|Henry Gray (18251861). Anatomy of the Human Body. 1918.|
|first and second phalanges are slightly hollow, but flattened and square-shaped in those between the second and third.|
Articulations.The sternoclavicular joint is subcutaneous, and its position is indicated by the enlarged sternal extremity of the clavicle, lateral to the long cord-like sternal head of Sternocleidomastoideus. If this muscle be relaxed a depression between the end of the clavicle and the sternum can be felt, defining the exact position of the joint.
| The position of the acromioclavicular joint can generally be ascertained by determining the slightly enlarged acromial end of the clavicle which projects above the level of the acromion; sometimes this enlargement is so considerable as to form a rounded eminence.|
| The shoulder-joint is deeply seated and cannot be palpated. If the forearm be slightly flexed a curved crease or fold with its convexity downward is seen in front of the elbow, extending from one epicondyle to the other; the elbow-joint is slightly distal to the center of the fold. The position of the radiohumeral joint can be ascertained by feeling for a slight groove or depression between the head of the radius and the capitulum of the humerus, at the back of the elbow-joint.|
| The position of the proximal radioulnar joint is marked on the surface at the back of the elbow by the dimple which indicates the position of the head of the radius. The site of the distal radioulnar joint can be defined by feeling for the slight groove at the back of the wrist between the prominent head of the ulna and the lower end of the radius, when the forearm is in a state of almost complete pronation.|
| Of the three transverse skin furrows on the front of the wrist, the middle corresponds fairly accurately with the wrist-joint, while the most distal indicates the position of the midcarpal articulation.|
| The metacarpophalangeal and interphalangeal joints are readily available for surface examination; the former are situated just distal to the prominences of the knuckles, the latter are sufficiently indicated by the furrows on the volar, and the wrinkles on the dorsal surfaces.|
Muscles (Figs. 1194, 1231, 1232).The anterior border of the Trapezius presents as a slight ridge running downward and forward from the superior nuchal line of the occipital bone to the junction of the intermediate and lateral thirds of the clavicle. The inferior border of the muscle forms an undulating ridge passing downward and medialward from the root of the spine of the scapula to the spinous process of the twelfth thoracic vertebra.
| The lateral border of the Latissimus dorsi (Fig. 1215) may be traced, when the muscle is in action, as a rounded edge starting from the iliac crest and slanting obliquely forward and upward to the axilla, where it takes part with the Teres major in forming the posterior axillary fold.|
| The Pectoralis major (Fig. 1219) conceals a considerable part of the thoracic wall in front. Its sternal origin presents a border which bounds, and determines the width of the sternal furrow. The upper margin is generally well-marked medially and forms the medial boundary of a triangular depression, the infraclavicular fossa, which separates the Pectoralis major from the Deltoideus; it gradually becomes less marked as it approaches the tendon of insertion and is closely blended with the Deltoideus. The lower border of Pectoralis major forms the rounded anterior axillary fold. Occasionally a gap is visible between the clavicular and sternal parts of the muscle.|
| When the arm is raised the lowest slip of origin of Pectoralis minor produces a fulness just below the anterior axillary fold and serves to break the sharp outline of the lower border of Pectoralis major.|
| The origin of the Serratus anterior (Figs. 1215, 1219) causes a very characteristic surface marking. When the arm is abducted the lower five or six serrations form