During the third week of development, the blastocyst undergoes a variety of differentiation processes responsible for the formation of the gastrula and, eventually, the embryo. This differentiation creates cell lineages that eventually become a variety of body systems. What cell lineage, present at this date, is responsible for the formation of the liver?
ANeuroectoderm
BSyncytiotrophoblasts
CEctoderm
DEndoderm
EMesoderm
A 68-year-old man presents to his primary care physician complaining of a bulge in his scrotum that has enlarged over the past several months. He is found to have a right-sided inguinal hernia and undergoes elective hernia repair. At his first follow-up visit, he complains of a tingling sensation on his scrotum. Which of the following nerve roots communicates with the injured tissues?
AS1-S3
BL1-L2
CS2-S4
DL4-L5
EL2-L3
A 25-year-old woman comes to the physician because of pain and weakness in her right forearm and hand for several months. Two years ago, she sustained a fracture of her ulnar shaft with dislocation of the radial head that was treated surgically. Physical examination shows mild tenderness a few centimeters distal to the lateral epicondyle. She has marked weakness when attempting to extend her right middle finger. There is radial deviation on extension of the wrist. Sensation is not impaired. Which of the following nerves is most likely affected in this patient?
AUlnar nerve
BMusculocutaneous nerve
CPosterior interosseous nerve
DSuperficial radial nerve
EAnterior interosseous nerve
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