Fig. 17.
Fig. 17. 1, The shaft of the femur, (thigh-bone.) 2, A projection, called the trochantar minor, to which are attached some strong muscles. 4, The trochantar major, to which the large muscles of the hip are attached. 3, The head of the femur. 5, The external projection of the femur, called the external condyle. 6, The internal projection, called the internal condyle. 7, The surface of the lower extremity of the femur, that articulates with the tibia, and upon which the patella slides.
Fig. 18.
Fig. 18. 1, The tibia. 5, The fibula. 8, The space between the two, filled with the inter-osseous ligament. 6, The junction of the tibia and fibula at their upper extremity. 2, The external malleolar process, called the external ankle. 3, The internal malleolar process, called the internal ankle. 4, The surface of the lower extremity of the tibia, that unites with one of the tarsal bones to form the ankle-joint. 7, The upper extremity of the tibia, upon which the lower extremity of the femur rests.
Explain fig. 17. Explain fig. 18.
111. The METATARSAL bones are five in number. They articulate at one extremity with one range of tarsal bones; at the other extremity, with the first range of the toe-bones.
Fig. 19.
Fig. 19. A representation of the upper surface of the bones of the foot. 1, The surface of the astragulus, where it unites with the tibia. 2, The body of the astragulus. 3, The calcis, (heel-bone.) 4, The scaphoid bone. 5, 6, 7, The cuneiform bones. 8, The cuboid. 9, 9, 9, The metatarsal bones. 10, The first bone of the great toe. 11, The second bone. 12, 13, 14, Three ranges of bones, forming the small toes
Fig. 20.
Fig. 20. A side view of the bones of the foot, showing its arched form. The arch rests upon the heel behind, and the ball of the toes in front. 1, The lower part of the tibia. 2, 3, 4, 5, Bones of the tarsus. 6, The metatarsal bone. 7, 8, The bones of the great toe. These bones are so united as to secure a great degree of elasticity, or spring.
Observation. The tarsal and metatarsal bones are united so as to give the foot an arched form, convex above, and concave 45 below. This structure conduces to the elasticity of the step, and the weight of the body is transmitted to the ground by the spring of the arch, in a manner which prevents injury to the numerous organs.
111. Describe the metatarsal bones. Explain fig. 19. What is represented by fig. 20? What is said of the arrangement of the bones of the foot?
112. The PHALANGES (fig. 19) are composed of fourteen bones; each of the small toes has three ranges of bones, while the great toe has but two.
113. The JOINTS form an interesting part of the body. In their construction, every thing shows the regard that has been paid to the security and the facility of motion of the parts thus connected together. They are composed of the extremities of two or more bones, Car´ti-lages, (gristles,) Syn-o´vi-al membrane, and Lig´a-ments.
Fig. 21.
Fig. 21 The relative position of the bones, cartilages, and synovial membrane. 1, 1, The extremities of two bones that concur to form a joint. 2, 2, The cartilages that cover the end of the bones. 3, 3, 3, 3, The synovial membrane which covers the cartilage of both bones, and is then doubled back from one to the other; it is represented by the dotted lines.
Fig. 22.
Fig. 22. A vertical section of the knee-joint. 1, The femur. 3, The patella. 5, The tibia. 2, 4, The ligaments of the patella. 6, The cartilage of the tibia 12, The cartilage of the femur. * * * *, The synovial membrane.
114. Cartilage is a smooth, solid, elastic substance, of a pearly whiteness, softer than bone. It forms upon the articular 46 surfaces of the bones a thin incrustation, not more than the sixteenth of an inch in thickness. Upon convex surfaces it is the thickest in the centre, and thin toward the circumference; while upon concave surfaces, an opposite arrangement is presented.
112. Describe the phalanges. 113–118. Give the anatomy of the joints. 113. What is said of the joints? Of what are the joints composed? What is illustrated by fig. 21? By fig. 22? 114. Define cartilage.
115. The SYNOVIAL MEMBRANE is a thin, membranous layer, which covers the cartilages, and is thence bent back, or reflected upon the inner surfaces of the ligaments which surround and enter into the composition of the joints. This membrane forms a closed sac, like the membrane that lines an egg-shell.
Fig. 23.
Fig. 23. The anterior ligaments of the knee-joint. 1, The tendon of the muscle that extends the leg. 2, The patella. 3, The anterior ligament of the patella, near its insertion. 4, 4, The synovial membrane. 5, The internal lateral ligament. 6, The long external lateral ligament. 7, The anterior and superior ligament that unites the fibula to the tibia.
