USMLE Step 1 Qs (6)
Questions from various sources for practicing
- 1.
. The accompanying diagram shows a cross section of a developing human endometrium and myometrium. Hormonal ratios control the development of which of the labeled vessels?- A.
A
- B.
B
- C.
C
- D.
D
- E.
E
- 2.Which of the following statements is true of the uterus during the menstrual cycle?
- A.
Progesterone secretion initiates proliferation in the endometrium
- B.
Estrogen secretion stimulates secretory changes in the endometrium
- C.
Cessation of estrogen and progesterone secretion results in the degeneration of the endometrium
- D.
Incorporation of 3H-thymidine in the uterus of an experimental animal would occur primarily during the secretory phase
- E.
Studies with an antibody to the estrogen receptor would demonstrate a peak in immunocytochemically positive endometrial cells after involution of the corpus luteum
- 3.
In the accompanying transmission electron micrograph of the renal corpuscle, which of the following is the function of the cell marked with an asterisk?
- A.
Synthesize extracellular matrix for support of the capillary wall
- B.
Exert an antithrombogenic effect
- C.
Synthesize vasoactive factors
- D.
Separate the urinary space and the blood in the capillaries
- E.
Form the filtration slits through the interdigitations of the pedicels
- 4.Which of the following is found exclusively in the renal medulla?
- A.
Proximal convoluted tubules
- B.
Distal convoluted tubules
- C.
Collecting ducts
- D.
Afferent arterioles
- E.
Thin loops of Henle
- 5.In the surgical procedure known as radial keratotomy, slits are made in the cornea to flatten it slightly. Which of the following will most likely result?
- A.
Decreased refraction of light by the cornea
- B.
A decreased amount of light entering through the cornea
- C.
Conversion of the cornea from a "stationary" to an "adjustable" form of refraction
- D.
Maintenance of the lens in a more flattened state
- E.
Focusing of light on the retina at a point other than the fovea
- 6.Retinal detachment most commonly results from which of the following?
- A.
Local swelling in specific retinal layers
- B.
Leakage of blood from the inner retinal capillaries
- C.
Fluid accumulation between the retina and the retinal pigment epithelium (RPE)
- D.
Impaired pumping of water toward the photoreceptors by the retinal pigment epithelium
- E.
Increased phagocytosis of outer segments by the retinal pigment pithelial cells
- 7.Which of the following occurs in diabetic retinopathy?
- A.
Reduction in the thickness of the basal lamina of small retinal vessels
- B.
Microaneurysms
- C.
Decreased capillary permeability
- D.
Increased retinal blood flow
- E.
Loss of phagocytic ability of the pigmented epithelium
- 8.Which of the following is directly involved in sound transduction?
- A.
Release of neurotransmitter onto the afferent endings of cranial nerve VIII
- B.
Shearing motion of the basilar membrane against hair cell stereocilia
- C.
Movement of the tectorial membrane resulting in hair cell depolarization
- D.
Equalization of the pressure in the middle ear and nasopharynx by the Eustachian tube
- E.
Vibration at the round window via the stapes
- 9.Perilymph is located in which of the following structures?
- A.
Utricle
- B.
Saccule
- C.
Semicircular canals
- D.
Scala media
- E.
Scala tympani
- 10.Which of the following is the function of the vestibular membrane?
- A.
Maintain the gradient between the endolymph and the perilymph
- B.
Maintain communication between the tympanic and vestibular cavities
- C.
Transmit sound to the oval window
- D.
Maintain the concentration gradient necessary for sensory transduction
- E.
Dampen the action of the auditory ossicles
- 11.Detection of angular acceleration is accomplished by which of the following structures?
- A.
Maculae of the utricle and saccule
- B.
Hair cells of the organ of Corti
- C.
Cristae ampullaris of the semicircular canals
- D.
Interdental cells
- E.
Pillar cells
- 12.A 28-year-old man is treated in an emergency room for a superficial gash on his forehead. The wound is bleeding profusely, but examination reveals no fracture. While the wound is being sutured, he relates that while he was using an electric razor, he remembers becoming dizzy and then waking up on the floor with blood everywhere. The physician suspects a hypersensitive cardiac reflex. The patient's epicranial aponeurosis (galea aponeurotica) is penetrated, which results in severe gaping of the wound. Which of the following is the structure overlying the epicranial aponeurosis?
- A.
A layer containing blood vessels
- B.
Bone
- C.
The dura mater
- D.
The periosteum (pericranium)
- E.
The tendon of the epicranial muscles (occipitofrontalis)
- 13.Which pair of venous structures contributes to the confluence of dural sinuses on the interior surface of the occipital bone?
- A.
Sigmoid and transverse sinuses
- B.
Inferior sagittal and cavernous sinuses
- C.
Occipital and straight sinuses
- D.
Transverse and inferior petrosal sinuses
- E.
Superior petrosal and occipital sinuses
- 14.Which of the following is the most direct route for spread of infection from the paranasal sinuses to the cavernous sinus of the dura mater?
- A.
Pterygoid venous plexus
- B.
Superior ophthalmic vein
- C.
Frontal emissary vein
- D.
Basilar venous plexus
- E.
Parietal emissary vein
- 15.A 55-year-old man was brought into the hospital with a severe burn to his left hand. The man had placed his hand on the hot burner of an electric stove but had not sensed anything wrong until he smelled burning flesh. Neurologic examination revealed loss of pain and temperature sensation over dermatomes C4 through T6 bilaterally. However, pain and temperature were perceived bilaterally both above C4 and below T6. Discriminative touch was present in unburned dermatomes on the left and in the right extremity. Although the left hand was too damaged to accurately assess muscle function, weakness and wasting of small muscles of the right hand was noted. Muscle strength and reflexes were otherwise normal. Pain and temperature sensations from the extremities ascend in the spinal cord in which of the following?
