Gray's - Head & Neck - Jen

Question 1

A 2-month-old male infant had a small pit at the
anterior border of the sternocleidomastoid muscle, with mucus dripping intermittently from the opening. The pit extended to the tonsillar fossa as a branchial fistula. Which of the following embryologic structure(s) is (are) involved in this anomaly?
A. Second pharyngeal arch
B. Second pharyngeal pouch and groove
C. Third pharyngeal pouch
D. Thyroglossal duct
E. Second pharyngeal pouch and cervical sinus

Answer 1

E. The child in this problem suffers from a fistula that indicates an open malformation.

This implies that the defect must be due to failure of closure for both an internal and an external structure. A branchial fistula results from failure of closure of both the second pharyngeal pouch and the cervical sinus, the cervical sinus being the consolidation of the second through fourth pharyngeal clefts, external structures. The second pharyngeal groove merges with the third and fourth pharyngeal grooves to form the cervical sinus.

Question 2

A 2-day old infant was born with a cleft palate. The major portion of the palate develops from which of the following embryonic structures?
A. Lateral palatine process
B. Median palatine process
C. Intermaxillary segment
D. Median nasal prominences
E. Frontonasal eminence

Answer 2

A. Lateral palatine process

The largest part of the palate is formed by the
secondary palate, which is embryologically derived
from the lateral palatine processes.

Question 3

A 3-day-old infant has a small area of the right iris missing, and a diagnosis of coloboma of the iris is made. Which of the following is the most likely embryologic cause of the coloboma?
A. Failure of the retinal/choroid fissure to close
B. Abnormal neural crest formation
C. Abnormal interactions between the optic vesicle
and ectoderm
D. Posterior chamber cavitation
E. Weak adhesion between the inner and outer
layers of the optic vesicle

Answer 3

A. Failure of the retinal/choroid fissure to close

A coloboma of the iris is caused by failure of the retinal fissure to close during the sixth week.

Question 4

Early closure of the fontanelles of the infant skull can result in compression of the brain, restricting brain growth. Which of the following fontanelles is located at the junction of sagittal and coronal sutures and at what age does this fontanelle typically close?

A. Posterior fontanelle, which closes at about 2 years

B. Mastoid fontanelle, which closes at about 16 months

C. Lambdoid fontanelle, which closes at 8 months to 1 year

D. Sphenoidal fontanelle, which closes at 3 years

E. Anterior fontanelle, which closes at 18 months

Answer 4

E. Anterior fontanelle, which closes at 18 months

The anterior fontanelle is located at the junction
of the sagittal and coronal sutures and closes at
around 18 months of age.

Question 5

A 3-year-old boy is admitted to the hospital because of a soft, anterior, midline cervical mass. When the patient is asked to protrude his tongue, the mass in the neck is observed to move upward. Which of the following is the most likely diagnosis?
A. A thyroglossal duct cyst
B. Defect in sixth pharyngeal arch
C. A branchial cyst
D. Cystic fistula of the third pharyngeal arch
E. Defect in first pharyngeal arch

Answer 5

A. A Thyroglossal duct cyst

Thyroglossal duct cysts occur due to retention
of a remnant of the thyroglossal duct along the path followed by the descending thyroid gland during development. The path begins from the foramen cecum of the tongue and descends in the midline to the final position of the thyroid.

Question 6

A 2-day-old infant male has a noticeable gap in his upper lip. The diagnosis is a cleft lip. Failure of fusion of which of the following structures is the most likely cause of this anomaly?
A. Lateral nasal and maxillary prominences/ processes
B. Medial nasal prominences/processes
C. Lateral nasal and medial nasal prominences/ processes
D. Lateral prominences/processes
E. Maxillary prominences/processes and the inter maxillary segment

Answer 6

E. Maxillary prominences/processes and the intermaxillary segment

The most common cause of cleft lip is failure of fusion of the maxillary process and the inter maxillary segment.

Question 7

A 3-day-old male has a noticeably small mandible. A CT scan and physical examinations reveal hypoplasia of the mandible, cleft palate, and defects of the eye and ear. Abnormal development of which of the following pharyngeal arches will most likely produce such symptoms?
A. First arch
B. Second arch
C. Third arch
D. Fourth arch
E. Sixth arch

Answer 7

A. First arch

The listed symptoms are typical of first arch syndrome because the first arch normally gives rise to muscles of mastication, mylohyoid, anterior belly of the digastric, tensor tympani, tensor veli palatini, malleus, and incus.

Question 8

A 5-day-old infant male has an abnormally large head. A CT scan examination reveals enlarged lateral and third ventricles but a normal-size fourth ventricle. Stenosis of the cerebral aqueduct (of Sylvius) is suspected. Which of the following conditions will be characteristic of these symptoms?
A. Nonobstructive hydrocephalus
B. Anencephaly
C. Obstructive hydrocephalus
D. Meroanencephaly
E. Holoprosencephaly

Answer 8

C. Obstructive hydrocephalus

Obstructive hydrocephalus, in this case resulting from obstruction of the cerebral aqueduct, refers to a condition in which flow of cerebrospinal fluid (CSF) is obstructed within the ventricular system. This leads to pressure increasing in the CSF above the obstruction, explaining the enlarged lateral and third ventricles.

Question 9

A 3-month-old male infant has a lump in his neck. A biopsy of the lump shows it to be thymic tissue. Based on embryonic origin, which of the following additional structures is most likely to have an ectopic location?
A. Jugulodigastric lymph node
B. Lingual tonsil
C. Parathyroid gland
D. Submandibular gland
E. Thyroid gland

Answer 9

C. Parathyroid gland

Both the inferior parathyroid glands and the thymus are derived from the third pharyngeal pouch. Therefore, an ectopic thymus is likely to be associated with ectopic parathyroid tissue, indicating abnormal development of the third pharyngeal pouch.

Question 10

A 3-month-old male is under observation in the pediatric clinic. The patient has no thymus, congenital parathyroidism, and thyroid hypoplasia. Abnormal development of which of the following pharyngeal pouches or arches will most likely produce these defects?
A. First and second
B. Second and third
C. Third and fourth
D. Fourth
E. Fourth and sixth

Answer 10

C. Third and fourth

The defect is likely in the development of third and fourth pharyngeal pouches because the superior parathyroid glands are derived from the fourth pouch, whereas the inferior parathyroid glands are derived from the third pouch In addition, the third pouch gives rise to the thymus, and the parafollicular cells of the thyroid gland are derived from the fourth pharyngeal pouch.

