Head and Neck Congenital Flashcards

Question

Which of the following nerves supplies sensory innervation to the buccal mucosa? (A) Trigeminal (V) nerve (B) Facial (VII) nerve (C) Glossopharyngeal (IX) nerve (D) Vagus (X) nerve (E) Lingual nerve

Answer 1

The correct response is Option A. The buccal branch of the trigeminal (V) nerve provides sensation to the buccal mucosa. It is important for the surgeon to know the anatomy of this nerve branch to plan and perform neurotized free flap reconstruction and reinnervation of the intraoral cavity. The buccal branch of the facial (VII) nerve innervates the muscles surrounding the buccal mucosa. The glossopharyngeal (IX) and vagus (X) nerves do not provide sensory innervation to the intraoral mucosa. The lingual nerve provides sensation to a portion of the tongue.

Answer 2

The correct response is Option B. A ranula is a mucocele or mucous extravasation phenomenon in the floor of the mouth, arising from the ducts of the sublingual or submandibular glands, often as a sequela of obstruction of the sublingual gland. It usually presents as a unilateral swelling of the floor of the mouth that is fluctuant and tinted blue or glossy white. Treatment includes marsupialization or surgical excision including the sublingual gland. The ranula may herniate through the muscles of the floor of the mouth and present as a €œplunging ranula € or cervical mass. A lingual thyroid is an uncommon condition in which the embryonic thyroid gland does not descend into the neck and presents as a firm, nontender mass at the tongue base. A thyroglossal duct cyst represents residual epithelium-lined tracts that trace the path of descent of the thyroid and can be found anywhere in the paramedial region of the neck but are usually in the midline. A torus is an exostosis and is a slow-growing, hard mass arising from the palate or mandible. The enlargement consists of bone covered by mucosa. Excision is indicated for tori that become symptomatic or bothersome. Vascular anomalies are present at birth and grow with the patient. It would be unusual for a vascular anomaly to initially present in an adult.

Answer 3

The correct response is Option D. Development of the six branchial arches occurs within the walls of the anterior foregut during the fourth week of gestation, as neural crest cells migrate into the future head and neck region and alternating ridges and depressions develop. Each branchial arch is composed of endoderm, ectoderm, and mesoderm. During development, a series of clefts forms to create the branchial grooves externally and the pharyngeal pouches internally. The branchial grooves are lined with surface ectoderm and the pharyngeal pouches are lined with foregut endoderm. During the sixth week of gestation, six hillocks appear on the first (mandibular) and second (hyoid) branchial arches, which give rise to the auricle. The first branchial arch gives rise to the anterior (first through third) hillocks, and the second branchial arch gives rise to the posterior (fourth through sixth) hillocks. By the end of the eighth week of gestation, the auricle assumes its characteristic shape following differential growth and fusion of the hillocks. The external auditory meatus develops from the dorsal aspect of the first branchial groove, which is a cleft between the first and second branchial arches. The second, third, and fourth branchial grooves are obliterated within the cervical sinus during the later stages of embryologic development. The cervical sinus develops as a result of caudal overgrowth of the second branchial arch.

Answer 4

The correct answer is option b. With more than 4 mm of the upper limbus covered by the eyelid margin, the ptosis is considered severe, and with levator function at 4 mm, it is considered poor. Therefore, a frontalis suspension is the appropriate procedure. It can achieve excellent symmetry and long-lasting results. Most patients with congenital ptosis have severe ptosis and poor levator function and will need frontalis suspension. Ptosis is defined by how much the upper limbus is covered by the lid margin at rest and forward gaze. It is 1 to 2 mm normally. Ptosis: Mild = 2 mm Moderate = 3 mm Severe = 4+ mm Levator function: Excellent = 12–15 mm Good = 8–12 mm Fair = 5–7 mm Poor = 2–4 mm In terms of treatment: Fasanella-Servat: mild ptosis and good levator function Frontalis suspension: severe ptosis and poor levator function Levator advancement: moderate ptosis and fair levator function Müller muscle resection: mild ptosis, fair to good levator function

Answer 5

The correct response is Option A. Encephaloceles are neural tube defects that result in sac-like protrusions of the meninges (meningocele) or brain and meninges (meningoencephalocele) in various locations along the cranium, such as between the forehead and nose (including naso-orbital, frontonasal, and nasoethmoidal locations) or on the back of the skull. They tend to be soft, compressible masses that transilluminate that may be sessile or pedunculated. Biopsy may result in a cerebrospinal fluid leak. Glioma is a mass of ectopic neural tissue that does not transilluminate. Hemangiomas are benign vascular lesions that are present at birth and characterized by a rapid growth phase around the age of 1 to 6 months, followed by gradual involution over 1 to 12 years. They have no intracranial connection and no cerebral pulsations. Nasopharyngeal angiofibromas, also known as juvenile nasopharyngeal angiofibromas, are benign but locally invasive vascular tumors that occur almost exclusively in adolescent males. They present with unilateral or bilateral nasal obstruction, frequent epistaxis or blood-tinged nasal discharge. Nasal dermoid cyst is a benign cystic lesion that does not pulsate and does not transilluminate.

Answer 6

The correct answer is option c. Levator function is measured indirectly by determining the excursion of the eyelid margin as the patient looks from downgaze to upgaze. The eyebrow is manually fixed against the supraorbital rim during this measurement, preventing the frontalis muscle from contributing to eyelid movement. Many patients subconsciously raise their eyebrow in a compensatory effort to elevate the drooping eyelid, a beneficial finding in individuals requiring frontalis suspension. Normal adults typically demonstrate 12 to 16 mm of levator function. Lesser measurements may indicate the presence of a developmental or acquired myopathy.

Answer 7

The correct response is Option B. The muscles of facial expression receive their innervation from cranial nerve VII (facial nerve). The facial nerve innervates the muscles of facial expression along the posterior surface of the muscle in most cases. The exceptions to this rule include the levator anguli oris, the buccinator, and the mentalis muscle. At the modiolus, the fibers of the levator anguli oris coalesce with fibers of the zygomaticus major, orbicularis oris, risorius, buccinator, and depressor anguli oris. The levator anguli oris lies deep to the other muscles and receives its innervation along its anterior surface.

Answer 8

The correct response is Option B. The 26-year-old woman described has the typical history of Bell palsy. In patients with Bell palsy, the entire nerve is inflamed, but the maximum conduction block is either in the meatal or labyrinthine segments. Because the conduction block is proximal to the chorda tympani and stapedial nerve, patients also experience a change in taste and a decreased ability to accommodate (ie, dampen) loud noises. When an acoustic tumor causes facial paralysis, the paralysis is usually slowly progressive. Patients generally present with a hearing loss, not a hypersensitivity to noise. The tensor tympani muscle attaches to the malleus and is innervated by the trigeminal nerve, not the facial nerve. The tensor veli palatini muscle is also innervated by the trigeminal nerve and is responsible for active dilatation of the eustachian tube. Blockage of the eustachian tube would cause a hearing loss. The zygomaticus major muscle is innervated by the facial nerve. Denervation causes a decreased ability to smile, not hearing loss. The levator palatini muscle is innervated by the vagus nerve.

Answer 9

The correct response is Option B. The lingual nerve provides sensation to the anterior two thirds of the tongue. Injury to the lingual nerve is a rare complication of airway manipulation. Virtually all equipment associated with airway management and/or oral cavity retraction has been implicated in its damage. Examples include direct laryngoscopy, tracheal intubation, laryngeal mask airway, and tonsillectomy. The etiology of lingual nerve damage is likely compression of the nerve in the floor of mouth against the mandible caused by forceful compression of the floor of mouth. The mental nerve exits the mental foramen just below the first or second premolar and supplies sensation to the lower lip and chin. The superior laryngeal nerve provides sensory innervation to the supraglottis. The glossopharyngeal nerve provides sensory innervation and taste sensation to the base of the tongue. The recurrent laryngeal nerve provides motor innervation to the laryngeal musculature.

