Which of the following is an example of ball-and-socket joints?

Appeared in: AIIMS Patna NO - 2020

Explanation

The hip joint is a ball-and-socket (spheroidal) type of synovial joint.
This structure involves the spherical head of the femur ('ball') fitting into the cup-shaped acetabulum of the pelvis ('socket').
This arrangement allows for multiaxial movement, including flexion-extension, abduction-adduction, and rotation, providing a wide range of motion for the leg.

Option A: The joints in the skull are sutures, which are a type of fibrous joint. They are immovable (synarthrosis) and do not allow for the free movement characteristic of a ball-and-socket joint.
Option B: The carpometacarpal joint of the thumb is a classic example of a saddle joint. While it allows for a good range of motion (biaxial), its articulating surfaces are reciprocally concavo-convex, not a ball-in-socket shape.
Option D: The elbow joint is a hinge joint (ginglymus). It primarily allows for movement in one plane only (uniaxial), specifically flexion and extension, like the hinge of a door.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of synovial joints as background academic context rather than a clinical decision trigger.
Understanding joint types is crucial for assessing a patient's range of motion (ROM). A nurse assessing a patient with hip pain would evaluate flexion, extension, abduction, adduction, and rotation, which are all movements expected of a healthy ball-and-socket joint.
The ball-and-socket structure of the hip makes it strong and weight-bearing but also susceptible to dislocation from trauma and degenerative conditions like osteoarthritis, which can necessitate a total hip replacement (arthroplasty).
What if the question asked for the most mobile joint in the body? The answer would be the shoulder joint (glenohumeral joint), which is also a ball-and-socket joint but has a shallower socket (glenoid fossa) compared to the hip's acetabulum, allowing for greater mobility at the cost of stability.

How to Approach the Question

First, understand the question. It asks for a specific example of a 'ball-and-socket' joint.
Recall the definition of a ball-and-socket joint: a joint where a rounded bone head fits into a cup-like socket, allowing for movement in many directions.
Mentally (or on paper) list the main examples of ball-and-socket joints you know. The two primary ones are the shoulder and the hip.
Evaluate each option against this knowledge:
Skull joint: Recognize these are fixed sutures, not synovial joints.
Thumb joint: Recall this is the classic example of a saddle joint.

Concept Tested & Keywords

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E6 Nursing Fundamentals Taylor p. 305-307

E6 Anatomy Applied Ashalatha 4e p. 297-299

Practise the full AIIMS Patna NO - 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.