Clinical Anatomy by Regions 9th Edition (Richard S. Snell)
This book provides medical students, dental students, allied health students, and nursing students with a basic knowledge of anatomy that is clinically relevant.
In this new edition, further efforts have been made to weed out unnecessary material and reduce the size of the text. The following changes have been introduced.
1. The text and tables have been reviewed and trimmed where necessary.
2. All the illustrations have been reviewed and some have been discarded where duplication occurs.
3. The anatomy of common medical procedures has been carefully reviewed. Sections on the complications caused by the ignorance of normal anatomy have been retained.
4. The Clinical Problems and Review Questions are available online at www.thePoint.lww.com/Snell9e
Each chapter of Clinical Anatomy is constructed in a similar manner. This gives students ready access to mate-rial and facilitates moving from one part of the book to another. Each chapter is divided into the following categories:
1. Clinical Example: A short case report that dramatizes the relevance of anatomy in medicine introduces each chapter.
2. Chapter Objectives: This section focuses the student on the material that is most important to learn and under-stand in each chapter. It emphasizes the basic structures in the area being studied so that, once mastered, the student is easily able to build up his or her knowledge base. This section also points out structures on which exam-iners have repeatedly asked questions.
3. Basic Clinical Anatomy: This section provides basic information on gross anatomic structures that are of clinical importance. Numerous examples of normal radiographs, CT scans, MRI studies, and sonograms are also provided. Labeled photographs of cross-sectional anatomy of the head, neck, and trunk are included to stimulate students to think in terms of three-dimensional anatomy, which is so important in the interpretation of imaging studies.
4. Surface Anatomy: This section provides surface land-marks of important anatomic structures, many of which are located some distance beneath the skin. This section is important because most practicing medical personnel seldom explore tissues to any depth beneath the skin.
5. Clinical Problem Solving and Review Questions: Available online at www.thePoint.lww.com, the
purpose of these questions is threefold: to focus attention on areas of importance, to enable students to assess their areas of weakness, and to provide a form of self- evaluation for questions asked under examination conditions. Many of the questions are centered around a clinical problem that requires an anatomic answer.
To assist in the quick understanding of anatomic facts, the book is heavily illustrated. Most figures have been kept simple, and color has been used extensively. Illustrations summarizing the nerve and blood supply of regions have been retained, as have overviews of the distribution of cranial nerves.
THE THORAX: THE THORACIC WALL
20-year-old woman was the innocent victim of a street shoot-out involving drugs. On exami-nation, the patient showed signs of severe hemorrhage and was in a state of shock. Her pulse was rapid, and her blood pressure was dangerously low. There was a small entrance wound about 1 cm across in the fourth left intercostal space about 3 cm from the lateral margin of the sternum. There was no exit wound. The left side of her chest was dull on percussion, and breath sounds were absent on that side of the chest. A chest tube was immediately introduced through the chest wall. Because of the massive amounts of blood pouring out of the tube, it was decided to enter the chest (thoracotomy). The physician carefully counted the ribs to find the fourth intercostal space and cut the layers of tissue to enter the pleural space (cavity). She was particularly careful to avoid important anatomic structures.
The incision was made in the fourth left intercostal space along a line that extended from the lateral margin of the sternum to the anterior axillary line. The following structures were incised: skin, subcutaneous tissue, pectoral muscles and serratus anterior muscle, external intercostal muscle and anterior intercostal membrane, internal intercostal muscle, innermost intercostal muscle, endothoracic fascia, and parietal pleura. The internal thoracic artery, which descends just lateral to the sternum and the intercostal vessels and nerve, must be avoided as the knife cuts through the layers of tissue to enter the chest. The cause of the hemorrhage was perforation of the left atrium of the heart by the bullet. A physician must have knowledge of chest wall anatomy to make a reasoned diagnosis and institute treatment.
THE THORAX: THE THORACIC CAVITY
54-year-old woman complaining of a sudden excruciating knifelike pain in the front of the chest was seen by a physician. During the course of the examination, she said that she could also feel the pain in her back between the shoulder blades. On close questioning, she said she felt no pain down the arms or in the neck. Her blood pressure was 200/110 mm Hg in the right arm and 120/80 mm Hg in the left arm.
