The glossopharyngeal nerve sends motor innervation to only the stylopharyngeus. The cartilaginous bar forms the hyoid (greater cornu and lower part of body). The pharyngeal pouch and groove give rise to the inferior parathyroids, thymus, and cervical sinus. The vascular elements contribute to the internal carotid and common carotid.

The fourth branchial arch is supplied by the vagus nerve (superior laryngeal, inferior laryngeal). Musculature innervated includes the cricothyroid and all intrinsic muscles of the soft palate, including the levator veli palatini. The thyroid and epiglottic cartilage develop from the cartilaginous bar. The pharyngeal pouch and groove form the superior parathyroids, and the thyroid parafollicular cells. The right fourth aortic arch forms the subclavian artery, while the left fourth aortic arch forms the aortic arch.

The sixth branchial arch also is supplied by the vagus nerve (recurrent laryngeal nerve). This area supplies all intrinsic muscles of the larynx (except the ciricothyroid-fourth arch). This includes the thyroarytenoid muscle, which makes up the primary mass of the vocal fold. It consists of two parts, the ventricularis and vocalis. Skeletal derivations form the cricoid, arytenoid, corniculate, and cuneiform cartilages. The right sixth aortic arch gives rise to the right pulmonary artery and the left sixth aortic arch forms the left pulmonary artery and the ductus arteriosus.

 

17

A 65-year-old man undergoes surgery for management of a subtotal massive squamous cell carcinoma of the posterior larynx. History includes chemoradiation and subsequent bilateral selective neck dissections for persistent disease 9 months ago. An anterolateral thigh free flap is chosen for reconstruction, but the operative notes state that both external carotid systems were sacrificed. Which of the following recipient vessels is most appropriate in this patient?

A) Facial
B) Internal mammary
C) Occipital
D) Subclavian
E) Transverse cervical

The correct response is Option E.

When performing head and neck microsurgery, a strong background in the vascular anatomy of that region is imperative. As chemotherapy regimens have become commonplace for laryngopharyngeal cancers, so have the challenges of failures which generally require surgery. These cases have much higher complication rates, including fistulas, strictures, and carotid injury, among others. This case demonstrates another complexity that is increasingly observed, the “vascular or vessel-depleted neck.” The facial and occipital arteries are branches of the external system and would not be available. The subclavian is generally not a viable option due to its size, location, and potential complications through dissection. The internal mammary system has potential, but requires dissection through the ribs and has morbidities and the potential need of vein grafts. Generally speaking, even radical neck dissections do not sacrifice the transverse cervical vessels as they are usually used as the caudal margin. A number of reports have detailed the usefulness of these vessels as recipients in cases like the one described.

 

18

Which of the following cranial nerves provides parasympathetic innervention of the parotid gland?

A) V
B) VII
C) VIII
D) IX
E) X

The correct response is Option D.

Innervation of the parotid gland comes from parasympathetic fibers that travel with the glossopharyngeal nerve (cranial nerve IX). It also receives taste sensation (afferent) from the posterior one-third of the tongue.

The maxillary nerve of cranial nerve V (V2) is a sensory nerve and receives sensation from the mid face.

Parasympathetic fibers (efferent) innervate the submandibular and sublingual glands via the chorda tympani. Afferent fibers, via the chorda tympani, send taste sensation of the anterior two-thirds of the tongue.

The vestibulocochlear nerve (cranial nerve VIII) supplies sound and equilibrium to the brain.

The auricular branch of the vagus nerve (cranial nerve X), innervates the external acoustic meatus. Stimulation of the vagus nerve can lead to reflex coughing (Arnold reflex).

19

Which of the following muscles is associated with the hyoid or second branchial arch?

A) Lateral pterygoid
B) Levator veli palatini
C) Posterior digastric
D) Stylopharyngeus
E) Thyroarytenoid

The correct response is Option C.

The first branchial arch, also known as the mandibular arch, has the trigeminal nerve (ophthalmic, maxillary, and mandibular branches) as its neurologic component. The muscles of mastication (i.e., temporalis, masseter, medial, and lateral pterygoids); mylohyoid; anterior digastric; tensor tympanic; and the tensor veli palatini are the muscle components. The cartilaginous bar gives rise to the premaxilla; maxilla, zygomatic bone; part of the temporal bone; incus; malleus; anterior malleolar ligament; and the sphenomandibular ligament. The pharyngeal pouch and groove develop the tubotympanic recess (tympanic cavity, mastoid antrum and pharyngotympanic tube, internal acoustic meatus, tympanic membrane, adenoids). The vascular element largely disappears, but gives rise to the maxillary and external carotid arteries.

