Functional Anatomy — MCQs

Functional Anatomy Indian Medical PG Practice Questions and MCQs

Question 11: Muscles involved in centric relation

A. Medial and lateral pterygoids
B. Temporalis & masseter (Correct Answer)
C. Temporalis and lateral pterygoid
D. None of the options

Explanation: ***Temporalis & masseter*** - The **temporalis** and **masseter** muscles are primary elevators of the mandible and play a significant role in forcefully seating the condyles into their most **superior-anterior position** against the articular eminences, which defines **centric relation**. - These muscles contribute to the controlled **retraction** and **elevation** required to achieve a stable and reproducible condylar position in the glenoid fossa. *Medial and lateral pterygoids* - The **lateral pterygoid muscle** is primarily responsible for **protrusion** and **depression** of the mandible, as well as initiating lateral movements, which are movements away from centric relation. - The **medial pterygoid muscle** also aids in **protrusion** and **elevation**, but its primary action is to assist in **side-to-side movements** with the lateral pterygoid. *Temporalis and lateral pterygoid* - While the **temporalis** is critical for achieving centric relation by elevating and retracting the mandible, the **lateral pterygoid** muscle's primary actions of **protrusion** and depression work against establishing centered condylar position. - The combined action of these two muscles in this context would make it difficult to achieve or maintain the **retruded, superior-anterior position** of the condyles characteristic of centric relation. *None of the options* - This option is incorrect because the **temporalis** and **masseter** muscles are indeed directly involved in establishing and maintaining centric relation. - These muscles, through their **elevating** and **retracting** actions, seat the condyles in their most stable and reproducible position within the glenoid fossae.

Question 12: During a routine physical examination a 65-year-old male patient is tested for ease and flexibility of the movements of his lumbar region. Which of the following movements is most characteristic of the intervertebral joints in the lumbar region?

A. Rotation
B. Circumduction
C. Lateral flexion (Correct Answer)
D. Extension

Explanation: ***Lateral flexion*** - **Lateral flexion** (side bending) is the most characteristic movement of the lumbar spine among the given options. - This movement is primarily facilitated by the **frontal plane orientation of the facet joints** in the lumbar region. - The lumbar spine allows approximately **20-30 degrees of lateral flexion** to each side. - The structure of the intervertebral discs and facet joint orientation in the lumbar region particularly favor this movement. *Rotation* - **Rotation** is the LEAST characteristic movement of the lumbar spine. - The lumbar facet joints are oriented in the **sagittal plane**, which significantly **restricts rotational movement**. - The lumbar spine allows only about **5 degrees of rotation**, much less than the thoracic or cervical regions. - Most trunk rotation actually occurs at the thoracic spine, not the lumbar region. *Circumduction* - **Circumduction** is a combined, sequential movement (flexion → lateral flexion → extension → lateral flexion) typically seen in ball-and-socket joints. - While the spine can perform these individual movements, circumduction is not considered a characteristic or distinct movement of intervertebral joints. - This term is more applicable to joints like the shoulder and hip. *Extension* - **Extension** (backward bending) is certainly possible and important in the lumbar spine. - However, it is not the MOST characteristic movement—the lumbar spine allows approximately **20-25 degrees of extension**. [1] - Flexion (forward bending, 40-60 degrees) and lateral flexion are more prominent movements in the lumbar region during functional activities.

Question 13: What action is most affected by severing the tendon of the long head of the biceps brachii?

A. Shoulder abduction
B. Forearm supination (Correct Answer)
C. Elbow flexion
D. Wrist extension

Explanation: ***Forearm supination*** - The **long head of the biceps brachii** is the **most powerful supinator** of the forearm, especially when the elbow is flexed. - The biceps has a **longer moment arm** for supination compared to the supinator muscle, making it biomechanically more effective. - Severing its tendon results in **significant weakness (20-30% loss)** in supination strength, particularly during resisted supination. - While the **supinator muscle** can still perform this action, it is considerably weaker and cannot fully compensate. *Elbow flexion* - Although the biceps contributes to elbow flexion, the **brachialis** is the primary elbow flexor (the "workhorse" of elbow flexion). - The **brachioradialis** also assists significantly. - Loss of the long head of biceps results in only **5-10% loss** of elbow flexion strength, as other muscles compensate effectively. *Shoulder abduction* - **Shoulder abduction** is primarily performed by the **deltoid** and **supraspinatus** muscles. - The biceps brachii is not a primary mover for shoulder abduction. *Wrist extension* - **Wrist extension** is controlled by muscles in the posterior compartment of the forearm, such as the **extensor carpi radialis longus** and **brevis**, and **extensor carpi ulnaris**. - The biceps brachii has no direct action on the wrist.

Question 14: What is the role of the anconeus muscle in elbow movement?