The evaluation of chest pain is one of the most common problems facing an emergency physician. The cause can vary from the simple to one of life-threatening proportions. The severe nature of the pain and its radiation through to the back made a preliminary diagnosis of aortic dissection a strong possibility. Myocardial infarction commonly results in referred pain down the inner side of the arm or up into the neck.
Pain impulses originating in a diseased descending thoracic aorta pass to the central nervous system along sympathetic nerves and are then referred along the somatic spinal nerves to the skin of the anterior and posterior chest walls. In this patient, the aortic dissection had partially blocked the origin of the left subclavian artery, which would explain the lower blood pressure recorded in the left arm.
THE ABDOMEN: THE ABDOMINAL WALL
26-year-old man complaining of a painful swelling in the right groin was seen by his physician; he had vomited four times in the previous 3 hours. On examination, he was dehydrated and his abdomen was moderately distended. A large, tense swelling, which was very tender
on palpation, was seen in the left groin and extended down into the scrotum. An attempt to gently push the contents of the swelling back into the abdomen was impossible. A diagnosis of a right complete, irreducible, indirect inguinal hernia was made. The vomiting and abdominal distention were secondary to the intestinal obstruction caused by the herniation of some bowel loops into the hernial sac.
An indirect inguinal hernia is caused by a congenital persistence of a sac formed from the lining of the abdomen. This sac has a narrow neck, and its cavity remains in free communication with the abdominal cavity. Hernias of the abdominal wall are common. It is necessary to know the anatomy of the abdomen in the region of the groin before one can make a diagnosis or understand the different hernial types that can exist. Moreover, without this knowledge, it is impossible to appreciate the complications that can occur or to plan treatment. A hernia may start as a simple swelling, but it can end as a life-threatening problem.
THE ABDOMEN: THE ABDOMINAL CAVITY
15-year-old boy complaining of pain in the lower right part of the anterior abdominal wall was seen by a physician. On examination, he was found to have a temperature of 101°F (38.3°C). He had a furred tongue and was extremely tender in the lower right quadrant. The abdominal muscles in that area were found to be firm (rigid) on palpation and became more spastic when increased pressure was applied (guarding). A diagnosis of acute appendicitis was made.
Inflammation of the appendix initially is a localized disease giving rise to pain that is often referred to the umbilicus. Later, the inflammatory process spreads to involve the peritoneum covering the appendix, producing a localized peritonitis. If the appendix ruptures, further spread occurs and a more generalized peritonitis is produced. Inflammation of the peritoneum lining the anterior abdominal wall (parietal peritoneum) causes pain and reflex spasm of the anterior abdominal muscles. This can be explained by the fact that the parietal peritoneum, the abdominal muscles, and the overlying skin are supplied by the same segmental nerves. This is a protective mechanism to keep that area of the abdomen at rest so that the inflammatory process remains localized.
The understanding of the symptoms and signs of appendicitis depends on having a working knowledge of the anatomy of the appendix, including its nerve supply, blood supply, and relationships with other abdominal structures.
THE PELVIS: THE PELVIC WALLS
51-year-old man was involved in a light-plane accident. He was flying home from a business trip when, because of fog, he had to make a forced landing in a plowed field. On landing, the plane came abruptly to rest on its nose. His companion was killed on impact, and he wasthrown from the cockpit. On admission to the emergency department, he was unconscious and showed signs of severe hypovolemic (loss of circulating blood) shock. He had extensive bruising of the lower part of the anterior abdominal wall, and the front of his pelvis was prominent on the right side. During examination of the penis, it was possible to express a drop of blood-stained fluid from the external ori-fice. No evidence of external hemorrhage was present.
Radiographic examination of the pelvis showed a dislocation of the symphysis pubis and a linear fracture through the lateral part of the sacrum on the right side. The urethra was damaged by the shear-ing forces applied to the pelvic area, which explained the blood-stained fluid from the external orifice of the penis. The pelvic radiograph (later confirmed on computed tomography scan) also revealed the presence of a large collection of blood in the loose connective tissue outside the peritoneum, which was caused by the tearing of the large, thin-walled pelvic veins by the fractured bone and accounted for the hypovolemic shock.
This patient illustrates the fact that in-depth knowledge of the anatomy of the pelvic region is nec-essary before a physician can even contemplate making an initial examination and start treatment in cases of pelvic injury.
