Anatomy Lessons From the Great Masters
Page 7
The outside curve of the trapezius (F) is interrupted by the prominence of the outer clavicle or collarbone (G), site of the acromioclavicular joint. The curve is picked up again by the outline of the middle portion of the deltoid (H).
Now follow the shaded lines of the posterior deltoid (I) to the hatchings along the spine of the scapula (J). The varied forms and relationships of Raphael’s marks show his total awareness of the forms of the shoulder girdle: the vertebral border of the scapula (K), the rhomboids (L) over the spinal muscles, the latissimus dorsi (M) holding in the inferior angle of the scapula (N), and the hatchings at the side of the teres major (O) and the infraspinatus (P).
Observe and compare the changes in Raphael’s drawings from the simple surface markings of the shoulder girdle in the drawing at the lower right, where the arms are moved forward, to the more complex forms in the drawing on the left, where the arms are back.
Raphael Sanzio (1483-1520)
FIVE NUDE MEN
pen and ink
10 5/8″ × 7 3/4″ (269 × 197 mm)
British Museum, London
Sternoclavicular Articulation, Elevation and Lowering
The sternoclavicular joint is the center from which all movements of the shoulder girdle originate and is its only bony connection with the rib cage. This joint is made up of the inner end of the clavicle (A), on the one hand, and the upper lateral part of the manubrium (B), the upper bone on the sternum, on the other hand. Strong ligaments hold the inner end of this swinging spiral clavicle to its base in the sternum of the rib cage.
Normally, the sternoclavicular joint is active to some degree in all movements of the arm, as is the acromioclavicular joint. But the greatest movement of the sternoclavicular joint occurs in the first ninety degrees of upward movement of the arm.
In this drawing, the shoulders are hunched, as in shrugging, in order to meet and support the laterally inclined head. In this action, the clavicle in the front and the scapula behind are elevated upon the rib cage by the levator anguli scapulae (C) and the upper trapezius (D) in the back, and by the clavicular head of the sternocleidomastoid muscle (E) in the front. This upward shift of the shoulder girdle is followed from the sternoclavicular joint by upward movement of the clavicle.
Michelangelo has clearly indicated many anterior surface changes. On the left, as the upper clavicle (F) moves upward to the sternocleidomastoideus and the side of the neck, the posterior triangle of the neck (G) all but disappears. As the shoulder is raised, the anterior portion of the deltoid (H) presses upward and inward, the infraclavicular fosset (the space between the pectoralis and the deltoid) (I) deepens, and the shape of the pectoralis (J) elongates.
Michelangelo Buonarotti (1475-1564)
STUDY FOR A PIETÀ
black chalk
10″ × 12 1/2″ (254 × 318 mm)
Louvre, Paris
Sternoclavicular Articulation, Forward and Back
Forward elevation or flexion of the arm takes place by the synchronous action of the parts of the shoulder girdle. The action is initiated by the contractions of the anterior portion of the deltoid (A) and the clavicular portion of the pectoralis major (B), with some participation of the coracobrachialis and the biceps (C).
As the arm is moved from the side to the front of the body, the clavicle (D) rotates upward on its long axis from the sternoclavicular joint (E), and the acromion process (F) and the scapula follow. The convex curve of the inner clavicle (G) permits this bone some freedom in its limited movements over the contour of the rib cage beneath. As the clavicle moves away from the sternocleidomastoid (H) and the column of the neck, which occurs when the arm is thrust forward, the posterior triangle of the neck (I) deepens and the angle formed by the spine of the scapula and the clavicle is diminished.
Michelangelo knew that the inside end of the clavicle at the sternoclavicular joint (E) is less prominent when the shoulder is moved forward, so he emphasized the adjacent muscles instead.
Michelangelo Buonarotti (1475-1564)
STUDY OF ST. LAWRENCE FOR THE LAST JUDGMENT
black chalk
9 1/2″ × 7 1/4″ (242 × 183 mm)
Teyler Museum, Haarlem
Acromioclavicular Articulation, Forward and Back
The acromioclavicular joint, where the clavicle meets the acromion process of the scapula, is active in nearly all movements of the shoulder girdle and contributes to its great mobility.