A. Assists in elbow extension (Correct Answer)
B. Wrist extension
C. Thumb abduction
D. Elbow flexion

Explanation: ***Assists in elbow extension*** - The **anconeus muscle** is a small muscle located on the posterior aspect of the **elbow joint**. - Its primary role is to assist the **triceps brachii** in **elbow extension** and to stabilize the elbow joint during pronation. - It acts as an **accessory extensor** and also tenses the capsule of the elbow joint to prevent it from being pinched during extension. *Wrist extension* - **Wrist extension** is primarily performed by muscles originating from the lateral epicondyle of the humerus, such as the **extensor carpi radialis longus and brevis** and **extensor carpi ulnaris** [1]. - The anconeus muscle is not involved in wrist movements. *Thumb abduction* - **Thumb abduction** is the movement of the thumb away from the palm, controlled by muscles like the **abductor pollicis longus** and **abductor pollicis brevis** [1]. - The anconeus muscle has no role in thumb movements. *Elbow flexion* - **Elbow flexion** is performed by anterior compartment muscles including the **biceps brachii**, **brachialis**, and **brachioradialis**. - The anconeus is located in the **posterior compartment** and produces the opposite action (extension), not flexion.

Question 15: Which muscle plays a key role in preventing lateral dislocation of the patella?

A. Rectus femoris
B. Vastus intermedius
C. Vastus lateralis
D. Vastus medialis (Correct Answer)

Explanation: ***Vastus medialis*** - The **vastus medialis obliquus (VMO)** fibers pull the patella medially, counteracting the natural lateral pull exerted by the quadriceps femoris. - Its strength and proper activation are crucial in maintaining **patellar tracking** and preventing lateral subluxation or dislocation. *Rectus femoris* - The **rectus femoris** primarily acts as a hip flexor and knee extensor, with its pull being largely in the superior-inferior direction. - While it contributes to knee extension, its role in **medial stabilization** of the patella is minimal. *Vastus intermedius* - The **vastus intermedius** lies deep to the rectus femoris and primarily contributes to knee extension. - Its fibers run predominantly in the superior-inferior direction, offering little direct lateral-to-medial pull on the patella for stability. *Vastus lateralis* - The **vastus lateralis** pulls the patella in a superior and lateral direction, increasing the tendency for **lateral patellar dislocation**. - An imbalance where the vastus lateralis is significantly stronger or more active than the vastus medialis often contributes to patellar instability.

Question 16: Which of the following statements about articular cartilage is true?

A. Very vascular structure
B. Surrounded by thick perichondrium
C. Has no nerve supply (Correct Answer)
D. Fibrocartilage

Explanation: ***Has no nerve supply*** - Articular cartilage is **aneural**, meaning it lacks nerve endings, which is why damage to it doesn't immediately cause pain until underlying bone or surrounding tissues are affected [1]. - Its aneural nature contributes to its low metabolic activity and limited capacity for repair. *Very vascular structure* - Articular cartilage is **avascular**, meaning it lacks a direct blood supply [1]. - It receives nutrients primarily through diffusion from the synovial fluid [1]. *Surrounded by thick perichondrium* - Articular cartilage is typically **not covered by a perichondrium**, unlike most other types of cartilage. - The absence of perichondrium prevents potential ossification of the articular surface. *Fibrocartilage* - Articular cartilage is primarily composed of **hyaline cartilage**, not fibrocartilage [1]. - **Hyaline cartilage** provides a smooth, low-friction surface for joint movement and acts as a shock absorber [1].

Question 17: Yoke muscle for the right superior rectus is:

A. Left Inferior Oblique (Correct Answer)
B. Left Lateral Rectus
C. Left Superior rectus
D. Left Inferior rectus

Explanation: ***Left Inferior Oblique*** - Yoke muscles are pairs of synergistic muscles, one in each eye, that act together to produce conjugate eye movements in the same direction of gaze. - The **right superior rectus** and **left inferior oblique** are yoke muscles that work together during **upward and rightward gaze** (dextro-elevation) [1]. - Right SR elevates the **adducted** right eye, while left IO elevates the **abducted** left eye, producing coordinated upward-right movement [1]. - This follows **Hering's Law of Equal Innervation**, where yoke muscles receive equal and simultaneous innervation. *Left Superior rectus* - The left superior rectus is the **contralateral homologous muscle**, not a yoke muscle for the right superior rectus. - Both superior recti work together for **upward gaze in primary position**, but they are versional muscles, not yoke pairs. - Yoke muscles produce conjugate movements in oblique directions, not straight up. *Left Inferior rectus* - The left inferior rectus depresses the left eye and is an antagonist to elevation. - It would pair with the **right superior oblique** for downward-left gaze (levo-depression), not with the right superior rectus. *Left Lateral Rectus* - The left lateral rectus is responsible for **abduction** of the left eye (leftward gaze). - Its yoke muscle is the **right medial rectus** for leftward horizontal gaze (levoversion), not for upward-right gaze.