Question 11

Cleft lip, with or without cleft palate occurs about once in 1000 births. Which of the following is considered to be the most important causative factor in the production of this anomaly?
A. Riboflavin deficiency
B. Infectious disease
C. Mutant genes
D. Cortisone administration during pregnancy
E. Irradiation

Answer 11

C. Mutant genes

Whereas all forms of clefts are considered to have a multifactorial etiology, cleft lip in particular seems to have a strong genetic factor. This has been determined using studies of twins. The other listed factors may or may not play a role in the development of a cleft lip, but genetics remains the most important causative factor.

Question 12

A 5-week-old male infant is born without a thymus or inferior parathyroid glands. Which of the following pharyngeal arches is most likely involved?
A. First
B. Second
C. Third
D. Fourth
E. Fifth

Answer 12

C. Third

Absence of the thymus and inferior parathyroid glands would be due to defective development of the third pharyngeal pouch, their normal site of origin.

Question 13

A 5-day-old infant was born with a laryngeal defect. The greater cornu and the inferior part of the hyoid bone were absent at birth. Failure of development of which of the following embryonic structures most likely led to these defects?
A. Maxillary prominence
B. Mandibular prominence
C. Second pharyngeal arch
D. Third pharyngeal arch
E. Fourth pharyngeal arch

Answer 13

D. Third pharyngeal arch

The third pharyngeal arch gives rise to the greater cornu and lower part of the hyoid bone in addition to the stylopharyngeus muscle.

Question 14

A 22-year-old woman visits the outpatient clinic with a painless swelling on the right side of her neck. A CT scan examination reveals a well-defined cystic mass at the angle of the mandible, just anterior to the sternocleidomastoid muscle. What is the most likely diagnosis?
A. Dermoid cyst
B. Inflamed lymph node
C. Accessory thyroid tissue
D. Thyroglossal duct cyst
E. Lateral cervical cyst

Answer 14

E. Lateral cervical cyst

A lateral cervical cyst is caused by remnants of the cervical sinus and would present anterior to the sternocleidomastoid.

Question 15

A 5-day-old infant is diagnosed with a noncommunicating hydrocephalus. Which of the following is most likely to lead to such a condition?

A. Obstruction in the circulation of the cerebrospinal fluid

B. Excess production of cerebrospinal fluid

C. Increased size of the head

D. Disturbances in the resorption of cerebrospinal fluid

E. Failure of the neural tube to close

Answer 15

A. Obstruction in the circulation of the cerebrospinal fluid

Noncommunicating hydrocephalus, also known as obstructive hydrocephalus, is due to an obstruction to flow of CSF within the ventricular system.

Question 16

A 5-day-old infant was born with a normal Apgar score. One month later the external acoustic meatus was atretic Which of the following conditions was the most likely cause of this defect?

A. Otic pit did not form.

B. Development of the first pharyngeal pouch
was affected.

C. Meat 1 plug did not canalize.

D. Auricular hillocks did not develop.

E. The tubotympanic recess degenerated.

Answer 16

C. Meat 1 plug did not canalize.

A normal Apgar score indicates that the child appeared normal and healthy at birth, based on skin color, heart rate, reflexes, muscle tone, and breathing. An atretic external acoustic canal occurs due to failure of the meatal plug to canalize, an event that normallyoccurs in late fetal life.

Question 17

A 50-year-old woman complained of pain over her chin and lower lip. A few days later small vesicles appeared over the same area and soon began erupting. She was diagnosed with a dermatomal herpes zosterinflammation (shingles). Which of the following nerves was most likely responsible for the transmission of the virus in this case?
A. Auriculotemporal
B. Buccal
C. Lesser petrosal
D. Mental
E. Infraorbital

Answer 17

D. Mental

The chin and lower lip area are supplied by the mental nerve, a branch of the inferior alveolar nerve, which in turn is a branch of the mandibular division of the trigeminal nerve.

Question 18

A 68-year-old woman is suffering from excruciating, sudden bouts of pain over the area of her mid face. Laboratory studies indicate that she has tic douloureux (trigeminal neuralgia). Which ganglion is the location of the neural cell bodies of the nerve mediating the pain?
A. Geniculate
B. Trigeminal (semilunar or Gasserian)
C. Inferior glossopharyngeal
D. Otic
E. Pterygopalatine

Answer 18

B. Trigeminal (semilunar or Gasserian)

The semilunar ganglion, also known as the trigeminal or Gasserian ganglion, is the location of the sensory neuron cell bodies of the trigeminal nerve. Tic douloureux is a condition in which pain occurs over the area of distribution of trigeminal nerve branches.

Question 19

A 17-year-old woman is admitted to the hospital with signs of cavernous sinus thrombosis, as revealed by radiographic and physical examinations. Thrombophlebitis in the “danger area” of the face can spread to the cavernous sinus and involve the ophthalmic branch of the trigeminal nerve. Which of the following symptoms will most likely be present during physical examination?
A. Pain in the hard palate
B. Anesthesia of the upper lip
C. Pain from the eyeball
D. Pain over the lower eyelid
E. Tingling sensation over the buccal region of
the face

Answer 19

C. Pain from the eyeball

The ophthalmic branch of the trigeminal nerve supplies sensory innervation to the eyeball, leading to p in upon damage.

Question 20

A 34-year-old man is admitted to the hospital with severe headaches, dizziness, and vomiting. Imaging studies reveal a tumor at the hypoglossal canal. Which of the following muscles will most likely be affected?
A. Geniohyoid
B. Mylohyoid
C. Palatoglossus
D. Genioglossus
E. Thyrohyoid

Answer 20

D. Genioglossus

A tumor at the hypoglossal canal would compress the hypoglossal nerve and affect the genioglossus, a muscle it supplies.

Question 21

A 45-year-old female is admitted to the hospital with severe headaches, dizziness, and vomiting. Radiographic examination reveals an intracranial tumor. Upon physical examination the patient has dryness of the nasal and paranasal sinuses, loss of lacrimation,and loss of taste from the anterior two thirds of the tongue. Which of the following structures is most likely involved with the tumor?
A. Auriculotemporal nerve
B. Lesser petrosal nerve
C. Facial nerve
D. Inferior salivatory nucleus
E. Pterygopalatine ganglion

Answer 21

C. Facial nerve

The superior salivatory nucleus is the autonomic nucleus for the facial nerve Parasympathetic fibers carried by the greater petrosal branch of the facial nerve are responsible for supply of the lacrimal gland and sinuses, via the pterygopalatine ganglion. The geniculate ganglion contains the cell bodies for taste from the anterior two thirds of the tongue carried by the chorda tympani branch of the facial nerve. This branch also carries the parasympathetic supply for the submandibular and sublingual salivary glands.