Answer 10

The correct response is Option D. This child has Carpenter syndrome. This syndrome is caused by a mutation in the RAB23 gene, which is located on chromosome 6. Carpenter syndrome is inherited in an autosomal recessive manner, but is can also be caused by de novo mutation in RAB23. In addition to synostosis, symbrachydactyly and preaxial polydactyly are found in patients with Carpenter syndrome. Mutations in the other genes listed are all associated with syndromic craniosynostoses. Fibroblast growth factor receptor (FGFR) mutations have been associated with several differing syndromes: FGFR1 mutations cause Pfeiffer syndrome, FGFR2 mutations cause Apert and Crouzon syndromes, and FGFR3 mutations cause Muenke syndrome. A mutation of the TWIST1 gene causes Saethre-Chotzen syndrome.

Answer 11

The correct response is Option C. Hypothenar hammer syndrome (HHS) describes digital ischemic symptoms secondary to either occlusion or aneurysmal dilation of the ulnar artery adjacent to the hamate. Although typically related to activities that involve repetitive trauma (eg, use of vibrating tools) to the palm, evidence exists to suggest that the condition arises in vessels with preexisting abnormalities, even in the absence of trauma. In cases of critical digital ischemia with characteristic segmental occlusion on arteriography, optimal treatment involves resection of the diseased segment and reconstruction. Reversed vein graft represents the standard bypass conduit; however, as in coronary artery bypass grafting, arterial conduits (inferior epigastric artery) have been suggested as better matched in size and less prone to aneurysmal dilation later. Calcium channel blockers and sympathetic blockade may alleviate vasospastic responses in the patent vessels distal to the occlusion. These interventions may be combined with surgical therapy and can be considered as primary interventions in patients with less symptomatic hands and a digital brachial index less than 0.7. Intraarterial thrombolysis should not be used in the setting of the chronic, occlusive disease of HHS. Smoking has been associated with HHS, but cessation alone in the setting of severe ischemia will not reverse the changes.

Answer 12

The correct response is Option D. The great auricular nerve emerges from behind the sternocleidomastoid muscle 9 cm below the caudal edge of the external auditory canal and 6 cm inferior to the tragus. The nerve lies posterior and superficial to the submuscular aponeurotic system (SMAS) and platysma at this point and is at greatest risk for injury during rhytidectomy. Injury to this nerve can result in numbness or painful dysesthesias of the lower two thirds of the ear and the adjacent skin of the neck and cheek.

Answer 13

The correct answer is A. Proboscis lateralis, which is illustrated in the photograph, is thought to be a failure of fusion between the lateral and maxillary nasal processes. A cleft lip is the result of a failure of fusion of the maxillary prominence with the medial nasal prominence. A midline cleft or Tessier Zero cleft is a result of the failure of fusion of the medial nasal prominences. Choanal atresia is a result of a failure of the oronasal membrane to rupture. Finally, a mandibular cleft or Tessier # 30 cleft is a result of the failure of fusion of the mandibular prominences.

Answer 14

The correct answer 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.

Answer 15

The correct response is Option A. Although the maxilla has an extensive blood supply as a result of its multiple anastomotic connections, much of its vascularity is irreversibly severed during the incisions and mobilization required for the Le Fort I osteotomy. Prior to surgery, the internal maxillary artery supplies blood to the maxilla through the descending palatine, posterior superior alveolar, and infraorbital arteries. However, after a Le Fort I osteotomy is performed, the ascending palatine branch of the facial artery and the palatine branch of the ascending pharyngeal artery provide the primary vascular supply. Both vessels are branches of the external carotid artery and contribute somewhat to the maxillary blood supply prior to surgery. The greater palatine artery emerges from the greater palatine foramen and courses anteriorly; its arterial branches are distributed to the palate and soft tissue of the roof of the mouth. The lesser palatine artery emerges from the lesser palatine foramen and supplies vascularity to the soft palate and palatine tonsils.

Answer 16

The correct response is Option C. The most appropriate area for block infiltration is an intraoral blockade of the mental nerve. The inferior alveolar nerve travels through the mandible entering at the medial ramal border and exits at the mental nerve at the mental foramen at the level of the first and second bicuspid teeth, 1 cm below the alveolar ridge. Blockage of the inferior alveolar nerve foramen requires injection at its entry in the posterior mandible, or within the bony canal €”an area not easily accessible. Numbness of the upper lip and nasal sidewall can be accomplished with blockade of the infraorbital nerve. Nasal palatine anesthetic produces numbness of the external nose. Sphenopalatine nerve blockade produces anesthesia in the internal nose and palate.

Answer 17

The correct response is Option C. The findings in this neonate are consistent with a glioma. Nasal gliomas are thought to originate as encephaloceles but fail to maintain their intracranial connections. They may be external, internal, or a combination of both. External gliomas typically appear at or just lateral to the nasal root. They are reddish, firm, noncompressible, lobular lesions that exhibit telangiectasias of the overlying skin, but do not transilluminate or pulsate. Bony defects, intracranial connections, and cerebrospinal fluid leakage occur only rarely. Histologic evaluation shows astrocytic neuroglial cells and fibrous and vascular connective tissue that is covered with skin or nasal mucosa. A nasal dermoid cyst arises from a dermoid sinus, which is a cutaneous inward passage lined with stratified squamous epithelium. These masses can also be external or internal. An external nasal dermoid is a firm, noncompressible, nonpulsatile lesion that does not transilluminate and may be lobulated. Although bony defects are infrequent, cerebrospinal fluid leakage and meningitis may occur. Nasal dermoid cysts are derived from ectoderm and mesoderm, lined with squamous epithelium, and contain specialized adnexal structures such as hair follicles, pilosebaceous glands, and smooth muscles. Encephaloceles involve herniation of cranial tissue through a skull defect. They may be classified as meningoceles (containing meninges only), meningoencephaloceles (containing meninges and brain), or meningoencephalocystoceles (containing meninges, brain, and part of the ventricular system). External, or sincipital, encephaloceles are soft, bluish, compressible, pulsatile masses that are located at the nasal root and transilluminate. They typically enlarge with crying and Valsalva maneuver. Hemangiomas are raised lesions that arise from a proliferation of endothelial cells. Most appear shortly after birth and involute spontaneously after a period of rapid growth. Discoloration of the overlying skin is often associated. Lipomas are soft, skin colored, compressible lesions that do not have cutaneous telangiectasias and do not transilluminate or pulsate. They may appear at the nasal root, but are not predisposed to that location.

Answer 18

The correct response is Option A. During preparation of recipient vessels for free tissue transfer in a patient undergoing head and neck reconstruction, the branches of the carotid artery and internal jugular vein are dissected. The digastric tendon is divided or retracted, and then the carotid artery and hypoglossal nerve are exposed. The hypoglossal nerve passes between the internal carotid artery and internal jugular vein. It turns anteriorly, spiraling around the internal carotid artery, and passes under the occipital artery. It then loops across the lateral surface of the external carotid artery and passes deep to the insertion of the stylohyoid muscle and digastric sling before disappearing beneath the posterior edge of the mylohyoid muscle. The surgeon must take great care to avoid injuring the hypoglossal nerve because injury would lead to impaired tongue mobility and potential difficulties with speech and swallowing.

Answer 19

The correct response is Option B. The first visceral arch ultimately forms the malleus, incus and the structures of the mandible. The second arch forms the stapes, the styloid and the facial musculature. The third arch forms the stylopharyngeus. The fourth, fifth and sixth arches contribute to the pharyngeal and laryngeal muscles as well as the thyroid cartilage.

Answer 20

The correct response is Option A. The frontal sinus drains into the middle meatus via the frontonasal duct. In addition, the anterior ethmoidal air cells and maxillary sinus drain into the middle meatus. It is important to assess the patency of this drainage system when managing fractures of the frontal sinus because any occlusion of the frontonasal duct may result in infection or mucocele. The mastoid air cells communicate with the mastoid antrum, which then communicates with the tympanic cavity. The nasolacrimal duct drains into the inferior meatus, and the posterior ethmoidal air cells drain into the superior meatus. The sphenoid sinus drains into the sphenoethmoid recess, which is located above and behind the superior concha.

