Clinical anatomy by systems PDF
Preview Clinical anatomy by systems
C A LINICAL NATOMY SYSTEMS BY Richard S. Snell, MD, PhD CD-ROM Preface Welcome to Clinical Anatomy by Systems by Richard S. logic investigations. The anatomy of Common Medical Snell, MD, PhD. This CD-ROM is designed for medical Procedures has also been included, and the complications students doing their clinical rotations, allied health stu- caused by an ignorance of normal anatomy have been dents, dental students, nurses, and residents. emphasized. The information provided is in the form of Clinical Examples of clinical cases are given at the end of each Notes, which are linked to the appropriate chapters of the group of Clinical Notes. Each clinical vignette is followed main text. This gives students ready access to the basic by multiple choice questions. Answers and explanations for anatomic and clinical material. Sections on Congenital the problems are given at the end of the section in the CD- Anomalies are also included. ROM. The clinical material provides the medical professional *No part of this CD-ROM may be reproduced in any with the practical application of anatomic facts that he or form or by any means without written permission from the she will require when examining patients. It will also be of copyright owner. great assistance when interpreting the findings of techno- iii 1 Introduction to Clinical Anatomy Chapter Outline Skin 2 Blood Vessels 4 Lines of Cleavage 2 Diseases of Blood Vessels 4 Skin Infections 3 Lymphatic System 5 Sebaceous Cyst 3 Diseases of the Lymphatic System 5 Shock 3 Nervous System 5 Skin Burns 3 Segmental Innervation of Skin 5 Skin Grafting 3 Segmental Innervation of Muscle 5 Fasciae 3 Clinical Modification of the Activities of the Fasciae and Infection 3 AutonomicNervous Systems 5 Skeletal Muscle 3 Mucous and Serous Membranes 5 Muscle Attachments 3 Mucous and Serous Membranes and Inflammatory Disease 5 Muscle Shape and Form 3 Bones 6 Cardiac Muscle 3 Bone Fractures 6 Necrosis of Cardiac Muscle 3 Rickets 7 Joints 4 Epiphyseal Plate Disorders 7 Examination of Joints 4 Clinical Significance of Sex, Race, and Ligaments 4 Age on Structure 9 Damage to Ligaments 4 Clinical Problem Solving Questions 9 Bursae and Synovial Sheaths 4 Trauma and Infection of Bursae and Synovial Sheaths 4 Answers and Explanations 11 SKIN Lines of Cleavage In the dermis, the bundles of collagen fibers are mostly arranged in parallel rows. A surgical incision through the skin made along or between these rows causes the mini- mum of disruption of collagen, and the wound heals with minimal scar tissue. Conversely, an incision made across the rows of collagen disrupts and disturbs it, resulting in the massive production of fresh collagen and the formation of a broad, ugly scar. The direction of the rows of collagen is known as the lines of cleavage (Langer’s lines), and they tend to run longitudinally in the limbs and circumferen- tially in the neck and trunk (CD Fig. 1-1). CD Figure 1-1 Cleavage lines of the skin. Introduction to Clinical Anatomy 3 A general knowledge of the direction of the lines of new circulation within it at the recipient site. The donor site cleavagegreatly assists the surgeon in making incisions that is usually covered with a split-thickness graft. In certain cir- result in cosmetically acceptable scars. This is particularly cumstances the full-thickness graft is made in the form of a important in those areas of the body not normally covered pedicle graft, in which a flap of full-thickness skin is turned by clothing. A salesperson, for example, may lose his or her and stitched in position at the recipient site, leaving the base job if an operation leaves a hideous facial scar. of the flap with its blood supply intact at the donor site. Later, when the new blood supply to the graft has been Skin Infections established, the base of the graft is cut across. FASCIAE The nail folds, hair follicles, and sebaceous glands are common sites for entrance into the underlying tissues of pathogenic organisms such as Staphylococcus aureus. Infection occurring between the nail and the nail fold is Fasciae and Infection called a paronychia. Infection of the hair follicle and seba- ceous gland is responsible for the common boil.A carbuncle Knowledge of the arrangement of the deep fasciae often is a staphylococcal infection of the