STEP1 Exam Questions and Answers | Exam-Dumps (Page: 9)

QUESTION: 41

A 19-year-old man was in a barroom brawl and was punched squarely in the right eye. He comes to the emergency room the next day and complains of diplopia. An X-ray reveals fracture of the orbital floor. Neurological examination shows loss of sensation of the skin of the right face below the right eye and the upper gums. Which of the following nerves may be injured?

frontal nerve
infraorbital nerve
nasociliary nerve
supraorbital nerve
trochlear nerve

Answer(s): B

Explanation:

The infraorbital nerve, a branch of the maxillary (V2) division of the trigeminal (fifth cranial) nerve, courses below the orbital floor to reach the area of skin below the eye. It provides superior alveolar branches to supply the upper gums and is vulnerable in fractures involving the floor of the orbit and face area. All the nerves mentioned in the other choices will be spared by this type of injury. The frontal nerve (choice A) and nasociliary nerve (choice C) are branches from the ophthalmic division (V1) of the trigeminal (fifth cranial) nerve and course within the orbit. The supraorbital (choice D) nerve is a continuation branch of the frontal nerve onto the forehead, providing sensory innervation for this area. The trochlear (fourth cranial) nerve is also located within the orbit.

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QUESTION: 42

Cells in the pancreas that secrete glucagon and insulin are which of the following?

A and B cells
acinar cells
D cells
pancreatic D1 cells
pancreatic polypeptide cells

Answer(s): A

Explanation:

In the human pancreas, A and B cells of the islets of Langerhans secrete glucagon and insulin, respectively. Pancreatic D1 cells (choice D) release a product similar to vasoactive intestinal polypeptide.
Pancreatic polypeptide cells (choice E) secrete pancreatic polypeptide and D cells (choice C) release somatostatin. All the aforementioned cells belong to the endocrine pancreas. Acinar cells (choice B) are part of the exocrine pancreas and do not secrete glucagon or insulin.

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QUESTION: 43

Below figure is a high magnification photomicrograph of the gall bladder. The arrow points to the internal lining that is formed by which of the following?

pseudostratified columnar epithelium
simple columnar epithelium
stratified cuboidal epithelium
stratified squamous epithelium
transitional epithelium

Answer(s): B

Explanation:

The lining of the gallbladder is a simple columnar epithelium identifiable by tall cells with elongated nuclei arranged at the same level. Pseudostratified epithelium (choice A) is distinguishable from the simple columnar epithelium by the cell nuclei being arranged at different levels. Stratified cuboidal epithelium (choice C) is characterized by short cells with nuclei arranged at different levels. Stratified epithelium (choice D) has a characteristic cellular basal layer with flat degenerate cells in its upper layer. Transitional epithelium (choice E) is a type of stratified epithelium exclusively confined to the urinary tract.

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QUESTION: 44

During surgery at the root of the neck, an attending surgeon cautions her resident to locate important structures which need to be protected. One of these is the phrenic nerve, responsible for the innervation of the diaphragm and thus, respiration. The phrenic nerve can be positively identified by which of the following anatomical relationships?

It is found immediately between the common carotid artery and the internal jugular vein.
It lies immediately between the esophagus and the trachea.
It lies on the scalenus medius muscle.
It wraps around the right subclavian artery.
The suprascapular and transverse cervical arteries cross over it anteriorly.

Answer(s): D

Explanation:

At the root of the neck, the phrenic nerve (C3, C4, C5) lies on the scalenus anterior muscle, not the scalenus medius (choice C). The transverse cervical and suprascapular arteries course over it. The vagus (tenth cranial) nerve, not the phrenic nerve is located between the common carotid artery and the internal jugular vein (choice A). The recurrent laryngeal branch from the vagus nerve wraps around the right subclavian artery (choice D), and courses cranially between the esophagus and the trachea (choice B).

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QUESTION: 45

A premature female infant is born about 24 weeks after fertilization and develops rapid, labored breathing shortly after birth. She is immediately transferred to intensive care where she is diagnosed with hyaline membrane disease (HMD). Which of the following is most likely deficient in the infant?

alveolar ducts
lung surfactant
terminal saccules
type I alveolar cells
type II alveolar cells

Answer(s): D

Explanation:

HMD is also known as respiratory distress syndrome, which is most often caused by the lack of lung surfactant, due to a premature birth. Lung surfactant production begins around 20 weeks after fertilization.
But it is present only in small amounts until the last 2 weeks before birth when its amount increases significantly. Alveolar ducts (choice A) branch from the respiratory bronchioles during development. Type I alveolar cells (choice D) or pneumocytes are squamous epithelial cells, which participate in gas exchange.
These epithelial cells line the terminal saccules (choice C). Type II alveolar cells (choice E) synthesize surfactant.

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USMLE STEP1 Exam (page: 9) USMLE Step1 Updated on: 15-Feb-2026

QUESTION: 41

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QUESTION: 42

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QUESTION: 43

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QUESTION: 44

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QUESTION: 45

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USMLE STEP1 Exam (page: 9)
USMLE Step1
Updated on: 15-Feb-2026