Systemic Anatomy — MCQs

Systemic Anatomy Indian Medical PG Practice Questions and MCQs

Question 171: Zonula of Zinn is

A. Suspensory ligament of the lens (Correct Answer)
B. Ciliary muscle
C. Ciliary processes
D. Ciliary body

Explanation: ***Suspensory ligament of the lens*** - The **Zonula of Zinn**, also known as the **suspensory ligaments of the lens**, are a series of fibers connecting the ciliary body to the lens of the eye. - These ligaments play a crucial role in **accommodation** by transmitting the tension from the ciliary muscle to the lens, thereby changing its shape and focal length. *Ciliary muscle* - The **ciliary muscle** is a smooth muscle ring in the eye's ciliary body, primarily responsible for contracting and relaxing to alter the tension on the suspensory ligaments. - Its action directly controls the **shape of the lens** for focusing [2]. *Ciliary processes* - **Ciliary processes** are folds or ridges of the ciliary body that secrete **aqueous humor**, the fluid that fills the anterior and posterior chambers of the eye [1]. - They are primarily involved in maintaining **intraocular pressure** and nourishing eye structures. *Ciliary body* - The **ciliary body** is a ring of tissue behind the iris, composed of the ciliary muscle and ciliary processes [1]. - It functions in both **aqueous humor production** and **lens accommodation**.

Question 172: True about the Serratus anterior muscle is

A. Supplied by the subscapular nerve
B. Bipennate muscle
C. Helps in forced inspiration (Correct Answer)
D. Originates from the lower four ribs

Explanation: ***Helps in forced inspiration*** - The **serratus anterior muscle** elevates the ribs when the scapula is fixed, aiding in **forced inspiration**. [1] - It is a significant accessory muscle of respiration, particularly during strenuous breathing. [1] *Supplied by the subscapular nerve* - The serratus anterior muscle is innervated by the **long thoracic nerve** (from the C5, C6, C7 nerve roots), not the subscapular nerve. - Damage to the long thoracic nerve can lead to **"winged scapula,"** characterized by medial scapular protraction. *Bipennate muscle* - The serratus anterior muscle has a **multi-pennate (or serrated)** arrangement, not bipennate. - Its shape is described as fan-shaped, with multiple slips attaching to the ribs. *Originates from the lower four ribs* - The serratus anterior muscle originates from the **first eight or nine ribs**, not just the lower four. - Its extensive origin allows it to spread broadly over the thoracic wall.

Question 173: Blood is supplied to bone from which arteries?

A. Nutrient
B. Periosteal
C. Metaphyseal
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - **Nutrient arteries**, **periosteal arteries**, and **metaphyseal arteries** all contribute significantly to the blood supply of bone. - The combined supply ensures adquate perfusion to different regions of the bone, including the **diaphysis**, **epiphysis**, and outer cortical layers. *Nutrient* - **Nutrient arteries** enter the bone through the **nutrient foramen** and primarily supply the **marrow** and the inner two-thirds of the **cortical bone**. - While crucial, they do not exclusively provide all blood supply to the entire bone. *Periosteal* - **Periosteal arteries** ramify within the **periosteum** and supply the outer one-third of the **cortical bone**. - They are particularly important for **bone growth** and **repair**, but also do not solely supply the entire bone. *Metaphyseal* - **Metaphyseal arteries** arise from surrounding systemic arteries and supply the **metaphysis** of the bone, particularly during bone growth. - These arteries anastomose with the epiphyseal and nutrient arteries, but also are not the sole source of blood flow.

Question 174: NOT true about right atrium:

A. Fossa ovalis represent remnant of foramen ovale
B. Posterior part is smooth
C. Anterior and posterior parts are divided by valve of inferior vena cava (Correct Answer)
D. Anterior part is derived from absorption of right horn of sinus venosus

Explanation: ***Anterior and posterior parts are divided by valve of inferior vena cava*** - The **crista terminalis**, a muscular ridge, divides the anterior and posterior parts of the right atrium [1]. - The **valve of the inferior vena cava (Eustachian valve)** is a rudimentary fold guarding the inferior vena cava orifice, not a divider of the atrial chambers [1]. *Fossa ovalis represent remnant of foramen ovale* - The **fossa ovalis** is indeed a depression in the interatrial septum, representing the fibrous remnant of the **foramen ovale** [1]. - The foramen ovale is a fetal shunt that allowed blood to bypass the pulmonary circulation. *Posterior part is smooth* - The **posterior part of the right atrium**, also known as the **sinus venarum**, is embryologically derived from the sinus venosus and has **smooth walls**. - This contrasts with the rough, muscular walls of the anterior part of the atrium. *Anterior part is derived from absorption of right horn of sinus venosus* - The **anterior part of the right atrium**, which contains the **pectinate muscles**, is derived from the embryonic **primitive atrium**. - The **posterior smooth part (sinus venarum)** is derived from the absorption of the **right horn of the sinus venosus**.

