Developmental Anatomy — MCQs

Developmental Anatomy Indian Medical PG Practice Questions and MCQs

Question 51: Gland homologous to prostate in females is

A. Skene's gland (Correct Answer)
B. Bartholin's gland
C. Gartner's duct
D. Cowper's gland

Explanation: ***Skene's gland*** - **Skene's glands**, also known as the **paraurethral glands**, are located on either side of the female urethra [1]. - They are considered homologous to the male prostate gland as they share similar embryological origins and secrete a fluid that is believed to play a role in sexual function [1]. *Bartholin's gland* - **Bartholin's glands** are located at the posterior aspect of the vaginal opening and secrete mucus to lubricate the vagina. - These glands are homologous to the **bulbourethral glands (Cowper's glands)** in males, not the prostate [1]. *Gartner's duct* - **Gartner's duct** is a vestigial remnant of the **Wolffian (mesonephric) duct** in females. - It is not a functional gland and has no homology to the prostate gland. - Gartner's duct cysts may occasionally be found along the anterolateral wall of the vagina. *Cowper's gland* - **Cowper's glands**, or **bulbourethral glands**, are male accessory glands located below the prostate. - Their female homologue is the **Bartholin's gland**, not the prostate [1].

Question 52: Perichondrial ring is -

A. Seen around epiphyseal plate (Correct Answer)
B. Plays a role in adult bone remodeling
C. Involved in tensile strength of cartilage
D. Associated with cranial sutures

Explanation: ***Seen around epiphyseal plate*** - The perichondrial ring, also known as the **ring of LaCroix**, is a fibrous structure that encircles the **epiphyseal plate (growth plate)**, particularly at the junction of the epiphysis and metaphysis [3]. - It plays a crucial role in maintaining the structural integrity and shape of the growth plate by restraining its sideways expansion, thus directing longitudinal bone growth [3]. *Associated with cranial sutures.* - Cranial sutures are specialized **fibrous joints** that connect the bones of the skull and allow for skull growth and flexibility during birth [1]. - They are composed of fibrous connective tissue and **do not contain cartilage** or a perichondrial ring [1]. *Plays a role in adult bone remodeling.* - Adult bone remodeling is primarily carried out by **osteoblasts** (bone-forming cells) and **osteoclasts** (bone-resorbing cells) within established bone tissue [2]. - The perichondrial ring is a structure associated with **cartilaginous growth plates** and is not active in the remodeling processes of mature bone. *Involved in tensile strength of cartilage.* - The tensile strength of cartilage itself is primarily attributed to its extracellular matrix, particularly the strong network of **collagen fibers** and the presence of proteoglycans [1]. - While the perichondrial ring is a fibrous structure, its main function is to support the growth plate, not to directly provide tensile strength to articular or other cartilages.

Question 53: A 12-year-old patient presents with midline neck swelling. This swelling moves upwards during protrusion of tongue, patient describes this as painless and gives a long history of its presence. What is the most common site for this condition?

A. Near the foramen cecum
B. Below the hyoid bone (Correct Answer)
C. Above the hyoid bone
D. In the floor of the mouth

Explanation: ***Below the hyoid bone*** - The clinical presentation describes a **thyroglossal duct cyst**, a common congenital neck mass that arises from persistent remnants of the embryological thyroglossal duct. [1] - Most thyroglossal duct cysts are found **below the hyoid bone**, often adjacent to the membrane connecting the hyoid to the thyroid cartilage. [1] *Near the foramen cecum* - While the thyroglossal duct originates from the **foramen cecum** at the base of the tongue, a cyst forming at this exact location is less common than one along the duct's more distal course. - Cysts near the foramen cecum are typically located within the **posterior aspect of the tongue** itself. *Above the hyoid bone* - Cysts are found above the hyoid bone in roughly 15-20% of cases, often in the **submental region**. - However, the most frequent location is inferior to the hyoid bone, reflecting the duct's descent during thyroid development. [1] *In the floor of the mouth* - Lesions in the **floor of the mouth** are more commonly associated with conditions like **ranulas** (mucoceles of the sublingual gland) or **dermoid cysts**. - Thyroglossal duct cysts are typically located in the **midline of the neck**, not directly within the oral cavity floor.

