Thorax Practice Questions

Q: All the following openings in the right atrium are guarded by a valve except

Superior vena cava. ***Superior vena cava*** - The opening of the **superior vena cava** into the right atrium is generally not guarded by a valve. - Its blood flow into the heart is maintained by relatively low pressure and directly continuous with the right atrium. *Inferior vena cava* - The opening of the **inferior vena cava** into the right atrium is guarded by a rudimentary valve called the **Eustachian valve** [1]. - This valve is more prominent in fetal life, helping to direct oxygenated blood from the umbilical vein to the foramen ovale [1]. *Coronary sinus* - The opening of the **coronary sinus** into the right atrium is guarded by the **Thebesian valve**. - This valve's function is to prevent regurgitation of blood from the right atrium into the coronary sinus during atrial systole. *Atrioventricular opening* - The **right atrioventricular opening** is guarded by the **tricuspid valve** [2]. - This valve prevents backflow of blood from the right ventricle into the right atrium during ventricular systole [2].

Q: Careful examination of the central depressed area of the nipple demonstrates multiple small openings, which are from which of the following?

Lactiferous ducts. ***Lactiferous ducts*** - The **nipple** has approximately 15-20 small openings, which are the terminations of the **lactiferous ducts** [1]. - These ducts are responsible for transporting **milk** from the mammary glands to the outside during lactation [1]. *Areolar tissue* - The **areolar tissue** is the pigmented skin surrounding the nipple, not the nipple itself, and does not contain the openings for milk release. - It contains **sebaceous glands** and smooth muscle fibers, but no direct ducts for milk [1]. *Montgomery glands* - **Montgomery glands** are sebaceous glands located in the **areola**, not the nipple, and become more prominent during pregnancy and lactation [1]. - They secrete an **oily substance** that lubricates and protects the nipple and areola. *Sweat glands* - While present in the skin, **sweat glands** are generally distributed throughout the body and are not concentrated as distinct openings in the central depressed area of the nipple. - Their primary function is **thermoregulation**, not milk secretion.

Q: The 8th, 9th, and 10th ribs are attached to their respective costal cartilages by which type of joint?

Primary cartilaginous. ***Primary cartilaginous*** - These joints, also known as **synchondroses**, are formed by **hyaline cartilage** and allow for little to no movement, providing stability to the rib cage. - The attachment of ribs 8, 9, and 10 to their respective **costal cartilages** is characteristic of this joint type, where bone and cartilage are directly united. *Fibrous* - **Fibrous joints** are characterized by connective tissue uniting the bones, which are generally immovable, such as the sutures of the skull. - This type of joint does not allow for the flexibility needed in the rib cage for breathing and would be structurally inappropriate for articulations involving cartilage. *Synovial* - **Synovial joints** are highly mobile, characterized by a joint capsule, synovial fluid, and articular cartilage, such as those found in the appendicular skeleton. - While some rib articulations (e.g., costovertebral) are synovial, the specific junction between the ribs and their costal cartilages is not, as it prioritizes stability over significant movement. *Secondary cartilaginous* - **Secondary cartilaginous joints**, or **symphyses**, are characterized by a plate of **fibrocartilage** between the bones, allowing for limited movement (e.g., intervertebral discs). - This type of joint is not found between the individual ribs and their costal cartilages; rather, the connections are more rigid and directly cartilaginous.

Question 1

All the following openings in the right atrium are guarded by a valve except

Accepted Answer

Superior vena cava

Answer

Inferior vena cava

Answer

Coronary sinus

Answer

Atrioventricular opening

Question 2

Liver biopsy is performed through the 8th intercostal space at the midaxillary line to avoid injury to which structure?

Accepted Answer

Pleural cavity

Answer

Lung

Answer

Subdiaphragmatic space

Answer

Gall bladder

Question 3

Careful examination of the central depressed area of the nipple demonstrates multiple small openings, which are from which of the following?

Accepted Answer

Lactiferous ducts

Answer

Sweat glands

Answer

Areolar tissue

Answer

Montgomery glands

Question 4

The 8th, 9th, and 10th ribs are attached to their respective costal cartilages by which type of joint?

Accepted Answer

Primary cartilaginous

Answer

Fibrous

Answer

Synovial

Answer

Secondary cartilaginous

Thorax — MCQs

Thorax — MCQs

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