Question 175: Length of the nasolacrimal duct is about:

A. 20-25 mm
B. 10-14 mm
C. 16-20 mm
D. 12-18 mm (Correct Answer)

Explanation: ***12-18 mm*** - The **nasolacrimal duct** averages around **12-18 mm** in length, with most standard anatomy references citing this as the typical range. - This measurement extends from the **lacrimal sac** to where it opens into the **inferior meatus** of the nasal cavity. - This is the most commonly cited range in medical education resources and textbooks. *20-25 mm* - This range is generally **too long** for the typical human nasolacrimal duct. - While anatomical variations exist, values in this upper range are uncommon and exceed standard anatomical references. *10-14 mm* - This range is **shorter than the typical length** for the average nasolacrimal duct. - While the lower end approaches acceptable values, this range overall underestimates the duct's usual length. *16-20 mm* - While this range has **some overlap** with the correct answer (16-18 mm), the upper limit of **20 mm** extends beyond the commonly accepted anatomical range. - The range **12-18 mm** is more consistently cited in standard anatomy textbooks and is the preferred reference value for medical examinations.

Question 176: Which of the following is another term for the colliculus seminalis?

A. Prostatic utricle
B. Verumontanum (Correct Answer)
C. Ejaculatory ducts
D. Prostatic sinus

Explanation: ***Colliculus seminalis*** - The **colliculus seminalis** (also called **verumontanum**) is a rounded elevation located on the posterior wall of the prostatic urethra. - It is situated in the middle of the **urethral crest (crista urethralis)**, which is the longitudinal ridge running along the prostatic urethra. - The colliculus seminalis contains the openings of the prostatic utricle (centrally) and the two ejaculatory ducts (on either side). - **Verumontanum** (meaning "mountain ridge") is the classical synonym used interchangeably with colliculus seminalis. *Prostatic utricle* - The **prostatic utricle** is a small blind pouch located within the colliculus seminalis. - It is an embryonic remnant of the paramesonephric (Müllerian) ducts in males. - It opens at the summit of the colliculus seminalis but is not a synonym for it. *Ejaculatory ducts* - The **ejaculatory ducts** are formed by the union of the vas deferens and seminal vesicle duct. - They open on either side of the prostatic utricle on the colliculus seminalis. - They are structures that open onto the colliculus, not synonyms for it. *Prostatic sinus* - The **prostatic sinuses** are shallow grooves on either side of the urethral crest in the prostatic urethra. - They contain the openings of the prostatic ducts that drain the prostate gland. - They flank the urethral crest but are not synonymous with the colliculus seminalis.

Question 177: The first costochondral joint is a type of:

A. Synovial joint
B. Syndesmosis
C. Synchondrosis (Correct Answer)
D. Fibrous joint

Explanation: ***Synchondrosis*** - The first costochondral joint is a **primary cartilaginous joint**, specifically a **synchondrosis**, where the **first rib is united to its costal cartilage** by **hyaline cartilage** [1]. - This type of joint allows for little to no movement, serving primarily for stability during respiration. - All costochondral joints (ribs 1-10) are synchondroses, providing strong yet slightly flexible connections. *Synovial joint* - **Synovial joints** are characterized by a **joint capsule**, **synovial fluid**, and **articular cartilage**, allowing for significant movement [1]. - The **sternocostal joints** (where costal cartilages 2-7 meet the sternum) are synovial joints, but costochondral joints are not. *Syndesmosis* - A **syndesmosis** is a type of **fibrous joint** where bones are joined by a sheet of **fibrous connective tissue**, such as the interosseous membrane between the tibia and fibula. - This type of connection is not found in the costochondral joints. *Fibrous joint* - **Fibrous joints** are united by **dense connective tissue** and typically allow very little or no movement (e.g., sutures of the skull). - Synchondroses are **cartilaginous joints** (not fibrous), united by hyaline cartilage rather than fibrous tissue [1].