Answer 21

The Correct answers is option B. Blepharophimosis syndrome, which is classified according to three types, is a form of congenital ptosis. Patients with blepharophimosis syndrome, type 1 have large epicanthal folds with epicanthus inversus, horizontally shortened eyelids, and severe ptosis. Patients with type 2 have telecanthus, absence of the epicanthal folds, severe bilateral ptosis, absence of levator function, and skin shortage involving all four lids. Blepharophimosis syndrome, type 3 involves absence of epicanthal folds, telecanthus, an antimongoloid slant of the palpebral fissures, severe ptosis, mild orbital hypertelorism, and skin deficiencies. As with many congenital syndromes, the malformations are isolated. Forehead and ear anomalies are also common. Although epicanthus and epiblepharon comprise a portion of this patient's condition, the presence of severe congenital ptosis leads to a diagnosis of blepharophimosis syndrome type 1. Surgical correction of blepharophimosis syndrome involves repair of the epicanthal folds and correction of eyelid ptosis. Levator resection, medial canthoplasty, and fascial suspension techniques have all been used in combination to correct the abnormalities. A five-flap technique that combines double Z-plasties and a Y-to-V flap is most often used for repair of the epicanthal folds. Ideally, the canthus should lie halfway between the pupil and the center of the nasal bridge following all repair procedures. Blepharochalasis and blepharospasm are not seen in patients with blepharophimosis syndrome.

Answer 22

The correct response for Item 142 is Option C and for Item 143 is Option B. The superficial fascia envelops the sternocleidomastoid, the trapezius, and the suprahyoid muscles. The prevertebral fascia incorporates all of the scalene and paravertebral muscles. The pretracheal fascia incorporates the thyroid and trachea.

Answer 23

The correct response is Option A. The stylomastoid foramen is located anterior to the mastoid process and posterior to the styloid root. The facial nerve and stylomastoid artery pass through the stylomastoid foramen as they exit the temporal bone; from this point, the facial (VII) nerve gives off branches to sites throughout the face. The main trunk of the facial nerve supplies innervation to the posterior belly of the digastric muscle as it leaves the foramen and enters the parotid gland. The glossopharyngeal (IX), vagus (X), and spinal accessory (XI) nerves and the internal jugular vein pass through the foramen jugulare. The mandibular nerve and accessory meningeal artery pass through the foramen ovale, which lies anteromedial to the foramen spinosum; the lesser petrosal nerve may also be transmitted through the foramen ovale. The great auricular nerve is derived from the nerve roots of C2-3 and not from cranial nerves. It travels around the posterior border of the sternocleidomastoid muscle to innervate the skin of the mastoid area. The posterior auricular nerve branches off from the facial nerve just after it passes through the stylomastoid foramen and supplies innervation to the skin behind the ear.

Answer 24

The correct response is Option E. The palatine bone is located posterior to the maxilla and pterygoid lamina; it is composed of horizontal and pyramidal processes. The horizontal process contributes to the posterior aspect of the hard palate and becomes the floor of the choana. The pyramidal process extends vertically to contribute to the floor of the orbit. The anterior nasal spine is a prominence of the maxillary bone. The dental arch lies anterior to the palatine bone because it includes a portion of the maxilla. The hamulus extends inferiorly from the medial pterygoid plate, posterior to the palatine bone. The external nose is comprised of the paired nasal bones and frontal processes of the maxilla.

Answer 25

The correct response is Option E. This 8-year-old boy has a thyroglossal duct cyst, a slowly enlarging, painless mass of the midline of the neck that results from incomplete degeneration of the thyroglossal duct before birth. This duct connects an endodermal diverticulum (which later becomes the thyroid gland) to the foramen cecum in the developing fetus; in most cases, the duct degenerates once the diverticulum becomes a solid gland. Although thyroglossal duct cysts can be found from the base of the tongue to the cricoid cartilage, most cysts are located inferior to the hyoid bone. Infection and rupture are fairly uncommon; if these occur, antibiotics should be administered. Definitive management of a thyroglossal duct cyst is complete surgical excision of the cyst and central portion of the hyoid bone; this is known as the Sistrunk procedure. Branchial cleft cysts rarely occur in the midline of the neck. Instead, most of these cysts develop from remnants of the second branchial cleft and are found at the anterior border of the sternocleidomastoid muscle. Dermoid cysts are also rare in the neck and are more likely to affect the nasion, lateral brow, or calvarium. A laryngocele is an air pocket that normally communicates with the larynx and often enlarges with coughing or other changes in pressure within the trachea; the report of a slowly enlarging, painless mass would not be expected to describe a laryngocele. Lymphatic malformations are present at birth and would not be seen in the midline of the neck. Because these malformations do not occur in a specific plane, diffuse involvement of head and neck tissues is common.

Answer 26

The correct response is Option D. The soft palate consists of the levator veli palatini muscle as well as the muscles of the uvula and the palatopharyngeus, palatoglossus, and tensor veli palatini muscles. The levator veli palatini muscle raises and retracts the soft palate to bring it in touch with the posterior pharyngeal wall. It also opens the eustachian tube. The uvular muscles draw the uvula superiorly and anteriorly. The palatopharyngeus and palatoglossus muscles lower the soft palate and narrow the faucial isthmus. The tensor veli palatini muscle tenses and lowers the soft palate and opens the eustachian tube. In the repair of a cleft of the soft palate, the tensor veli palatini muscle is difficult to approximate because the tendon runs over the hamulus. In contrast, the levator veli palatini muscle can be easily approximated. To avoid separation of the tensor tendon, it can be dissected off the hamulus by fracturing the hamulus. Paralysis of the soft palate may cause nasal regurgitation and interfere with speech. In unilateral paralysis of the soft palate, the uvula deviates toward the normal side during elevation.

Answer 27

The correct response is Option E. The foramen rotundum is situated within the sphenoid bone in the middle cranial fossa, not on a lesser wing of the sphenoid bone, which is located in the anterior cranial fossa. The foramen rotundum transmits the maxillary branch (V2) of the trigeminal (V) nerve from the middle cranial fossa into the pterygopalatine fossa. The anterior cranial fossa contains the frontal and ethmoid bones and the lesser wings of the sphenoid bone. The foramina of the anterior cranial fossa include the foramen cecum, foramina of the cribriform plate, and the anterior and posterior ethmoidal canals. The cribriform plate (the horizontal component of the ethmoid bone) comes in contact with the anterior cranial fossa on one side and with the nasal cavity on the other. The cribriform plate contains multiple foramina for the olfactory (I) nerves. The lesser petrosal sinus is located in the anterior wall of the petrous part of the temporal bone in the middle cranial fossa. It transmits the lesser petrosal nerve. The orbit has three important foramina: the optic canal and the superior orbital fissure, which connect posteriorly with the middle cranial fossa, and the inferior orbital fissure, which faces the pterygopalatine fossa posteriorly. The optic canal transmits the optic (II) nerve and the ophthalmic artery. The superior orbital fissure transmits the oculomotor (III), trochlear (IV), and abducens (VI) nerves and the ophthalmic division of the trigeminal (V) nerve. The inferior orbital fissure transmits the maxillary and zygomatic nerves and the infraorbital vessels.

