A neonate has a reddish 1.5-cm mass of the nasal root with overlying cutaneous telangiectasias. A photograph is shown above. On physical examination, the mass is firm, noncompressible, and nonpulsatile. It does not transilluminate or change with Valsalva maneuver. Which of the following is the most likely diagnosis?

(A) Dermoid cyst
(B) Encephalocele
(C) Glioma
(D) Hemangioma
(E) Lipoma

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.

References
1. Bartlett SP, Lin KY, Grossman R, et al. The surgical management of orbitofacial dermoids in the pediatric patient. Plast Reconstr Surg. 1993;91:1208-1215.
2. Pensler JM, Ivescu AS, Ciletti SJ, et al. Craniofacial gliomas. Plast Reconstr Surg. 1996;98:27-30.

A 25-year-old woman is scheduled to undergo lip augmentation using dermal allograft. Blockade of the infraorbital and mental nerves will be performed bilaterally. In this patient, direct infiltration of local anesthetic is most likely to be required at which of the following sites?

(A) Central upper vermillion
(B) Central lower vermillion
(C) Commissures
(D) Cupid’s bow
(E) Philtrum

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.

References
1. Moore KL, Dalley II AF. Summary of cranial nerves. In: Moore KL, Dalley II AF, eds. Clinically Oriented Anatomy. 4th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999:1082-1096.
2. Williams PL, Warwick R, Dyson M, et al, eds. Gray’s Anatomy. 37th ed. Edinburgh, Scotland: Churchill Livingstone, Inc; 1989:570-575, 1098-1107.
3. Zide BM, Swift R. How to block and tackle the face. Plast Reconstr Surg. 1998;101:840-851.

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

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.

References
1. Lutz BS, Wei FC. Microsurgical reconstruction of the buccal mucosa. Clin Plast Surg. 2001;28:339.
2. Marieb EN, ed. Overview of the digestive system. In: Human Anatomy and Physiology. Redwood City, Ca: Benjamin/Cummings Publishing; 1995.

A 38-year-old woman sustains an injury to the auriculotemporal nerve during superficial parotidectomy for removal of a mixed tumor. Which of the following is the most likely postoperative finding?

(A) Numbness of the concha, helix, lobule, and temporal skin
(B) Numbness of the tragus, external auditory canal, and temporal skin
(C) Numbness of the entire pinna and paralysis of the temporalis muscle
(D) Paralysis of the auricularis anterior, superior, and posterior muscles
(E) Paralysis of the temporalis muscle

The correct response is Option B.

Injury to the auriculotemporal nerve is most likely to result in numbness of the tragus, external auditory meatus, tympanum, and temporal skin. The auriculotemporal nerve is a branch of the mandibular division of the trigeminal nerve (V3). The fascicles of this nerve divide soon after the nerve originates to allow for passage of the middle meningeal artery. The nerve then courses between the sphenomandibular ligament and the neck of the condyle, emerges from behind the temporomandibular joint, and travels toward the posterior surface of the upper portion of the parotid gland, where it may be vulnerable to injury during parotidectomy. It ascends with the superficial temporal vessels over the posterior zygomatic arch and divides into three branches, which provide cutaneous sensory innervation to the tragus, external acoustic meatus, tympanic membrane, and temporal region. Minor branches of the auriculotemporal nerve convey secretomotor fibers to the parotid gland and articular fibers to the temporomandibular joint.

The concha and antihelix receive sensory innervation from the auricular branch of the vagus (X) nerve. Sensory innervation to the helix and lobule is supplied by the great auricular nerve and lesser occipital nerve, which are derived from C2-3.

The auricularis anterior, superior, and posterior muscles receive motor innervation from the temporal and posterior auricular branches of the facial (V) nerve.

The temporalis muscle is innervated by the deep temporal nerves, which are derived from the anterior, or motor, branch of the mandibular division of the trigeminal nerve (V3).

References
1. Netter FH, ed. Atlas of Human Anatomy. 2nd ed. East Hanover, NJ: Novartis/Hoechstetter Printing Co, Inc; 1997:18-21.
2. Pegington J. The side of the mouth and parapharynx. In: Pegington J, ed. Clinical Anatomy In Action – The Head and Neck. Edinburgh, Scotland: Churchill Livingstone, Inc; 1986;2:150-153.
3. Williams PL, Warwick R, Dyson M, et al, eds. Gray’s Anatomy. 37th ed. Edinburgh, Scotland: Churchill Livingstone, Inc; 1989:1098-1107.
4. Wright T. Anatomy and development of the ear and hearing. In: Ludman H, Wright T, eds. Diseases of the Ear. 6th ed. London, England: Arnold; 1998:8-13.

Which of the following structures passes though the foramen ovale?

(A) Accessory nerves
(B) Optic (II) nerve
(C) Ophthalmic division of the trigeminal nerve (V1)
(D) Maxillary division of the trigeminal nerve (V2)
(E) Mandibular division of the trigeminal nerve (V3)

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).

References
1. Hochman M. Reconstruction of midfacial and anterior skull base defects. Otolaryngol Clin North Am. 1955;28:1269-1277.
2. Langstein HN, Chang DW, Robb GL. Coverage of skull base defects. Clin Plast Surg. 2001;28:375.

The external auditory meatus develops from which of the following embryologic structures?

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

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.

References
1. Gosain AK, Moore OF. 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.
2. Moore KL, ed. The branchial apparatus and the head and neck. The Developing Human. 4th ed. Philadelphia, Pa: WB Saunders Co; 1988:170.

Which of the following cranial nerves provides innervation to the temporalis muscle?

(A) Ophthalmic division of the trigeminal nerve (V1)
(B) Maxillary division of the trigeminal nerve (V2)
(C) Mandibular division of the trigeminal nerve (V3)
(D) Abducens (VI) nerve
(E) Facial (VII) nerve

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.

References
1. Burggasser G, Happak W, Gruber H, et al. The temporalis: blood supply and innervation. Plast Reconstr Surg. 2002;109:1862-1869.
2. Chen CT, Robinson JB Jr, Rohrich RJ, et al. The blood supply of the reverse temporalis muscle flap: anatomic study and clinical applications. Plast Reconstr Surg. 1999;103:1181-1188.

Which of the following neural structures does NOT pass through the superior orbital fissure?

(A) Optic (II) nerve
(B) Oculomotor (III) nerve
(C) Trochlear (IV) nerve
(D) Abducens (VI) nerve
(E) Sympathetic nerve fibers

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.

References
1. Clemente CD, ed. Gray's Anatomy of the Human Body. 30th ed. Philadelphia, Pa: Lea & Febiger; 1985:161-172.
2. Moore KL, Dalley AF, eds. Clinically Oriented Anatomy. 4th ed. Philadelphia, Pa: Lippincott, Williams & Wilkins; 1999:845, 899.