Question 22

A 17-year-old female was admitted to the hospital with a high fever. Following intravenous administration of antibiotics, a routine CT scan revealed a “thoracic outlet” syndrome. Which symptom would most likely result from this syndrome?
A. Problems with respiration because of pressure
on the phrenic nerve
B. Reduced blood flow to the thoracic wall
C. Reduced venous return from the head and neck
D. Numbness in the upper limb
E. Distention of the internal jugular vein

Answer 22

D. Numbness in the upper limb

Thoracic outlet syndrome is characterized by the presence of a cervical rib, accessory muscles, or connective tissue bands that constrict the limited dimensions of the thoracic outlet. The cervical rib is usually located on the C7 vertebra and can impinge on the brachial plexus, resulting in loss of some feeling to the upper limb.

Question 23

A 31-year-old female is admitted to the hospital after an automobile collision. A CT scan examination reveals a large hematoma inferior to the right jugular foramen. Physical examination reveals right pupillary constriction (miosis) and anhydrosis (loss of sweating) of the face. Which of the following ganglia is most likely affected by the hematoma?
A. Submandibular
B. Trigeminal (semilunar or Gasserian)
C. Superior cervical
D. Geniculate
E. Ciliary

Answer 23

C. Superior cervical

The superior cervical ganglion (SCG), which is the uppermost part of the sympathetic chain, supplies sympathetic innervation to the head and neck. The usual symptoms for SCG injury are mitosis and anhydrosis in the head and neck region.

Question 24

A 35-year old male patient is admitted to the hospital with severe headaches. A CT scan evaluation reveals a tumor in the infra temporal fossa. Physical examination reveals loss of general sensation from the anterior two thirds of his tongue, but taste and salivation are intact. Wh ch of the following nerves is most likely affected by the tumor?
A. Lingual proximal to its junction with the
chorda tympani
B Chorda tympani
C. Inferior alveolar
D. Lesser petrosal
E. Glossopharyngeal

Answer 24

A. Lingual proximal to its junction with the
chorda tympani

The lingual nerve joins the chorda tympani in the infratemporal fossa, and a lesion to the lingual nerve before it joins the chorda tympani would account for the loss of general sensation, with no loss to the special sense of taste and saliva production

Question 25

A 70-year-old man is admitted to the hospital with chronic headache and enlarged lymph nodes. A CT scanshows a tumor at the jugular foramen. Which of the following would be the most likely neurologic deficit?
A. Loss of tongue movements
B. Loss of facial expression
C. Loss of sensation from the face and the scalp
D. Loss of hearing
E. Loss of gag reflex

Answer 25

E. Loss of gag reflex

The jugular foramen is the route of exit for three nerves (glossopharyngeal, vagus, and accessory nerves) and one vein (internal jugular) from the cranial cavity. The glossopharyngeal nerve provides the sensory input for the gag reflex, whereas the vagus nerve provides the motor output. Nerve compression within this foramen would lead to a loss of both systems and thus no gag reflex.

Question 26

A 40-year-old unconscious man is admitted to the emergency department after being hit in the head with a baseball. A CT scan examination reveals a fractured pterion and an epidural hematoma. Branches of which of the following arteries re most likely to be injured?
A. External carotid
B. Superficial temporal
C. Maxillary
D. Deep temporal
E. Middle meningeal

Answer 26

E. Middle meningeal

The middle meningeal artery is a branch of the maxillary artery and courses between the dura mater and skull close to the area of the pterion. Any fracture or impact trauma to this location typically results in a laceration of the middle meningeal artery resulting in an epidural hematoma

Question 27

An unconscious 48-year-old woman is admitted to the hospital. CT scan reveals a tumor in her brain. When she regains consciousness, her right eye is directed laterally and downward, with complete ptosis of her upper eyelid, and her pupil is dilated. Which of the following structures was most likely affected by the tumor to result in these symptoms?
A. Oculomotor nerve
B. Optic nerve
C. Facial nerve
D. Ciliary ganglion
E. Superior cervical ganglion

Answer 27

A. Oculomotor nerve

An injury to the oculomotor nerve would cause the eye to point downward and laterally due to the unopposed contractions of the trochlear and abducens nerves. The oculomotor nerve also provides innervation to the levator palpebrae superioris; thus, any injury would cause complete ptosis or drooping of the eyelid. The constriction of the pupil is provided by parasympathetic nerves via the oculomotor nerve.

Question 28

A 55-year-old man is admitted to the hospital after an injury sustained at work in a factory. He presents with severe scalp lacerations, which were sutured. After three days the wound is inflamed, swollen, and painful. Between which tissue layers is the infection most likely located?
A. The periosteum and bone
B. The aponeurosis and the periosteum
C. The dense connective tissue and the
aponeurosis
D. The dense connective tissue and the skin
E. The dermis and the epidermis

Answer 28

B. The aponeurosis and the periosteum

The scalp is divided into five layers: skin, dense connective tissue, aponeurosis, loose connective tissue, and periosteum. Typically, infections will be located in the loose connective tissue because of the ease with which infectious agents spread via the many veins located in this region. This area is usually referred to as the “danger zone” of the scalp mainly because scalp infections here can be transmitted into the skull via emissary veins, then via diploic veins of the bone to the cranial cavity.

Question 29

A 36-year-old woman is admitted to the hospital with severe head injuries after a car crash. During neurologic examination her uvula is deviated to the right. Which nerve is most likely affected to result in this deviation?
A. Left vagus
B. Right vagus
C. Right hypoglossal
D. Left glossopharyngeal
E. Right glossopharyngeal

Answer 29

A. Left vagus

An injury to the left vagus nerve would cause the uvula to become deviated to the right. This is because of the innervation of the musculus uvulae muscle that makes up the core of the uvula.

Question 30

A 22-year-old male is admitted to the emergency department and intubated. An endotracheal tube is passed through an opening between the vocal folds. What is the name of this opening?
A. Piriform recess
B. Vestibule
C. Ventricle
D. Vallecula
E. Rima glottidis

Answer 30

E. Rima glottidis

The rima glottidis is the opening between the
vocal folds and the arytenoid cartilages.