The second branchial arch, also known as the hyoid arch, accounts for 95% of all branchial arch anomalies. The cranial nerve is the facial nerve. It supplies the muscles of facial expression; buccinators; stapedius; stylohyoid; posterior digastric; auricular and platysma muscles. The skeletal contributions from Reichert’s cartilage include the stapes, styloid process, stylohyoid ligament, and hyoid (lesser cornu and upper part of body). The pharyngeal pouch and groove shape the crypts of the palatine tonsil and the cervical sinus. The vascular component again primarily disappears but forms the stapedial and hyoid arteries.

Third branchial cleft anomalies are rare. The glossopharyngeal nerve sends motor innervation to only the stylopharyngeus. The cartilaginous bar forms the hyoid (greater cornu and lower part of body). The pharyngeal pouch and groove give rise to the inferior parathyroids, thymus, and cervical sinus. The vascular elements contribute to the internal carotid and common carotid.

The fourth branchial arch is supplied by the vagus nerve (superior laryngeal, inferior laryngeal). Musculature innervated includes the cricothyroid and all intrinsic muscles of the soft palate, including the levator veli palatini. The thyroid and epiglottic cartilage develop from the cartilaginous bar. The pharyngeal pouch and groove form the superior parathyroids, and the thyroid parafollicular cells. The right fourth aortic arch forms the subclavian artery, while the left fourth aortic arch forms the aortic arch.

The sixth branchial arch also is supplied by the vagus nerve (recurrent laryngeal nerve). This area supplies all intrinsic muscles of the larynx (except the ciricothyroid-fourth arch). This includes the thyroarytenoid muscle, which makes up the primary mass of the vocal fold. It consists of two parts, the ventricularis and vocalis. Skeletal derivations form the cricoid, arytenoid, corniculate, and cuneiform cartilages. The right sixth aortic arch gives rise to the right pulmonary artery and the left sixth aortic arch forms the left pulmonary artery and the ductus arteriosus.

 

20

A 6-year-old boy is brought to the emergency department because of a laceration of the hard palate. Repair of the laceration with local anesthesia for greater palatine nerve block is planned. As the anterior portion is sutured in place, the patient feels pain. Which of the following additional nerve blocks is most appropriate?

A) Anterior superior alveolar
B) Infraorbital
C) Lesser palatine
D) Middle superior alveolar
E) Sphenopalatine

The correct response is Option E.

The sphenopalatine nerve arises from the incisive foramen and provides sensation to the anterior hard palate. Blockade of this nerve is essential for adequate blockade of the palatal mucosa for laceration repair.

The anterior superior alveolar nerve arises from the second branch of the trigeminal nerve before it exits the infraorbital foramen. The nerve supplies the maxillary anterior teeth and is part of the superior dental plexus of nerves that also includes the middle superior alveolar and the posterior superior alveolar nerves.

The infraorbital nerve provides sensation to the ipsilateral lateral nose, upper lip, and cheek.

The lesser palatine descends through the greater palatine foramen and provides innervation to the soft palate and uvula.

 

21

A 4-year-old boy is brought for evaluation because his mother is concerned about a growth on his neck. Physical examination shows a nontender mass in the midline of the neck that moves vertically when the patient swallows. Which of the following is the most likely cause of this patient's condition?

A) Failure of vascular apoptosis at 12 weeks' gestation
B) Failure of the thyroglossal duct to atrophy
C) Ossification of cartilage from the second and third pharyngeal arches
D) Persistent ectopic parathyroid tissue in the neck
E) Persistent ectopic parathyroid tissue in the neck

The correct response is Option B.

The patient described has a persistent thyroglossal duct cyst.