You can find this important joint of the shoulder girdle by the projection of the enlarged outer end of the clavicle (A) as it rises slightly above the acromion process of the spine (B) of the scapula.
You can find the line of the spine of the scapula by drawing a spiral line between the bulge (A) at its outer and upper end to the inner end of the origin of the posterior portion (C) of the deltoid. If you follow the edge of the bulging muscular masses of the supraspinatus (D), infraspinatus (E), and teres major (F), all of which originate in the scapula, you will find the inner or vertebral border of the scapula (G). The inferior or lower border of the scapula (H) is being pulled forward by the lower and stronger fibers of the serratus anterior (I), several fingerlike digitations of which are visible. From its insertion in the spine of the scapula, the middle portion of the trapezius (J) assists by inward and upward action to lift the shoulder. The scapula tilts on its vertical axis and follows the movement of the arm.
By way of the acromioclavicular joint (A) and its connection with the clavicle, the scapula acts as an adjustable base or platform for the humerus of the arm and, at the same time, takes part in the movement of the whole shoulder girdle.
Michelangelo Buonarotti (1475-1564)
STUDY FOR THE NUDE AT RIGHT ABOVE THE PERSIAN SIBYL
red chalk
11″ × 8 1/8″ (278 × 211 mm)
Teyler Museum, Haarlem
Acromioclavicular Articulation, Up and Down
Elevation of the arm above the horizontal level calls for increased activity at the acromioclavicular joint (G). The deltoid (A) has reached its limit of upward action in lifting the arm to the horizontal level. As the arm is raised, the lower fibers of the serratus anterior (B) draw the inferior angle of the scapula (C) to the front of the body, along the wall of the rib cage. This tilts the scapula upward, placing the shoulder joint in a better position to raise the arm higher.
The scapula is held against the ribs by the serratus (B), the latissimus dorsi (D), and by the trapezius (E). The middle (E) and upper (F) fibers of the trapezius aid the upward movement of the shoulder. The acromion process of the scapula (G) swings in an arc around the upward-moving clavicle to accommodate this strong elevation of the arm. This is accompanied by the external rotation of the humerus. The forward or flexion movement of the arm is carried out by the pectoralis major (H) and by the anterior portion of the deltoid (A).
The acromion process (G) is pointed to by a bony groove into which the trapezius (I) dips and inserts on one side, and the deltoid (J) originates on the other. The projection of the enlarged outer end of the clavicle above the acromion process is shown as just a bump (K).
Raphael Sanzio (1483-1520)
NUDE MAN BETWEEN TWO FEMALES
pen and ink
11 1/2″ × 8 1/2″ (290 × 215 mm)
Musée Bonnat, Bayonne
6
THE ARM
Axilla, Arm in Flexion
When the arm moves forward, away from the body, in a movement known as “flexion,” a small portion of the hollow under the arm becomes visible. This is the axilla or armpit, where the arm emerges from the trunk.
This pyramidal area is partly formed by the muscles that pass from the trunk to the humerus bone of the arm. The posterior fold or wall of the armpit is formed by the latissimus dorsi (A) and the teres major (B). They go from their origins in the pelvic and shoulder girdles, respectively, to insert (C,D) in the humerus bone. In this view, the hollow of the armpit is concealed by the long head of the triceps (E). You can also see the serra
tions of the serratus anterior (F) that, with the rib cage, form the inner wall of the axilla. The edge of the pectoralis major (G), which forms its anterior or front wall, is just barely visible beneath the triceps.
Notice the contour lines of the latissimus dorsi (A), teres major (B), the infraspinatus (H), and the posterior (I) and middle (J) portions of the deltoid. Their lines converge as lines and wedgelike pointers from their inner bases to the outstretched arm. You can easily follow the rhythmical flow of these transitions of line and mass from the trunk to the arm.