Question 31

A 5-year-old male has a complaint of left-sided
maxillary tooth pain. A dental examination reveals no abnormalities of his teeth. During physical examination tapping on his right maxilla elicits sharp pain on the right side of his face. The patient reports that he has no allergies. Which of the following conditions will be the most likely diagnosis?
A. Sphenoid sinusitis
B. Anterior ethmoidal sinusitis
C. Posterior ethmoidal sinusitis
D. Maxillary sinusitis
E. Frontal sinusitis

Answer 31

D. Maxillary sinusitis

Maxillary sinusitis is an infection of the maxillary sinus, which is located in the body of the maxillary bone. Sharp pain can be a major symptom of maxillary sinusitis.

Question 32

A 70-year-old man is admit ed to the hospital with severe headaches. During physical examination he has difficulty coughing and swallowing. A CT scan shows a tumor affecting a cranial nerve. Which nerve is most likely affected?
A. Mandibular
B. Maxillary
C. Glossopharyngeal
D. Vagus
E. Hypoglossal

Answer 32

D. Vagus

The vagus nerve is responsible for sensation in the mucosa of the larynx down to the level of the vocal folds, and also motor innervation of the muscles that initiate a cough reflex and swallowing (motor).

Question 33

A 7-year-old boy with a high fever is brought to the pediatrician During physical examination the patient complains of pain in his ear. His throat appears red and inflamed, confirming the diagnosis of pharyngitis. Which of the following structures provided a pathway for the infection to spread to the tympanic cavity (middle ear)?
A. Choanae
B. Internal acoustic meatus
C. External acoustic meatus
D. Pharyngotympanic tube
E. Pharyngeal recess

Answer 33

D. Pharyngotympanic tube

The pharyngotympanic (eustachian) tube connects the middle ear and the nasopharynx and is the conduit for spreading infections.

Question 34

A 33-year-old woman is unconscious when she is admitted to the hospital after she fell, hitting her head. The physician in the emergency department performs a pupillary light reflex test. The integrity of which of the following nerves is being checked?
A. Optic and facial
B. Optic and oculomotor
C. Maxillary and facial
D. Ophthalmic and oculomotor
E. Ophthalmic and facial

Answer 34

B. Optic and oculomotor

The optic and oculomotor nerves are responsible for the sensory and motor portions, respectively, of the pupillary light reflex.

Question 35

A 48-year old male patient complains of diplopia (double vision). On neurologic examination he is unable to adduct his left eye and lacks a corneal reflex on the left side. Where is he most likely location of the lesion resulting in the symptoms?
A. Inferior orbital fissure
B. Optic canal
C. Superior orbital fissure
D. Foramen rotundum
E. Foramen ovale

Answer 35

C. Superior orbital fissure

The superior orbital fissure is the opening that allows the passage of the oculomotor nerve and the trochlear nerve; the lacrimal, frontal, and nasociliary branches of ophthalmic division of the trigeminal nerve; the abducens nerve; the superior and inferior divisions of the ophthalmic vein; and the sympathetic fibers from the cavernous plexus. The sensory and motor components of the corneal reflex are the ophthalmic division of the trigeminal nerve and the oculomotor nerve, whereas the eye impairment is due to a lesion to the oculomotor nerve, all of which are transmitted through the superior orbital fissure.

Question 36

A 34-year-old male complains of hyperacusis sensitivity to loud sounds). Injury to which of the following cranial nerves is responsible?
A. Hypoglossal
B. Facial
C. Accessory
D. Vagus
E. Glossopharyngeal

Answer 36

B. Facial

The facial nerve innervates the stapedius muscle, which is responsible for limiting movement of the stapes, thereby reducing the intensity of the sound entering the inner ear.

Question 37

A 34-year-old swimmer presents to your office with an external ear canal infection (otitis externa). The patient coughs during inspection of the external auditory meatus with a speculum. The cough results from the irritation of which nerve that innervates an area of the external auditory meatus?
A. Vestibulocochlear
B. Vagus
C. Trigeminal
D. Facial
E. Accessory

Answer 37

B. Vagus

The vagus nerve innervates a part of the external auditory meatus and, when stimulated, can trigger a cough reflex in about 20 % of people. This is thought to be due to “referred sensation” from the vestibule of the larynx, which is innervated by the vagus nerve.

Question 38

A 29-year-old woman underwent a thyroidectomy. Postoperatively, the patient presented with hoarseness. Which of the following nerves was most likely injured during the operation?
A. Internal laryngeal
B. External laryngeal
C. Recurrent laryngeal
D. Superior laryngeal
E. Glossopharyngeal

Answer 38

C. Recurrent laryngeal

The recurrent laryngeal nerve supplies most of the motor innervation to the larynx and sens tion below the true vocal folds. The thyroid gland and the recurrent laryngeal nerve are in close proximity and thus the nerve is likely to be injured with a thyroidectomy. Injury to the recurrent laryngeal nerve can result in speech defects, including hoarseness.

Question 39

A 48-year-old man presents with a constricted right pupil that does not react to light. His left pupil and vision in both eyes are normal. These findings are most likely due to a lesion involving which of the following right-sided structures?
A. Oculomotor nerve
B. Superior cervical ganglion
C. Nervus intermedius
D. Edinger-Westphal nucleus
E. Trigeminal (semilunar, Gasserian) ganglion

Answer 39

B. Superior cervical ganglion

The superior cervical ganglion provides sympathetic innervation o the face and neck regions. Sympathetics travel along the branches of the internal carotid artery, and one result of stimulation of these nerves is to dilate the pupil during a sympathetic response (“flight or fight”).

Question 40

A 55-year-old woman is diagnosed with a tumor at the base of the skull, resulting in a decrease in tear production. Which of the following nerves is most likely injured?
A. Chorda tympani
B. Deep petrosal
C. Greater petrosal
D. Lesser petrosal
E. Nasociliary

Answer 40

C. Greater petrosal

The greater petrosal nerve, a parasympathetic branch of the facial nerve, provides innervation to the lacrimal gland of the orbit.

Question 41

A 24-year-old man is admitted to the hospi al after a street fight. Radiographic examination reveals an inferior (blow-out) fracture of the orbit. Orbital structures would most likely be found interiorly in which of the following spaces?
A. Ethmoidal sinus
B. Frontal sinus
C. Maxillary sinus
D. Nasal cavity
E. Sphenoidal sinus

Answer 41

C. Maxillary sinus

The maxillary sinus is located inferior to the orbit. Any trauma to the inferior bony wall of the orbit will likely displace the orbital structures in the compartment to the space below the orbit (maxillary sinus).