Answer 28

The correct response is Option B. The lingual nerve, which supplies sensation to the anterior two thirds of the tongue, is a branch of the mandibular division of the trigeminal nerve (V3). Other structures that arise from this nerve include the inferior alveolar nerve, which supplies sensation to the mandibular teeth; the long buccal branch, which supplies sensation to the buccal mucosa; and the mental nerve, which supplies sensation to the skin of the chin and lower lip and the mucosa of the lip and adjacent gingiva. In addition, the auriculotemporal nerve divides from the posterior border of V3 immediately after exiting the foramen ovale, passes around the middle meningeal artery as two units, and then courses between the external auditory canal and temporomandibular joint (TMJ). This nerve supplies sensory innervation to the anterior auricle, a large portion of the temporal region, and part of the external auditory canal and gives off a branch to supply the TMJ. The infraorbital nerve, nasopalatine nerve, posterosuperior alveolar nerve, and posterosuperior nasal nerve are branches of the maxillary division of the trigeminal nerve (V2).

Answer 29

The correct response is Option B. The inferior alveolar nerve (IAN) is closest to the lingual cortex at the level of the first and second molars. The anatomy of the IAN is relevant in orthognathic and trauma surgery. The incidence of nerve transection during sagittal split osteotomy is 3.5% and usually occurs at the level of the third molar. Osteotomy design and chisel placement are based on knowledge of the anatomy of the IAN. The IAN enters the mandible on the medial side of the ramus approximately 10 mm below the sigmoid notch. It then courses through the canal that is closest to the buccal cortical plate in the region of the ramus and angle and down to the third molar; the average distance is 1.8 ±1 mm. The nerve then swerves away at a position of 4.1 ±1 mm from the buccal cortex as it passes the region of the first and second molars. As it traverses the mandibular body, it is lowest and closest to the inferior cortex (7.5 ±1.5 mm) near its exit site at the level of the first molar and second premolar.

Answer 30

The correct response is Option C. The superior oblique muscle primarily acts to depress the globe. Its secondary actions include abduction and intorsion. This muscle originates outside of and superomedial to the annulus of Zinn (the common tendinous ring at the orbital apex). It courses around the trochlear nerve to insert onto the globe. Sensory innervation to the superior oblique muscle is provided by the trochlear nerve.

Answer 31

The correct response is Option E. Stensen's duct can be found within the buccal space, which is bordered anteriorly by the orbicularis oris muscle, posteriorly by the edge of the masseter muscle, superiorly by the zygomaticus major muscle, and inferiorly by the fascial attachment of the buccinator muscle to the mandible. The duct develops deep within the parotid gland and emerges from the superior third of the gland at its anterior border, then courses below the zygomatic arch and enters the buccal space, inserting into the buccinator and then entering the oral cavity opposite the upper second molar. The facial artery and vein, buccal branches of the facial nerve, and buccal fat pad can also be found within the buccal space. Although Stensen's duct and branches of the facial nerve are vulnerable to inadvertent dissection in the area of the parotid gland, there are no major arterial branches in this region. The external carotid artery can be found within the angle of the mandible, while the superficial temporal artery is located within the preauricular border. The transverse facial artery is found at the zygomatic arch. These locations do not lie within the typical course of Stensen's duct.

Answer 32

The correct response is Option B. The origin of the lateral pterygoid muscle (shown below) has two components: one that attaches to the temporomandibular joint capsule and disc, and one that attaches to the fovea in the neck of the mandible. Proximally (anteriorly), the superior head attaches to the greater wing of the sphenoid bone, and the inferior head to the lateral surface of the lateral pterygoid plate. Therefore, in a subcondylar fracture, the lateral pterygoid muscle is in position to draw the proximal fragment forward. The digastric muscle extends from the mastoid process of the temporal bone to the hyoid bone and to the anterior mandible. It depresses the mandible (inferior movement) or elevates the hyoid. The masseter, medial pterygoid, and temporalis elevate the mandible from the region of the ramus, angle, or coronoid process. The masseter originates in the zygomatic arch and inserts on the lateral surface of the ramus. The medial pterygoid originates on the lateral pterygoid plate and the tuberosity of the maxilla and attaches to the medial surface of the angle of the mandible. The temporalis muscle is fan-shaped and originates from the floor of the temporal fossa and inserts in the coronoid process and anterior border of the ramus.

Answer 33

The correct response is Option C. The child described has a branchial cleft sinus or fistula, which is an embryologic remnant of the cleft between the second and third branchial arches. The fistulas can be bilateral in up to 30% of cases. Histologically, they are lined with stratified squamous epithelium but may also have some pseudostratified columnar ciliated epithelium in their walls. They also contain keratin, hair follicles, sweat glands, and sebaceous glands. They must be completely excised to prevent recurrence. The second branchial arch descends over the third, resulting in an external opening in the lower neck. The internal opening lies at the anterior aspect of the posterior pillar of the fauces, just behind the tonsil (which is the junction between the second and third branchial arches). Usually, the fistula will follow the carotid sheath upwards before crossing the hypoglossal (XII) nerve and passing between the internal and external carotid arteries to reach the tonsillar fossa. As a result, the hypoglossal nerve is at risk during surgery. The facial (VII) nerve is not in the vicinity of the fistula. The facial nerve is intimately related to first branchial arch sinuses and cysts. The spinal accessory (XI) nerve is in the posterior triangle of the neck and is not in the vicinity of the surgical field to remove this type of fistula. The lingual nerve lies at a higher level and is safe. The left recurrent laryngeal nerve arises from the vagus (X) nerve low in the neck before hooking around the subclavian artery and passing medially behind the common carotid artery to reach the groove between the trachea and the esophagus. As a result of this anatomy, it too is out of harm €™s way. The vagus (X) nerve lies in the carotid sheath behind, and somewhat between, the internal jugular vein and the common carotid artery. The fistula lies on the other side of the great vessels. At the carotid bifurcation, the vagus nerve is lateral to the fistulous tract and stands less chance of injury than does the hypoglossal nerve.

Answer 34

The correct response is Option D. Knowledge of the anatomy of the sinuses is important in the management of patients who have fractures of the frontal sinus. Patency of the drainage system, including the frontonasal and nasolacrimal ducts, must be assessed, as occlusion of the ducts may result in the development of infection or mucocele. The nasolacrimal duct drains into the inferior meatus. In contrast, the anterior ethmoid air cells and maxillary sinus drain into the middle meatus; the frontal sinus also drains into the middle meatus via the frontonasal duct. The sphenoid sinus drains into the sphenoethmoid recess, which is found above and behind the superior concha.

Answer 35

The correct response is Option E. The first molar is the first permanent tooth to erupt; this typically occurs between ages 6 and 7 years. The age of mixed dentition, in which there are both deciduous (primary) and permanent (secondary) teeth erupted in the oral cavity simultaneously, begins with the eruption of the first molars. In addition, Angle's classification, which describes the relationship between the mesiobuccal cusp of the maxillary first molar and the buccal groove of the mandibular first molar, has its basis in this pattern of eruption. Knowledge of the eruption pattern of the teeth is crucial for management of facial fractures in children, especially for coordination of any necessary bone grafting and/or orthognathic surgery. The central incisors erupt between ages 6 and 8 years, the lateral incisors between ages 7 and 9 years, the canine teeth between ages 9 and 12 years, and the first premolars between ages 10 and 12 years.

Answer 36

The correct response is Option E. General sensation of the anterior two thirds of the tongue is supplied by the lingual nerve, which is a branch of the mandibular division of the trigeminal. Taste in the anterior two thirds of the tongue is supplied by the chorda tympani from the facial nerve. The chorda tympani joins the lingual nerve and runs anteriorly in its sheath. The glossopharyngeal nerve supplies the mucosa of the posterior one third of the tongue. The hypoglossal nerve is the motor nerve to the tongue, and the facial nerve is the motor nerve to the face.

Answer 37

The correct response is Option D. The mandible is subject to muscular forces, which tend to add to the instability of certain fractures and necessitate treatment. The masseter, temporalis, and medial pterygoid muscles elevate the mandible, and the geniohyoid, genioglossus, mylohyoid, and digastric muscles tend to depress the mandible. The lateral pterygoid muscle inserts into the capsule of the temporomandibular joint and tends to remain attached and pull the condyle head medial when there is a high fracture.