Question 178: Cholecystocaval line:-

A. Separate left medial and left lateral sectors
B. Separate right anterior and right posterior sectors
C. Separate gall bladder from portal vein
D. Separate right and left hepatic lobes (Correct Answer)

Explanation: ***Separate right and left hepatic lobes*** - The **cholecystocaval line**, also known as **Cantlie's line**, is an imaginary plane that divides the **anatomical right and left lobes** of the liver [1]. - This line runs from the **gallbladder fossa** anteriorly to the **inferior vena cava (IVC)** posteriorly. *Separate left medial and left lateral sectors* - The division between the **left medial (segment IV)** and **left lateral (segments II and III)** sectors of the liver is demarcated by the **left hepatic vein** or the falciform ligament internally [3], [4]. - The cholecystocaval line's primary function is not to separate these specific left lobe sectors. *Separate right anterior and right posterior sectors* - The division between the **right anterior (segments V and VIII)** and **right posterior (segments VI and VII)** sectors of the liver is typically defined by the **right hepatic vein** [2]. - This anatomical landmark is distinct from the cholecystocaval line. *Separate gall bladder from portal vein* - The cholecystocaval line is a plane that **originates from the gallbladder**, but it divides the liver parenchyma rather than separating the gallbladder itself from the portal vein. - The gallbladder is a separate organ adjacent to the liver, and the portal vein is a major vessel within the liver parenchyma [1].

Question 179: Shape of trapezius muscle is:

A. Quadrilateral
B. Triangular (Correct Answer)
C. Quadrangular
D. Trapezium

Explanation: ***Triangular*** - The **trapezius muscle** is a large, flat, **triangular muscle** extending over the posterior neck and upper thorax. - Each trapezius muscle has a **triangular shape** with the base along the vertebral column (from occipital protuberance to T12 vertebra) and the apex pointing laterally toward the shoulder (acromion and spine of scapula). - This triangular configuration is the standard anatomical description found in **Gray's Anatomy** and other authoritative anatomy texts. - The muscle has three parts: **descending (superior), transverse (middle), and ascending (inferior)** fibers, all converging toward the lateral shoulder. *Trapezium* - The name "trapezius" is derived from the **trapezoid/trapezium shape** formed when **both left and right trapezius muscles are viewed together** as a pair meeting at the midline. - However, the question asks about the shape of "trapezius muscle" (singular), which anatomically refers to the **individual muscle**, not the bilateral pair. - While the etymology relates to trapezium, the actual anatomical description of each muscle is **triangular**. *Quadrilateral* - This is a **general geometric term** for any four-sided polygon, which is too non-specific for anatomical description. - While technically a triangle is not a quadrilateral (it has three sides, not four), this option doesn't accurately capture the specific shape of the trapezius muscle. - Many muscles could loosely be called quadrilateral, making this term anatomically imprecise. *Quadrangular* - **Quadrangular** is synonymous with quadrilateral, referring to a four-sided figure. - This term is too broad and does not specifically describe the distinctive **three-sided (triangular)** shape of the individual trapezius muscle. - Not the standard anatomical terminology used for this muscle.

Question 180: Liver is divided into eight segments according to Couinaud's classification based upon

A. Bile Duct
B. Hepatic artery
C. Hepatic Vein
D. Portal vein (Correct Answer)

Explanation: ***Portal vein*** - Couinaud's classification divides the liver into eight functional segments based on the distribution of the **portal vein** and hepatic artery [1]. - Each segment has its own portal pedicle, including a portal vein branch, hepatic artery branch, and bile duct, allowing for anatomical resections [1]. *Bile Duct* - While bile ducts run alongside the portal vein and hepatic artery, they are not the primary basis for the **Couinaud segmentation**. - The branching pattern of bile ducts generally follows the portal venous system, but the vasculature is the defining factor. *Hepatic artery* - The hepatic artery branches accompany the portal vein and bile ducts within the portal triad but are secondary to the **portal vein** in defining the liver's functional segments [1]. - Hepatic artery distribution is crucial for blood supply to each segment, but the primary segmentation landmark is the portal venous branching. *Hepatic Vein* - **Hepatic veins** divide the liver into sections and sectors [1], rather than the eight functional segments described by Couinaud. - The main hepatic veins (right, middle, left) run between the segments, creating boundaries, whereas the portal vein branches feed into the segments [1].

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