Gross Anatomy and Embryology Test 1 — Questions and Answers

Question 1: A 45-year-old woman has a uterine leiomyoma that is 5 cm in diameter and is pressing on the urinary bladder, causing urinary frequency. Which of the following is the most likely location of the leiomyoma?

Cervical canal
Lateral margin of the uterine cavity
Subendometrially in the uterine cavity
Subperitoneally on the anterior surface of the uterine corpus (Correct answer)
Subperitoneally on the posterior surface of the uterine fundus

Correct answer: Subperitoneally on the anterior surface of the uterine corpus

A leiomyoma (fibroid) pressing on the urinary bladder and causing urinary frequency indicates an anterior location. Specifically, a subperitoneal (subserosal) fibroid on the anterior surface of the uterine corpus would be positioned to exert pressure on the adjacent bladder, leading to symptoms like frequency.

Question 2: A 5-year-old girl is brought to the emergency department because of fever and severe abdominal pain. Acute appendicitis is diagnosed. In the examination room, she keeps her right hip flexed and resists active extension of the hip. The inflamed structure associated with these symptoms is most likely in contact with which of the following structures?

Abdominal wall and the external oblique muscle
Obturator internus muscle
Psoas major muscle (Correct answer)
Quadratus lumborum muscle
Transversus abdominis muscle

Correct answer: Psoas major muscle

The patient's symptoms of keeping the right hip flexed and resisting extension are indicative of a positive psoas sign. This occurs when an inflamed appendix (especially a retrocecal appendix) irritates the psoas major muscle, which lies posterior to the appendix. Flexing the hip relieves tension on the muscle, while extension stretches it, causing pain.

Question 3: A 61-year-old man comes to the physician because of a 3-month history of episodes of headache, heart palpitations, and excessive sweating. He has had a 10-kg (22-lb) weight loss during this period. While being examined, during an episode his blood pressure is 210/110 mm Hg. Physical examination shows no other abnormalities. Urine studies show increased catecholamine concentrations. A CT scan of the abdomen is most likely to show a mass in which of the following locations?

Adrenal glands (Correct answer)
Appendix
Kidneys
Pancreas
Stomach

Correct answer: Adrenal glands

The classic triad of headache, palpitations, and sweating, along with paroxysmal hypertension and weight loss, strongly suggests a pheochromocytoma. This diagnosis is confirmed by elevated urinary catecholamines. Pheochromocytomas are neuroendocrine tumors that typically arise from chromaffin cells in the adrenal medulla.

Question 4: A 6-year-old boy has a large intra-abdominal mass in the midline just above the symphysis pubis. During an operation, a cystic mass is found attached to the umbilicus and the apex of the bladder. Which of the following is the most likely diagnosis?

Hydrocele
Meckel cyst
Meckel diverticulum
Omphalocele
Urachal cyst (Correct answer)

Correct answer: Urachal cyst

The urachus is an embryonic remnant of the allantois that connects the fetal bladder to the umbilicus. If the urachus fails to involute completely, it can form a cyst, which is typically located in the midline between the umbilicus and the bladder apex, precisely matching the description of the mass found in this patient.

Question 5: A 55-year-old man who has alcoholic cirrhosis is brought to the emergency department because he has been vomiting blood for 2 hours. He has a 2-month history of abdominal distention, dilated veins over the anterior abdominal wall, and internal hemorrhoids. Which of the following veins is the most likely origin of the hematemesis?

Inferior mesenteric veins
Left gastric vein (Correct answer)
Periumbilical veins
Superior rectal vein
Superior vena cava

Correct answer: Left gastric vein

In alcoholic cirrhosis, portal hypertension leads to the development of portosystemic shunts. Hematemesis in this context is most commonly due to ruptured esophageal varices, which form as a result of increased pressure in the left gastric (coronary) vein, a tributary of the portal vein, anastomosing with esophageal veins.

Question 6: A 3-year-old girl with mild craniofacial dysmorphosis has profound hearing deficits. Further evaluation indicates profound sensory auditory deficits and vestibular problems. Altered development of which of the following is most likely to account for these observations?

Ectodermal placode
Intermediate mesoderm
Lateral plate mesoderm
Neural crest cell (Correct answer)
Paraxial mesoderm
Prochordal mesoderm

Correct answer: Neural crest cell

Neural crest cells are multipotent cells that migrate extensively during embryonic development and contribute to a wide array of structures, including many components of the craniofacial region, the peripheral nervous system (including sensory ganglia of cranial nerves involved in hearing and balance), and structures of the inner ear. Altered development of neural crest cells can therefore lead to the constellation of craniofacial dysmorphosis, profound sensory auditory deficits, and vestibular problems described.