Fig. 24.
Fig. 24. 2, 3, The ligaments that extend from the clavicle (1) to the scapula (4.) The ligaments 5, 6, extend from the scapula to the first bone of the arm.
116. Beside the synovial membrane, there are numerous smaller sacs, called bur´sæ mu-co´sæ. These are often associated with the articulation. In structure, they are analogous to synovial membranes, and secrete a similar fluid.
115. Describe the synovial membrane. 116. Describe the bursæ mucosæ. What is represented by fig. 23? By fig. 24?
117. The LIGAMENTS are composed of numerous straight fibres, collected together, and arranged into short bands of various breadths, or so interwoven as to form a broad layer, which completely surrounds the articular extremities of the bones, and constitutes a capsular ligament. These connecting bands are white, glistening, and inelastic. Most of the ligaments are found exterior to the synovial membrane.
118. The bones, cartilages, ligaments, and synovial membrane are insensible when in health; yet they are supplied with organic nerves, as well as with arteries, veins, and lymphatics.
Observation. The joints of the domestic animals are similar in their construction to those of man. To illustrate this part of the body, a fresh joint of the calf or sheep may be used. After divesting the joints of the skin, the satin-like bands, or ligaments, will be seen passing from one bone to the other, under which may be observed the membranous bag, called the capsular ligament. This is very smooth, as it is lined with the soft synovial membrane, beneath which will be seen the cartilage, that may be cut with a knife, and under this the rough extremity of the ends of the bones.
117. Of what are ligaments composed? What is the appearance of these bands? Where are they found? 118. With what vessels are the cartilages and ligaments supplied? How can the structure of the joints be explained?
119. The bones are the framework of the system. By their solidity and form, they not only retain every part of the fabric in its proper shape, but afford a firm surface for the attachment of the muscles and ligaments. By means of the bones, the human frame presents to the eye a wonderful piece of mechanism, uniting the most finished symmetry of form with freedom of motion, and also giving security to many important organs.
120. To give a clear idea of the relative uses of the bones and muscles, we will quote the comparison of another, though, as in other comparisons, there are points of difference. The “bones are to the body what the masts and spars are to the ship,—they give support and the power of resistance. The muscles are to the bones what the ropes are to the masts and spars. The bones are the levers of the system; by the action of the muscles their relative positions are changed. As the masts and spars of a vessel must be sufficiently firm to sustain the action of the ropes, so the bones must possess the same quality to sustain the action of the muscles in the human body.”
121. Some of the bones are designed exclusively for the protection of the organs which they enclose. Of this number are those that form the skull, the sockets of the eye, and the cavity of the nose. Others, in addition to the protection they give to important organs, are useful in movements of certain 49 kinds. Of this class are the bones of the spinal column, and ribs. Others are subservient to motion. Of this class are the upper and lower extremities.
119–128. Give the physiology of the bones. 119. How may the bones be considered? 120. To what may the bones be compared? 121. Give the different offices of the bones.
122. The bones are subject to growth and decay; to removal of old, useless matter, and the deposit of new particles, as in other tissues. This has been tested by the following experiment. Some of the inferior animals were fed with food that contained madder. In a few days, some of the animals were killed, and their bones exhibited an unusually reddish appearance. The remainder of the animals were, for a few weeks, fed on food that contained no coloring principle. When they were killed, their bones exhibited the usual color of such animals. The coloring matter, which had been deposited, had been removed by the action of the lymphatics.
123. The extremities of the bones that concur in forming a joint, correspond by having their respective configurations reciprocal. They are, in general, the one convex, and the other concave. In texture they are porous, and consequently more elastic than if more compact. These are covered with a cushion of cartilage. The elastic character of these parts acts as so many springs, in diminishing the jar which important organs of the system would otherwise receive.
124. The synovial membrane secretes a viscous fluid, which is called syn-o´vi-a. This lubricating fluid of the joints enables the surfaces of the bones and tendons to move smoothly upon each other, thus diminishing the friction consequent on their action.
Observations. 1st. In this secretion is manifested the skill and omnipotence of the Great Architect; for no machine of human invention supplies to itself, by its own operations, the necessary lubricating fluid. But, in the animal frame, it is 50 supplied in proper quantities, and applied in the proper place, and at the proper time.