Question 42

A 35-year-old woman is hospitalized due to cavernous sinus thrombosis resulting from an infection on the face. Which of the following is the most direct route for spread of infection from the face to the cavernous sinus?
A. Pterygoid venous plexus
B. Superior ophthalmic vein
C. Frontal venous plexus
D. Basilar venous plexus
E. Parietal emissary vein

Answer 42

B. Superior ophthalmic vein

The superior ophthalmic vein drains directly into the cavernous sinus. The danger area of the face is located in the triangular region from the lateral angle of the eye to the middle of the upper lip, near the nose, and is drained by the facial vein. The facial vein communicates directly with the cavernous sinus through the superior ophthalmic vein.

Question 43

A 7-year-old boy was suffering from a severe infection of the middle ear (otitis media), which spread to the mastoid air cells (mastoiditis). Surgery was required but resulted in the following: right corner of the mouth drooping, unable to close his right eye, food collection in his right oral vestibule. Which nerve was injured?
A. Glossopharyngeal
B. Vagus
C. Facial
D. Maxillary division of the trigeminal nerve
E. Mandibular division of the trigeminal nerve

Answer 43

C. Facial

A lesion of the facial nerve is likely to lead to the symptoms described (drooping mouth, unable to close right eye, and food collection in the oral vestibule) because the muscles of facial expression are paralyzed. There is a bony prominence over the facial nerve located on the medial wall of the middle ear. Because of its close proximity, the facial nerve can be damaged due to otitis media. The other nerves listed are not located in close proximity to the middle ear and, if injured, would not present with the symptoms described.

Question 44

The arterial circle (of Willis) contributes greatly to cerebral arterial circulation when one primary artery becomes occluded by atherosclerotic disease. Which of the following vessels does not contribute to the circle?
A. Anterior communicating artery
B. Posterior communicating artery
C. Middle cerebral artery
D. Internal carotid artery
E. Posterior cerebral artery

Answer 44

C. Middle cerebral artery

The arterial circle (of Willis) receives its blood supply from the internal carotid and vertebral arteries. The actual circle is formed by the bifurcation of the basilar, posterior cerebral, posterior communicating, internal carotid, anterior cerebral, and anterior communicating arteries. The middle cerebral artery is the lateral continuation of the internal carotid artery. Although it receives its blood supply from the arterial circle (of Willis), it does not actually form any part of the circle.

Question 45

A 45-year-old woman is admitted to the hospital for severe ear pain. Physical examination reveals chronic infection of the mastoid air cells (mastoiditis). The infection can erode the thin layer of the bone between the mastoid air cells and the posterior cranial fossa and spread most commonly into which of the following venous structures?
A. Superior sagittal sinus
B. Inferior sagittal sinus
C. Straight sinus
D. Cavernous sinus
E. Sigmoid sinus

Answer 45

E. Sigmoid sinus

The sigmoid venous sinus empties into the internal jugular vein and drains the cranial vault. It runs along the posterior cranial fossa near the suture between the temporal and occipital bones. The superior sagittal sinus lies within the superior aspect of the longitudinal fissure, between the two cerebral hemispheres. The inferior sagittal sinus runs inferior to the superior sagittal sinus within the falx cerebra and joins the great cerebral vein (of Galen) to form the straight sinus. The straight sinus drains the great cerebral vein (of Galen) into he confluence of sinuses. The cavernous sinus is located within the middle cranial fossa and receives the ophthalmic veins, the greater petrosal sinus, nd other venous vessels.

Question 46

A 63-year-old man with hearing loss in his left ear complains of a loss of taste and drooling from the left side of his mouth. A CT scan shows a tumor compressing the nerve entering the skull through which of the following openings?
A. Foramen ovale
B. Foramen rotundum
C. Internal acoustic meatus
D. Jugular foramen
E. Superior orbital fissure

Answer 46

C. Internal acoustic meatus

The tumor is compressing the facial nerve, which runs through the internal acoustic meatus along with the vestibulocochlear nerve, which provides sense of taste to the anterior two thirds of the tongue via the chorda tympani and also mediates all of the facial muscles except the muscles of mastication. The mandibular branch of the trigeminal nerve courses through the foramen ovale and mediates motor to the muscles of mastication and sensory to the lower third of the face. The maxillary branch of the trigeminal passes through the foramen rotundum and is sensory to the middle third of the face. The jugular foramen has the glossopharyngeal, vagus, and accessory nerves coursing through it. Finally, the superior orbital fissure has the ophthalmic branch of the trigeminal nerve coursing through it, along with the oculomotor, trochlear, and abducens nerves.

Question 47

A 70-year-old man has a biopsy of a growth on his lower lip. The biopsy reveals a squamous cell carcinoma. Which lymph nodes will most likely be first involved in the spread of the cancer cells?
A. Occipital
B. Parotid
C. Retropharyngeal
D. Jugulodigastric
E. Submental

Answer 47

E. Submental

The submental lymph nodes drain roughly the anterior two thirds of the mouth and tongue, including the lower lips. The occipital nodes serve the inferoposterior aspect of the head. The parotid nodes lie anterior to the ear and serve the region of the lateral aspect of the eye, the parotid gland, and anterior ear. The retropharyngeal nodes ie posterior to the pharynx and drain the posterior aspect of the throat and pharynx. The jugulodigastric node is a large node posterior to the parotid gland and just below the angle of the mandible, and it receives lymph from much of the face and scalp

Question 48

A 54-year-old man is admitted to the hospital due to severe headaches. A CT examination reveals an internal carotid artery aneurysm inside the cavernous sinus. Which of the following nerves would be typically affected first?
A. Abducens nerve
B. Oculomotor nerve
C. Ophthalmic nerve
D. Maxillary nerve
E. Trochlear nerve

Answer 48

A. Abducens nerve

The abducens nerve would be affected first due to aneurysmal dilation of the internal carotid artery (ICA) because the nerve runs in closest proximity to the artery within the cavernous sinus. The other nerves running in the wall of the cavernous sinus are the oculomotor nerve, trochlear nerve, and both the maxillary and ophthalmic branches of the trigeminal nerve. Each of these nerves, however, courses along, or within, the lateral wa Is of the cavernous sinus and may not be immediately affected by an aneurysm of the ICA.

Question 49

A 24-year-old male had a third molar (wisdom tooth) extracted from his lower jaw. This resulted in the loss of general sense and taste sensation from the anterior two thirds of the tongue. This loss was most likely due to injury of which of the following nerves?
A. Auriculotemporal
B. Chorda tympani
C. Lingual
D. Mental
E. Inferior alveolar

Answer 49

C. Lingual

The lingual nerve is the most likely nerve
damaged because there is loss both of taste and general sensory supply to the anterior two thirds of the tongue, which is innervated by the lingual nerve, which at this point has been joined by the chorda tympani. The chorda tympani would be a likely choice; however, it carries only taste and does not mediate other general sensation to the tongue. The auriculotemporal nerve is a posterior branch of the mandibular division of the trigeminal nerve and innervates skin near the ear and temporal region. The mental nerve is the terminal branch of the inferior alveolar nerve and innervates the skin of the chin.