Question 54: Nasopharyngeal chordoma arises from:-

A. Luschka's bursa
B. Pharyngeal bursa
C. Rathke's pouch
D. Notochord (Correct Answer)

Explanation: Correct Option: Notochord - **Chordomas** are rare malignant tumors that arise from embryonic remnants of the **notochord** [1] - The notochord is a flexible rod-like structure that forms the primitive axial skeleton during embryonic development - Chordomas typically occur along the **midline** at sites where notochordal remnants persist, most commonly at the **skull base (clivus/nasopharynx)** and **sacrococcygeal region** [1] Incorrect Option: Luschka's bursa - **Luschka's bursa** (also known as the pharyngeal bursa) is a small indentation or pocket in the nasopharynx posterior to the pharyngeal tonsil - While located in the nasopharynx, it is a **normal anatomical structure**, not an embryological remnant that gives rise to tumors - Not associated with chordoma development Incorrect Option: Pharyngeal bursa - **Pharyngeal bursa** is another term for **Luschka's bursa** (they are synonymous) - It is a normal anatomical structure in the nasopharynx - Not related to the embryonic remnants that give rise to chordomas Incorrect Option: Rathke's pouch - **Rathke's pouch** is an embryonic invagination of the stomodeum (primitive oral cavity) that gives rise to the **anterior pituitary gland** - Tumors arising from remnants of Rathke's pouch are **craniopharyngiomas**, which are distinct from chordomas - Craniopharyngiomas are typically suprasellar, while chordomas are more commonly found at the clivus or sacrum

Question 55: Which of the following sinus grows till early adulthood?

A. Ethmoidal
B. Frontal
C. Sphenoid
D. Maxillary (Correct Answer)

Explanation: ***Maxillary*** - The **maxillary sinuses** are the largest paranasal sinuses and continue to grow and expand until **early adulthood**, typically reaching their full size around 18-20 years of age. - This **post-pubertal growth** contributes to the shaping of the facial skeleton. *Ethmoidal* - The **ethmoidal sinuses** are present at birth and continue to develop, but their major growth spurt occurs in **early childhood**. - They reach close to adult size by around 7-10 years of age, not early adulthood. *Frontal* - The **frontal sinuses** begin to develop around age 6-7, starting as extensions of the ethmoid air cells. - While they continue to pneumatize, their significant growth largely finishes by **late adolescence**, earlier than the maxillary sinuses. *Sphenoid* - The **sphenoid sinuses** are rudimentary at birth and begin to pneumatize the sphenoid bone during childhood. - Their significant growth and expansion are usually complete by **late adolescence**, around 12-15 years of age.

Question 56: Which embryological structure forms the adult aorta and pulmonary trunk?

A. Conus arteriosus
B. Truncus arteriosus (Correct Answer)
C. Sinus venosus
D. Bulbus cordis

Explanation: ***Truncus arteriosus*** - The **truncus arteriosus** is the embryonic structure that undergoes septation by the **aorticopulmonary septum** to form the ascending aorta and the pulmonary trunk [1]. - Failure of proper septation of the truncus arteriosus leads to congenital heart defects like **persistent truncus arteriosus** [1]. *Conus arteriosus* - The **conus arteriosus** (also known as the infundibulum) is the outflow tract of the **right ventricle**, contributing to the development of the smooth walled part of the right ventricle. - It does not directly form the great arteries themselves but rather the structure immediately preceding the pulmonary artery. *Sinus venosus* - The **sinus venosus** is an embryonic chamber that initially receives blood from the cardinal, vitelline, and umbilical veins. - It primarily develops into the smooth part of the **right atrium** (sinus venarum) and the **coronary sinus**. *Bulbus cordis* - The **bulbus cordis** is a part of the primitive heart tube that is cranial to the primitive ventricle. - It forms the **trabeculated part of the right ventricle**, the **conus arteriosus**, and a portion of the **aortic vestibule** of the left ventricle.

Question 57: During development, the ductus venosus connects the umbilical vein to which structure?

A. Aorta
B. Right atrium
C. Liver
D. Inferior vena cava (Correct Answer)

Explanation: ***Inferior vena cava*** - The **ductus venosus** is a fetal shunt that allows oxygenated blood from the **umbilical vein** to bypass the **hepatic circulation** [1]. - It connects directly into the inferior vena cava, mixing with deoxygenated blood returning from the lower extremities, and thereby delivering oxygenated blood to the heart [1]. *Aorta* - The **aorta** receives blood directly from the **left ventricle** and distributes it to the systemic circulation [1]. - While it eventually carries oxygenated blood, it is not directly connected to the umbilical vein via the ductus venosus. *Right atrium* - The **right atrium** receives mixed blood from the **inferior and superior vena cava** during fetal circulation [1]. - The ductus venosus shunts blood *to* the inferior vena cava, which then drains into the right atrium, but it doesn't directly connect to the right atrium [1]. *Liver* - The **umbilical vein** initially carries blood to the **liver**, but the ductus venosus *bypasses* the majority of the liver's sinusoids [1]. - This bypass mechanism ensures highly oxygenated blood reaches the fetal heart and brain more efficiently [1].