superficial fascia. It fre- helps explain the path taken by an infection when it spreads quently occurs in the nape of the neck and usually starts as an from its primary site. In the neck, for example, the various infection of a hair follicle or a group of hair follicles. fascial planes explain how infection can extend from the Sebaceous Cyst region of the floor of the mouth to the larynx. SKELETAL MUSCLE A sebaceous cyst is caused by obstruction of the mouth of a sebaceous duct and maybe caused by damage from a comb or by infection. It occurs most frequently on the scalp. Muscle Attachments Shock The importance of knowing the main attachments of all A patient who is in a state of shockis pale and exhibits goose- the major muscles of the body need not be emphasized. flesh as a result of overactivity of the sympathetic system, Only with such knowledge is it possible to understand the which causes vasoconstriction of the dermal arterioles and normal and abnormal actions of individual muscles or contraction of the arrector pili muscles. muscle groups. How can one even attempt to analyze, for example, the abnormal gait of a patient without this Skin Burns information? Muscle Shape and Form The depth of a burn determines the method and rate of healing. A partial-skin-thickness burn heals from the cells of the hair follicles, sebaceous glands, and sweat glands as well The general shape and form of muscles should also be as from the cells at the edge of the burn. A burn that extends noted, since a paralyzed muscle or one that is not used (such deeper than the sweat glands heals slowly and from the as occurs when a limb is immobilized in a splint) quickly edges only, and considerable contracture will be caused by atrophies and changes shape. In the case of the limbs, it is fibrous tissue. To speed up healing and reduce the inci- always worth remembering that a muscle on the opposite dence of contracture, a deep burn should be grafted. side of the body can be used for comparison. Skin Grafting CARDIAC MUSCLE Skin grafting is of two main types: split-thickness grafting and full-thickness grafting. In a split-thickness graft the Necrosis of Cardiac Muscle greater part of the epidermis, including the tips of the der- mal papillae, are removed from the donor site and placed on the recipient site. This leaves at the donor site for repair pur- The cardiac muscle receives its blood supply from poses the epidermal cells on the sides of the dermal papillae the coronary arteries. A sudden block of one of the large and the cells of the hair follicles and sweat glands. branches of a coronary artery will inevitably lead to necro- A full-thickness skin graft includes both the epidermis sis of the cardiac muscle and often to the death of the and dermis and, to survive, requires rapid establishment of a patient. 4 Chapter 1 clot at the damaged site is invaded by blood vessels and JOINTS fibroblasts. The fibroblasts lay down new collagen and elas- tic fibers, which become oriented along the lines of me- chanical stress. Examination of Joints When examining a patient, the clinician should assess BURSAE AND the normal range of movement of all joints. When the bones of a joint are no longer in their normal SYNOVIAL anatomic relationship with one another, then the joint is said to be dislocated.Some joints are particularly suscep- SHEATHS tible to dislocation because of lack of support by ligaments, the poor shape of the articular surfaces, or the absence of adequate muscular support. The shoulder joint, tem- poromandibular joint, and acromioclavicular joints are Trauma and Infection of Bursae good examples. Dislocation of the hip is usually congeni- tal, being caused by inadequate development of the and Synovial Sheaths socket that normally holds the head of the femur firmly in position. Bursae and synovial sheaths are commonly the site of The presence of cartilaginous discs within joints, espe- traumatic or infectious disease. For example, the extensor cially weightbearing joints, as in the case of the knee, makes tendon sheaths of the hand may become inflamed after ex- them particularly susceptible to injury in sports. During cessive or unaccustomed use; an inflammation of the a rapid movement the disc loses its normal relationship prepatellar bursa may occur as the result of trauma from re- to the bones and becomes crushed between