Question 18: Which muscle plays a role in winking?

A. Levator labii superioris
B. Orbicularis oculi (Correct Answer)
C. Levator palpebrae
D. Corrugator supercilii

Explanation: ***Orbicularis oculi*** - This muscle is responsible for **closing the eyelid** and is essential for actions like blinking, squinting, and winking. - Its fibers encircle the eye and facilitate the **controlled closure** required for winking. *Levator labii superioris* - This muscle primarily functions to **elevate the upper lip**, playing a role in facial expressions such as sneering or smiling. - It has no direct involvement in the movement of the eyelids or the act of winking. *Corrugator supercilii* - This muscle is located in the eyebrow region and is responsible for **drawing the eyebrows medially and inferiorly**, creating vertical wrinkles between the eyebrows. - It is associated with expressions of frowning or concern, not eyelid closure. *Levator palpebrae* - This muscle is responsible for **opening the upper eyelid**, thus counteracting the action of the orbicularis oculi. - While essential for eye movement, it is not involved in the closing action required for winking.

Question 19: Which is the primary muscle causing supination of the forearm?

A. Brachioradialis
B. Anconeus
C. Biceps brachii
D. Supinator (Correct Answer)

Explanation: ***Supinator*** - The **supinator muscle** is the **primary muscle** responsible for **supination** of the forearm, rotating the palm anteriorly or superiorly. - It is a deep muscle of the **posterior compartment** of the forearm. - Its action is especially prominent when **supinating against resistance** or in very slow movements, as it works synergistically with the biceps brachii. *Biceps brachii* - While the **biceps brachii** is also a powerful **supinator** of the forearm, especially when the elbow is flexed, it is a **secondary supinator**. - It is primarily a major **flexor** of the elbow, whereas the supinator is dedicated specifically to supination. *Brachioradialis* - The **brachioradialis** is primarily a **flexor** of the forearm at the elbow joint. - It helps to bring the forearm into a **mid-prone or mid-supine position** from either full pronation or full supination, but does not actively supinate. *Anconeus* - The **anconeus** is a small muscle that assists the **triceps brachii** in **extension of the forearm** at the elbow. - It helps to **stabilize the elbow joint** and slightly abducts the ulna during pronation, but has no role in supination.

Question 20: Which statement accurately describes a characteristic of synovial joints?

A. Hyaline cartilage covers the articular surfaces of synovial joints. (Correct Answer)
B. The metacarpo-phalangeal joint is a condyloid joint.
C. Cartilage can sometimes divide the joint into two cavities.
D. Stability is inversely proportional to mobility in synovial joints.

Explanation: ***Hyaline cartilage covers the articular surfaces of synovial joints.*** - The articular surfaces of bones within a **synovial joint** are covered by a thin layer of **hyaline cartilage**, providing a smooth, low-friction surface for movement [1]. - This **articular cartilage** absorbs shock and protects the underlying bone from wear and tear [1]. - This is a **universal structural characteristic** of all synovial joints, making it the most accurate answer. *The metacarpo-phalangeal joint is a condyloid joint.* - While this statement is factually true (MCP joints are indeed **condyloid/ellipsoid joints** allowing movement in two planes), it describes a **specific type** of synovial joint, not a general characteristic of all synovial joints. - The question asks for a characteristic that describes synovial joints as a category, not an example of one specific joint classification. - This makes it incorrect as the best answer to this question. *Cartilage can sometimes divide the joint into two cavities.* - This statement refers to an **articular disc** or **meniscus**, which is a fibrocartilaginous structure that can partially or completely divide a synovial joint cavity. - This feature is present in **some** synovial joints (like the knee or temporomandibular joint) but is **not universal**. - Since it's not a characteristic of all synovial joints, it's not the best answer. *Stability is inversely proportional to mobility in synovial joints.* - Generally, there is an **inverse relationship** between **stability** and **mobility** in joints; joints designed for great mobility (e.g., shoulder) tend to be less stable, and vice-versa (e.g., hip). - However, this describes a **functional principle** or trade-off rather than a **structural characteristic** that defines synovial joints. - While true, it's not the defining characteristic being asked for in this question.

Practice by Chapter

Anatomical Basis of Movement

Practice Questions

Biomechanics of Joints

Practice Questions

Functional Anatomy of Respiratory System

Practice Questions

Functional Anatomy of Cardiovascular System

Practice Questions

Functional Anatomy of Digestive System

Practice Questions

Functional Anatomy of Urinary System

Practice Questions

Functional Anatomy of Reproductive System

Practice Questions

Neuroanatomical Basis of Functions

Practice Questions

Functional Correlations in Clinical Practice

Practice Questions

Anatomical Aspects of Exercise Physiology

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free