Given the importance of a certain required function, which anatomical structure provides the ability to perform that function?
The student should be able to relate the anatomical structure to a function. When approaching the upper extremity, for instance, the student may begin with the statement, “The upper extremity must be able to move in many different directions to be able to reach up (flexion), reach backward (extension), reach to the side (abduction), bring the arm back (adduction), or turn a screwdriver (pronation/supination).” Because the upper extremity must move in all these directions, the joint between the trunk and arm must be very versatile. Thus, the shoulder joint is a ball-and-socket joint to allow movement in the different directions required. Further, the shallower the socket is, the more mobility the joint has. However, the versatility of the joint makes its dislocation easier.
Given the anatomical description of a body part, what is its function?
This is the counterpart to the previous question regarding the relation between function and structure. The student should try to be imaginative and not merely accept the textbook (rote) information. One should be inquisitive, perceptive, and discriminating. For example, a student might speculate as to why bones contain marrow and are not completely solid and might theorize as follows: “The main purpose of bones is to support the body and protect various organs. If the bones were solid, they might be slightly stronger, but they would be much heavier and be a detriment to the body. Also, production of blood cells is a critical function of the body. Thus, by having the marrow within the center of the bone, the process is protected.”
Given a patient's symptoms, what structure is affected?
This is one of the most critical questions of clinical anatomy. It is also one of the major questions that a clinician must answer when evaluating a patient. In clinical problem solving, the physician elicits information by asking questions (taking the history) and performing a physical examination while making observations. The history is the single most important tool for making a diagnosis. A thorough understanding of the anatomy aids the clinician tremendously because most diseases affect body parts under the skin and require “seeing under the surface.” For example, a clinical observation might be: “a 45-year-old woman complains of numbness of the perineal area and has difficulty voiding.” The student might speculate as follows: “The sensory innervation of the perineal area is through sacral nerves S2 through S4, and control of the bladder is through the parasympathetic nerves, also S2 through S4. Therefore, two possibilities are a spinal cord problem involving those nerve roots or a peripheral nerve lesion. The internal pudendal nerve innervates the perineal region and is involved with micturition.” Further information is supplied: “The patient states that she has experienced back pain since a fall 2 weeks ago.” Now the lesion can be isolated to the spine, most likely the cauda equina (“horsetail”), which is a bundle of spinal nerve roots traversing through the cerebrospinal fluid.
Which lymph nodes are most likely to be affected by cancer at a particular location?
The lymphatic drainage of a particular region of the body is important because cancer may spread through the lymphatics, and lymph node enlargement may result from infection. The clinician must be aware of these pathways to know where to look for metastasis (spread) of cancer. For example, if a cancer is located on the vulva labia majora (or the scrotum in the male), the most likely lymph node involved is a superficial inguinal node. The clinician would then be alert to palpating the inguinal region for lymph node enlargement, which would indicate an advanced stage of cancer and a worse prognosis.
If an injury occurs to one part of the body, what is the expected clinical mani festation?
If a laceration, tumor, trauma, or bullet causes injury to a specific area of the body, it is important to know which crucial bones, muscles, joints, vessels, and nerves might be involved. Also, an experienced clinician is aware of particular vulnerabilities. For example, the thinnest part of the skull is located in the temporal region, and underneath this is the middle meningeal artery. Thus, a blow to the temple may be disastrous. A laceration to the middle meningeal artery would lead to an epidural hematoma because this artery is located superficial to the dura and can cause cerebral damage.
Given an anomaly such as weakness or numbness, what other symptoms or signs would the patient most likely have?
This requires a three-step process in analysis. The student must be able to (a) deduce the initial injury on the basis of clinical findings, (b) determine the probable site of injury, and (c) make an educated guess as to which other structures are in close proximity and, if injured, what the clinical manifestations would be. To develop skill in discerning these relationships, one can begin from a clinical finding, propose an anatomical deficit, propose a mechanism or location of the injury, identify another nerve or vessel or muscle in that location, propose the new clinical finding, and so on.
What is the male or female homologue to the organ in question?
Knowledge of male-female homologous correlates is important in understanding the embryologic relations and, hence, the resultant anatomical relations because fewer structures need to be memorized, as homologous relations are easier to discern than are two separate structures. For example, the vascular supplies of homologous structures are usually similar. The ovarian arteries arise from the abdominal aorta below the renal arteries; likewise, the testicular arteries arise from the abdominal aorta.