the weight- peated kneeling on a hard surface. bearing surfaces. In certain diseases of the nervous system (e.g., sy- ringomyelia), the sensation of pain in a joint is lost. This BLOOD VESSELS means that the warning sensations of pain felt when a joint moves beyond the normal range of movement are not experienced. This phenomenon results in the destruction of the joint. Diseases of Blood Vessels Knowledge of the classification of joints is of great value because, for example, certain diseases affect only certain Diseases of blood vessels are common. The surface anatomy types of joints. Gonococcal arthritis affects large synovial of the main arteries, especially those of the limbs, is dis- joints such as the ankle, elbow, or wrist, whereas tubercu- cussed in the appropriate sections of this book. The collat- lous arthritis also affects synovial joints and may start in the eral circulationof most large arteries should be understood, synovial membrane or in the bone. and a distinction should be made between anatomic end Remember that more than one joint may receive the arteries and functional end arteries. same nerve supply. For example, the hip and knee joints All large arteries that cross over a joint are liable to be are both supplied by the obturator nerve. Thus, a patient kinked during movements of the joint. However, the distal with disease limited to one of these joints may experience flow of blood is not interrupted because an adequate anas- pain in both. tomosis is usually between branches of the artery that arise both proximal and distal to the joint. The alternative blood LIGAMENTS channels, which dilate under these circumstances, form the collateral circulation. Knowledge of the existence and posi- tion of such a circulation may be of vital importance should it be necessary to tie off a large artery that has been damaged Damage to Ligaments by trauma or disease. Coronary arteries are functional end arteries, and if Joint ligaments are very prone to excessive stretching and they become blocked by disease (coronary arterial occlusion even tearing and rupture. If possible, the apposing damaged is common), the cardiac muscle normally supplied by that surfaces of the ligament are brought together by positioning artery will receive insufficient blood and undergo necrosis. and immobilizing the joint. In severe injuries, surgical Blockage of a large coronary artery results in the death of the approximation of the cut ends may be required. The blood patient. Introduction to Clinical Anatomy 5 LYMPHATIC Learning the segmental innervation of all the muscles of the body is an impossible task. Nevertheless, the segmen- SYSTEM tal innervation of the following muscles should be known because they can be tested by eliciting simple muscle reflexes in the patient (CD Fig. 1-4): Diseases of the Lymphatic System (cid:2) Biceps brachii tendon reflex: C5 and 6 (flexion of the elbow joint by tapping the biceps tendon) The lymphatic system is often de-emphasized by anatomists (cid:2) Triceps tendon reflex: C6, 7, and 8 (extension of the on the grounds that it is difficult to see on a cadaver. However, elbow joint by tapping the triceps tendon) it is of vital importance to medical personnel, since lymph (cid:2) Brachioradialis tendon reflex:C5, 6, and 7 (supination nodes may swell as the result of infection, metastases, or pri- of the radioulnar joints by tapping the insertion of the mary tumor. For this reason, the lymphatic drainage of all ma- brachioradialis tendon) jor organs of the body, including the skin, should be known. (cid:2) Abdominal superficial reflexes (contraction of underly- A patient may complain of a swelling produced by the ing abdominal muscles by stroking the skin): Upper enlargement of a lymph node. A physician must know the abdominal skin T6–7, middle abdominal skin T8–9, and areas of the body that drain lymph to a particular node if he lower abdominal skin T10–12 or she is to be able to find the primary site of the disease. Of- (cid:2) Patellar tendon reflex (knee jerk):L2, 3, and 4 (exten- ten the patient ignores the primary disease, which may be a sion of the knee joint on tapping the patellar tendon) small, painless cancer of the skin. (cid:2) Achilles tendon reflex (ankle jerk):S1and S2 (plantar Conversely, the patient may complain of a painful ulcer flexion of the ankle joint on tapping the