Andrea del Sarto (1486-1531)
STUDY OF ST. JOHN THE BAPTIST FOR BAPTISM OF THE MULTITUDE
red chalk
Felton Bequest, 1936
National Gallery of Victoria, Melbourne
Axilla, Arm in Vertical Elevation
The shape and size of the axilla, or armpit, varies with each movement of the arm. In this figure by Rembrandt, with the arm raised above the head, we see more of the hollow of the armpit.
The masses of the teres major (A) and the latissimus dorsi (B) constitute the posterior wall of the axilla and conceal the medial wall (C). Two little oblique lines, called the anterior furrow, separate the masses of pectoralis major (D) from the latissimus dorsi (B). This furrow twists around the coracobrachialis (E) and follows the edge of the pectoralis major (F) which forms the anterior wall of the armpit.
Students often make use of memory devices. Scottish medical students use one to learn the placement and order of muscles about the axilla from back to front. The sounds of the first syllables of the names of the muscles are made into a sentence: triceps, teres major, latissimus dorsi, corocobrachialis, biceps, pectoralis, which is read as, “Try to let corbie pet.” “Corbie” is Scottish for “crow.” This is an imaginative use of positional order that, when combined with a word order, creates an easily remembered mental image.
Rembrandt van Rijn (1606-1669)
STUDY OF A NUDE
pen and brush with bistre wash on brown paper
9 1/8″ × 7 1/8″ (233 × 178 mm)
Collection of Tiffany and Margaret Blake
Art Institute of Chicago
Biceps Brachii, Anterior Aspect
The fleshy masses of the upper arm lie along both sides of the humerus, the bone of the upper arm. From its ball and socket joint in the shoulder blade, the humerus extends downward about two shoulder blade or sternum lengths. Its upper cylindrical shaft curves slightly to accommodate the rib cage. Its lower end is flattened and widened into two condyles, which receive the radius and ulna at the elbow.
Two muscles help fill out the inside of the arm in the figure on the right: the coracobrachialis (A) and the brachialis (B), both of which lie in the groove between the short or inner head of the biceps (C), and the medial head of the triceps (D). The long outer (E) and short (C) heads of the biceps lie upon the brachialis (B) or “pillow muscle” below.
Together with the coracobrachialis (A) and brachialis (B), the biceps flex the forearm. These muscles bulge when they contract, becoming shorter and thicker as they pull upon the radius bone of the forearm when the elbow is bent. In the drawing, compare the surface changes of the biceps during its different phases: from its relaxed extension position (F), to its flexion at right angle (G).
Observation and knowledge of anatomical structure can help you to harmonize the breaks between forms when you draw the body. For example, the small curved plane created by the tendon of the biceps (H) as it inserts into the forearm, softens the right angle between upper arm and forearm. As another example, the distinct separation and varied lengths of the long (E) and short (C) heads of the biceps adds an interesting contrast of size and shape to these two masses, as they move between scapula and radius.
Jacopo Pontormo (1494-1556)
STUDY OF FIGURES
black and red pencil blended on white paper
8″ × 6 1/4″ (204 × 158 mm) Uffizi, Florence
Biceps Brachii, Lateral Aspect
Function creates form. The form of the fish allows it to flow easily through water, maneuvering like an airfoil. The limbs of a running animal must move clear of the body, so the curve of the humerus bone performs a practical function. In man, the dominant muscular masses of the upper arm follow the slightly curving shape of the humerus beneath.
Draw the muscles of the upper arm from their origins in the bone of the shoulder to their insertion in the bones of the lower arm. First locate the bump of the outer edge of the clavicle (A). This leads you to the summit of the shoulder (B) and the acromioclavicular joint, where the clavicle rises above the acromion process of the scapula. The acromion process, in turn, hovers protectively over the glenoid cavity (C), which holds the head of the humerus. The rounded highlight on the deltoid reflects the head of the humerus below that fits into this cavity. Put your pencil at the top of the glenoid cavity (C) and follow the edge of the long head of the biceps (D) to its inserting tendon (E) in the radius. Now place your pencil at the bottom of the glenoid cavity (C) and move it down to the outside contour line of the triceps (F). Follow the triceps to its insertion in the olecranon process of the ulna (G).
