Musculoskeletal Anatomy

Gene L. Colborn, D.B. Lause

• Publisher: CRC Press
• Year: 2022
• eBook ISBN: 9781000605303
• Edition: 1
• Topic: Medicine
• Subtopic: Anatomy

This book is a guide for the dissection of the back and limbs - regions which are specifically relevant in the education of students in occupation and physical therapy. It contains data pertinent to many of the structures which are to be examined in the gross anatomy laboratory.

PART I

INTRODUCTION

CHAPTER 1: GENERAL ANATOMY

CHAPTER 1

GENERAL ANATOMY

Basic Terminology

Anatomical Nomenclature. Nomenclature is, essentially, the systematic naming of things (from the Latin nomen + calare = to call). The nomenclature of anatomy has a long and colorful history. In the past, over 50,000 anatomical terms were in use internationally to name the parts of the body, often with numerous terms applied to the same structure.

In 1895 the German Anatomical Society met in Basle and devised the Basle Nomina Anatomica (BNA), a list of some 5,000 words, to replace the confusing, often contradictory terminology which had developed in the scientific world to that time. The Commission set forth guidelines for the devising of names for anatomic structures, as follows:

1. With few exceptions, there should be only one name for each structure.

2. All names should be in Latin for international use.

3. The names of structures should be aids for memorization; that is, each term should have some informative or descripitive value.

4. Each term should be as brief and simple as possible.

5. Structures which are related topographically should have similar names (such as femoral nerve, femoral artery, femoral vein).

6. There should be usage of adjectives as opposites (for examples: pectoralis major, pectoralis minor; flexor digitorum superficialis and profundus; medial, lateral).

7. There should be no changes in familiar terms for purely pedantic reasons.

8. Eponyms should be discarded. Eponyms are names associated with persons, such as “Hunter’s canal” for the adductor canal; “Poupart’s ligament” for the inguinal ligament.

Revisions and corrections of the Nomina Anatomica have been made periodically during the twentieth century to make the language of anatomy truly international. In actual usage the Latin terminology of the Nomina Anatomica is often translated or transliterated to some degree into the language of the country wherein it is employed to facilitate understanding.

You will become aware of outmoded terms which are still used by anatomists and clinicians who do not know of, or are resistant to changes in the nomenclature of anatomy. Note for examples, the use of “internal mammary artery” for the internal thoracic artery and “innominate” for the brachiocephalic artery. The term “innominate” (definition: having no name) is really inappropriate for a major blood vessel which does, as a matter of fact, have a name. Some terms in rather common use are simply wrong, such as “calvarium,” used as the singular for the calvaria or skull cap, the plural for which is calvariae.

The Skin

Composition. The skin is composed of two layers, the epidermis and the dermis (Fig. 1:1). The epidermis, the external layer of the skin, is derived embryologically principally from ectoderm. This outermost, cornified stratum of the skin is especially thick on the palms of the hands and the soles of the feet. It is very thin over the eyelids.

The dermis, or corium, is derived embryologically from mesenchyme; it is a strong layer of tough, fibrous connective tissue and it is rich in numbers of small blood vessels and nerves. This layer tends to be thicker on the extensor surfaces of the body such as the back, thinner on the flexor surfaces.

Fibrous bands, or strands, called retinacula cutis pass from the deep aspect of the corium into, and through the subcutaneous fat to attach the skin to underlying deep fascia. Compare the mobility of the skin of the palmar surfaces of your hands with that of the skin on the backs of your hands. The difference is, in part, a reflection of the presence or absence of the retinacula cutis. The retinacula cutis of the breast tissues, referred to clinically as the “suspensory ligaments” of the breast, may become contracted in breast cancer, resulting in a dimpling of the skin overlying a tumor. The dimpling provides a useful diagnostic aid to detection of the disease process.

Smooth muscle bundles, called pilomotor muscles (arrector pili) are present in the dermis (Fig. 1:1). Such muscles attach to the undersurface of hair follicles. The pilomotor muscles are supplied by sympathetic autonomic nerve fibers. When stimulated to contract, these muscles cause elevation of the hairs (as in “goosebumps”).

Figure 1:1 Skin and underlying fascial layers. E, epidermis; D, dermis; A adipose layer of subcutaneous tissue; M, membranous layer of subcutaneous tissue; F, deep fascia overlying skeletal muscle; S, skeletal muscle.

Glands of the Skin. Sebaceous glands secrete greasy sebum. These glands are situated within the dermis and are found frequently in hairy skin. The duct of a sebaceous gland usually ends at the side of an adjacent hair follicle. Some sebaceous glands are present in the dermis of the face; blockage of their ducts, with infection, results in acne.

Sweat glands are located adjacent to the deep surface of the dermis in hairy or hairless skin. The sweat gland ducts pass outward through the dermis and epidermis to empty upon the surface of the skin. The openings of these glands can be seen easily with a low power magnifying lens.

Embryologic Derivatives of the Epidermis. Hairs grow from epithelial follicles, which are downgrowths of the epidermis. Hair is more plentiful upon the extensor surfaces of the limbs than upon the flexor surfaces. Nails develop from the epidermis. Sweat glands, sebaceous glands and the glandular elements of the mammary gland (breast) develop as downgrowths from the epidermis into, and through the dermis into the underlying fatty tissue.

Skin Creases and Lines of Cleavage of the Skin. The skin overlying the flexor surface of some joints is bound firmly to underlying structures such as deep fascia - creating the flexion creases. Note the palmar surfaces of the joints of your fingers and your wrists for examples of such creases.

Collagen bundles of the dermis tend to be arranged in parallel, creating cleavage lines in the skin known as the lines of Langer (Fig. 1:2). Where flexion creases are apparent, it can be assumed that the cleavage lines run parallel with them. The cleavage lines of the skin tend to pass circumferentially around the neck and trunk, but longitudinally in the limbs.

Incisions made parallel with the lines of cleavage heal with much less scarring and contracture than incisions made at right angles to the cleavage lines. This fact is especially important in cosmetic surgery, surgery of the hand and incisions in the abdominal wall.

Functions of the Skin. Forming nearly one-fifth of the weight of the body, the skin is one of the largest organs in the body, and performs a variety of functions - some obvious, and some not so obvious. The skin acts in the conservation of body fluid. The significance of this function is of special importance in burn patients.

The skin participates in the regulation of body temperature by acting as an insulator - together with the underlying subcutaneous tissues - by sweating, by insensible perspiration (diffusion of body fluid through the skin) and by neurovascular reflexes of cutaneous blood vessels.

The skin provides good frictional properties for locomotion and manipulation. It also acts in protection of the body against injury, invasion by microorganisms, etc. Sensory perception of the environment is provided by various somatic sensory nerve endings in the skin. It functions somewhat as an excretory and absorptive organ, and is important in the formation of Vitamin D in response to ultraviolet light.

“Refe...

Table of contents

• Cover
• Half Title
• Dedication
• Title Page
• Copyright Page
• Table of Contents
• Preface
• In Memoriam
• Acknowledgements
• Part I Introduction
• Part II The Back
• Part III The Upper Limb
• Part IV The Lower Limb
• Index