Question 7: A 19-year-old woman comes to the physician because of a 5-day history of increasingly severe right lower abdominal pain and bloody vaginal discharge. Her last menstrual period was 8 weeks ago. Abdominal examination shows exquisite tenderness of the right lower quadrant. A serum pregnancy test result is positive. Ultrasonography shows no gestational sac in the uterus. Which of the following is the most likely location of this patient’s fertilized egg?

Cervix
Peritoneum of the right lower abdominal wall
Rectouterine pouch (of Douglas)
Right fallopian tube (Correct answer)
Right ovary

Correct answer: Right fallopian tube

The combination of a positive pregnancy test, absence of an intrauterine gestational sac, and symptoms of unilateral abdominal pain and vaginal bleeding in a sexually active woman strongly indicates an ectopic pregnancy. The most common location for an ectopic pregnancy is the fallopian tube, specifically the ampulla.

Question 8: A 22-year-old man is brought to the emergency department because of a suprahyoid stab wound that extends from one side of the neck to the other. His tongue deviates to the right when protruded; there is no loss of sensory modality on the tongue. The injury most likely involves which of the following nerves?

Left hypoglossal
Left vagus
Right glossopharyngeal
Right hypoglossal (Correct answer)
Right lingual

Correct answer: Right hypoglossal

The hypoglossal nerve (CN XII) innervates the intrinsic and extrinsic muscles of the tongue, primarily controlling tongue movement. Damage to the hypoglossal nerve results in ipsilateral tongue weakness and atrophy. When protruded, the tongue deviates *towards* the side of the lesion due to the unopposed action of the contralateral genioglossus muscle; therefore, right deviation indicates a right hypoglossal nerve injury.

Question 9: A 45-year-old woman is found to have adenocarcinoma of the left breast. Resection of the tumor is scheduled, and the physician also plans to obtain samples of the draining nodes. To find these nodes, a radiotracer is injected adjacent to the tumor and images are obtained. The first draining sentinel node in this patient is most likely found at which of the following locations?

Contralateral neck
Ipsilateral axilla (Correct answer)
Ipsilateral mediastinum
Ipsilateral supraclavicle
Medial contralateral breast

Correct answer: Ipsilateral axilla

The primary lymphatic drainage for most of the breast, especially the lateral quadrants, is to the ipsilateral axillary lymph nodes. These are typically the first nodes to receive lymphatic flow from a breast tumor, making them the sentinel nodes for biopsy in breast cancer staging.

Question 10: A 3629-g (8-lb) male newborn is delivered at term. During the initial examination, urine is found to be leaking from the umbilicus. This patient most likely has an abnormality of which of the following fetal structures?

Umbilical arteries
Umbilical vein
Urachus (Correct answer)
Urogenital sinus
Urorectal septum

Correct answer: Urachus

The urachus is an embryonic remnant connecting the fetal bladder to the umbilicus. Normally, it obliterates after birth to become the median umbilical ligament. If it remains patent, it can allow urine to leak from the bladder through the umbilicus, a condition known as a patent urachus.

Question 11: A 70-year-old man has a 90% blockage at the origin of the inferior mesenteric artery. He does not have intestinal angina. Which of the following arteries is the most likely additional source of blood to the descending colon?

Left gastroepiploic
Middle colic (Correct answer)
Sigmoid
Splenic
Superior rectal

Correct answer: Middle colic

The inferior mesenteric artery (IMA) supplies the distal transverse colon, descending colon, sigmoid colon, and superior rectum. In cases of IMA occlusion, collateral circulation is typically provided by the marginal artery of Drummond, which connects the superior mesenteric artery (SMA) and IMA territories. The middle colic artery, a branch of the SMA, is a key component of this collateral pathway, anastomosing with branches of the IMA to supply the descending colon.

Question 12: A 30-year-old man comes to the emergency department 1 hour after injuring his left knee in a volleyball game. He says he twisted his left leg when he fell to the floor after he and a teammate accidentally collided. He cannot bear weight on his left leg. Physical examination shows tenderness and swelling of the left knee. When the patient sits on the edge of the examination table, the left knee can be displaced anteriorly at an abnormal degree. Which of the following is most likely injured in this patient?