Question 50

A 56-year-old worn n is admitted to the hospital with rheumatoid arthritis of her temporomandibular joint (TMJ) and severe ear pain. Which of the following nerves is most likely responsible for conducting the pain sensation?
A. Facial
B. Auriculotemporal
C. Lesser petrosal
D. Vestibulocochlear
E. Chorda tympani

Answer 50

B. Auriculotemporal

The auriculotemporal nerve is a posterior branch of the mandibular division of the trigeminal nerve. It encircles the middle meningeal artery and courses medially to the TMJ and then ascends up near the auricle. Because this nerve supplies the TMJ and skin of the external auditory canal, pain from the joint can be referred to the ear as in this case. The facial nerve courses over the ascending ramus of the mandible, passing superficial to the masseter muscle and below the TMJ through the parotid gland, and would not be involved in this problem. The lesser petrosal nerve courses through the middle cranial fossa and exits through the foramen ovale, where it joins the otic ganglion. The vestibulocochlear nerve exits the cranial cavity through the internal acoustic meatus and innervates structures in the inner ear. Finally, the chorda tympani is a branch of the facial nerve and joins the mandibular division of the trigeminal nerve anterior to the TMJ.

Question 51

Where is he location of the postganglionic parasympathetic neur 1 cell bodies that directly innervate the parotid gland?
A. Trigeminal (semilunar Gasserian) ganglion
B. Inferior salivatory nucleus
C. Superior cervical ganglion
D. Otic ganglion
E. Submandibular ganglion

Answer 51

D. Otic ganglion

The otic ganglion is the location of the postganglionic parasympathetic neural cell bodies innervating the parotid gland. The ganglion lies on the mandibular division of the trigeminal nerve near the foramen ovale. The trigeminal ganglion contains cell bodies for neurons innervating sensory aspects of the face. The inferior salivatory nucleus lies within the brainstem and contains preganglionic parasympathetic neurons whose axons pass within the lesser petrosal nerve to the otic ganglion for synapse in the supply of the parotid. The superior cervical ganglion has the cell bodies of postganglionic sympathetic fibers innervating sympathetic structures to the head. The submandibular ganglia contain the cell bodies of postganglionic parasympathetic fibers innervating the sublingual and submandibular salivary glands.

Question 52

The arachnoid villi allow cerebrospinal fluid to pass between which two of the following spaces?
A. Choroid plexus and subdural space
B. Subarachnoid space and superior sagittal sinus
C. Subdural space and cavernous sinus
D. Superior sagittal sinus and jugular vein
E. Epidural and subdural space

Answer 52

B. Subarachnoid space and superior sagittal sinus

The arachnoid villi are extensions of the arachnoid mater into the superior sagittal sinus. The villi allow for proper drainage of the CSF into the venous bloodstream from the subarachnoid space in which the CSF circulates. The villi are a crucial element in maintaining proper intracranial pressure and circulation of the CSF.

Question 53

A 22-year-old woman is admitted to the hospital with an injury to her eye. The corneal reflex is tested and found to be present. Which of the following nerves is responsible for the afferent limb of this reflex?
A. Frontal
B. Lacrimal
C. Nasociliary
D. Oculomotor
E. Optic

Answer 53

C. Nasociliary

The afferent/sensory limb of the corneal (blink) reflex is carried by the nasociliary nerve. It is a branch of the ophthalmic division of the trigeminal nerve. The frontal and lacrimal nerves provide cutaneous supply to parts of the orbit and face, but they do not innervate the cornea. The facial nerve is the efferent limb of the corneal reflex and mediates the closing of both eyes in response to irritation of the cornea. The oculomotor nerve mediates the reopening of the eyes by contraction of the levator palpebrae superioris. The optic nerve also innervates the eye for the sense of vision and is the afferent limb of the pupillary light reflex.

Question 54

A 21-year-old man was brought to the emergency department because of severe epistaxis (nosebleed) from the nasal septum. This area, knows as Kiesselbach’s (or Little’s) area, involves mostly anastomoses between which of the following arteries?
A. Ascending palatine and ascending pharyngeal
B. Posterior superior alveolar and accessory
meningeal
C. Lateral branches of posterior ethmoidal and
middle meningeal
D. Septal branches of the sphenopalatine and superior labial
E. Descending palatine and tonsillar branches of
the pharyngeal

Answer 54

D. Septal branches of the sphenopalatine and superior labial

Kiesselbach (also called Little) plexus is an anastomosis of four arteries on the anterior nasal septum. The four arteries are the anterior ethmoidal artery, sphenopalatine artery, superior labial artery, and greater palatine artery. The two largest contributors, however, are the septal branches of the sphenopalatine (from the maxillary artery) and superior labial arteries (branches of the facial artery, which in turn is a branch of the external carotid artery).

Question 55

An 11-year-old boy is examined by an ENT doctor for his swollen palatine tonsils. The palatine tonsils are located between the anterior and posterior tonsillar pillars. Which of the following muscles form these pillars?
A. Levator veli palatini and tensor veli palatini
B. Palatoglossus and palatopharyngeus
C. Styloglossus and stylopharyngeus
D. Palatopharyngeus and salpingopharyngeus
E. Superior and middle pharyngeal constrictors

Answer 55

B. Palatoglossus and palatopharyngeus

The palatine tonsils lie in tonsillar beds with muscular (covered with mucosa) anterior and posterior pillars forming the boundaries of the bed. These pillars are formed by the palatoglossal arch, anteriorly, and the palatopharyngeal arch posteriorly. The anterior pillar, part of the palatoglossal arch, contains the palatoglossus muscle; the posterior pillar, provided by the palatopharyngeal arch, is formed by the palatopharyngeus muscle.

Question 56

A 35-year-old female is under general anesthesia. Prior to laryngeal intubation the rima glottides is opened by which pair of muscles?
A. Posterior cricoarytenoids
B. Lateral cricoarytenoids
C. Thyroarytenoids
D. Transverse arytenoids
E. Cricothyroids

Answer 56

A. Posterior cricoarytenoids

The posterior cricoarytenoid muscles lie on the superoposterior aspect of the lamina of the cricoid cartilage. When these muscles contract, they cause lateral rotation (abduction) of the vocal processes of the arytenoid cartilages, thereby opening the space between the vocal folds, the rima glottidis. The lateral cricoarytenoid is involved with adducting the arytenoid cartilage and closing the rima glottidis. The thyroarytenoid muscles lie alongside either vocal ligament and are also involved in adducting the vocal folds. The transverse arytenoid muscle connects both arytenoid cartilages and also aids in closing the rima glottidis. Finally, the cricothyroid muscle is located on the anterior aspect of the cricoid cartilage and aids in elongation and tensing of the vocal folds.