- A.
Intermediolateral cell column
- B.
Cuneate fasciculus
- C.
Lateral spinothalamic tract
- D.
Dorsal columns
- E.
Fasciculus gracilis
- 16.The vertebral arteries are correctly described by which of the following statements?
- A.
They arise from the common carotid artery on the left and the brachiocephalic artery on the right
- B.
They enter the cranium via the anterior condylar canals
- C.
They enter the cranium via the posterior condylar canals
- D.
They pass through the transverse processes of several cervical vertebrae
- E.
They directly give rise to the posterior cerebral arteries
- 17.A cranial fracture through the foramen rotundum that compresses the enclosed nerve results in which of the following?
- A.
Inability to clench the jaw firmly
- B.
Loss of the sneeze reflex
- C.
Paralysis of the inferior oblique muscle of the orbit
- D.
Regurgitation of fluids into the nasopharynx during swallowing
- E.
Uncontrolled drooling from the mouth
- 18.. A 72-year-old male presents in the Emergency Room with dizziness and nystagmus. Examination reveals a loss of pain and temperature sensation over the right side of the face and the left side of the body. The patient exhibits ataxia and intention tremor on the right in both the upper and lower extremities and is unable to perform either the finger-to-nose or heel-to-shin tasks on the right. In addition, he is hoarse and demonstrates pupillary constriction and drooping of the eyelid on the right. Finally, the right side of his face is drier than the left. Following vascular blockage, necrotic damage in which of the following would explain the patient's hoarseness?
- A.
Nucleus ambiguus
- B.
Lateral spinothalamic tract
- C.
Spinal nucleus of CN V
- D.
Descending sympathetic pathways
- E.
Inferior cerebellar peduncle
- 19.The pterygomandibular raphe is a useful landmark in the oral cavity. This tendinous tissue marks the juncture of two muscles that are innervated by which of the following cranial nerves?
- A.
Maxillary (CN V2) and mandibular (CN V3)
- B.
Mandibular (CN V3) and glossopharyngeal (CN IX)
- C.
Mandibular (CN V3) and vagus (CN X)
- D.
Facial (CN VII) and glossopharyngeal (CN IX)
- E.
Facial (CN VII) and vagus (CN X)
- 20.A 63-year-old woman was brought into the emergency room by her son, who suspected she had suffered a stroke the previous night. Subsequent examination revealed spastic hemiplegia on the left side with hyperreflexia and a positive Babinski's sign. The left side of the patient's face was paralyzed below the eye, and the right eye was turned out and down. The right pupil made direct and consensual responses to light, but the left pupil was fixed and unresponsive. There were no apparent sensory deficits. Which of the following is the most likely location of the lesion?
- A.
Left motor cortex
- B.
Right sensory cortex
- C.
Right midbrain
- D.
Left thalamus
- E.
Right thalamus
- 21.A 75-year-old man was rushed to the hospital from his retirement community when he suddenly became confused and could not speak but could grunt and moan. The patient could follow simple commands and did recognize his wife and children although he could not name them or speak to them. Additional immediate examination revealed weakness of the right upper extremity. Several days later, a more comprehensive examination revealed weakness and paralysis of the right hand and arm with increased biceps and triceps reflexes. Paralysis and weakness were also present on the lower right side of the face. Pain, temperature, and touch modalities were mildly decreased over the right arm, hand, and face, and proprioception was reduced in the right hand. The patient had regained the ability to articulate with great difficulty a few simple words but could not repeat even simple two or three word phrases. Which artery or major branch of a large artery suffered the occlusion that produced the observed symptoms?
- A.
Anterior choroidal artery
- B.
Middle cerebral artery
- C.
Posterior communicating artery
- D.
Ophthalmic artery
- E.
Anterior cerebral artery
- 22.. A 53-year-old banker develops paralysis on the right side of the face, which produces an expressionless and drooping appearance. He is unable to close the right eye and also has difficulty chewing and drinking. Examination shows loss of blink reflex in the right eye to stimulation of either right or left conjunctiva. Lacrimation appears normal on the right side, but salivation is diminished and taste is absent on the anterior right side of the tongue. There is no complaint of hyperacusis. Audition and balance appear to be normal. Which of the following is the most likely location of the lesion?
- A.
In the brain and involves the nucleus of the facial nerve and superior salivatory nucleus
- B.
Within the internal auditory meatus
- C.
At the geniculate ganglion
- D.
In the facial canal just distal to the genu of the facial nerve
- E.
Just proximal to the stylomastoid foramen
- 23.
The dark structure in the midbrain indicated by the arrow in this midsagittal MRI represents a passage for which of the following?
- A.
Venous blood
- B.
Arterial blood (in the basilar artery)
- C.
Neurons of the corticospinal tract
- D.
Cerebrospinal fluid
- E.
Spinothalamic (sensory) fibers
- 24.Which of the following is true of neural tube development?
- A.
Closure of the neural tube proceeds in a craniocaudal sequence
- B.
The basic organization of the neural tube features peripheral neuronal cell bodies and centrally located myelinated processes
- C.
The primitive neurectoderm cells of the neural tube give rise to both neurons and all glial components
- D.
During development, neuronal and glial precursors are born near the central canal and migrate to the periphery
- E.
Mature neurons migrate out of the spinal cord to form the sensory ganglia
- 25.Which of the following structures is found in the lateral wall of the tonsillar fossa?
- A.
Facial nerve
- B.
Glossopharyngeal nerve
- C.
Hypoglossal nerve
- D.
Lingual nerve
- E.
Vagus nerve
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