Anterior cruciate ligament (Correct answer)
Fibular collateral ligament
Meniscofemoral ligament
Oblique popliteal ligament
Transverse ligament of the knee

Correct answer: Anterior cruciate ligament

The anterior displacement of the tibia relative to the femur (implied by the knee being displaced anteriorly at an abnormal degree) is the classic sign of an anterior cruciate ligament (ACL) injury. The ACL prevents anterior translation of the tibia on the femur and hyperextension of the knee, and its rupture often occurs with twisting injuries during sports.

Question 13: A 70-year-old man is brought to the emergency department because of a 1-week history of increasingly severe left-sided lower abdominal pain and passing gas in his urine. His temperature is 38.9°C (102°F). A CT scan of the abdomen shows gas in the bladder and edema of the fat surrounding the sigmoid colon. There is no obvious lymph node enlargement. Which of the following is the most likely cause of this patient’s condition?

Appendicitis with fistula
Bladder infection
Diverticulitis with fistula (Correct answer)
Prostate cancer with fistula
Urinary tract infection

Correct answer: Diverticulitis with fistula

Left-sided lower abdominal pain and fever are characteristic of diverticulitis. The key symptom here is pneumaturia (passing gas in urine), which indicates a fistula between the bowel and the bladder. Given the location and the CT findings of edema around the sigmoid colon and gas in the bladder, a colovesical fistula secondary to diverticulitis is the most likely diagnosis.

Question 14: A 60-year-old man has tenderness in the region distally between the tendons of the extensor pollicis longus and extensor pollicis brevis (anatomical snuffbox) after falling on the palm of his right hand. A fracture of which of the following carpal bones is most likely in this patient?

Hamate
Lunate
Scaphoid (Correct answer)
Trapezium
Triquetrum

Correct answer: Scaphoid

A fall on an outstretched hand (FOOSH injury) is a common mechanism for carpal bone fractures. Tenderness specifically in the anatomical snuffbox, located between the tendons of the extensor pollicis longus and extensor pollicis brevis, is the classic clinical sign of a scaphoid fracture. Scaphoid fractures are particularly concerning due to their risk of avascular necrosis.

Question 15: A 20-year-old man is brought to the emergency department 1 hour after he was involved in a motorcycle collision. He was not wearing a helmet. Physical examination shows clear fluid dripping from the nose. X-rays show a fracture of the cribriform plate of the ethmoid bone. This patient is at greatest risk for impairment of which of the following senses?

Balance
Hearing
Olfaction (Correct answer)
Taste from the anterior two thirds of the tongue
Taste from the posterior one third of the tongue
Vision

Correct answer: Olfaction

The cribriform plate of the ethmoid bone is perforated by the olfactory nerve filaments (Cranial Nerve I), which transmit the sense of smell. A fracture in this area, as described, directly damages these delicate nerves. This damage leads to anosmia, or the loss of the sense of olfaction. The clear fluid dripping from the nose is cerebrospinal fluid (CSF rhinorrhea), indicating a breach of the meninges and a direct connection between the subarachnoid space and the nasal cavity, further confirming the severity of the injury to this region.

Question 16: A 7-year-old boy tires easily while running. On auscultation, a harsh continuous murmur is heard at the left of the sternum between the first two ribs. Arterial blood oxygen content is slightly higher in the right hand than in the left hand. X-rays of the chest show no abnormalities. Which of the following is the most likely diagnosis?

Anomalous return of pulmonary blood to the right atrium
Patent ductus arteriosus (Correct answer)
Patent foramen ovale
Stenosis of the aortic valve
Tricuspid atresia

Correct answer: Patent ductus arteriosus

A patent ductus arteriosus (PDA) is characterized by a harsh continuous murmur, often described as 'machine-like,' heard best at the left upper sternal border. The key finding of higher arterial blood oxygen content in the right hand compared to the left hand indicates a right-to-left shunt at the level of the ductus. This occurs because the right subclavian artery (supplying the right arm) originates before the PDA, while the left subclavian artery (supplying the left arm) originates after it, allowing deoxygenated blood from the PDA to mix with oxygenated blood going to the left arm. Fatigue is a common symptom due to the increased workload on the heart and potential pulmonary hypertension.