122. What is said of the change in bones? How was it proved that there was a constant change in the osseous fabric? 123. What is said of the extremities of the bones that form a joint? 124. What is synovia? Its use? What is said of this lubricating fluid?
2d. In some cases of injury and disease, the synovial fluid is secreted in large quantities, and distends the sac of the joint. This affection is called dropsy of the joint, and occurs most frequently in that of the knee.
125. The function of the ligaments is to connect and bind together the bones of the system. By them the small bones of the wrist and foot, as well as the large bones, are as securely fastened as if retained by clasps of steel. Some of them are situated within the joints, like a central cord, or pivot, (3, fig. 26.) Some surround it like a hood, and contain the lubricating synovial fluid, (8, 9, fig. 25,) and some in the form of bands at the side, (5, 6, fig. 23.)
Fig. 25.
Fig. 25. 8, 9, The ligaments that extend from the hip-bone (6) to the femur, (5.)
Fig. 26.
Fig. 26. 2, The socket of the hip-joint. 5, The head of the femur, which is lodged in the socket. 3, The ligament within the socket.
126. By the ligaments the lower jaw is bound to the temporal bones, and the head to the neck. They extend the whole 51 length of the spinal column, in powerful bands, on the outer surface, between the spinal bones, and from one spinous process to another. They bind the ribs to the vertebræ, to the transverse process behind, and to the sternum in front; and this to the clavicle; and this to the first rib and scapula; and this last to the humerus.
What is the effect when the synovial fluid is secreted in large quantities? 125. What is the function of the ligaments? 126. Mention how the bones of the system are connected.
127. They also bind the two bones of the fore-arm at the elbow-joint; and these to the wrist; and these to each other and to those of the hand; and these last to each other and to those of the fingers and thumb. In the same manner, they bind the bones of the pelvis together; and these to the femur; and this to the two bones of the leg and patella; and so on, to the ankle, foot, and toes, as in the upper extremities.
Fig. 27.
Fig. 27. 1, A front view of the lateral ligaments of the finger-joints. 2, A view of the anterior ligaments (a, b,) of the finger-joints. 3, A side view of the lateral ligaments of the finger joints.
128. The different joints vary in range of movement, and in complexity of structure. Some permit motions in all directions, as the shoulder; some move in two directions, permitting only flexion and extension of the part, as the elbow; while others have no movement, as the bones of the head in the adult.
Explain fig. 27. 128. Describe the variety of movements in the different joints.
Fig. 28
Fig. 28. 1, 1, The spinal column. 2, The skull. 3, The lower jaw. 4, The sternum. 5, The ribs. 6, 6, The cartilages of the ribs. 7, The clavicle. 8, The humerus. 9, The shoulder-joint. 10, The radius. 11, The ulna. 12, The elbow joint. 13, The wrist. 14, The hand. 15, The haunch-bone. 16, The sacrum. 17, The hip-joint. 18, The thigh-bone. 19, The patella. 20, The knee-joint. 21, The fibula. 22, The tibia. 23, The ankle-joint. 24, The foot. 25, 26, The ligaments of the clavicle, sternum, and ribs. 27, 28, 29, The ligaments of the shoulder, elbow, and wrist. 30, The large artery of the arm. 31, The ligaments of the hip-joint. 32, The large blood-vessels of the thigh. 33, The artery of the leg. 34, 35, 36, The ligaments of the patella, knee, and ankle.
Note. Let the pupil, in form of topics, review the anatomy and physiology of the bones from fig. 28, or from anatomical outline plates No. 1 and 2.
129. The bones increase in size and strength by use, while they are weakened by inaction. Exercise favors the deposition of both animal and earthy matter, by increasing the circulation and nutrition in this texture. For this reason, the bones of the laborer are dense and strong, while those who neglect exercise, or are unaccustomed to manual employment, are deficient in size, and have not a due proportion of earthy matter to give them the solidity and strength of the laboring man.
Observation. The tendons of the muscles are attached near the extremities of the bones. Exercise of the muscles increases the action of the vessels of that part to which the tendons are attached, and thus increases the nutrition and size of this portion of the bone. Hence the joints of an industrious mechanic or farmer are larger than those of an individual who has not pursued manual vocations.
