Developmental Anatomy Practice Questions

Q: From which structure does the spleen develop?

Dorsal mesogastrium. ***Dorsal mesogastrium*** - The spleen develops from **mesenchymal cells** in the **dorsal mesogastrium**, a fold of peritoneum suspending the stomach from the posterior abdominal wall. - As the stomach rotates during development, the dorsal mesogastrium elongates and differentiates, forming the spleen. *Foregut diverticulum* - A foregut diverticulum typically refers to an out-pouching of the primitive **foregut**, which forms structures like the esophagus, stomach, and duodenum. [2] - While the stomach is derived from the foregut, the spleen originates from the **mesoderm** within its supporting mesentery, not directly from an epithelial diverticulum of the gut tube. *Pleuroperitoneal membrane* - The pleuroperitoneal membranes are crucial for the development of the **diaphragm**, separating the pleural and peritoneal cavities. - They play no direct role in the development of the spleen, which is an abdominal organ derived from the mesoderm. *Septum transversum* - The septum transversum is a thick mass of mesoderm that contributes to the formation of the **diaphragm** and the **ventral mesentery of the foregut**. [1] - It is involved in the development of the liver, but not directly in the formation of the spleen. [1]

Q: Closure of coronal sutures starts at the age of:

30-35 years. ***30-35 years*** - **Coronal suture closure** typically begins around the age of **30 years**, starting endocranially and progressing to the ectocranial surface. - The fusion usually initiates at the **pterion** (lateral aspect) and progresses medially, though patterns can vary. - This represents the normal timeline for **initiation** of coronal suture obliteration in the adult skull. *20 years* - At this age, the **sagittal suture** typically begins its closure process, not the coronal suture. - The coronal suture remains patent and open at 20 years in normal development. [1] - Premature closure at this age would indicate **craniosynostosis**, a pathological condition. *25 years* - The **lambdoid suture** begins closure around 26 years, making this closer but still earlier than coronal suture fusion. - The coronal suture typically remains largely unfused at this age. - This is still within the normal period where most cranial sutures remain patent. *50-60 years* - By this age, most major cranial sutures including the coronal are in **advanced stages** of obliteration or completely fused. - This represents the age of **complete obliteration**, not the initiation of closure. - The question specifically asks about when closure **starts**, not when it completes.

Q: What is the MOST clinically significant anatomical difference between pediatric and adult airways?

Narrowest part is cricoid cartilage. ***Narrowest part is cricoid cartilage*** - In **pediatric airways**, the **cricoid cartilage** is the narrowest point, making it the **most critical consideration** for endotracheal tube sizing and intubation. - This contrasts with adults where the **glottic opening** (vocal cords) is typically the narrowest. - This difference is **clinically crucial** as it determines tube selection, risk of subglottic stenosis, and why uncuffed tubes were traditionally preferred in children. *Proportionally larger tongue* - Pediatric patients indeed have a **proportionally larger tongue** relative to their oral cavity, which can contribute to airway obstruction [1]. - While this is a true anatomical difference, it is **less critical** for intubation decisions than the cricoid narrowing. *Funnel-shaped vs cylindrical airway shape* - Pediatric airways are **funnel-shaped** with narrowing at the cricoid, whereas adult airways are more **cylindrical**. - This morphological difference is a **consequence** of the cricoid being the narrowest point, not a separate primary consideration. *Larynx in higher position* - The **larynx** in infants and young children is positioned more **superiorly** (C3-C4 vs C4-C6 in adults). - While this affects intubation technique and angle, it is **less directly relevant** to airway sizing than the cricoid narrowing.

Q: How many fontanelles are present in a newborn child?

6. ***Correct Answer: 6*** - A newborn typically has **six fontanelles**: the **anterior** (bregma), **posterior** (lambda), two **sphenoidal** (anterolateral), and two **mastoid** (posterolateral) [1]. - These are fibrous membranes where the cranial bones meet, allowing for **brain growth** and flexibility of the skull during birth [1]. *Incorrect: 1* - This is incorrect as newborns have more than one fontanelle. - While the **anterior fontanelle** is the most prominent and commonly assessed, it is not the only one present [2]. *Incorrect: 2* - This is incorrect. While the anterior and posterior fontanelles are the most commonly discussed, there are additional, smaller fontanelles. - Focusing only on the **anterior** and **posterior fontanelles** overlooks the paired sphenoidal and mastoid fontanelles. *Incorrect: 3* - This is incorrect, as a newborn has a total of six fontanelles. - Three fontanelles account for less than the total number of fontanelles present at birth.

Q: Anterior fontanelle corresponds to all structures except which of the following?

Lambdoid suture. ***Lambdoid suture*** - The **anterior fontanelle** is located at the intersection of the **coronal**, **sagittal**, and **metopic sutures** [1]. - It is bounded by the **frontal bones anteriorly** and the **parietal bones posteriorly** [1]. - The **lambdoid suture** is located at the posterior aspect of the skull, separating the parietal bones from the occipital bone, and corresponds to the **posterior fontanelle**, NOT the anterior fontanelle [1]. - This is the structure that does NOT correspond to the anterior fontanelle. *Frontal bones* - The **frontal bones** (or two halves of the frontal bone before fusion) form the anterior boundary of the anterior fontanelle [1]. - The anterior fontanelle is located where the frontal bones meet the parietal bones [1]. *Coronal suture* - The **coronal suture** forms part of the lateral boundaries of the anterior fontanelle, separating the frontal bone from the parietal bones [1]. - It runs transversely across the top of the skull on both sides. *Sagittal suture* - The **sagittal suture** runs through the middle of the anterior fontanelle, lying between the two parietal bones [1]. - It extends longitudinally along the midline from the anterior fontanelle posteriorly to the posterior fontanelle [1].

