During dissection to the level of the digastric tendon in a patient undergoing microsurgical head and neck reconstruction, the hypoglossal nerve can be found in which of the following positions?

(A) Lateral to both the internal and external carotid arteries
(B) Medial to both the internal and external carotid arteries
(C) Lateral to the internal carotid artery and medial to the external carotid artery
(D) Medial to the internal carotid artery and lateral to the external carotid artery

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.

References
1. Clemente C. Anatomy: A Regional Atlas of the Human Body. 2nd ed. Baltimore, Md: Urban & Schwarzenberg; 1981.
2. Wind GG, Valentine RJ. Anatomic Exposures in Vascular Surgery. Baltimore, Md: Williams & Wilkins; 1991.

Intracranial communication of a frontonasal encephalocele is most likely to occur through which of the following anatomic structures?

(A) Cribriform plate
(B) Foramen rotundum
(C) Foramen ovale
(D) Foramen cecum
(E) Superior orbital fissure

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).

References
1. Abrahams JJ, Eklund JA. Diagnostic radiology of the cranial base. Clin Plast Surg. 1995;22:373-405.
2. McCarthy JG, Thorne CH, Wood-Smith D. Principles of craniofacial surgery: orbital hypertelorism. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;5:2974-3012.

In a patient who has undergone Le Fort I osteotomy, which of the following arteries provides the primary blood supply to the maxilla?

(A) Ascending pharyngeal artery
(B) Greater palatine artery
(C) Infraorbital artery
(D) Lesser palatine artery
(E) Posterior superior alveolar artery

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.
References
1. McCarthy JG, Kawamoto HK, Grayson BH, et al. Surgery of the jaws. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:1187.
2. Siebert JW, Angrigiani C, McCarthy JG, et al. Blood supply of the Le Fort I maxillary segment: an anatomic study. Plast Reconstr Surg. 1997;100:843.

During a rhytidectomy procedure, the risk for injury to the great auricular nerve is greatest at which of the following locations?

(A) 1 cm anterior to the tragus
(B) 2 cm posterior to the lobule
(C) 4 cm posterior to the lobule
(D) 6 cm inferior to the tragus
(E) 10 cm inferior to the tragus

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.

References
1. McKinney P, Katrana DJ. Prevention of injury to the great auricular nerve during rhytidectomy. Plast Reconstr Surg. 1980;66:675.
2. Seckel BR. Facial Danger Zones: Avoiding Nerve Injury in Facial Plastic Surgery. Saint Louis, Mo: Quality Medical Publishing, Inc; 1994.

The external acoustic meatus is derived from which of the following structures?

(A) First branchial arch
(B) Second branchial arch
(C) First branchial groove
(D) Second branchial groove
(E) Third branchial groove

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.

References
1. Gosain AK, Moore FO. Embryology of the head and neck. In: Aston SJ, Beasley RW, Thorne CH, eds. Grabb & Smith's Plastic Surgery. 5th ed. Philadelphia, Pa: Lippincott-Raven; 1997:223-236.
2. Moore KL. The Developing Human. 4th ed. Philadelphia, Pa: WB Saunders Co; 1988:170-206.

Which of the following permanent teeth erupts first?

(A) Central incisor
(B) Lateral incisor
(C) Canine
(D) First premolar
(E) First molar

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.

References
1. Ferraro JW. Oral anatomy. In: Ferraro JW, ed. Fundamentals in Maxillofacial Surgery. New York, NY: Springer-Verlag; 1997:127-157.
2. Kelly KJ. Pediatric facial trauma. In: Achauer BM, Eriksson E, Guyuron B, et al, eds. Plastic Surgery: Indications, Operations, and Outcomes. Saint Louis, Mo: Mosby Ð Year Book, Inc; 2000;2:941-969.
3. Simmons KE. Orthodontic role in clefts. In: Booth PW, Schendel SA, Hausamen JE, eds. Maxillofacial Surgery. London, England: Churchill Livingstone, Inc; 1999;2:1101-1111.

In addition to the zygoma, which of the following bones forms the lateral orbital wall?

(A) Frontal bone
(B) Greater wing of the sphenoid
(C) Lacrimal bone
(D) Lesser wing of the sphenoid
(E) Maxilla

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.