Achilles of the tongue, for example, and the physician must know the tendon) lymph drainage of the tongue to be able to determine whether Clinical Modification of the the disease has spread beyond the limits of the tongue. Activities of the Autonomic NERVOUS SYSTEM Nervous System Segmental Innervation of the Skin Many drugs and surgical procedures that can modify the activity of the autonomic nervous system are available. For example, drugs can be administered to lower the blood The area of skin supplied by a single spinal nerve, and pressure by blocking sympathetic nerve endings and causing therefore a single segment of the spinal cord, is called a vasodilatation of peripheral blood vessels. In patients with dermatome. On the trunk, adjacent dermatomes overlap severe arterial disease affecting the main arteries of the lower considerably; to produce a region of complete anesthesia, at limb, the limb can sometimes be saved by sectioning the least three contiguous spinal nerves must be sectioned. Der- sympathetic innervation to the blood vessels. This produces matomal charts for the anterior and posterior surfaces of the a vasodilatation and enables an adequate amount of blood to body are shown in CD Figs. 1-2 and 1-3. flow through the collateral circulation, thus bypassing the In the limbs, arrangement of the dermatomes is more obstruction. complicated because of the embryologic changes that take place as the limbs grow out from the body wall. MUCOUS AND A physician should have a working knowledge of the segmental (dermatomal) innervation of skin, because with the help of a pin or a piece of cotton he or she can determine SEROUS whether the sensory function of a particular spinal nerve or segment of the spinal cord is functioning normally. MEMBRANES Segmental Innervation of Muscle Mucous and Serous Membranes Skeletal muscle also receives a segmental innervation. Most of these muscles are innervated by two, three, or four spinal and Inflammatory Disease nerves and therefore by the same number of segments of the spinal cord. To paralyze a muscle completely, it is thus nec- essary to section several spinal nerves or to destroy several Mucous and serous membranes are common sites for in- segments of the spinal cord. flammatory disease. For example, rhinitis,or the common 6 Chapter 1 transverse cutaneous nerve of neck C2 C3 supraclavicular nerves anterior cutaneous branch of second C4 intercostal nerve upper lateral cutaneous nerve of arm C5 T3 medial cutaneous nerve of arm T2 T4 lower lateral cutaneous nerve of arm C6 T5 medial cutaneous nerve of forearm T6 T1 T7 T8 lateral cutaneous nerve of forearm T9 lateral cutaneous branch of T10 subcostal nerve C8 T11 L1 T12 femoral branch of genitofemoral C7 nerve median nerve ulnar nerve S3 ilioinguinal nerve S4 lateral cutaneous nerve of thigh obturator nerve L2 medial cutaneous nerve of thigh L3 intermediate cutaneous nerve of thigh infrapatellar branch of saphenous nerve L4 lateral sural cutaneous nerve L5 saphenous nerve superficial peroneal nerve S1 deep peroneal nerve CD Figure 1-2 Dermatomes and dis- tribution of cutaneous nerves on the anterior aspect of the body. cold, is an inflammation of the nasal mucous membrane, rections taken by the bony fragments depend not only on and pleurisyis an inflammation of the visceral and parietal the mechanism of injury, but also on the pull of the mus- layers of the pleura. cles attached to the fragments. Ligamentous attachments also influence the deformity. In certain situations—for BONES example, the ileum—fractures result in no deformity be- cause the inner and outer surfaces of the bone are splinted by the extensive origins of muscles. In contrast, a fracture of the neck of the femur produces considerable displace- Bone Fractures ment. The strong muscles of the thigh pull the distal frag- ment upward so that the leg is shortened. The very strong Immediately after a fracture, the patient suffers severe lo- lateral rotators rotate the distal fragment laterally so that cal pain and is not able to use the injured part. Deformity the foot points laterally. may be visible if the bone fragments have been displaced Fracture of a bone is accompanied by a considerable relative to each other. The degree of deformity and the di- hemorrhage of blood between the bone ends and into the
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