Q: The first primary ossification centre to appear of the carpal bones is

Capitate. The first primary ossification centre to appear of the carpal bones is ***Capitate*** - The **capitate** is the first carpal bone to show an ossification center, typically appearing around **1-3 months of age**. [1] - This early ossification is an important marker in assessing **bone age** in children. *Scaphoid* - The **scaphoid** ossifies later than the capitate, usually between **4 and 6 years of age**. - Its ossification center is often **bi-lobed** and can be confused with a fracture on X-ray if not recognized. *Triquetral* - The **triquetral** ossification center generally appears between **2 and 4 years of age**. - This makes it a mid-range ossifier among the carpal bones, not the first. *Pisiform* - The **pisiform** is typically the last carpal bone to ossify, with its center appearing between **8 and 12 years of age**. - Its delayed ossification makes it a useful indicator for assessing **skeletal maturity** in older children and adolescents.

Q: Which of the following is supplied by the abdominal aorta?

Sequestrated lung tissue. Sequestrated lung tissue - Sequestrated lung tissue is lung tissue that lacks normal connection to the tracheobronchial tree and receives its blood supply from a systemic artery, most commonly a branch of the abdominal aorta or thoracic aorta. - This anomalous arterial supply from the abdominal aorta is a key defining feature of pulmonary sequestration, distinguishing it from normal lung tissue. Accessory lung lobes - Accessory lung lobes are anatomical variations where an additional lobe of lung tissue is present, but it typically has a normal bronchial connection and receives blood supply from the pulmonary arteries, not the systemic circulation. - These lobes develop from the normal foregut and share the same vascular supply as the rest of the lung. Bronchopulmonary segment - A bronchopulmonary segment is a functionally independent unit of the lung, defined by its own segmental bronchus and segmental artery, both derived from the main pulmonary artery and primary bronchi. - Its blood supply is invariably from the pulmonary circulation, not systemic arteries like the abdominal aorta. Base of lung - The base of the lung refers to the lower surface of the lung resting on the diaphragm, and its blood supply is primarily from the pulmonary arteries, which originate from the right ventricle of the heart. - Normal lung parenchyma, including the base, receives its functional blood supply from the pulmonary circulation [1].

Q: By what age is the metopic suture typically completely fused?

2 years. ***2 years*** - The **metopic suture** typically begins to fuse shortly after birth and is usually completely **obliterated by 2 years of age**. - Complete fusion by this age results in a **single frontal bone**, a normal anatomical variation. *8 years* - This age is **too_late** for normal metopic suture fusion; persistence beyond 2-3 years is considered **metopism**. - Other cranial sutures, such as the sagittal or coronal, fuse much later, but not the metopic. *4 years* - While some variability exists, fusion of the metopic suture by 4 years would be considered **delayed** or a mild form of metopism. - The majority of individuals have complete fusion significantly earlier than this age. *6 years* - Fusion at 6 years would be an even **later** presentation of metopism, indicating a persistent metopic suture into childhood. - This is far beyond the typical age range for natural obliteration of this specific suture.

Question 1

From which structure does the spleen develop?

Accepted Answer

Dorsal mesogastrium

Answer

Pleuroperitoneal membrane

Answer

Septum transversum

Answer

Foregut diverticulum

Question 2

What is the primary cause of omphalocele?

Accepted Answer

Failure of the gut to return to the abdominal cavity after physiological herniation

Answer

Failure of lateral body wall closure

Answer

Reversed rotation of intestinal loops

Answer

Duplication of intestinal loops

Question 3

Closure of coronal sutures starts at the age of:

Accepted Answer

30-35 years

Answer

50-60 years

Answer

20 years

Answer

25 years

Question 4

What embryological failure leads to the formation of a double aortic arch?

Accepted Answer

Failure of regression of the right dorsal aorta

Answer

Failure of neural crest cell migration

Answer

Abnormal development of the ductus arteriosus

Answer

Failure of the 6th aortic arch to develop

Question 5

What is the MOST clinically significant anatomical difference between pediatric and adult airways?

Accepted Answer

Narrowest part is cricoid cartilage

Answer

Funnel-shaped vs cylindrical airway shape

Answer

Proportionally larger tongue

Answer

Larynx in higher position

Question 6

How many fontanelles are present in a newborn child?

Accepted Answer

6

Answer

1

Answer

2

Answer

3

Question 7

Anterior fontanelle corresponds to all structures except which of the following?

Accepted Answer

Lambdoid suture

Answer

Coronal suture

Answer

Sagittal suture

Answer

Frontal bones

Question 8

The first primary ossification centre to appear of the carpal bones is

Accepted Answer

Capitate

Answer

Pisiform

Answer

Triquetral

Answer

Scaphoid

Question 9

Which of the following is supplied by the abdominal aorta?

Accepted Answer

Sequestrated lung tissue

Answer

Bronchopulmonary segment

Answer

Accessory lung lobes

Answer

Base of lung

Question 10

By what age is the metopic suture typically completely fused?

Accepted Answer

2 years

Answer

8 years

Answer

4 years

Answer

6 years

Developmental Anatomy — MCQs

Developmental Anatomy — MCQs

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