Question 58: Skeletal remains of a male are found, and radiographic examination shows that the epiphysis of the clavicle has not yet fused. What does this indicate about his age?

A. He is likely under 18 years of age
B. He is likely between 18-25 years old (Correct Answer)
C. He is likely over 25 years old
D. Age cannot be determined

Explanation: ***He is likely between 18-25 years old*** - The **medial clavicular epiphysis** is the **last epiphysis to fuse** in the entire human skeleton, typically completing between ages **18 and 25 years** (some sources extend to 28-30 years). - An unfused clavicular epiphysis in skeletal remains indicates the individual was **still within this active growth period**. - This is a well-established principle in **forensic anthropology** for age estimation. *He is likely under 18 years of age* - While most growth plates remain open before 18, the **clavicle's medial epiphysis** specifically begins fusion around 18-20 years. - Most other major long bone epiphyses (distal femur, proximal tibia, proximal humerus) would have already fused by age 18. - An isolated unfused clavicular epiphysis would be **highly unusual** if the person were younger than 18, as other epiphyses would also be unfused. *He is likely over 25 years old* - By 25 years of age (certainly by 28-30 years), **epiphyseal fusion of the clavicle is complete** in the vast majority of individuals. - An unfused clavicle would be **extremely atypical** in someone over 25 years old, indicating cessation of growth has occurred. *Age cannot be determined* - The state of **clavicular epiphyseal fusion** is one of the **most reliable indicators** for age estimation in young adult skeletal remains. - The clavicle's unique status as the last bone to complete fusion provides a **specific and narrow age range** for forensic determination.

Question 59: Trigonocephaly is due to premature closure of which suture?

A. Sagittal suture
B. Metopic suture (Correct Answer)
C. Lambdoid suture
D. Coronal suture

Explanation: ***Metopic suture*** - Premature closure of the **metopic suture** (between the two frontal bones) results in a triangular-shaped forehead known as **trigonocephaly** [1]. - This fusion leads to a prominent ridge in the midline of the forehead and a narrowing of the front of the skull [1]. *Sagittal suture* - Premature closure of the **sagittal suture** causes **scaphocephaly**, characterized by a long, narrow head. - This type of craniosynostosis results in restricted growth in width and compensatory growth in length. *Lambdoid suture* - Premature closure of the **lambdoid suture** leads to **posterior plagiocephaly**, causing flattening of one side of the back of the head. - This is a rare form of craniosynostosis and should be differentiated from positional plagiocephaly. *Coronal suture* - Premature closure of a **unilateral coronal suture** results in **anterior plagiocephaly**, characterized by flattening of one side of the forehead and orbital region. - Bilateral coronal suture closure causes **brachycephaly**, resulting in a short, wide skull.

Question 60: Which of the following is NOT a recognized cause of pelvic kidneys?

A. Inability to ascend during fetal life
B. Fusion of the lower poles of the kidneys
C. Obstruction by branches of the aorta
D. p53 mutation (Correct Answer)

Explanation: ***p53 mutation*** - A **p53 mutation** is not a direct or recognized cause of **pelvic kidneys**. This gene is primarily involved in **tumor suppression** and cellular responses to DNA damage. - While genetic factors can contribute to congenital anomalies, a **p53 mutation** is not specifically linked to renal ectopia. *Inability to ascend during fetal life* - This is a direct cause of **pelvic kidneys**, as the kidneys normally ascend from the pelvis to the lumbar region during fetal development. - Failure of this **normal ascent** results in the kidneys remaining in the pelvic cavity. *Fusion of the lower poles of the kidneys* - This condition is known as a **horseshoe kidney**, where the lower poles fuse, often preventing complete ascent and resulting in an **aberrant location**, sometimes within the pelvis. - The fused inferior pole can get **trapped** under the inferior mesenteric artery, preventing further ascent. *Obstruction by branches of the aorta* - The **renal arteries** originate from the aorta. If these branches or other major vessels obstruct the **upward migration** of the kidney, it can lead to failure of ascent and a **pelvic kidney**. - This physical obstruction prevents the kidney from reaching its normal **retroperitoneal position**.

Practice by Chapter

Prenatal Development

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Postnatal Growth and Development

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Age-Related Anatomical Changes

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Developmental Abnormalities

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Principles of Teratology

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Developmental Basis of Congenital Anomalies

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Molecular Aspects of Development

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Genetic Factors in Developmental Anatomy

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Environmental Influences on Development

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Clinical Aspects of Developmental Anatomy

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