130. The gelatinous bones of the child are not so well adapted for labor and severe exercise as those of an adult. 1st. They are liable to become distorted. 2d. They are consolidated by the deposition of earthy material before they are fully and properly developed. If a young animal, as the colt, be put to severe, continued labor, the deposition of earthy 54 matter is hastened, and the bones are consolidated before they attain full growth. Such colts make small and inferior animals. Similar results follow, if a youth is compelled to toil unduly before maturity of growth is attained. On the other hand, moderate and regular labor favors a healthy development and consolidation of the bones.
129–148. Give the hygiene of the bones. 129. What effect has exercise upon the bones? What effect has inaction? Why are the joints of the industrious farmer and mechanic larger than those of a person unaccustomed to manual employment? 130. Give the first reason why the bones of the child are not adapted to severe exercise. The second reason.
131. The kind and amount of labor should be adapted to the age, health, and development of the bones. Neither the flexible bones of the child nor the brittle bones of the aged man are adapted, by their organization, to long-continued, and hard labor. Those of the one bend too easily, while those of the other fracture too readily. In middle age, the proportions of animal and earthy matter are, usually, such as to give the proper degree of flexibility, firmness, and strength for labor, with little liability to injury.
132. The imperfectly developed bones of the young child will not bear long-continued exertions or positions without injury. Hence the requisitions of the rigid disciplinarian of schools, are unwise when he compels his pupils to remain in one position for a long time. He may have a “quiet school;” but, not unfrequently, by such discipline, the constitution is impaired, and permanent injury is done to the pupils.
133. The lower extremities, in early life, contain but a small proportion of earthy matter; they bend when the weight of the body is thrown upon them for a long time. Hence, the assiduous attempts to induce children to stand or walk, either naturally or artificially, when very young, are ill advised, and often productive of serious and permanent evil. The “bandy” or bow legs are thus produced.
What effect has moderate, regular labor upon the growing youth? 131. What remark respecting the kind and amount of labor? At what age are the bones best fitted for labor? 132. What effect has long-continued exertions or positions on the bones of a child? What is said of the requisitions of some teachers, who have the famed “quiet schools”? 133. Why should not the child be induced to stand or walk, either naturally or artificially, at too early an age?
134. The benches or chairs for children in a school-room should be of such a height as to permit the feet to rest on the floor. If the bench is so high as not to permit the feet to rest upon the floor, the weight of the limbs below the knee may cause the flexible bone of the thigh to become curved. The child thus seated, is inclined to lean forward, contracting an injurious and ungraceful habit. Again, when the feet are not supported, the child soon becomes exhausted, restless, and unfit for study. In the construction of a school-room, the benches should be of different heights, so as to be adapted to the different pupils, and they should also have appropriate backs.
Fig. 29.
Fig. 30.
Fig. 29. The position assumed when the seat is of proper height, and the feet supported.
Fig. 30. The position a child naturally assumes when the seat is so high that the feet are not supported.
134. What is said of the benches or chairs in a school-room? What is represented by fig. 29? By fig. 30? What is the effect when the lower limbs are not supported?
135. Compression of the chest should be avoided. In children, and also in adults, the ribs are very flexible, and a small amount of pressure will increase their curvature, particularly at the lower part of the chest, and thus lessen the size of this cavity. The lower ribs are united to the breast-bone, by long, yielding cartilages, and compression may not only contract the chest, but an unseemly and painful ridge may be produced, by the bending of the cartilages, on one or both sides of the sternum.
Fig. 31.
Fig. 32.
Fig. 31. A natural and well-proportioned chest.
Fig. 32. A chest fashionably deformed.
135. Why should compression of the chest be avoided? What is represented by fig. 31? By fig. 32?
136. Again, the cartilages on one side may be bent outward, while those on the opposite side are bent inward, thus forming a depression parallel with the sternum. In some instances, the anterior extremity of the lower ribs on each side 57 are brought nearly or quite together. In these instances, the movable extremities of the ribs are drawn down toward the haunch-bones, while the space between the ribs is lessened. All this may be effected by tight or “snug” clothing. Therefore the apparel of a child should be loose, and supported over the shoulders, to avoid the before-mentioned evils. The same may be said of the clothing for adults.
