Shoulder girdle, arm, forearm and hand
Upper-limb organization connects bones, joints, muscles, vessels and nerves. The quiz follows the limb from the shoulder girdle to the hand, emphasizing anatomical relationships.
212 explained questions · practice, exam and sprint · freeClavicle and scapula form the pectoral girdle. The sternoclavicular joint is its principal bony connection to the axial skeleton. At the glenohumeral joint, the humeral head articulates with the glenoid cavity. Scapulothoracic movement occurs over the chest wall without a typical synovial joint. Arm elevation combines glenohumeral and girdle movements, so the humerus alone does not explain the whole action.
Anatomical arm extends from shoulder to elbow; forearm extends from elbow to wrist. The arm contains the humerus, while the forearm contains radius and ulna. Radius is lateral in anatomical position. During pronation it crosses anterior to the ulna; during supination they are approximately parallel. Elbow flexion differs from forearm pronation. The elbow region includes humeroulnar, humeroradial and proximal radioulnar relationships.
The anterior arm mainly contains elbow flexors supplied by the musculocutaneous nerve; the posterior arm contains triceps supplied by the radial nerve. Forearm anterior groups chiefly flex and pronate, while posterior groups chiefly extend and supinate, with individual exceptions. The brachial plexus typically organizes C5–T1 anterior rami into roots, trunks, divisions, cords and terminal branches. Cord names describe their relationships to the axillary artery.
Extrinsic hand muscles originate in the forearm and send tendons into the hand; intrinsic muscles have attachments within the hand itself. The carpal tunnel transmits the median nerve and flexor tendons, whereas the ulnar nerve follows a different wrist route. Thumb opposition combines movements for pinch. Use palmar or dorsal, radial or ulnar, and proximal or distal references. Peripheral nerve sensory territories are not identical to single-root dermatomes.
| Structure or concept | Distinguishing feature |
|---|---|
| Musculocutaneous | Principal motor supply of the anterior arm. |
| Radial | Extensors of arm and forearm. |
| Median | Passes through the carpal tunnel. |
| Radius / ulna | Radius lateral and ulna medial in anatomical position. |
Try answering before opening the explanation. Each example develops a point from the guide.
Answer: Humerus
The humerus occupies the arm, and its head articulates with the scapular glenoid cavity at the glenohumeral joint. Clavicle and scapula also form other shoulder-girdle relationships.
Why the other options do not fit: Radius and ulna are forearm bones relating to the humerus at the elbow. Clavicle belongs to the pectoral girdle, not the arm region described.
Answer: Elbow joint
The elbow region includes humeroulnar, humeroradial and proximal radioulnar articulations. Flexion–extension interacts with forearm rotation, although these are distinct movements.
Why the other options do not fit: Shoulder relates humerus and scapula; wrist relates forearm and carpus. Scapula is a bone, not the requested joint complex.
Answer: Radius
The radius is lateral in anatomical position on the thumb side. During pronation it crosses anterior to the ulna, demonstrating why the reference posture must be specified first.
Why the other options do not fit: Ulna is medial in anatomical position; humerus belongs to the arm. Scaphoid is a carpal bone rather than one of the two forearm bones.
If a relationship is missing, return to the relevant section. Then practice a short set and save persistent uncertainties in your review notebook.
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