Answer 38

The correct response is Option E. The tensor veli palatini muscle is innervated predominantly by the mandibular branch of the trigeminal nerve (V3). In contrast, the other palatal muscles, including the levator veli palatini, musculus uvula, palatoglossus, and palatopharyngeus, are innervated predominantly by branches of the pharyngeal plexus of the vagus (X) nerve.

Answer 39

The correct response is Option A. There are only two muscles that would be in the area of a high bifurcation of the carotid that may need to be cut for better exposure: posterior belly of the digastric and the stylohyoid, which span across the skull base to the hyoid. Because the stylohyoid is not mentioned, the digastric muscle is the correct choice. The microsurgeon usually divides the digastric muscle at the level of the fibrous loop for the intermediate digastric tendon. The other muscles are never dissected or divided during this procedure.

Answer 40

The correct response is Option D. The sternocleidomastoid muscle attaches to the mastoid process superiorly and to the clavicle and sternum inferiorly. The blood supply to this muscle is segmental and is derived from three equally dominant sources, each perfusing a portion of the muscle with some internal connections; each portion has its own musculocutaneous perforators that supply a small area of overlying skin. Vascularity to the superior third of the muscle is supplied by a branch of the occipital artery, to the middle third by a branch of the superior thyroid artery, and to the inferior third by a branch of the thyrocervical trunk. Knowledge of this pattern of arterial anatomy is important when harvesting the muscle for reconstruction of the neck and mandible. If the entire muscle is harvested for use but is based only on the inferior or superior pedicle, the portion of muscle farthest from the pedicle may not be reliable.

Answer 41

The correct response is Option A. The auricular branch of the vagus nerve (Arnold nerve) carries sensory input from the ipsilateral concha and oropharynx. Chronic external ear pain may alert the astute physician of more serious intraoral pathology. The auriculotemporal nerve carries sensory information from the anterior and superior external auditory canal, and the great auricular nerve relays sensation from the lower half of the ear. The lesser occipital nerve provides sensory input from the superior cranial surface of the ear. Although the superficial temporal nerve is not an anatomically recognized structure, the superficial temporal artery supplies vascular inflow to the anterior external ear.

Answer 42

Correct answer is option B. Frontalis suspension is the most appropriate procedure for correction of the poor levator function and severe ptosis seen in this 6-year-old boy. Appropriate preoperative evaluation should be performed in any patient with ptosis to classify the type and severity of the ptosis and the amount of levator function. Ptosis is classified as congenital or acquired. Patients with congenital ptosis often have poor function of the levator muscle, characterized by absence of eyelid excursion and a static eyebrow. In acquired ptosis, levator function is typically moderate to good. The amount of levator function is critical to determine the appropriate surgical correction. Blepharoplasty is appropriate in patients with excess skin and fat around the eyelids, but not in patients with true ptosis. Placement of gold weights in the eyelids is indicated for patients with facial paralysis to assist with eyelid closure. Plication and/or resection of the levator muscle is appropriate for patients who have moderate ptosis and levator function that is rated as fair to good.

Answer 43

The correct response is Option E. The mandibular division of the trigeminal nerve (V3) passes through the foramen ovale. This foramen is located in the region of the superior orbital fissure, which contains the nerves to the extraocular muscles, sympathetic fibers, and vessels and is found within the middle cranial fossa. The accessory nerves, glossopharyngeal (IX) nerve, and vagus (X) nerve pass through the foramen jugulare. The optic foramen transmits the optic (II) nerve and ophthalmic artery. The ophthalmic division of the trigeminal nerve (V1) passes through the superior orbital fissure. The foramen rotundum transmits the maxillary division of the trigeminal nerve (V2).

Answer 44

The correct response is Option D. Intracranial communication of a frontonasal encephalocele is most likely to occur through the foramen cecum because anterior encephaloceles herniate through this foramen. In contrast, the cribriform plate transmits the fibers of the olfactory nerve, the foramen rotundum transmits the maxillary division of the trigeminal nerve (V2), and the foramen ovale transmits the mandibular division of the trigeminal nerve (V3). The superior orbital fissure transmits the oculomotor (III), trochlear (IV), and abducens (VI) nerves, as well as the ophthalmic division of the trigeminal nerve (V1).

Answer 45

The correct response is Option B. The other mimetic muscles innervated by the mandibular branch of the facial nerve include the depressor labii inferioris and the mentalis muscle. These muscles control movement of the lower lip to either pull it down and laterally or to protrude it. Paralysis of the nerve results in elevation of the angle of the mouth and of the lower lip on the affected side. This nerve is at risk for injury during rhytidectomy or neck lift procedures, parotidectomy, and neck dissection. The buccinator, levator anguli oris, orbicularis oris, and risorius are all innervated by the buccal branch of the facial nerve. Anatomic variation may be encountered with the risorius muscle, which is rarely innervated by the mandibular branch.

Answer 46

The correct response is Option D. Attachments to the lateral orbital tubercle (also referred to as Whitnall's tubercle), which is found within the zygomatic bone approximately 10 mm beneath the lateral orbital rim, include the fascial extension of the lateral rectus muscle, the lateral check ligament, the lateral horn of the levator aponeurosis, and the lateral palpebral ligament, which anchors the tarsal plates. Although the suspensory ligament of Lockwood attaches to the walls of the orbit and contributes to the thickened lower portion of the bulbar sheath, it does not attach to the lateral orbital tubercle. This contribution to the bulbar sheath is formed by fascia from the inferior rectus and inferior oblique muscles as they cross beneath the globe.

Answer 47

The correct response is Option E. The patient described has a thyroglossal duct cyst. Thyroglossal duct cysts can form anywhere along the thyroglossal duct, which extends from the foramen cecum of the tongue to the final position of the thyroid gland in the neck, below the laryngeal cartilage. Normally, the thyroglossal duct atrophies and disappears. However, a remnant of it may persist and form a cyst in the tongue or anterior midline of the neck, most commonly inferior to the hyoid bone. Thyroglossal duct cysts are often asymptomatic unless they become infected, as this one has. Reactive lymph nodes are the most common neck mass in children. They are usually found laterally in the submandibular and jugulodigastric areas. Branchial cleft remnants (sinuses and cysts) arise from the branchial apparatus. They are also located laterally, along the anterior border of the sternocleidomastoid muscle, usually just inferior to the angle of the mandible. Lingual thyroid glands are a type of ectopic thyroid located within the tongue. Ectopic thyroid glands can be located along the course of the thyroglossal duct and are a result of failure of the thyroid to descend. Unlike thyroglossal duct cysts, they represent the only thyroid tissue present in the patient. Mucoepidermoid carcinomas are salivary gland malignancies found in children, and they most commonly appear within the parotid gland.

Answer 48

The correct response is Option A. The superior orbital fissure transmits the oculomotor (III), trochlear (IV), and abducens (VI) nerves and sympathetic nerve fibers from the cavernous plexus. In patients who sustain high-velocity fractures of the orbital roof, the fractures may extend to involve the structures of the superior orbital fissure, resulting in a condition known as superior orbital fissure syndrome. This syndrome manifests as loss of ocular motion resulting from paralysis of the motor nerves that pass through the superior orbital fissure, but does not affect vision. The optic (II) nerve and ophthalmic artery pass through the optic foramen, which is separated from the superior orbital fissure by the lesser wing of the sphenoid bone. Orbital apex syndrome, which involves injury to the optic nerve resulting from extension of the fracture into the optic canal, is characterized by loss of vision.