137. The erect position in sitting and standing should be assiduously observed. The spinal column, in its natural position, curves from front to back, but not from side to side The admirable arrangement of the bones, alternating with cartilages, permits a great variety of motions and positions; and when the spine is inclined to either side, the elasticity of its cartilages tends to restore it to its natural position. For this reason we may incline the spinal column in any direction for a short time, without danger of permanent curvature, if, afterward, the erect position is assumed.[4]
138. But if a stooping position, or a lateral curved posture, is continued for a long time, the spinal column does not easily recover its proper position, for the compressed edges of the cartilages lose their power of reaction, and finally one side of the cartilage becomes thinned, while the other is thickened; and these wedge-shaped cartilages produce a permanent curvature of the spinal column. In a similar way, the student, seamstress, artisan, and mechanic acquire a stooping position, and become round shouldered, by inclining forward to bring their books or work nearer the eyes.
136. May simply “snug” clothing compress the cartilages? How should the apparel of a child be worn? 137. In what direction does the spinal column, in its natural position, curve? What restores it to its natural position when curved laterally? 138. What is the effect if a lateral curved position of the spinal column is continued for a long time? 139. When one shoulder is elevated for a long time, what is the effect upon the spinal column?
139. Pupils, while writing, drawing, and sometimes while 58 studying, frequently incline the spinal column to one side, in order to accommodate themselves to the desks at which they are seated. Often, these are higher than the elbow as it hangs from the shoulder while at rest. This attitude elevates one shoulder while it depresses the other; consequently, the upper part of the spinal column is inclined toward the elevated shoulder, and the lower part is curved in the opposite direction, giving the form of the letter S to the supporting column of the body.
Fig. 33.
Fig. 33. The table is of proper height, the position is correct, and the spinal column, 1, 1, is straight, while the shoulders are of equal height.
What does fig. 33 represent?
Experiment. Let a pupil be placed at a desk or table with one elbow raised, as is frequently seen while writing, or at study, and observe the condition of the shoulder and spinal column in this position. Place another pupil at a table no higher than the elbow when it hangs by the side while sitting, and observe the appearance of the shoulders and spinal column. By a comparison of the two attitudes, the preceding remarks will be comprehended and appreciated.
Fig. 34.
Fig. 34. The table is too high, and the position is oblique and improper. The right shoulder is seen higher than the left, while the spinal column, 1, 1, exhibits three curves.
140. One shoulder may be elevated, and no injurious results 60 follow, provided care is taken not to keep it in the raised position too long, or if the opposite shoulder is elevated for the same period of time. The right shoulder projects more frequently than the left. This arises from the greater use of the right hand with the shoulder elevated, and not unfrequently the oblique positions assumed in performing the daily vocations of life. With proper care, and by calling into action the left shoulder, this deformity can be prevented.
What experiment is mentioned? What does fig. 34 represent? 140. How can one shoulder be elevated and no injurious results follow?
Fig. 35.
Fig. 35. A representation of a deformed trunk.
141. The loss of symmetry and diminution of height from deformed spines are minor considerations, compared with the distortions that the chest experiences, thereby impairing respiration and inducing diseases of the heart and lungs. The 61 invasion of the functions of these two important organs lessens the vitality of the whole system, and causes general ill health. Again, the curvature of the spinal column is frequently attended by irritation and disease of the spinal cord.
Why does the right shoulder project more frequently than the left? How can this deformity be prevented? 141. What is said of deformed spinal columns?
142. Eminent physicians, both in this country and France state that not more than one female in ten, who has been fashionably educated, is free from deformities of the shoulder or spinal column. Teachers, as well as mothers, should notice the positions of the child in performing the tasks allotted to it, whether studying or pursuing any employment. The feebler the organization of the child, the more frequently should there be a change of position.
143. When a slight projection of the shoulder, with a curvature of the spine, exists, it can be improved by walking with a book, or something heavier, upon the head; to balance which, the spinal column must be nearly erect. Those people that carry burdens upon their heads seldom have crooked spines.
Observation. Persons from the North, in travelling through the Southern States, are surprised to see the heavy burdens that the porters carry on their heads. It is not unusual to see them walking at a rapid pace, with one or two trunks, weighing fifty or eighty pounds each, upon their heads. Occasionally, we meet an itinerant toy-man, with his tray of fragile merchandise upon his head, walking with as much apparent security, as though his toys, or images, were in his hands. This is the easiest method of carrying burdens, because the position of the head and spinal column is erect.
144. If the animal and earthy matter of the bones is not deposited in proper proportions, they are deficient in strength. If the gelatin predominates, the bones are weak, and become 62 distorted. When nutrition is defective in the cylindrical bones, the heads are generally enlarged, and the shafts crooked; if in the spinal column, it may be curved; or in the cranium, it may be enlarged. This disease is familiarly known by the name of rickets. It is most common among these who have poor and insufficient food, live in dark, damp rooms, and breathe a vitiated air. The prevention and remedies for this disease are cleanliness, regular exercise, pure air, and nutritious food.