The thyroid gland is the first of the body’s endocrine glands to develop, at approximately 24 days’ gestation. The gland originates as a proliferation of endodermal epithelial cells on the median surface of the developing pharyngeal floor known as the foramen cecum. The foramen cecum originates from between the first and second pouches and represents the opening of the thyroglossal duct into the tongue. Descent of the thyroid gland carries it anterior to the hyoid bone and anterior to the laryngeal cartilages. As the thyroid gland descends, it forms its mature shape. The thyroid completes its descent in the seventh gestational week, coming to rest in its final location immediately anterior to the trachea.

If the thyroglossal duct does not atrophy, then the remnant can manifest clinically as a thyroglossal duct cyst. While half of these generally midline cystic masses are located at or just below the level of the hyoid bone, they may be located and can track anywhere from the thyroid cartilage up the base of the tongue. Because the hyoid bone develops in an anterior direction and may surround the thyroglossal duct, the surgeon should resect the central portion on the hyoid bone along with the cyst.

The thyroid gland is ensheathed by the visceral fascia, which attaches it firmly to the laryngoskeleton (i.e., Berry ligament). This firm attachment of the gland to the laryngoskeleton is responsible for movement of the thyroid gland and related structures during swallowing. This also causes a thyroglossal duct cyst to move on physical examination.

Ectopic thyroid gland may occur anywhere along the path of initial descent of the thyroid, although it is most common at the base of the tongue, just posterior to the foramen cecum.

Ectopic parathyroid glands occur in 15 to 20% of patients. The glands may be located anywhere near or even within the thyroid or thymus. For example, if parathyroid IVs do not descend entirely, they may be located as high as the bifurcation of the common carotid artery. Conversely, if parathyroid IVs do not release from the thymus, they may be located intrathoracically, as low as the aortopulmonary window. Other common ectopic locations include the anterior mediastinum, posterior mediastinum, and retroesophageal and prevertebral regions. However, even when the parathyroid glands are in an ectopic location, they still often are symmetrical from side to side, making localization somewhat easier.

Ossification of cartilages from the second and third pharyngeal arches gives rise to the hyoid bone.

 

22

Which of the following structures (A-E) is responsible for anchoring the tooth in its socket?

 

Q image thumb

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.

 

A image thumb
23

A 32-year-old woman comes to the office for consultation regarding cosmetic improvement of her nose. On examination, facial animation (smiling) causes marked descent of the nasal tip, shortening of the upper lip, and a transverse crease in the mid philtral area. These findings are most consistent with the action of which of the following muscles?

A) Depressor septi nasi
B) Nasalis
C) Procerus
D) Risorius
E) Zygomaticus major

The correct response is Option A.

A deformity upon facial animation characterized by descent of the nasal tip, shortening of the upper lip, and a transverse crease in the mid philtral area may be created or accentuated by the action of the depressor septi nasi muscles. These are small, paired muscles located on each side of the nasal septum, which originate at the medial crura foot plates and insert either on the incisive fossa of the maxilla or into the fibers of the orbicularis oris muscle.

Physical examination upon facial animation should be part of the routine preoperative evaluation of the rhinoplasty patient. Those who present with the dynamic deformity as described may benefit from excision or transection of the depressor septi nasi muscles. Several surgical techniques have been described, as well as the use of botulinum toxin type A.

The nasalis muscle compresses the cartilaginous part of the nose and draws the ala toward the septum. Although this may generate some depression of the tip of the nose, it should not cause shortening of the upper lip.

The procerus muscle depresses the medial angle of the eyebrows, creating transverse rhytides over the bridge of the nose. The risorius muscles retract the angles of the mouth, as in a grinning expression. The zygomaticus major muscles draw the angles of the mouth posteriorly and superiorly, as in laughing. These muscles do not cause depression of the tip of the nose.

 

24

During the period of mixed dentition, which of the following is the first permanent tooth to erupt?

A) Mandibular canine
B) Mandibular first molar
C) Mandibular first premolar
D) Maxillary central incisor
E) Maxillary lateral incisor

The correct response is Option B.

The stage of mixed dentition is defined as the age range in which there are both deciduous (primary) and permanent (secondary) teeth erupted in the oral cavity at the same time. Normally, the mandibular and maxillary teeth erupt in a slightly different pattern. This usually occurs at age 6 to 7 years and is completed by age 11 to 12 years. In the maxilla, the order of eruption is as follows: first molar, central incisor, lateral incisor, first premolar, second premolar, canine, second molar, and third molar. In the mandible, the order is slightly different and is as follows: first molar, central incisor, lateral incisor, canine, first premolar, second premolar, and second molar. The permanent first molars erupt between ages 6 and 7 years, the central and lateral incisors erupt between ages 6 and 8 years, and the first premolars erupt between ages 8 and 9 years. The first tooth to erupt is the permanent mandibular first molar, which erupts first in a position posterior to the deciduous second molar. There are no premolars in deciduous teeth.

