A few days after a summer hiking trip, a 25-year-old man comes to the clinic with a rash. On examination, the nurse notes that the rash is red and circular with central clearing, and is located across his midriff and behind his knees. The nurse suspects:

Correct Answer: B

Rationale: The correct answer is B: Lyme disease. The presentation of a red circular rash with central clearing, known as erythema migrans, following a hiking trip in the summer is highly indicative of Lyme disease. The specific distribution of the rash across the midriff and behind the knees aligns with typical areas where the rash appears in Lyme disease cases. This rash is a hallmark sign of early Lyme disease caused by the bacterium Borrelia burgdorferi transmitted through the bite of an infected tick. Other answer choices are incorrect because rubeola presents with a different rash pattern, an allergy to mosquito bites would not typically present in this manner, and Rocky Mountain spotted fever typically presents with a different rash appearance and distribution.

Correct Answer: C

Rationale: The correct answer is C: Allergic rhinitis. The patient's symptoms of rhinorrhea, itching, and sneezing, along with pale, swollen turbinates and clear rhinorrhea, are indicative of allergic rhinitis. Allergic rhinitis is characterized by an allergic response to allergens, leading to inflammation of the nasal passages and increased mucus production. Nasal polyps (choice A) typically present with nasal congestion and reduced sense of smell. Acute sinusitis (choice B) would likely present with purulent nasal discharge and facial pain/pressure. Nasal carcinoma (choice D) is unlikely in this case due to the patient's symptoms and age.

Correct Answer: B

Rationale: Correct Answer: B Rationale: 1. Rubbing alcohol or 2% acetic acid eardrops help to maintain the pH balance in the ear canal, making it less conducive to bacterial growth. 2. These eardrops also help to dry out excess moisture, reducing the risk of otitis externa. 3. By using these eardrops after every swim, the student can prevent the recurrence of otitis externa. Summary of other choices: A: Using a cotton-tipped swab can push wax deeper into the ear canal, increasing the risk of infection. C: Irrigating the ears can introduce water into the ear canal, potentially worsening the condition. D: Mineral oil and hydrogen peroxide can be harsh on the delicate skin of the ear canal, causing irritation.

Correct Answer: B

Rationale: The correct answer is B: hyphema. Hyphema is the presence of blood in the anterior chamber of the eye, which can occur due to trauma like being hit with a baseball bat. This indicates bleeding inside the eye, specifically in the space between the cornea and iris. Hypopyon (A) is the accumulation of white blood cells in the anterior chamber. Corneal abrasion (C) is a scratch on the cornea, not related to blood in the anterior chamber. Iritis (D) is inflammation of the iris, which does not necessarily involve blood in the anterior chamber.

Correct Answer: D

Rationale: The correct answer is D: convergence of the axes of the eyes. During the accommodation response, the eyes converge to focus on a near object. This is necessary to maintain clear vision when looking at close objects. Dilation of the pupils (A) is not part of the accommodation response. A consensual light reflex (B) refers to both pupils constricting simultaneously in response to light, not specific to accommodation. Conjugate movement of the eyes (C) refers to both eyes moving together in the same direction, which is not the primary action during accommodation.

Correct Answer: A

Rationale: The correct answer is A: At birth, the head is one fifth the total length. This is because newborns have relatively larger heads compared to their body size. This is known as cephalocaudal growth, where development starts from the head and progresses down the body. The head being one-fifth of the total length is a normal proportion in newborns. Choice B is incorrect because at birth, the chest circumference is usually greater than the head circumference. Choice C is incorrect as the head size reaches about 80% of its final size by age 2, not 3 years old. Choice D is incorrect because the closure of the anterior fontanelle at 2 months does not necessarily mean the head will appear proportionate to the body; it continues to grow in proportion to the body size.

Correct Answer: D

Rationale: The correct answer is D because it provides an accurate explanation for the frequent ear infections in the 2-year-old. The eustachian tube in children is indeed shorter and wider compared to adults, making it easier for infections to develop. This anatomical difference predisposes young children to ear infections. Choice A is incorrect because it falsely implies that frequent ear infections in small children are unusual only if something else is wrong. Choice B is incorrect as checking the immune system is not typically the first step in addressing recurrent ear infections. Choice C is incorrect as cerumen (earwax) does not directly contribute to ear infections in the middle ear.

Correct Answer: C

Rationale: The correct answer is C because the trigeminal (CN V) and the trochlear (CN IV) nerves are indeed stimulated when the outer surface of the eye is stimulated. The trigeminal nerve is responsible for the sensation of touch in the face and controls the muscles involved in chewing. The trochlear nerve controls the superior oblique muscle of the eye, which helps with downward and inward eye movements. Therefore, when the outer layer of the eye is touched or stimulated, these nerves are activated to convey the sensation to the brain. Choices A, B, and D are incorrect: A: The outer layer of the eye is not particularly sensitive to touch compared to other areas like the cornea or conjunctiva. B: The outer layer of the eye is not darkly pigmented; the pigmented layer is actually the uvea inside the eye. D: The visual receptive layer of the eye, known as the retina, is located deeper within the eye, not

Correct Answer: C

Rationale: The correct answer is C: cephalhematoma. A cephalhematoma is a collection of blood between a baby's skull and the periosteum, typically occurring due to trauma during birth. In this case, the lump appeared 8 hours after birth, which aligns with the timeline for cephalhematoma development. It is soft because it consists of blood, and it can increase in size as the blood accumulates. Incorrect Choices: A: Hydrocephalus is an abnormal accumulation of cerebrospinal fluid within the brain, not a collection of blood. B: Craniosynostosis is the premature fusion of skull bones, leading to an abnormal head shape, not a collection of blood. D: Caput succedaneum is swelling of the soft tissues of a newborn's scalp due to pressure during delivery, not a collection of blood.