Answer 49

(C) Fonticulus frontalis

Answer 50

The correct response is Option B. Congenital midline cervical clefts are a result of a failure of fusion of the paired second branchial arches in the midline during embryogenesis. It is a rare anomaly of the anterior neck diagnosed on the basis of the clinical presentation at birth. The most commonly reported features are a cleft of reddened, thinned tissue in the midline, a protuberance of skin superiorly, a blind epithelium-lined sinus tract caudally, and a fibrous subcutaneous cord. The cord may limit neck movement. There is some degree of retrognathia and variable degrees of clefting of the lip and mandible. Other anomalies that have been found in association with midline cervical cleft are thyroglossal duct cysts and ectopic bronchogenic cysts. Branchial arches begin to develop in the fourth week as neural crest cells migrate into the head and neck region. By the end of the fourth week, four pairs of branchial arches are visible externally. The fifth and sixth arches are small and not yet visible on the surface of the embryo. The branchial arches are separated by prominent clefts called branchial grooves.

Answer 51

The correct response is Option C. The external acoustic meatus is derived from the first branchial groove. During fetal development, the external ear arises from six hillocks derived from the first and second branchial arches. The anterior three hillocks (from the first branchial arch) form the anterior portion of the auricle, and the posterior auricle is formed from the fourth through sixth posterior hillocks (from the second branchial arch). The second through fourth branchial grooves are typically obliterated within the cervical sinus by the end of the seventh week of gestation, resulting in a neck with a smooth contour; however, a persistent branchial groove can manifest as a branchial fistula, sinus, or cyst.

Answer 52

The correct response is Option D. The accessory nerve descends through the jugular foramen into the neck between the internal carotid and internal jugular vein. It crosses the internal jugular vein and is joined by fibers from the ventral ramus of C2. It gives off a motor branch to the sternocleidomastoid muscle before passing deep to or through this muscle. It emerges on the posterior border of the sternocleidomastoid muscle always in the upper half of this muscle. It enters the posterior triangle of the neck passing obliquely across the floor over the levator scapulae just deep to the investing fascia and superficial to the prevertebral fascia. It supplies motor fibers to the trapezius.

Answer 53

The correct response is Option A. During the dissection of the neck vessels, the microsurgeon must be comfortable with the anatomy of the entire neck including the orientation and suitability of the available arteries. The branches of the external carotid artery, in order from proximal to distal, are as follows: superior thyroid, ascending pharyngeal, lingual, occipital, facial, posterior auricular, and maxillary arteries.

Answer 54

The correct response is Option B. The nasolacrimal duct, which maintains the drainage of the nasolacrimal system, drains into the inferior meatus just below the inferior concha (see diagram). Other structures also drain into the nose. The auditory tube opens into the nasopharynx just posterior to the inferior concha. The sphenoid sinus drains into the sphenoethmoid recess superior and posterior to the superior concha. The posterior ethmoid air cells drain into the superior meatus. The nasofrontal duct,

Answer 55

The correct response is Option D. Knowledge of the muscles of the mandibular region and their functions in the movement of the mandible and displacement of fracture segments is crucial to accurately diagnosing and effectively treating facial fractures. Contraction of the medial pterygoid muscle elevates the mandible and pulls it medially. This muscle arises inferiorly, laterally, and posteriorly from the medial surface of the pterygoid plate and inserts on the medial ramus and mandibular angle. A patient who sustains a fracture medial to the mandibular angle has displacement of the mandibular ramus medially and cephalad because of the forces of this muscle. The anterior belly of the digastric muscle originates from the inside lower border of the symphysis and attaches to the lateral corner of the hyoid bone, while the posterior belly of the digastric extends between the hyoid bone and mastoid notch of the temporal bone. The digastric muscle is part of the suprahyoid musculature, which in a patient with a mandibular fracture would pull the anterior mandibular fragments posteroinferiorly. The buccinator muscle arises from the pterygomandibular raphae to insert into the orbicularis oris muscle and the mucosa and skin of the lips. This muscle of facial expression is innervated by the buccal branches of the facial nerve and acts to flatten the cheek against the teeth. Because it does not arise within the condylar region, it does not exert any forces on the condyle or mandible. The lateral pterygoid muscle arises from the lateral pterygoid plate of the sphenoid bone and extends posteriorly and horizontally to insert on the neck of the condyle and into the anterior margin of the articular disk of the temporomandibular joint. As the condyle is moved forward, the lateral pterygoid acts to protrude the mandible, then slides down the articular eminence, opening the mouth. In patients with subcondylar fractures, the muscle pulls the condylar head in an anteromedial direction, whereas in patients with unilateral fractures the contralateral pterygoid continues to protrude, resulting in deviation of the mandible to the side of the fracture.

Answer 56

The correct answer is option C Levator function is measured indirectly by determining the excursion of the eyelid margin as the patient looks from downgaze to upgaze. The eyebrow is manually fixed against the supraorbital rim during this measurement, preventing the frontalis muscle from contributing to eyelid movement. Many patients subconsciously raise their eyebrow in a compensatory effort to elevate the drooping eyelid, a beneficial finding in individuals requiring frontalis suspension. Normal adults typically demonstrate 12 to 16 mm of levator function. Lesser measurements may indicate the presence of a developmental or acquired myopathy.

Answer 57

The correct response is Option A. The lateral and medial pterygoids, masseter, and temporalis muscles are muscles of mastication, capable of exerting force on the mandible. These muscles are innervated by the mandibular division of the trigeminal nerve (V3). The lateral pterygoid muscle has two heads, which arise from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone and the lateral surface of the lateral pterygoid plate, and insert on the mandibular neck and the articular capsule and disk of the temporomandibular joint. This muscle pulls the condylar process of the mandible and articular disk forward, opening the mouth. The medial pterygoid muscle arises from the medial surface of the lateral pterygoid plate and the pyramidal process of the palatine bone and inserts on the medial surface of the mandibular ramus and angle. It acts to elevate and protrude the mandible and produce side-to-side movements. The masseter muscle arises from the zygomatic arch and inserts on the mandibular ramus and coronoid process; during mastication it elevates the mandible to occlude the teeth. The temporalis muscle arises from the temporal fossa, passes deep to the zygomatic arch, and inserts on the coronoid process and anterior border of the mandibular ramus. This muscle elevates the mandible and contributes to side-to-side grinding movements. The posterior fibers of the temporalis aid in retraction of the mandible once it has been protruded. The buccinator muscle arises from the alveolar process of the maxilla, from the mandible opposite the molars, and from the anterior border of the pterygoid mandibular raphe; it inserts into the submucosa of the cheeks and lips and is used to compress the cheeks against the teeth and gums. It is innervated by the facial (VII) nerve. Although it is not a muscle of mastication, it assists the tongue in directing food between the molars during mastication.

Answer 58

The correct response is Option D. IRF6 mutations that result in loss-of-function have been reported in both syndromic Van der Woude syndrome as well as nonsyndromic orofacial clefting; Van der Woude syndrome can include popliteal pterygium. PIK3CA gain-of-function mutations have been reported with venous malformations and lymphatic malformations. Mutations in TCOF1 are associated with Treacher Collins syndrome; these patients may have cleft palate, but they do not have lip pits. Gain-of-function mutations in FGFR2 have been implicated in syndromic craniosynostosis (Apert syndrome, Crouzon syndrome, and others). Mutations in NF1 result in increased RAS/MAPK signaling and neurofibromatosis type 1.

Answer 59

The correct response is Option B. The maxillary division of the trigeminal nerve travels through the foramen rotundum. The ophthalmic division of the trigeminal nerve travels through the superior orbital fissure. The mandibular division of the trigeminal nerve travels through the foramen ovale. The foramen spinosum carries the middle meningeal artery. The optic nerve travels through the optic foramen.

Answer 60

The correct response is Option C. The pterygomaxillary fissure appears on lateral cephalograms as an upside-down teardrop. It serves as a radiographic point of orientation. The posterior border of this opening is the anterior aspect of the pterygoid plates. The anterior border is the posterior aspect of the maxilla, and the superior border is the pterygopalatine fossa and sphenoid bone and the orbital process of the palatine bone. The inferior orbital fissure and the pterygomaxillary fissure are oriented at right angles to each other. They are separated by the small pterygopalatine fossa. The pterygomaxillary fissure connects the small pterygopalatine fossa with the much larger infratemporal fossa. It transmits the terminal branches of the maxillary artery and veins. The inferior orbital fissure transmits the maxillary nerve and branches of the pterygopalatine ganglion from the pterygopalatine fossa to the orbit. The mandibular nerve and branches pass through the infratemporal fossa but not through the pterygomaxillary fissure. Appropriate care must be taken during separation of the face from the pterygoid plates to avoid injury to the maxillary artery and veins. After separation of these components, down-fracture is often performed using digital pressure alone.