Question 17: A 50-year-old woman is brought to the emergency department because of severe upper abdominal pain for 24 hours. She has a 2-day history of intermittent fever and pale stools. Her temperature is 38.9°C (102°F), pulse is 120/min, respirations are 20/min, and blood pressure is 90/50 mm Hg. Physical examination shows jaundice and tenderness of the right upper quadrant of the abdomen. Serum studies show a bilirubin concentration of 5 mg/dL, alkaline phosphatase activity of 450 U/L, and lipase activity of 400 U/L (N=14–280). Which of the following is the most likely cause of this patient’s symptoms?

Impaction of a gallstone in the hepatopancreatic ampulla (Correct answer)
Intestinal obstruction secondary to diverticulitis
Pancreatic mucinous cystadenoma
Penetration and perforation of a peptic ulcer
Ulcerative colitis

Correct answer: Impaction of a gallstone in the hepatopancreatic ampulla

The patient's presentation of severe upper abdominal pain, fever, jaundice, pale stools, hypotension, tachycardia, and elevated bilirubin, alkaline phosphatase, and lipase is highly suggestive of ascending cholangitis with associated pancreatitis. Impaction of a gallstone in the hepatopancreatic ampulla (ampulla of Vater) can obstruct both the common bile duct and the pancreatic duct. This dual obstruction leads to biliary stasis, infection (cholangitis), and reflux of bile or pancreatic enzymes, causing inflammation of the pancreas (pancreatitis), perfectly explaining all the clinical and laboratory findings.

Question 18: A 6-year-old boy is brought to the physician by his parents for a follow-up examination because of a heart murmur that has been present since birth. His only symptom is fatigue. His pulse is 110/min, and blood pressure is 80/40 mm Hg. Physical examination shows no cyanosis or clubbing of the fingers. Cardiac examination shows a normal S1 and a split S2 . A grade 3/6 pansystolic murmur is heard maximally at the lower left to mid left sternal border. He undergoes cardiac catheterization and is found to have a higher than expected oxygen level in the right ventricle. Which of the following is the most likely cause of these findings?

Coarctation of the aorta
Congenital bicuspid aortic valve
Pulmonary artery stenosis
Tricuspid stenosis
Ventricular septal defect (Correct answer)

Correct answer: Ventricular septal defect

A ventricular septal defect (VSD) is characterized by a pansystolic murmur heard maximally at the lower left to mid-left sternal border. The most definitive diagnostic finding is the higher than expected oxygen level in the right ventricle during cardiac catheterization. This indicates a left-to-right shunt, where oxygenated blood from the left ventricle flows into the right ventricle, increasing its oxygen saturation. This shunting can lead to symptoms like fatigue due to increased pulmonary blood flow and cardiac workload.

Question 19: A 32-year-old woman, gravida 2, para 2, develops fever and left lower abdominal pain 3 days after delivery of a full-term male newborn. Abdominal examination shows a tender, palpable mass. Ultrasonography of the mass shows an ovarian vein thrombosis. The thrombus is most likely to extend into which of the following veins?

Hemiazygos vein
Inferior vena cava
Left internal iliac vein
Left internal pudendal vein
Left renal vein (Correct answer)

Correct answer: Left renal vein

The left ovarian vein drains into the left renal vein, whereas the right ovarian vein drains directly into the inferior vena cava. Therefore, a thrombus originating in the left ovarian vein would naturally extend proximally along its anatomical drainage pathway. This means the thrombus is most likely to propagate into the left renal vein. Postpartum ovarian vein thrombosis is a rare but serious complication, and understanding the venous anatomy is crucial for predicting its extension.

Question 20: During a study of bladder function, a healthy 20-year-old man drinks 1 L of water and delays urination for 30 minutes after feeling the urge to urinate. Which of the following muscles permits his voluntary control of micturition?

Coccygeus
Detrusor
External urethral sphincter (Correct answer)
Internal urethral sphincter
Obturator internus

Correct answer: External urethral sphincter

Voluntary control of micturition, or the ability to delay urination despite feeling the urge, is primarily mediated by the external urethral sphincter. This sphincter is composed of skeletal muscle and is under conscious, somatic nervous system control. While the detrusor muscle contracts to expel urine and the internal urethral sphincter is an involuntary smooth muscle, it is the external urethral sphincter that allows for conscious inhibition of urination until an appropriate time and place.

Gross Anatomy and Embryology Test 1

A 45-year-old woman has a uterine leiomyoma that is 5 cm in diameter and is pressing on the urinary bladder, causing urinary frequency.
Which of the following is the most likely location of the leiomyoma?