Controversial Questions And Answer For Exam 2015

Controversial Questions And Answer For Exam 2015 WITH ANSWER KEY 2015

Q The nasolacrimal groove separates the:

A. mandibular and maxillary swellings
B. lateral nasal swelling and maxillary swelling
C. medial nasal swelling and maxillary swelling
D. first and second branchial arches
E. otic and optic vesicles
B. is correct.
The nasolacrimal groove lies between the maxillary swelling or prominence and the lateral nasal swelling. This groove ultimately forms the nasolacrimal duct and lacrimal sac. In the adult, it is the passage used by tears to travel from the eye to inferior meatus of the nasal cavity, to make your nose run when you cry.

Q. Many facial malformations are believed to be due to:

A. a failure of the oral membrane to rupture
B. a failure to neural crest cells to migrate into the facial processes
C. a failure in growth of the head fold
D. an abnormal persistence of the pharyngeal clefts
E. none of the above
B. is correct
Proper migration of neural crest cells into the face area is vitally important to facial development. Neural crest tissue will form much of the facial skeleton.

Q. The foramen cecum of the adult tongue:

A. marks the point of embryonic evagination of the thymus gland
B. divides the tongue into two parts, an anterior one-third and a posterior two-thirds
C. marks the point of embryonic evagination of the thyroid gland
D. develops into taste buds
E. has no embryologic significance
C. is correct.
The foramen cecum on the tongue is the point from which the thyroid gland evaginated and began its journey down into the neck. It lies at the apex of the V-shaped terminal sulcus, which divides the tongue into anterior 2/3rds, from the lateral lingual swellings and truberculum impar, and posterior 1/3rd, from the copula.

Q. Each pharyngeal arch includes:

A. derivatives of ectodermal neural crest cells
B. an aortic arch artery
C. a mesodermal core from paraxial mesoderm
D. a cranial nerve
E. all of the above
E. is correct.
The pharyngeal arches have their own mesodermal core, giving rise to cartilaginous and muscular components, cranial nerve components, vascular components and derivatives of neural crest cells, which supplement much of the connective tissue of the face.

Q. Which of the following are associated with the 2nd pharyngeal arch?

A. the malleus bone
B. facial nerve
C. glossopharyngeal muscle
D. the lower portion of the hyoid bone
E. anterior belly of digastric
B. is correct.
The stapes, styloid process, stylohyoid ligament, lesser horn of hyoid and upper part of hyoid body all come from 2nd arch. The nerve of the 2nd arch is CN VII or facial nerve, and the muscles are stapedius, stylohyoid, posterior belly of digastric and the muscles of facial expression.

Q. Branchial cysts or lateral cervical cysts:

A. are found along the anterior border of the sternocleidomastoid muscle
B. are formed from a rupture of the membrane between pharyngeal pouches and branchial clefts
C. are remnants of the thyroglossal duct
D. are found in front of the ear
A. is correct
Lateral cervical cysts are remnants of the cervical sinus, which forms when the 2nd arch grows over the 3rd and 4th arches. The cysts are found along the anterior border of the sternocleidomastoid muscle, usually just below the angle of the jaw. They have nothing to do with the rupture or anything.

Q. The heart is derived from:

A. splanchnic mesoderm
B. somatic mesoderm
C. septum transversum
D. intermediate mesoderm
E. paraxial mesoderm
A. is correct
The heart tubes form within the cardiogenic region cranial to the oropharyngeal membrane and beneath the intraembryonic coelom. If it is beneath the intraembryonic coelom, then it lies toward the yolk sac and must be splanchnic mesoderm. Somatic mesoderm would be the other side, or roof, of the intraembryonic coelom.

Q. The most superior part of the inferior vena cava is derived from:

A. left vitelline vein
B. right vitelline vein
C. right umbilial vein
D. left umbilical vein
E. sinus venosus
B. is correct.
The vitelline veins, as they pass through the developing liver, break up into hepatic sinusoids. When the left sinus horn regresses, blood is shunted from the left vitelline vein to the right, which enlarges and ultimately forms the posthepatic portion of the inferior vena cava.

Q. The embryonic origin of the ligamentum arteriosum is from the:

A. second arch artery
B. third arch artery
C. fourth arch artery
D. fifth arch artery
E. sixth arch artery
E. is correct
The sixth arch is the pulmonary arch, from which pulmonary arteries are derived. On the left side, this arch maintains its connection with the dorsal aorta. In the fetus, this connection is patent and is called the ductus arteriosus. Postnatally, it closes and persists as the ligamentum arteriosum.

Q. The following are true statements with regard to the fetal circulation EXCEPT:

A. Since the fetal liver is a hemopoietic organ, it is large and well supplied with oxygenated blood.
B. Fetal brain receives relatively pure arterial blood.
C. Fetal and maternal blood vessels anastomose in the placenta
D. In early developmental stages, one pulmonary vein buds from the left atrium of the heart.
E. Foramen primum of the interatrial septum closes after the formation of the foramen secundum.
C. is correct.
In the placenta, there is no anastomosis between the maternal and fetal vessels. Maternal blood from the spiral arteries enters the cotyledons, where it bathes the villi from the fetus. This all occurs without anastomosis.

Q. Each of the following statements are correctly paired EXCEPT:

A. right vitelline vein – inferior vena cava
B. left vitelline vein – liver sinusoids
C. right anterior cardinal vein – part of superior vena cava
D. right umbilical vein – definitive umbilical vein
E. left sinus horn – coronary sinus
D. is correct.
The right umbilical vein totally disappears. The definitive umbilical vein is the left one. After birth, it closes and becomes the ligamentum teres hepatis.