Observe in particular the mass of the deltoid (H) as it moves into the groove between the biceps and triceps enroute to its insertion. There it goes between the fibers of the brachialis (I), and bulges with the biceps as it helps flex the arm. Tintoretto has placed the highlight (J) and the strong dark (K) of the big cylinder of the arm well away from the groove of the brachialis (I), which forms a line between biceps and triceps. He thus makes certain that the mass conception (of the arm as a cylinder) dominates over the individual forms.
Jacopo Tintoretto (1518-1594)
STUDY OF A MODEL OF THE GIULIANO DE’ MEDICI BY MICHELANGELO
black and white chalk
The Governing Body of Christchurch, Oxford
Flexion
Flexion or bending of the forearm upon the upper arm is carried out by the biceps brachii (A) and the brachialis anticus (B). At rest, when the arm hangs limply at the elbow, the biceps is a long, tapered, cylindrical shape. Here, Tintoretto shows it contracting to flex the forearm upon the upper arm. He renders it short and globular-shaped, with its maximum thickness front to back, at about the middle of the upper arm. The upper portion of the biceps is covered by the deltoid (C), which moves into the intermuscular groove between the triceps (D) and the biceps (A).
The triceps muscle is the antagonist to the biceps. The biceps flexes or bends the arm and the triceps bulges slightly in counterbalancing resistance. The flexed elbow stretches the common tendon of the triceps (E) from mid-arm to its insertion into the posterior and superior part of the olecranon process (F). The flat surface of the tendon is distinct from the swelling fleshy heads of the surrounding muscles.
Tintoretto knows that the upper back of the olecranon process (F) of the ulna forms the tip of the elbow, and that it becomes very prominent when the arm is bent. Notice how he uses curved rather than flat lines around the point of the elbow, where ulna meets humerus.
The supinator mass (G) emerges from between triceps and brachialis, about one third of the way up the arm. When the radius crosses over the ulna, as it does here, it carries the supinator mass over these two underlying bones, widening the upper forearm. At the back of the lower arm, Tintoretto has emphasized the extensors (H), which contract synergetically, that is, working together as a counterbalance or mild opposition, when the wrist and fingers are flexed.
Jacopo Tintoretto (1518-1594)
STUDY OF A STATUE OF ATLANTIS
black chalk heightened with white, on blue paper
10 11/16″ × 7 1/8″ (268 × 181 mm)
Museum Boymans-van Beuningen, Rotterdam
Triceps, Posterior Aspect
The triceps, virtually three muscles in one, covers the entire posterior surface of the upper arm. All three heads of this muscle are inserted through a large tendon (A) to the end of the olecranon process of the ulna (B).
The t
riceps is the chief extensor of the lower arm. Its long or middle head (C) crosses the shoulder joint from its origin in the humerus, and also aids the extension and adduction of the upper arm.
Just above the curve of the lateral head of the biceps (D), the mass of the outer head of the triceps (E) moves out from under the deltoid (F), where it originates in the upper lateral surface of the humerus. The inner head of the triceps (G) also arises from the humerus, but from the lower medial portion, so that it covers the entire posterior surface of the lower part of the bone.
A characteristic of the triceps, which becomes more prominent in extension, is its outward slanting line (H). There the rounded fibers of the muscle meet the long, low, flat plane of the common tendon.
If you see a side view of the insertion of the common tendon at the olecranon process of the ulna, you will see the small triangular relief of the anconeus (I). This little muscle fills the gap between the back of the lateral epicondyle of the humerus (J) where it originates, the outer border of the olecranon process, and the posterior surface of the ulna (K) into which it inserts. In extension of the forearm, the anconeus (I) initiates the action and stabilizes the elbow joint. When more strength is needed, the inner, outer, and then the long heads of the triceps must come into play.