References
1. Clemente C. Anatomy: A Regional Atlas of the Human Body. 2nd ed. Baltimore, Md: Urban & Schwarzenberg; 1981.
2. Zide BM, Jelks GW. Surgical Anatomy of the Orbit. New York, NY: Raven Press; 1985.

Which of the following structures drains into the middle meatus?

(A) Frontal sinus
(B) Mastoid air cells
(C) Nasolacrimal duct
(D) Posterior ethmoidal air cells
(E) Sphenoid sinus

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.
References
1. Clemente CD, ed. Gray's Anatomy of the Human Body. 30th ed. Philadelphia, Pa: Lea & Febiger; 1985:210.
2. Hollinshead WA. Anatomy for Surgeons. New York, NY: Harper & Row Publishers; 1968:285.
3. Luce EA. Frontal sinus fractures: guidelines to management. Plast Reconstr Surg. 1987;80:500-510.

Which of the following best describes the primary action of the superior oblique muscle on the globe?

(A) Abduction
(B) Adduction
(C) Depression
(D) Elevation
(E) Extorsion

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.

References
1. Clemente C. Anatomy: A Regional Atlas of the Human Body. 2nd ed. Baltimore, Md: Urban & Schwarzenberg; 1981.
2. Zide BZ, Jelks GW. Surgical Anatomy of the Orbit. New York, NY: Raven Press; 1985.

Which of the following best describes the blood supply to the sternocleidomastoid muscle?

(A) One source
(B) One dominant source and one minor source
(C) Two equally dominant sources
(D) Three equally dominant sources
(E) Four equally dominant sources

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.

References
1. Ariyan S. Sternocleidomastoid muscle and musculocutaneous flap. In: Strauch B, Vasconez LO, Hall-Findlay EJ, eds. Grabb's Encyclopedia of Flaps. Boston, Mass: Little, Brown & Co; 1990;1:485-491.
2. Coleman JJ III. The pharynx. In: Achauer BM, Eriksson E, Guyuron B, et al, eds. Plastic Surgery: Indications, Operations, and Outcomes. Saint Louis, Mo: Mosby Ð Year Book, Inc; 2000;3:1289-1310.

Which of the following structures does NOT attach to the lateral orbital tubercle?

(A) Fascial extension of the lateral rectus muscle
(B) Lateral check ligament
(C) Lateral horn of the levator aponeurosis
(D) Lateral limb of Lockwood's ligament
(E) Lateral palpebral ligament

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.

References
1. Hollinshead WH, ed. Anatomy for Surgeons. Philadelphia, Pa: JB Lippincott Co; 1982;1:93-155.
2. Jelks GW, Smith BC. Reconstruction of the eyelids and associated structures. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:1671-1679.
3. Ricciardelli E, Persing JA. Anatomy/physiology/embryology. In: Ruberg RL, Smith DJ, eds. Plastic Surgery: A Core Curriculum. Saint Louis, Mo: CV Mosby Co; 1994:251-259.

The deep division of the supraorbital nerve provides sensation to which of the following areas?

(A) Central forehead
(B) Central scalp
(C) Nasal radix
(D) Temporal forehead
(E) Temporal scalp

The correct response is Option B.

Knowledge of the anatomy of the supraorbital nerve is crucial for minimizing the risk for nerve injury and subsequent numbness during endoscopic forehead lifting. The supraorbital nerve is a branch of the ophthalmic division of the trigeminal nerve (V1). This nerve arises from a foramen or notch along the superior orbital rim, and then divides immediately into deep and superficial branches. The deep division courses laterally toward the superior temporal line of the skull, and then continues to the coronal suture to supply sensation to the central frontoparietal scalp. In contrast, the superficial branch divides into multiple branches, each of which courses cephalad into the frontalis muscle to supply sensation to the central forehead and hairline.

Sensation to the nasal radix is supplied by the supratrochlear and infratrochlear nerves, while the maxillary and mandibular branches of the trigeminal nerve (V2 and V3) supply sensation to the temporal forehead. Sensation to the temporal scalp is supplied by the occipital nerve.

References
1. Knize DM. Limited-incision forehead lift for eyebrow elevation to enhance upper blepharoplasty. Plast Reconstr Surg. 1996;97:1334-1342.
2. Knize DM. Reassessment of the coronal incision and subgaleal dissection for foreheadplasty. Plast Reconstr Surg. 1998;102:478-489.
3. Knize DM. A study of the supraorbital nerve. Plast Reconstr Surg. 1995;96:564-569.