Answer 61

The correct response is Option D. The papilla of the parotid is located most frequently adjacent to the maxillary second molar as it empties the secretions of the parotid gland via Stensen’s duct.

Answer 62

The correct response is Option A. Understanding of the muscles of facial animation and its innervation is crucial for safe facial aesthetic surgery. The layers of the face include the skin, subcutaneous tissue, SMAS, fascia, and facial (VII) nerve. Dissection within the subcutaneous plane is safe because this plane does not contain the facial (VII) nerve. The SMAS is a heterogenous structure, consisting of facial muscles, fibrous tissue, and adipose tissue. Cephalad, the SMAS continues as the temporoparietal fascia. Dissection superficial to the SMAS layer is safe because the muscles of facial animation are innervated from below, except for the buccinator, mentalis, and levator anguli oris muscles, which are innervated via their superficial surfaces. The depressor anguli oris, orbicularis oculi, orbicularis oris, and zygomaticus major are all innervated from their deep surfaces. When dissecting below the SMAS plane, the zygomaticus major muscle serves as an important landmark. In this plane, dissection should proceed more superficially to preserve innervation of the zygomaticus major muscle.

Answer 63

The correct response is Option A. The ophthalmic branch or first division of the trigeminal nerve enters the orbit via the superior orbital fissure. The three sensory branches include the lacrimal, frontal, and nasociliary nerves. The nasociliary nerve courses above the optic nerve and below the superior rectus muscle. Its first branch is the posterior ethmoidal nerve, which provides sensation to the posterior ethmoid sinuses. The terminal branches of the nasociliary nerve are the anterior ethmoidal nerve and the infratrochlear nerve. The former exits via a foramen of the same name, and ultimately reaches the roof of the nose, providing sensation to the septum and lateral wall. Its terminal branch, the dorsal nasal nerve, supplies innervation to the tip.

Answer 64

The correct response is Option C. Torticollis is a congenital neck deformity involving shortening of the sternocleidomastoid muscle. The symptoms are head tilt and limited range of motion in the neck, and there is usually a firm mass in the body of the sternocleidomastoid muscle. The majority of the symptoms resolve in the first year of life. Occasionally, large portions of the muscle may become fibrotic, necessitating surgical release. On physical examination, findings include flexion of the head and neck toward the ipsilateral shoulder, rotation of the head and neck to the contralateral shoulder, and a lack of lateral flexion toward the contralateral shoulder. In the case of right-sided torticollis, the findings would be: Flexion of the head and neck toward the right shoulder Rotation of the head and neck toward the left shoulder Limited lateral flexion toward the left shoulder

Answer 65

The correct response is Option C. Because blockade of the infraorbital and mental nerves alone does not ensure adequate anesthesia of the oral commissures, direct infiltration of local anesthetic into the commissures is likely to be necessary. Although a portion of the sensibility of this region is supplied by contributions from the infraorbital and mental nerves, the greatest contributor is the buccal nerve, which is derived from the mandibular branch of the trigeminal nerve (V3). The buccal nerve supplies sensation to a large area of skin of the cheek that lies just lateral to the commissure and overlaps the area of the modiolus and buccinator muscle, as well as to a portion of the buccal mucosa on the opposite side of the buccinator. Although the infraorbital nerve may reach the upper half of the commissure and extend to 1.5 cm laterally, the border of this region follows an upward curve away from the commissure. Bilateral blockade of the infraorbital nerve in the midline provides complete anesthesia to all central components of the upper lip, including the vermillion, cupid’s bow, and philtrum. In addition, bilateral mental nerve blocks effectively anesthetize the central section of the lower lip because the regions supplied by these nerves meet in the midline.

Answer 66

The correct answer is option D Superior auricle is innervated by the auriculotemporal nerve, a branch of the mandibular branch of trigeminal (CN V3)

Answer 67

The correct response is Option A. The submental flap is a myocutaneous flap that is useful in head and neck reconstruction. This flap provides a contour, color, and tissue texture that is suitably matched to the face. The flap is elevated below the level of the platysma muscle and includes the submental artery and vein, which are direct branches of the facial artery and vein. The flap can be transposed to cover defects in the lower and central thirds of the face and into the inferior aspect of the upper third of the face. The submental artery is a consistent branch of the facial artery and gives off one or two cutaneous perforators to the submental skin. The submental artery runs in relation to the anterior belly of the diagastric muscle. Of the choices listed, the facial artery is the most superior branch of the external carotid artery. The lingual artery provides the blood supply to the tongue, the superior thyroid and inferior thyroid arteries provide the blood supply to the thyroid gland, and the transverse cervical artery gives off a descending branch, which provides the blood supply to the trapezius muscle.

Answer 68

The correct response is Option A. The inferior meatus provides the drainage ostium for the nasolacrimal duct into the nose. The maxillary, frontal, and anterior ethmoidal sinuses drain into the middle meatus, while the posterior ethmoid cells drain into the superior meatus. The sphenoid sinus drains into the supreme meatus, also referred to as the sphenoethmoidal recess.

Answer 69

The correct response is Option A. The muscles of mastication (temporalis, masseter, and medial and lateral pterygoids), the mylohyoid, and anterior belly of the digastric, and the tensors veli palatini and tympani are derived from the first branchial arch. Arch Nerve First- Mandibular Trigeminal, V2, V3 Second- Hyoid Facial (VII) Third Glossopharyngeal (IX) Fourth and Sixth Superior laryngeal branch of vagus (X) Recurrent laryngeal branch of vagus (X) Muscles Muscles of mastication Mylohyoid and anterior belly of digastric Tensor tympani Tensor veli palatini Muscles of facial expression Stapedius Stylohyoid Posterior belly of digastric Stylopharyngeus Cricothyroid Levator veli palatini Constrictors of pharynx Intrinsic muscles of larynx

Answer 70

The correct response is Option D. The parotid (Stensen) duct opens into the mouth at the level of the upper second molar. It is about 4 to 7 cm long, extends from the anterior border of the superficial lobe of the parotid gland, and is frequently accompanied by accessory parotid tissue. The duct runs anteriorly over the masseter muscle about halfway between the zygomatic arch and the angle of the mouth. It turns medially beyond the anterior border of the masseter muscle, pierces the buccinator muscle, and opens into the mouth through the parotid papilla at about the level of the upper second molar. The zygomatic and buccal branches of the facial (VII) nerve may cross superficially over the parotid duct. The location of the parotid duct has implications for placement of surgical incisions. Vertical incisions at the anterior border of the parotid gland may cause injury to the parotid duct or branches of the facial (VII) nerve. Horizontal incisions are less likely to damage these structures. Thus, parotid abscesses should be drained through a horizontal incision. Because the parotid gland is divided by fascial septa that extend from its capsule, a parotid abscess may be compartmentalized. Therefore, multiple horizontal incisions may be needed for adequate drainage. Also, a parotid abscess may not be fluctuant because of the septa. Pitting edema over the parotid gland usually indicates an abscess.

Answer 71

The correct response is Option C. Numbness in the left medial cheek and left infraorbital area suggest that the tumor has invaded the infraorbital nerve, which exits the middle cranial fossa from the foramen rotundum. Approximately 80% of patients with adenoid cystic carcinoma have perineural spread. The anterior ethmoid foramen emerges from the frontoethmoid suture line and contains the anterior ethmoid vessels. The foramen ovale and the stylomastoid foramen, respectively, contain the mandibular nerve (V3) and the facial nerve (cranial nerve VII). Cranial nerves IX (glossopharyngeal), X (vagus), and XI (spinal accessory) emerge from the jugular foramen.

