Anatomical Landmarks And Surface Stress

The artist can truly understand surface forms only by knowing their underlying structures and their form and behavior under tension, stress, and activity, Wc are still dealing with anatomy in this chapter, but from the viewpoint of dominant surface stress.

Anatomy Drawing

ELBOW AND ARM STRUCTURES

The skeletal detail below shows the broad lower end of the humerus from which two bony prominences emerge, the condyles (A A2). These are part of the joint which articulates with the lower arm bone. The inner condyle (A/) is remarkably extended, while the outer condyle (A2) is somewhat rounded and more visible when the elbow is flexed. The central protrusion of the ulna is the olecranon fB visible as an elbow projection. The small rotating head of the radius is seen as a pit when extended against the supinator mass but as a projection in elbow flexion (C).

I'hc drawing above displays the skeletal elbow and forearm forms against the musculature of the upper and lower arm and hand. The dominant bone protrusions which create surface stress can be seen here. The head of the ulna (D) appears at the outer wrist, and the small pisiform bone (E) rests at the base tine of the palm.

SIDE PLANE OF WRIST AND LITTLE FINGER

This drawing of the little finger side of the hand shows the wrist and the head of ihe uln3 in two views. The top view illustrates alignment of the ulnar head with the palm knuckle of the little finger from both top and side planes. The pisiform bone can be seen under the head of the ulna. The lower drawing shows these forms with the hand turned palm side up. Note that w hen placement of the little finger knuckle and palm is known, all other knuckles on the dorsal side of the hand can also be determined concctly.

Dimensioning Technical DrawingsDrawing Hands

SKELETAL ELBOW AND WRIST PROJECTIONS

This multiple action drawing illustrates the necessity of knowing underlying structure and surfacc stress. Note the five skeletal projections of elbow and wrist which become apparent under the stress of the positions shown. These are elbow (olecranon) projection (Aj. inner condyle projection (B). outer condvle projection (C), radius head (D}t and ulnar head, side plane projection (El Sec if you can locate other anatomical landmarks in the hand and elsewhere.

RADIAL EMINENCE AND STYLOID PROCESS

On the inner wrist line he (he radial eminence and the styloid process, which correspond to the ulnar head on the outer wristline. The schematic at top shows how the radius develops in a marked extended mound (sec arrows) followed hy the reverse curve of the styloid spur. The metacarpal bone of the thumb emerges from this juncture of the radius with the car* pals. This area also helps define the side plane of the arm higher up.

THE "SNUFFBOX"

Anatomy Arm Drawings

Note the triangular depression hi^h in the top of the palm (A) shown in this thumb-side dorsal view of the hand. This hollow develops when the thumb is extended outward and upward, an action produced by two thumb mus-ctcs, the extensor pollicis longus and (lie extensor poll ids tresis, and aided by the abductor polticis longus. The tendons of these muscles noted here* the extensor longus (B). extensor bre-vis {C) and abductor longus {[)) form the taut side waits of (his depression, white the high radius (E) closes the cavity at the top. This depression is known as tabatieref meaning "snuffbox," possibly derived from the habit of French and English gentlemen placing snuff in this hollow and then inhaling it.

Anatomy Finger Drawing

CARPALS UNDER STRESS When the hand is flexed downward, and the wrist is arched, the convex surface of the lunate bone becomes apparent (note arrow). In this position of surface stress, the array of lower arm and wrist protrusions can be seen under a taut skin and can be easily defined by touch.

Hand And Finger Anatomy Drawings

FINGER TENDONS IN ACTION

On the back of the hand, the grouped finger tendons, known collectively as the extensor digitorum communis. combine to form an elevated ramp rising to the wrist bones, shown by the arrow in the upper drawing. Generally these tendons blend on the dorsal side of the hand.

As (he tendons course over the knuckles of the palm, they become explicitly visible, especially under stress above and below the palm knuckles. This is shown in the middle sketch by arrows pointing down. Also note how the knuckle plane becomes markedly triangular above and below the knucklc capsules as the tendons ride over the knuckles.

When the fingers close in tight compression, as shown in the lower drawing, the outer appearance of the taut tendon and finger shank appears somewhat like a miniature flexed knee and lower leg.

Drawing Leg Fingers

THENAR EMINENCE

The ball of (he thumb {thenar eminence) is the largest form on the underside of the palm. Shaped like an egg (as shown in the upper palmar view and the schematic to its right), it is notably variable as it flexes and closes toward the palm. It will flatten when lying tightly flexed against the index finger, but will elevate and expand when the thumb rises and begins to rotate inward toward the palm, as shown in the drawing at lower right.

HYPOTHENAR PLATEAU

Opposite the thenar eminence is the flatter, more elongated hypothenar plateau (noted by arrows) on the little finger side of the palm. This is seen from the side plane in the upper drawings. Wedge shaped, it rises narrowly from the little finger metacarpal pad and swells upward to the wrist.

The drawing below, little finger side up, shows the higher thenar eminence on the other side of the deep trench at mid* palm. This mid-palm trench (marked by broken arrows) is a unique landmark in the hand, for it centrally divides the palm, running from the tip of the longest finger to the apex of the palm at the wrist. Even beyond, it ascends the forearm on the midline tendon of pal/nans longus.

Forearm Drawing TutorialStudy Hands

FINGERTIP AND FINGER SHANK PADS

Consistent with the wedge shape of all fingertip forms, the thumb padsĀ» marked by airows in die large drawing at left, form an isosceles triangle. This is true for all other fingertips as well.

The pads on the finger shanks, seen in the drawings of the open palm, arc somewhat lozenge shaped. >el are iightls creased at the center because of tte deep flexor tendons running ihe length of the fingers, Note the variations of fingertip and finger shank pads seen from these two different views.

Anatomy The Hand

STRESSES AM) ENERGY FLOWS

When the hand is in motion or performing an activity, the skin is stressed in the direction of the action, responding to the stress in the same way that clothing responds to the action of the body. Note the arrows expressing the spiraling swings of the fingers in the drawing at upper left. Follow the backward stress as the thumb surges forward and note the creases at the wrist.

The arrows m the draw ing at lower left express the skin ten* sions on the curved knuckle capsules and illustrate the conception of the drawing. They express energy flows and the dynamics that shape the drawing.

The drawing at upper right shows the direction of stress on finger pads and the palm during bends and thrusts. Also note the webs between the fingers which connect the finger mots without slowing or inhibiting movement.

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Responses

  • ayesha
    How to draw anatomy positions?
    6 years ago
  • rhoda
    What are the anatomical landmarks of the hand?
    5 years ago
  • Agnese Greco
    How to drawing hand and elbow?
    5 years ago
  • sarama
    How to draw mechanical drawing for elbow?
    5 years ago
  • Nahand
    How to draw surface anatomy?
    5 years ago
  • saku
    When the elbow is flexed what skeletal landmark receive this?
    5 years ago
  • Elias
    How to draw anime model skeletons?
    5 years ago
  • EDWARD
    How to draw forearm front view?
    4 years ago
  • Erkki
    How to draw tension/stress?
    1 year ago
  • prisca
    What are the two landmarks for the projection of the hand?
    3 months ago

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