Illustrations may be found in:
The ultimate objective in your study of anatomy is to develop an integrated 3-dimensional concept of structures in the living body. Text, atlases, films, skeletons and the cadaver are only aids towards achievement of this aim. You should by conscious effort develop the study habit of thinking in terms of your own body. To make a start, you are asked to observe the following structures on the living body and later to correlate your findings, where possible, with observations on the cadaver.
1. (COA p. 672) At the tip of the shoulder, outline the sloping plateau of bone formed by the acromion of the scapula (shoulder blade). At the medial border of the acromion, a bony knob marks an articulation with the lateral extremity of the clavicle (collarbone), which in turn should be traced medially along the S-shaped course of its body to another bony protuberance marking its medial end. This articulates on its inferomedial aspect with the sternum (breastbone - COA p. 73).
2. (COA p. 102) Between the sternal ends of the 2 clavicles is a deep suprasternal (jugular) notch, at the bottom of which is the top of the manubrium or uppermost of the 3 sternal components. It articulates with a second, much larger body of the sternum at the sternal angle to be felt running across the sternum about 4 centimeters below the notch. Respiratory movements at this joint are small and usually entirely absent in older individuals. The body of the sternum in turn articulates at its lower end with the third sternal component, the xiphoid process. The shape, size and accessibility of the xiphoid vary greatly from one individual to another and you will want, therefore to examine it in each of your partners. Learning the range of normal variation in the body's structures will be one of your objectives in the study of anatomy.
3. Returning to the sternal angle, locate the pair of ribs which attach to the sternum at that level. These are the costal cartilages of the second ribs, since attachment to the sternum is made by a flexible segment of cartilage. In older individuals an irregularity marking the juncture of the ossified cartilage and true bone can usually be made out 2 centimeters lateral to the edge of the sternum. Above and below the second rib are respectively the first and second intercostal spaces.
4. Using the sternal angle and second rib for orientation, identify and try to trace lateralward the uppermost rib and then the 10 lower ones.
5. (COA, p. 103) Distinguish the papilla (nipple), areola and mamma (breast). In males, of course, these are relatively undeveloped, although to the indiscriminating observer, large pectoral muscles may appear like breast tissue.
6. (COA, p. 103) Determine on the chest of one of your lab partners the midsternal (anterior median line), lateral sternal, parasternal and midclavicular lines. The term parasternal refers to a position beside the sternum, or midway between the margin of the sternum and midclavicular line. Determine the position of the nipple with reference to the midclavicular line and the specific rib or intercostal space. Lift the arm to the side (Abduct the arm). Now at what level does the nipple lie?
1. (COA, p. 185) Continuing onto the belly, define the limits of the abdominal wall starting with the infrasternal notch and costal margin. Follow the margin around to where the massive resistance of the longitudinally running musculature of the back is encountered. Now palpate forward along the bony iliac crest to its termination in the prominent anterior superior iliac spine. Note that the crest is bony the entire distance, i.e., no fleshy muscle crosses it (except in back). How much space is there between the rib cage and the iliac crest? You should check this out on individuals of asthenic and hypersthenic (pyknic) build.
2. Now skip medialward to the pubic tubercle of the pubic bone. An inguinal ligament stretches between the anterior superior iliac spine and the pubic tubercle and further delineates the abdominal wall. It is strong and clinically very important, but not easy to demonstrate on yourself. (Male students should at some more appropriate occasion identify the pubic tubercle and rising lateralward from it the fibrous ligament by palpating through the fat-free scrotum). Finally, trace the pubic crest of the pubic bone to where it meets its opposite number at the pubic symphysis. Note that the big rectus abdominis muscles that course downward at paramedian positions do not cross the bone.
3. Return to the infrasternal notch and note the presence along the midline of the abdomen of a change in direction taken by the fine hairs and perhaps also some change in skin coloration. This marks the presence at a subcutaneous level of the linea alba. At the top of this line is the xiphoid process, at the midlength the umbilicus (navel), and at its lower end the pubic symphysis. Two other lines, or rather grooves, running downward from the costal margin and curving somewhat medialward to the pubic tubercles can be brought out in thin subjects by tensing of the rectus muscles, since these semilunar lines mark the lateral margins of this pair of muscles (COA p. 210).
4. (COA p. 185) For descriptive purposes, reference is often made to 2 horizontal lines or planes crossing the abdomen. The higher one, the transpyloric plane, is arbitrarily considered to lie at a level half the distance from the suprasternal notch to the pubic symphysis. This places it several centimeters, above the umbilicus and also considerably above the lowest extent (subcostal plane) to which the rib cage reaches at the sides . The lower of the 2 planes, called the intertubercular (transtubercular) plane or line is located at the level of the tubercles on the iliac crest. These are laterally facing angulations along the iliac crest about 5 centimeters behind the anterior superior spine. They define a level somewhat below the highest part of the ilium.
5. The 2 pairs of lines (vertical semilunar lines and horizontal transpyloric and intertubercular lines), like a tic-tac-toe frame, mark out nine regions. These approximate and unequal regions are: in the midline, the epigastric, umbilical and hypogastric regions; and to either side, hypochondriac, lumbar and inguinal regions. An alternative scheme for reference is just to say that an organ or symptom is located in the lower right quadrant, etc ... using the umbilicus as a reference point.
