If your institution subscribes to this resource, and you don't have an Access Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
Part 1. Approach to Learning
Part 2. Basic Terminology
Part 3. Approach to Reading
Learning anatomy consists not only in memorization but also in visualization of the relations between the various structures of the body and understanding their corresponding functions. Rote memorization will quickly lead to forgetfulness and boredom. Instead, the student should approach an anatomical structure by trying to correlate its purpose with its design. Structures that are close together should be related not only spatially but also functionally. The student should also try to project clinical significance to the anatomical findings. For example, if two nerves travel close together down the arm, one could speculate that a tumor, laceration, or ischemic injury might affect both nerves; the next step would be to describe the deficits expected on physical examination.
The student must approach the subject in a systematic manner, by studying the skeletal relations of a certain region of the body, the joints, the muscular system, the cardiovascular system (including arterial perfusion and venous drainage), the nervous system (such as sensory and motor neural innervations), and the skin. Each bone or muscle is unique and has advantages due to its structure and limitions or perhaps vulnerability to specific injuries. The student is encouraged to read through the description of the anatomical relation in a certain region, correlate illustrations of the same structures, and then try to envision the anatomy in three dimensions. For instance, if the anatomical drawings are in the coronal plane, the student may want to draw the same region in the sagittal or cross-sectional plane as an exercise to visualize the anatomy more clearly.
Anatomical position: The basis of all descriptions in the anatomical sciences, with the head, eyes, and toes pointing forward; the upper limbs by the side with the palms facing forward; and the lower limbs together.
Anatomical planes: A section through the body, one of four commonly described planes. The median plane is a single vertically oriented plane dividing the body into right and left halves, whereas the sagittal planes are oriented parallel to the median plane but not necessarily in the midline.Coronal planes are perpendicular to the median plane and divide the body into anterior (front) and posterior (back) portions. Transverse, axial, or cross-sectional planes pass through the body perpendicular to the median and coronal planes and divide the body into upper and lower parts.
Directionality: Superior (cranial) is toward the head, whereas inferior (caudal) is toward the feet; medial is toward the midline, whereas lateral is away from the midline. Proximal is toward the trunk or attachment, whereas distal is away from the trunk or attachment. Superficial is near the surface, whereas deep is away from the surface.
Motion: Adduction is movement toward the midline, whereas abduction is movement away from the midline. Extension is straightening a part of the body, whereas flexion is bending the structure. Pronation is the action of rotating the palmar side of the forearm facing posteriorly, whereas supination is the action of rotating the palmar side of the forearm anteriorly.
The student should read with a purpose and not merely to memorize facts. Reading with the goal of comprehending the relation between structure and function is one of the keys to understanding anatomy. Also, the ability to relate the anatomical sciences to the clinical picture is critical. The following seven key questions are helpful in ensuring the effective application of basic science information to the clinical setting.
Given the importance of a certain required function, which anatomical structure provides the ability to perform that function?
Given the anatomical description of a body part, what is its function?
Given a patient's symptoms, what structure is affected?
Which lymph nodes are most likely to be affected by cancer at a particular location?
If an injury occurs to one part of the body, what is the expected clinical mani festation?
Given an anomaly such as weakness or numbness, what other symptoms or signs would the patient most likely have?
What is the male or female homologue to the organ in question?
Let us consider these seven issues in further detail.
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.
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.”
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.
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 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.
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.
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.
The student should approach an anatomical structure by visualizing the structure and understanding its function.
A standard anatomical position is used as a reference for anatomical planes and terminology of movement.
There are seven key questions to consider in ensuring the effective application of basic science information to the clinical arena.