The Skeleton of Limbs: Clavicle and Scapula

Which statement best contrasts the general characteristics of upper limb bones with lower limb bones in humans?

• Upper limb bones are thicker and more massive for support, while lower limb bones are thinner for grasping.

• Upper limb bones are thinner and lighter for grasping and varied work, while lower limb bones are thicker and more massive for support and upright posture.

• Both upper and lower limb bones are equally massive because they share identical locomotor functions.

• Lower limb bones are lighter to allow greater mobility than the upper limb.

Answer explanation

The correct choice highlights that upper limb bones are thinner and lighter for tasks like grasping, while lower limb bones are thicker and more massive to support body weight and maintain upright posture.

Which bones constitute the shoulder girdle of the upper limb?

• Humerus and ulna

• Clavicle and scapula

• Scapula and humerus

• Radius and ulna

Answer explanation

The shoulder girdle is formed by the clavicle and scapula, which connect the upper limb to the trunk. The humerus, radius, and ulna are bones of the arm and forearm, not part of the girdle.

Which anatomical feature is found on the inferior surface of the clavicle near the acromial end and serves as an attachment point for a ligament of the same name?

• Sternal articular surface

• Subclavian groove

• Conoid tubercle

• Nutrient foramen

• Scapular notch

Answer explanation

The conoid tubercle is located on the inferior surface of the clavicle near the acromial end and serves as the attachment point for the conoid ligament, making it the correct answer.

At the lateral angle of the scapula lies a cavity that articulates with the head of the humerus. Which statement correctly identifies this cavity and its neighboring tubercles?

• Glenoid cavity bounded above by the infraglenoid tubercle and below by the supraglenoid tubercle

• Glenoid cavity bounded above by the supraglenoid tubercle and below by the infraglenoid tubercle

• Acromial fossa bounded by the coracoid and acromial tubercles

• Subscapular fossa bounded by the trapezoid and conoid tubercles

Answer explanation

The glenoid cavity is the socket for the humerus, with the supraglenoid tubercle above and the infraglenoid tubercle below, making the correct choice: 'Glenoid cavity bounded above by the supraglenoid tubercle and below by the infraglenoid tubercle'.

Which structure of the proximal humerus lies between the greater and lesser tubercles and transmits the tendon of the long head of biceps brachii?

• Anatomical neck (collum anatomicum)

• Surgical neck (collum chirurgicum)

• Intertubercular sulcus (sulcus intertubercularis)

• Deltoid tuberosity (tuberositas deltoidea)

Answer explanation

The intertubercular sulcus lies between the greater and lesser tubercles of the proximal humerus and serves as a passage for the tendon of the long head of biceps brachii, making it the correct answer.

At the distal humerus, which pairing correctly matches the articular part with the bone it articulates with?

• Capitulum — Ulna

• Trochlea — Radius

• Capitulum — Radius

• Trochlea — Scaphoid

Answer explanation

The capitulum articulates with the radius, allowing for the movement of the forearm. The trochlea, on the other hand, articulates with the ulna. Therefore, the correct pairing is Capitulum — Radius.

Which feature is located on the proximal ulna and articulates with the trochlea of the humerus?

• Radial notch (incisura radialis)

• Trochlear notch (incisura trochlearis)

• Ulnar tuberosity (tuberositas ulnae)

• Head of ulna (caput ulnae)

Answer explanation

The trochlear notch (incisura trochlearis) is a concave surface on the proximal ulna that articulates with the trochlea of the humerus, allowing for hinge-like movement at the elbow joint.

Which set correctly lists the three main divisions of the hand from proximal to distal?

• Carpus, metacarpus, phalanges

• Phalanges, metacarpus, carpus

• Metacarpus, carpus, phalanges

• Carpus, phalanges, metacarpus

Answer explanation

The correct order from proximal to distal is carpus (wrist), metacarpus (palm), and phalanges (fingers). Therefore, the correct choice is 'Carpus, metacarpus, phalanges'.

Which statement best distinguishes the phalanges of the thumb from those of the other fingers?

• Thumb has three phalanges named proximal, middle, and distal

• Thumb has only proximal and distal phalanges, lacking a middle phalanx

• Thumb has a saddle-shaped proximal phalanx

• Thumb’s distal phalanx lacks a nail tuberosity

Answer explanation

The thumb has only two phalanges: the proximal and distal phalanges, unlike the other fingers which have three (proximal, middle, and distal). This key difference distinguishes the thumb's structure.

Which statement best characterizes the acromioclavicular joint and its stabilizing ligaments?

• It is a saddle joint with an obligatory articular disc and primarily allows rotation around a sagittal axis.

• It is a plane joint with oblique flat surfaces; stability is reinforced by the acromioclavicular and coracoclavicular ligaments, the latter dividing into trapezoid and conoid parts.

• It is a ball-and-socket joint stabilized mainly by the glenohumeral ligaments and labrum.

• It is a hinge joint allowing flexion–extension only and is stabilized by the transverse humeral ligament.

Answer explanation

The acromioclavicular joint is a plane joint with flat surfaces, and its stability is enhanced by the acromioclavicular and coracoclavicular ligaments, which include the trapezoid and conoid parts.