AXILLA and SHOULDER
1. (COA, p. 103) With the arm of your partner abducted (raised to the side), outline the anterior and posterior axillary folds and the axillary fossa between them. Where do you suppose the anterior, posterior and midaxillary lines would lie? Palpate the medial wall of the axilla. The ribs will be somewhat indistinct as they are overlaid by a large, flat muscle. Moving to the narrow lateral wall of the axillary fossa, trace the shaft of the humerus upward, and then while the arm is fully abducted, distinguish high in the axilla, the head of the humerus as it rotates downward. With extreme abduction, the hollow of the axilla will virtually disappear (Full abduction should not be attempted on the cadaver as the muscles may be torn).
2. (COA, p. 681) On the living subject, distinguish the upper end of the humerus from the acromion by rotating inward (medial rotation) and outward (lateral rotation) using the flexed forearm for leverage. A bony intertubercular sulcus separating a lesser tubercle facing anteriorly and the greater tubercle facing laterally, can be made out through the thick muscle extending downward from the clavicle and acromion. Verify that when the arm is at the side, the greater tubercle is the most lateral projecting bony structure at the shoulder. In abduction, the greater tubercle partly disappears beneath the acromion.
3. On the anterior aspect of the shoulder joint, a small infraclavicular fossa or depression (deltopectoral triangle) may be seen leading down and lateralward from the clavicle. Pressure deep within this fossa will disclose a bony resistance. This is the coracoid process of the scapula, and for that reason it will remain more or less fixed when the humerus is rotated over a large range.
UPPER ARM
1. (COA, p. 740) Have the subject tense the biceps brachii muscle by flexing and supinating the forearm. Note that this brings out to the medial side of its belly a medial bicipital groove; the lateral groove is less distinct. Trace the shaft of the humerus by pressing inward along the medial furrow. The pulse to be felt there is that of the brachial artery, which is the continuation of the axillary artery in the axilla. Distally, the pulsations disappear in the depth of the fossa found on the anterior aspect of the partially flexed elbow. The cubital fossa lying between common origins of medial flexor and lateral extensor muscles of the forearm is best appreciated by resting the forearm on a table to relax the biceps muscle, for if the forearm must be actively held up, the tensed bicipital tendon obscures the fossa. The large vein passing across this region is the cephalic vein (COA, p. 741). In a lean individual, it may be followed to the infraclavicular fossa, but not across the clavicle; therefore, it must go deep at that level. Where does the vein begin?
2. (COA, p. 740) On the dorsal surface of the elbow, the prominent tip of the olecranon process of the ulna can be felt to move relative to the humeral epicondyles as the arm is flexed from a position of initial extension. In the latter position, the 2 condyles and the tip of the olecranon are in a straight line, but in flexion of the elbow they frame a triangle. In some fractures, these relations are disturbed.
(COA, p. 765) Distalward from the olecranon, the ulna can be continuously palpated at a subcutaneous level down to its termination in the styloid process. The radius, on the other hand, is palpable only at its head, just inferior to the lateral epicondyle and again in its distal half, although even here some tendons can be felt crossing the bone. The radius also ends in a clearly palpable styloid process.
THE BACK
1. (COA, p. 708) Have the subject face about. Return to the acromion and trace its continuation along the spine of the scapula medialward and somewhat inferiorly to the vertebral margin of the scapula. Outline this margin, the inferior and superior angles, and through the heavy musculature the axillary margin; you will have no luck with the superior margin as it is too deep. Notice the position of the scapula with the arm adducted, then in full abduction and finally when the arms are crossed in front of the chest (flexed and adducted). It should be realized by now that only the sternoclavicular joint connects the shoulder girdle, consisting of the scapula and clavicle, to the axial skeleton (vertebral column).
2. (COA, p. 449, 453) Palpate the dorsal spinous processes of the vertebrae beginning at the vertebra prominens, which is usually formed by the 7th cervical vertebra (C7), and work down until distinction between the individual spines is lost on the sacrum. Now returning to C7, attempt to work out the spines of the other 6 cervical vertebrae. This will not be entirely successful as the spines become progressively deeper until only the resistance of the supraspinous ligament (ligamentum nuchae) is felt. This leads to the external occipital protuberance on the skull.
3. (COA p. 709) Accentuate one upper border of the vast trapezoid formed by the trapezius muscle by having the subject elevate his shoulder against resistance. Note that the muscle has a strong origin from the external occipital protuberance, and the superior nuchal ridge extending to the side of that prominence, and that it passes downward to attachments along the upper border of the scapular spine, the acromion and the outer 1/3 of the clavicle. You have now established that no major muscles cross superficial to this great bony arc.
4. Have the subject forcibly arch backwards so that the 2 columns of deep back muscles bordering the row of spinous processes are brought into visible relief. Where do these muscle masses seem to begin inferiorly? Notice that in the upper thoracic region they are less distinct, because several of the superficial back muscles lie over them.
5. By palpating the spinous processes while the subject flexes and extends his spinal column, mark the level where the flexible lumbar spine ends and the inflexible sacrum begins. Looking at the skeleton first for orientation, draw on the subject an imaginary line connecting the iliac crests and a second line between the dimpled areas marking the sites of the posterior iliac spines of the pelvis. Where does the lumbosacral joint lie relative to these lines (COA p. 453)?
These are only a few of the structures in these regions you will want to observe and palpate on the living body. More detailed description of the surface anatomy may be found in Clinically Oriented Anatomy, 6th edition.
Palpation (on yourself), incidentally, will be permitted in all exams!