25

A 22-year-old man comes to the emergency department after he sustained a machete laceration of the left cheek extending from the tragus through the midpoint of the upper lip. The wound is full thickness along the central third. Examination shows left upper lip droop and flattening of the associated nasolabial fold. Which of the following structures were most likely injured?

A) Lacrimal sac, mandibular branch of the facial nerve, and pterygoid muscle
B) Maxillary sinus, zygomatic branch of the facial nerve, and pterygoid muscle
C) Parotid duct, buccal branch of the facial nerve, and masseter muscle
D) Zygomatic arch, zygomatic branch of the facial nerve, and orbicular muscle

The correct response is Option C.

The middle third of a line drawn between the tragus and the middle of the upper lip defines the course of the parotid duct. The buccal and zygomatic branches of the facial nerve lie in close proximity to the parotid duct, which lies superficial to the masseter muscle. Deep penetrating trauma in this region is likely to injure all three of these structures. Evidence of injury to the zygomatic or buccal branch of the facial nerve with a central cheek laceration should raise concern for a parotid duct injury.

The lacrimal sac is outside of the described zone of injury, as is the mandibular branch of the facial nerve. The pterygoid muscle is deep to the mandible and would be outside of the described zone of injury.

The maxillary sinus and the zygomatic branch of the facial nerve could have been injured, but not in combination with the pterygoid muscle, which is outside the zone of injury.

Concomitant injury of the zygomatic arch and zygomatic branch of the facial nerve is possible, but because this injury was full thickness in the central third, the orbicularis muscle would not have been involved.

 

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A 4-year-old girl is brought to the office because of a congenital mucous-draining skin sinus located on the lower third of the neck, overlying the anterior border of the left sternocleidomastoid muscle. On physical examination, swallowing causes noticeable puckering of the sinus. Intraoperative probing shows that it communicates with the left tonsillar fossa. On surgical exploration, which of the following is the most likely ascending course of this sinus?

A) Deep to the hypoglossal nerve
B) Deep to the internal carotid artery
C) Superficial to the posterior belly of the digastric muscle
D) Superficial to the stylohyoid muscle
E) Superficial to the stylopharyngeal muscle

The correct response is Option E.

Surgical exploration is most likely to show the ascending course of this pharyngeal fistula to be superficial to the stylopharyngeal muscle.

Second pharyngeal cleft and pouch anomalies (including cysts, fistulas, and sinuses) account for 67 to 95% of the total anomalies of the pharyngeal apparatus. Cysts are the most common finding, occurring three times more often than fistulas. Fistulas usually present at birth. They derive from the ventral portion of the second pharyngeal cleft and pouch. The external opening is usually found along the anterior border of the sternocleidomastoid muscle, between the hyoid bone superiorly and the suprasternal notch inferiorly. Fistulas have a muscular coat, which is continuous superficially with the platysma and internally with the palatopharyngeal muscle. If this muscle coat is well developed, swallowing causes a pull on the fistulous opening, resulting in puckering.

The anatomical relations between a second pharyngeal cleft and pouch fistula and the surrounding cervical structures are dictated by the embryogenesis of the pharyngeal apparatus. As an anomaly of the second cleft and pouch, the fistula is expected to course deeply to the second arch structures and superficially to the structures derived from the third to sixth arches.

Therefore, the described fistula is expected to course deep to the stylohyoid muscle and posterior belly of the digastric muscle (derived from the second pharyngeal arch), and superficial to the internal carotid artery and stylopharyngeal muscle (derived from the third pharyngeal arch).

The hypoglossal nerve and associated infrahyoid muscles do not develop in the mesenchyme of the pharyngeal apparatus, instead being derived from occipital somites in the paraxial mesoderm. All pharyngeal anomalies derived from ectoderm (e.g., fistulas) will be found superficial to the hypoglossal nerve and the infrahyoid strap muscles.