Answer 72

The correct response is Option E. The hamulus, which is an inferior extension of the medial pterygoid plate, acts as a pulley for the tensor veli palatini muscle. This muscle arises from the medial pterygoid plate and consolidates into a tendon that changes course as it wraps around the hamulus, and then extends medially to form an aponeurosis in the anterior soft palate. The tensor veli palatini also inserts on the posterior hard palate. The levator veli palatini muscle arises from the inferior surface at the apex of the petrous portion of the temporal bone, and then passes obliquely downward and medially to join fibers from the contralateral muscle in forming the palatine velum. This muscle primarily acts to move the palate. A fibrous linkage exists between the fibers of the levator veli palatini and the tensor veli palatini; therefore, a patient who sustains a fracture of the pterygoid hamulus may have increased medial displacement of these muscles. The palatoglossus muscle arises from the soft palate and courses downward within the anterior tonsillar pillar to insert into the tongue. The palatopharyngeus muscle arises from the soft palate, coursing down the posterior tonsillar arch to join the stylopharyngeus, which then inserts on the thyroid cartilage. This muscle can be used for flap transfer in a patient undergoing sphincter pharyngoplasty for pharyngeal reconstruction. The superior pharyngeal constrictor muscle arises from the posterior aspect of the medial pterygoid plate and from the hamulus, pterygomandibular raphe, and alveolar process of the mandible. The fibers of this muscle wrap around the pharynx and insert on the median raphe to form Passavant's ridge, which contributes to velopharyngeal closure.

Answer 73

The correct response is Option E. Seven bones make up the orbit: the frontal bone, maxilla, zygoma, ethmoid, lacrimal, greater and lesser wings of the sphenoid, and the palatine bone. The frontal, maxilla, zygoma, and ethmoid bones constitute the strong outer rim of the orbit and protect the more delicate bones in the interior orbit. The lesser wing of the sphenoid forms the posterior aspect of the roof of the orbit and transmits the optic nerve and ophthalmic artery through the optic canal. The greater wing of the sphenoid contains the superior orbital fissure, which transmits the lacrimal nerve, frontal nerve, trochlear nerve, superior and inferior branches of the oculomotor nerve, the nasociliary nerve, and the abducens nerve.

Answer 74

The correct response is Option E. The seven ocular muscles in the orbit are the levator palpebrae superioris, the superior and inferior oblique, and the superior, inferior, medial, and lateral recti. The rectus muscles and the superior oblique arise from the fibrous ring around the optic nerve (the annulus tendineus communis). In contrast, the inferior oblique arises from the maxilla, while the levator palpebrae superioris arises from the lesser wing of the sphenoid bone.

Answer 75

The correct response is Option C. The temporalis muscle receives its innervation primarily from the branches of the mandibular division of the trigeminal nerve (V3), which then exits the skull via the foramen ovale. The motor branches of the buccal, masseteric, and mandibular nerves are derived from V3 and act to innervate the temporalis muscle. This muscle is a large, powerful muscle of mastication that originates along the temporal crest of the skull and inserts into the coronoid process of the mandible. The ophthalmic division of the trigeminal nerve (V1) provides sensation to the forehead and anterior scalp; this nerve branch exits the skull through the supraorbital foramen. The maxillary division of the trigeminal nerve (V2) provides sensation to the cheek and upper lip and to the upper teeth via the superior alveolar nerve. This nerve branch is transmitted through the infraorbital foramen. The abducens (VI) nerve provides motor innervation into the lateral rectus muscle of the eye. The facial (VII) nerve provides motor innervation to the muscles of facial expression.

Answer 76

The most common cause of epiblepharon is excess pretarsal skin and orbicular muscle at the lower eyelid margin. In this congenital anomaly, a fold of skin and underlying orbicular muscle of the eye override the eyelid margin, often pushing the cilia against the globe. The eyelid margin and tarsus are stable and maintain the proper orientation. Epiblepharon usually affects the lower eyelids, is more common in people of Asian descent, and is accentuated on downward gaze. Laxity of the tarsal plate and the lateral canthal tendons are seen in the aging lower eyelid. Abnormal attachment of the orbital septum can be seen after trauma.

Answer 77

The correct response is Option A. The inferior alveolar nerve enters the mandible on the medial side of the ramus about 10 mm below the sigmoid notch. It then courses through the canal closest to the buccal cortical plate in the region of the ramus, angle, and down to the third molar with an average distance of 1.8 mm ± 1 mm. The nerve then swerves away at a position of 4.1 mm + 1 mm from the buccal cortex as it passes the region of the first and second molars. As it traverses the mandibular body, it is lowest and closest to the inferior cortex (7.5 + 1.5 mm) near its exit site at the level of the first molar and second premolar via the mental foramen on the anterior surface of the mandible. The mental nerve supplies the skin of the lower lip and chin right up to the midline. The maxillary canine may be used as a landmark for needle insertion toward the infraorbital foramen during infiltration of the infraorbital nerve. The maxillary second molar is a landmark typically used to locate the opening of the Stensen duct. The oral commissure is used for facial aesthetic measurements and not for nerve blocks. The retromolar fossa, posterior to the mandibular third molar, is the preferred location for needle insertion to anesthetize the buccal nerve, which normally supplies sensibility to the central cheek. The sigmoid notch is used as a landmark to reference the location of the inferior alveolar nerve.

Answer 78

The correct response is Option A. Because the buccinator muscle is sandwiched between the facial artery and the oral mucosa, it must be included in a facial artery musculomucosal flap. The buccinator muscle originates from the pterygomandibular raphe and inserts into the orbicularis oris muscle and mucosa of the lateral lip elements. The other muscles listed are supplied by the facial nerve but are not included in a facial artery musculomucosal flap because of their location. The depressor anguli oris and zygomaticus major muscles lie superficial to the plane of dissection for this flap. The levator labii superioris muscle inserts into the lateral half of the lip, but its origin is from the infraorbital margin of the maxilla. The orbicularis oris muscle is anterior to the plane of dissection for the facial artery musculomucosal flap.

Answer 79

C Middle Meatus

Answer 80

The correct response is Option D. The stapes is derived from Reichert's cartilage, which is the precursor of the second branchial arch. Other structures derived from the second branchial arch include the stylohyoid process, the lesser cornu of the hyoid bone, and the upper part of the body of the hyoid bone. The other two ossicles of the middle ear (malleus and incus) are derived from the first branchial arch. Cartilage precursors in the first branchial arch are the quadrate cartilage and Meckel's cartilage, both of which give rise to skeletal elements through endochondral ossification. The quadrate cartilage gives rise to the greater wing of the sphenoid bone and the incus, while Meckel's cartilage gives rise to the malleus and the mandibular condyles. The skeletal elements of the maxillary and mandibular prominences originate from intramembranous ossification, which is derived from direct ossification of the dermal mesenchyme of the arches. The maxillary prominence gives rise to the maxilla, zygoma, and squamous portion of the temporal bone. The mandibular prominence gives rise to the body and ramus of the mandible.

Answer 81

The correct response is Option B. The lateral orbital wall is formed primarily by the orbital surface of the zygomatic bone and the greater wing of the sphenoid bone. In addition to the greater wing of the sphenoid, other bones that comprise the orbit include the ethmoid, frontal bone, lacrimal bone, maxilla, palatine bone, and the lesser wing of the sphenoid. The sphenoid portion of the lateral wall is separated from the roof of the orbit by the superior orbital fissure and from the floor of the orbit by the inferior orbital fissure. Appropriate anatomic reduction of the greater wing of the sphenoid and lateral wall of the orbit is critical for adequate reduction of a fracture of the zygomaticomaxillary complex. Because correct reduction of the inferior orbital rim, zygomaticofrontal suture, and orbital floor does not ensure reduction of the lateral wall, the surgeon should verify that the complete reduction of all structures has been performed.

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