A 2-year-old male patient develops progressive generalized weakness and muscle atrophy. The impairment first began with the muscles of the hips, and then progressed to the pelvic area, thigh, and shoulder muscles. The patient is diagnosed with Duchenne's muscular dystrophy, a congenital disorder where the protein dystrophin is deficient. Which of the following describes the role of dystrophin in muscle tissue?
Answer(s): A
Dystrophin anchors actin to the sarcolemma, reinforcing and stabilizing the latter during muscle contraction. Titin is a large protein which associates with myosin filaments and endows them with elastic recoil properties (choice B). Desmin filaments form a supportive network extending from Z disk to Zdisk (choice C). Troponin I inhibits the binding of myosin to actin (choice D). AlphaB-crystallin protects desmin filaments from stress-induced damage (choice E).
The third week of development is characterized by the appearance of the branchial apparatus, the embryonic primordium from which head and neck structures will be derived. The apparatus consists of five branchial arches, numbered 1, 2, 3, 4 and 6. Second arch anomalies represent 95% of all branchial anomalies and are classified into four types with types IIII being the most common. The anomalies manifest as cysts or fistulae in the lateral neck, located anterior and deep to the sternocleidomastoid muscle. Which of the following structures develop from the second branchial arch?
Answer(s): C
The posterior digastric muscle is derived from the second branchial arch and thus is innervated by its nerve, the facial (Seventh cranial) nerve. The anterior digastric muscle (choice A) is derived from the first branchial arch and is innervated by its nerve, the mandibular division of the trigeminal (fifth cranial) nerve.The posterior cricoarytenoideus muscle (choice B) and the superior constrictor muscle (choice E), derived from a combination of the fourth and sixth branchial arches, are innervated by the vagus (tenth cranial) nerve. The stylopharyngeus (choice D) is derived from the third branchial arch and is the only voluntary muscle innervated by the glossopharyngeal (ninth cranial) nerve.
A 10-year boy is examined because his parents noticed that "his eyes never seem to look in the right direction." On examination, the left eye of the child is unable to move laterally (abduction) and when asked to look toward the nose (adduction), the eyeball retracts into the socket and the eye opening narrows. Sometimes, the eye also moves superiorly. The child is diagnosed with Duane syndrome, a congenital ocular motility disorder characterized by limited abduction of the affected eye. This is due to absence of the abducens (fifth cranial) nerve with aberrant innervation by the oculomotor (third cranial) nerve. Which of the following muscles is normally innervated by the abducens nerve?
Answer(s): B
The abducens (sixth cranial) nerve normally innervates the lateral rectus muscle. The inferior oblique (choice A), medial rectus (choice C), and superior rectus (choice E) are all innervated by the oculomotor (third cranial) nerve. The superior oblique (choice D) is innervated by the trochlear (fourth cranial) nerve. In Duane syndrome, the absence of lateral rectus innervations by the abducens (sixth cranial) nerve is replaced by an aberrant innervation of the oculomotor (third cranial) nerve. Thus when the patient is asked to adduct the affected eye, there is cocontraction of the lateral and medial recti with globe retraction.
Retinitis pigmentosa is a hereditary disorder, which affects the photoreceptors (the rods and the cones) in the retina. These photoreceptors are located in which of the numbered layers in Figure below
Answer(s): E
The retina contains three layers of cells. They are, from top to bottom, the ganglion cells (choice A), the bipolar cells (choice C), and the photoreceptor cells (rods and cones, choice E). The internal plexiform layer (choice B) contains the synapses between the bipolar cells and the ganglion cells. The external plexiform layer (choice D) contains the synapses between the photoreceptors and the bipolar cells.Remember that light enters from the top and traverses all the layers to reach the photoreceptors in the bottom layer.
The structure indicated by arrow 1 in Fig. 1-2 is which of the following vessels?
Answer(s): D
Remember that in viewing axial or transverse CT scans through the body, the right side of the patient is to your left and the left side to your right. In other words, the feet of the patient are toward you and the head away from you. The back of the patient is at the bottom of the image and the front of the patient toward the top. Directional terms are always in reference to the patient. The insert at the bottom right indicates the level of the section. Arrow 1 indicates the right brachiocephalic vein. The left brachiocephalic vein (choice B) is seen as the elongated structure immediately posterior to the manubrium of the sternum and to the left of the right brachiocephalic vein. Immediately posterior to the left brachiocephalic vein is the brachiocephalic artery (choice A, arrow 2). To the left of the latter are the left common carotid artery (choice C) and the left subclavian artery (arrow 3). The superior vena cava (choice E) is not seen at this level because the right and left brachiocephalic veins are still separate.
Share your comments for USMLE STEP1 exam with other users:
am preparing for exam ,just nice questions
please upload c_tadm_23 exam
can we get tdvan4 vantage data engineering pdf?
want to clear the exam.
could you please upload the dumps of sap c_sac_2302
asm management configuration is about storage
kool thumb up
just passed the az-500 exam this last friday. most of the questions in this exam dumps are in the exam. i bought the full version and noticed some of the questions which were answered wrong in the free version are all corrected in the full version. this site is good but i wish the had it in an interactive version like a test engine simulator.
i can practice for exam
please i need this exam.
i need the dump
i want it bad, even if cs6 maybe retired, i want to learn cs6
i hate comptia with all my heart with their "choose the best" answer format as an argument could be made on every question. they say "the "comptia way", lmao no this right here boys is the comptia way 100%. take it from someone whos failed this exam twice but can configure an entire complex network that these are the questions that are on the test 100% no questions asked. the pbqs are dead on! nice work
very good materials
thanks for your support.
iam impressed with the quality of these dumps. they questions and answers were easy to understand and the xengine app was very helpful to use.
not bad but you question database from isaca
awesome contents
answer to 134 is casb. while data loss prevention is the goal, in order to implement dlp in cloud applications you need to deploy a casb.
are these brain dumps sufficient enough to go write exam after practicing them? or does one need more material this wont be enough?
i did attend the required cources and i need to be sure that i am ready to take the exam, i would ask you please to share the questions, to be sure that i am fit to proceed with taking the exam.
why only give explanations on some, and not all questions and their respective answers?
refresh db knowledge
interested for sap certification
could you please upload practice questions for scr exam ?
please upload free oracle cloud infrastructure 2023 foundations associate exam braindumps
sweating! they are tricky
i never use these dumps sites but i had to do it for this exam as it is impossible to pass without using these question dumps.
good practice and well sites.
passed my first exam last week and pass the second exam this morning. thank you sir for all the help and these brian dumps.
does anyone who attended exam csa 8.8, can confirm these questions are really coming ? or these are just for practicing?
kindly share the dumps
very nice content
passed today