Other cervical structures not mentioned in this scenario but which are relevant to the course of the described fistula include the external carotid artery (second pharyngeal arch) and the glossopharyngeal nerve (third pharyngeal arch). The expected fistula course is deep to the former and superficial to the latter.

 

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A 25-year-old man comes to the office for consultation regarding a 10-year history of gradual swelling of the right side of the face. Physical examination shows class I occlusion, normal interincisal distance, and smooth occlusal surfaces on the right molar teeth. The right cheek is enlarged when he clenches the teeth. CT scan shows a right masseter that is twice as large as the left one, and there is an outward curvature of the angle of the mandible. Which of the following is the most appropriate treatment?

A) Condylar reduction
B) Masseter resection
C) Orthodontics
D) Radiation therapy
E) Sagittal split osteotomy

The correct response is Option B.

Benign masseteric hypertrophy may present as a bilateral or a unilateral condition. When unilateral, it is associated with repetitive unilateral clenching of the teeth. Both the masseter and temporalis muscles of the affected side show varying degrees of enlargement. When mild, medical management may be offered first and can include muscle relaxants, anxiolytics, antiepileptic drugs, and botulinum toxin type A. Surgical resection of a portion of the masseter and/or bone contouring are appropriate surgical procedures for correction of the resulting cosmetic deformity.

Unilateral masseteric hypertrophy must be distinguished from unilateral condylar hyperplasia, the latter consisting of the enlargement or overgrowth of the mandibular condyle. Condylar hyperplasia may also present with unilateral facial enlargement (type IB or type II), deviation of the mandibular midpoint toward the unaffected side, class III occlusion on the ipsilateral side, and a crossbite on the contralateral side. Condylar resection is the mainstay of treatment.

Condylar reduction is appropriate for cases of condylar dislocation. This condition can occur unilaterally in patients with a hypermobile or stretched temporomandibular joint, or in patients with dystonia (hyperfunction of the lateral pterygoid muscle). Condylar dislocation occurs suddenly, and causes pain and a class III occlusion on the involved side. Condylar reduction is performed with the aid of muscle relaxants. Eminence surgery may be necessary (eminectomy, eminoplasty).

Orthodontics are unnecessary for someone with bruxism, which is a typical feature of masseteric hypertrophy. However, a mouth guard is appropriate.

Radiation is inappropriate for benign masseteric hypertrophy. It does not correct the underlying cause or the deformity associated with this condition.

Sagittal split osteotomy is indicated in cases of class II or III malocclusion in which reduction or lengthening of the anteroposterior length of the mandible will achieve dental harmony. This procedure is not appropriate for class I occlusion or flaring of the mandibular angle.

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Which of the following cranial nerves is responsible for parasympathetic innervation to the parotid gland?

A) Trigeminal (V) nerve
B) Vestibulocochlear (VIII) nerve
C) Glossopharyngeal (IX) nerve
D) Vagus (X) nerve
E) Hypoglossal (XII) nerve

The correct response is Option C.

The innervation of the parotid gland comes from parasympathetic fibers of the glossopharyngeal nerve (cranial nerve IX). It also receives taste sensation (afferent) from the posterior one third of the tongue.

The maxillary nerve of cranial nerve V (V2) is a sensory nerve and receives sensation from the mid face.

Parasympathetic fibers (efferent) innervate the submandibular and sublingual glands via the chorda tympani. Afferent fibers, via the chorda tympani, send taste sensation of the anterior two thirds of the tongue.

The vestibulocochlear nerve (cranial nerve VIII) supplies sound and equilibrium to the brain.

The Arnold nerve, also called the auricular branch of the vagus nerve (cranial nerve X), innervates the external acoustic meatus. Stimulation of the Arnold nerve can lead to reflex coughing (Arnold reflex).

 

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A 35-year-old woman is evaluated because of numbness of the upper helical rim of the left ear 30 days after she underwent neurosurgical decompression to treat facial pain. Which of the following nerves was most likely injured?

A) Auriculotemporal
B) Glossopharyngeal
C) Great auricular
D) Lesser occipital
E) Vagus

The correct response is Option A.