Question 57

A 32-year-old female patient asks you what is the
soft, thin ridge of tissue that she can feel running forward across the masseter muscle toward her upper lip. You reassure her that is perfectly normal. Which of the following is the most likely structure she is feeling?
A. Facial artery
B. Maxillary artery
C. Parotid duct
D. Marginal mandibular branch of facial nerve
E. Facial vein

Answer 57

C. Parotid duct

The parotid duct, also known as the Stensen’s duct, crosses the masseter muscle transversely and extends to the oral cavity. The facial artery can be palpated in the groove anterior to the mandibular angle. The facial vein lies anterior to the artery, passing toward the angle of the lips, but does not ascend in close proximity to the masseter. All of the other vessels are located more deeply and cannot be palpated.

Question 58

A 43 year-old man is diagnosed with laryngeal carcinoma. A surgical procedure is performed and the tumor is successfully removed from the larynx. The right ansa cervi alis is anastomosed with the right recurrent laryngeal nerve in order to reinnervate the muscles of the larynx and restore phonation. Which of the following muscles will most likely be paralyzed after this operation?
A. Sternocleidomastoid
B. Platysma
C. Sternohyoid
D. Trapezius
E. Cricothyroid

Answer 58

C. Sternohyoid

Because of the surgical division of the ansa cervicalis, the sternohyoid muscle will most likely be paralyzed following this tumor resection. The ansacervicalis innervates the strap muscles, including the sternohyoid, sternothyroid, and omohyoid muscles. The sternocleidomastoid is innervated by the accessory nerve, the spinal accessory nerve, and would not be involved with this surgery. The platysma is located most superficially on the neck and is innervated by cervical branch of the facial nerve. The trapezius muscle is also innervated by the spinal accessory nerve and plays no role in ansa cervicalis functions. Finally, the cricothyroid muscle is innervated by the external laryngeal branch of the vagus and would not be affected by the surgery.

Question 59

A 67-year-old female is admitted to the emergency department with a severe swelling on the right side of her neck. An MRI examination reveals an abscess. The abscess is surgically removed from the middle of the posterior cervical triangle on the right side. During recovery the patient notices that her shoulder droops and she can no longer raise her right hand above her head to brush her hair. Which of the following nerves has most likely been iatrogenically injured?
A. Accessory
B. Ansa cervicalis
C. Facial
D. Hypoglossal
E. Suprascapular

Answer 59

A. Accessory

The spinal accessory nerve passes across the
posterior triangle of the neck and innervates both the trapezius muscle and the sternocleidomastoid muscle for the respective side of the body. Upon surgical division of the nerve, the patient will lose the ability to raise the respective shoulder and will demonstrate weakness in turning the head to the opposite side. The trapezius will also lose tone and the shoulder will droop. The ansa cervicalis innervates strap muscles of the neck and, if cut, would not produce drooping of the shoulder. The facial nerve does not pass through any of the triangles of the neck; however, if it were divided, paralysis would result in the muscles of facial expression. The hypoglossal nerve innervates the intrinsic muscles of the tongue, plus the genioglossus, hyoglossus, and styloglossus and, if injured, would not result in any of the patient’s symptoms.

Question 60

A 20-year old man is admitted o the emergency
department with a stab wound in the superior region of his neck. A radiographic examination reveals that the wound has not affected any major structures. Physical examination reveals that the patient has lost sensation from the skin over the angle of the jaw. Which of the following nerves is most likely injured?
A. Supraclavicular
B. Transverse cervical
C. Great auricular
D. Greater occipital
E. Lesser occipital

Answer 60

C. Great auricular

Four nerves particip te in providing cutaneous supply to the neck. The nerves are the supraclavicular, great auricular, transverse cervical, and the lesser occipital. The area over the angle of the jaw is innervated by the great auricular nerve. It ascends from spinal segments from C2 and C3 and innervates the skin over the angle of the j w and posteroin erior to the auricle of the ear The transverse cervical also originates from C2-3 spin 1 segments but passes anteriorly to innervate the anterior and lateral aspects of the neck. The lesser occipital nerve innervates skin in the area of the back of the neck and posterior occiput. The supraclavicular nerves orig nate from C3-4 and innervate the more inferior aspects of the neck, the upper deltoid region, and skin inferior to the clavicles.

Question 61

A 6-year-old male child, whose medical history includes a complicated delivery, has a permanently tilted head posture, with the right ear near the right shoulder and the face turned upward and to the left. Which of the following muscles was most likely damaged during birth?
A. Anterior scalene
B. Omohyoid
C. Sternocleidomastoid
D. Trapezius
E. Platysma

Answer 61

C. Sternocleidomastoid

Because of its size and vulnerable position during birth, the sternocleidomastoid muscle is injured more often than other muscles of the head and neck during birth. When acting alone, the action of this muscle is to turn the head to the opposite side and bend it toward the ipsilateral shoulder. When using both muscles, the head will flex toward the chest. Therefore, the most likely muscle to have been injured here is the left sternocleidomastoid muscle.

Question 62

A 35-year-old woman is admitted to the emergency department after a violent automobile crash. The patient’s upper airway is obstructed with blood and mucus, and a midline tracheotomy inferior to the thyroid isthmus is performed. Which of the following vessels are most likely to be present at the site of incision and will need to be cauterized?
A. Middle thyroid vein and inferior thyroid
artery
B. Inferior thyroid artery and inferior thyroid
vein
C. Inferior thyroid vein and thyroidea ima artery
D. Cricothyroid artery and inferior thyroid vein
E. Left brachiocephalic vein and inferior thyroid
artery

Answer 62

C. Inferior thyroid vein and thyroidea ima artery

The most likely structures one would encounter while performing a midline incision below the isthmus of the thyroid gland would be the inferior thyroid vein and the thyroidea ima arte y. The inferior thyroid vein drains typically to the left brachiocephalic vein, which crosses superficially, just inferior to the isthmus. The thyroidea ima artery arises from the aortic arch, vertebral artery, or other source but is not a constant structure. The middle thyroid veins drain the thyroid gland to the in ernal jugular vein and are superior to the incision site. The inferior thyroid arteries branch from either subclavian artery and meet the thyroid gland at an oblique angle. They would not be ligated with a midline incision The brachiocephalic veins are inferior to the site of incision.