Knowledge of the innervation of the external ear is critical to the understanding of its embryologic development, as well as in the delivery of adequate local anesthesia for minor surgical procedures. Sensation to the external ear is derived from several cranial and extracranial nerve branches. The great auricular (C2 to C3) and lesser occipital (C2) are cranial nerves which innervate the posterior aspect of the auricle and lobule. While the distribution is variable, in most cases the lesser occipital supplies the superior ear and mastoid region while the great auricular nerve supplies the inferior ear and a portion of the preauricular area. The anterior surface of the ear, including the helix, scapha, and concha, is supplied by the auriculotemporal nerve (V3 trigeminal) and is most likely to be injured in a microvascular decompression for the treatment of trigeminal neuralgia. Branches of the vagus (X) and glossopharyngeal (IX) nerve innervate the external auditory meatus.

The innervation to the external ear follows its embryologic branchial arch origins with the great auricular nerve innervating first branchial arch structures and the auriculotemporal nerve innervating second branchial arch structures. An auriculotemporal nerve block provides anesthesia to the helix and tragus and is approached by injecting 2 to 4 mL of anesthesia superiorly and anteriorly to the tragus. The great auricular nerves and lesser occipital nerves are blocked by injecting 2 to 4 mL of anesthetic to the posterior sulcus from the inferior aspect of the earlobe. This will provide anesthesia to the earlobe and lateral helix.

 

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A 50-year-old man undergoes wide local excision and bilateral selective cervical lymphadenectomy because of a 6-month history of invasive squamous cell carcinoma of the anterior floor of the mouth. Free tissue transfer using an anterolateral thigh free flap, including harvest of the lateral femoral cutaneous nerve, reconstructs the ventral glossectomy and floor-of-mouth defect. Which of the following is the most likely recipient nerve for functional sensory recovery of the free flap in this patient?

A ) Cervical branch of facial
B ) Great auricular
C ) Hypoglossal
D ) Inferior alveolar
E ) Lingual

The correct response is Option E.

Oral mucosal sensation is important in many stomatognathic functions. Mastication, oral hygiene, phonation, and swallowing can all influence patient quality of life. A proportionally worsening functional impact with an increasing area of anesthesia has been noted. Therefore, restoration of sensibility should be one of the important components of the functional rehabilitation of glossectomy defects.

Although spontaneous reinnervation does occur in noninnervated flaps, it takes a longer period of time to develop, and it may not restore adequate functional sensation, nor does it provide useful tactile sensation or two-point discrimination. These sensory modalities are important in a patient's ability to handle oral secretions and food boluses.

Microsurgical anastomoses of the lateral femoral cutaneous nerve is most commonly performed to the lingual nerve stump left after tumor extirpation.

The cervical branch is the lowest division of facial motor nerve and would not provide sensory recovery to the freely transferred thigh tissue.

The great auricular nerve provides sensation to the earlobe and can serve as an ideal donor for segmental nerve grafting, if required. Bioprosthetic conduits (nerve tubes) or vein grafts have also been described for this purpose.

The hypoglossal nerve is commonly identified and preserved in selective cervical lymphadenectomy, and, if divided, causes a motor paralysis of the ipsilateral tongue.

The inferior alveolar nerve is part of the trigeminal system (V3) and is not divided during a floor-of-mouth resection and/or glossectomy, unless a segmental mandibulectomy is also performed.

 

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Which of the following best describes the anatomical location of the nerve that supplies sensation to the frontoparietal scalp at the level of the forehead?

A ) In the subcutaneous fat
B ) Superficial to the frontalis muscle
C ) Superficial to the galea aponeurosis
D ) Superficial to the periosteum
E ) Through the medial corrugator supercilii muscle

The correct response is Option D.

The supraorbital nerve (SON) supplies sensation to the forehead skin (paramedian) and anterior scalp as well as the frontoparietal scalp. The latter scalp is supplied by the deep division of the nerve, whereas the rest is supplied by its superficial division. Medially passing through the corrugator supercilii muscle is the supratrochlear nerve, which supplies the medial skin of the forehead. The deep division of the SON travels initially (just medial to the superotemporal line) along the temporal periosteum and then more cephalad pierces the deep galea plane and enters the galea fat pat. This information is the key to avoid injury when performing a forehead lift. Also, when planning a bicoronal incision for craniofacial surgery, one can use this information to preserve the sensation of the related scalp. The superficial branch of the SON, on the other hand, travels superficial to the frontalis muscle in the paramedian forehead area.

 

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