Question 63

A 34-year-old woman is admitted to the hospital
with a large mass at her thyroid gland. Ultrasound examination reveals a benign tumor. Twenty-four hours following a partial thyroidectomy, in which the inferior thyroid artery was also ligated, the patient speaks with a hoarse voice and has difficulty in breathing on exertion. Which of the following nerves was most likely injured during the surgical procedure?
A. Internal branch of superior laryngeal
B. Ansa cervicalis
C. Ansa subclavia
D. Recurrent laryngeal
E. External branch of superior laryngeal

Answer 63

D. Recurrent laryngeal

The recurrent laryngeal nerve is the most likely nerve damaged during the surgery because it runs in close proximity to the inferior thyroid artery and is easily injured or transected with the artery if extreme care is not exercised during operative procedures. The recurrent laryngeal nerve innervates the majority of the vocal muscles that open and close the rima glottidis, in addition to providing sensory supply to the larynx below the vocal folds. Even relatively mild trauma to the nerve can result in hoarseness. The internal branch of the superior laryngeal nerve is not in close proximity to the inferior thyroid artery and pierces the thyrohyoid membrane to enter the pharynx. The ansa cervicalis lies lateral to the site of surgery and does not innervate any structures that, if paralyzed, would cause hoarseness.

Question 64

A 55-year-old woman is admitted to the hospital
with difficulty swallowing. Physical examination reveals that the patient has episodes of severe headaches and frequently aspirates fluids when drinking them. A radiographic examination reveals a skull base tumor occupying the space behind the jugular foramen. Involvement of which of the following structures is most likely responsible for the findings in the patient?
A. Ansa cervicalis
B. Cervical sympathetic trunk
C. External laryngeal nerve
D. Hypoglossal nerve
E. Vagus nerve

Answer 64

E. Vagus nerve

The vagus nerve exits the skull at the jugular
foramen and is responsible for motor innervation to the smooth muscles of the trachea, bronchi, and digestive tract, in addition to the muscles of the palate, pharynx, larynx, and superior two thirds of the esophagus. The ansa cervicalis innervates the strap muscles of the neck, with the exception of the thyrohyoid muscle. The cervical sympathetic trunk does not enter into the jugular foramen; it runs behind the carotid sheath, parallel with the internal carotid artery; its carotid branch accompanies the artery into the carotid canal and carries sympathetic fibers to deep areas of the head. Damage to theexternal laryngeal nerve would result in paralysis of the cricothyroid muscle, presenting as an easily fatigued voice with hoarseness. Injury to the hypoglossal nerve would result in protrusion of the tongue toward the affected side and moderate dysarthria.

Question 65

A 5-year-old woman is admitted to the hospital
with severe hyper ension. Laboratory examination reveals hypertension (190/110 mm Hg) and hypercholesterolemia (250 mg/dl). During physical examination the patient complains of headaches and dizziness. Radiographic examination reveals 90% occlusion of both common carotid arteries A carotid endarterectomy is performed and large atherosclerotic plaques are removed. During a postoperative physical examination on the right side, it was noted that her tongue deviated toward the right when she was asked to stick it out. Which of the following nerves was most likely injured during the procedure?
A. Right glossopharyngeal
B. Right hypoglossal
C. Left hypoglossal
D. Left lingual
E. Left vagus

Answer 65

B. Right hypoglossal

The hypoglossal nerve provides motor innervation to the muscles of the tongue, with the exception of the palatoglossus. Injury to the hypoglossal nerve would result in deviation of the tongue toward the affected side when the tongue is protruded (in this case the right side), due mainly to the unilateral contraction of left genioglossus, and moderate dysarthria. Injury to the glossopharyngeal nerve would result in loss of taste in the posterior third of the tongue and a loss of soft palate sensation and gag reflex on the affected side. The inferior alveolar nerve supplies the tissues of the chin and lower teeth. The lingual nerve conveys parasympathetic preganglionic fibers to the submandibular ganglion and general sensation and taste fibers for the anterior two thirds of the tongue. Injury to the vagus nerve would cause sagging of the soft palate, deviation of the uvula to the unaffected side, hoarseness, and difficulty in swallowing and speaking.

Question 66

A 34-year-old woman is admitted to the hospital
with a large mass in her lower anterior neck. Ultrasonic examination reveals a benign tumor of her thyroid gland. Twenty-four hours following a partial thyroidectomy, it was noted that the patient frequently aspirates fluid into her lungs. Upon examination it was determined that the area of the piriform recess above the vocal fold of the larynx was anesthetized. Which of the following nerves was most likely iatrogenically injured?
A. External branch of the superior pharyngeal
B. Hypoglossal
C. Internal branch of the superior laryngeal
D. Lingual
E. Recurrent laryngeal

Answer 66

C. Internal branch of the superior laryngeal

During removal of the tumor, the internal branch of the superior laryngeal nerve was injured. Injury to this nerve results in loss of sensation above the vocal cords, at the entrance to the larynx, and loss of taste on the epiglottis. Loss of sensation in the laryngeal vestibule can precipitate aspiration of fluid into the larynx, trachea, and lungs. The pharyngeal nerve of the vagus supplies motor innervation to the muscles of the pharynx except the stylopharyngeus (glossopharyngeal nerve). Injury to the hypoglossal nerve would result in protrusion of the tongue toward the affected side and moder te dysarthria. The lingual nerve conveys parasympathetic preganglionic fibers to the submandibular ganglion and general sensation and taste fibers for the anterior two thirds of the tongue. The recurrent laryngeal provides sensory fibers to the larynx below the vocal cords and motor fibers to all of the muscles of the larynx except for the cricothyroid.

Question 67

A 38-year-old man is admitted to the hospital
with a large mass in his lower anterior neck. Ultrasonic examination reveals a benign tumor of his thyroid gland. Twenty-four hours following a partial thyroidectomy, it was noted that the patient could not abduct the true vocal cords due to a nerve injury during the operation. Which of the following muscles was most likely dennervated?
A. Posterior cricoarytenoid
B. Lateral cricoarytenoid
C. Thyroarytenoid
D. Arytenoid
E. Cricothyroid

Answer 67

A. Posterior cricoarytenoid

The posterior cricoarytenoids are the only muscle of the larynx that abducts the vocal cords. The remaining answer choices are muscles that act in adduction of the vocal cords.