142. What statement by eminent physicians respecting deformities of the spine? What caution to teachers and mothers? 143. Why should we stand and sit erect? How may slight deformities of the spine be prevented? What is frequently noticed in travelling South? 144. What is the effect upon the bones when the gelatin preponderates?
145. When a bone is broken, some days elapse before the substance that reunites it is thrown out from the blood. In young persons, it may be secreted during the second or third week, and in individuals advanced in life, usually during the third and fourth week. When the bone is uniting, during the second, third, or fourth week, the attention of a surgeon is more needed than during the first week. At this time, the ends of the bone should be placed together with accuracy, which requires the careful application of proper dressing. After the bones have united, it will take some weeks to consolidate the uniting material and render the “callus,” or union, firm. During this time, the limb should be used with care.
Observation. When a bone is fractured, a surgeon is immediately called, and the bone is “set.” While the limb remains swelled and painful, the surgeon is required to attend and keep the dressings (bandages and splints) on. When the swelling has abated, and the pain subsided, frequently the patient intimates to the surgeon that his services can be dispensed with, as the “limb is doing well.” This is the most important period, as the bone is uniting, and, unless the ends are nicely adjusted, the dressing properly applied, the person 63 will find, on recovery, a shortened and crooked limb. The surgeon is then censured, when he is not blamable.
What is one cause of rickets? What are the prevention and remedies for this disease? 145. Does the time vary when the reuniting substance of the bone is secreted from the blood? When is the surgeon’s care most needed? Why?
146. It is seldom that a bone is displaced without injury to the connecting ligaments and membranes. When these connecting bands are lacerated, pain, swelling, and other symptoms indicating inflammation succeed, which should be removed by proper treatment, directed by a surgical adviser.
147. In sprains, but few, if any, of the fibres of the connecting ligaments are lacerated; but they are unduly strained and twisted, which occasions acute pain at the time of the injury. This is followed by inflammation and weakness of the joints. The treatment of these injuries is similar to that of a dislocated bone after its reduction. The most important item in the treatment during the few first days, is rest.
148. In persons of scrofulous constitutions, and those in whom the system is enfeebled by disease, white swellings and other chronic diseases of the joints frequently succeed sprains. Such persons cannot be too assiduous in adopting a proper and early treatment of injured joints.
146. What parts are injured in the displacement of a bone? 147. What causes the acute pain in sprains? What is a good remedy for this kind of injury? 148. What caution to persons of scrofulous constitutions?
149. All the great motions of the body are caused by the movement of some of the bones which form the framework of the system; but these, independently of themselves, have not the power of motion, and only change their position through the action of other organs attached to them, which, by contracting, draw the bones after them. In some of the slight movements, as the winking of the eye, no bones are displaced. These moving, contracting organs are the Mus´cles, (lean meat.)
150. The MUSCLES, by their size and number, constitute the great bulk of the body, upon which they bestow form and symmetry. In the limbs, they are situated around the bones, which they invest and defend, while they form, to some of the joints, their principal protection. In the trunk, they are spread out to enclose cavities, and constitute a defensive wall, capable of yielding to internal pressure, and reassuming its original state.
151. In structure, a muscle is composed of fas-cic´u-li (bundles of fibres) of variable size. These are enclosed in a cellular membranous investment, or sheath. Every bundle composed of a number of small fibres, and each fibre consists of a number of filaments, each of which is enclosed in 65 a delicate sheath. Toward the extremity of the organ the muscular fibre ceases, and the cellular structure becomes aggregated, and so modified as to constitute ten´dons, (cords,) by which the muscle is tied to the surface of the bone. The union is so firm, that, under extreme violence, the bone will sooner break than permit the tendon to separate from its attachment. In some situations, there is an expansion of the tendon, in the manner of a membrane, called Ap-o-neu-ro´sis, or Fas´ci-a.
149. How are all the motions of the body produced? What are these motor organs called? 150–160. Give the anatomy of the muscles. 150. What is said of the muscles? 151. Give their structure.
Observation. The pupil can examine a piece of boiled beef, or the leg of a fowl, and see the structure of the fibres and tendons of a muscle.
Fig. 36.
Fig. 36. 1, A representation of the direction and arrangement of the fibres in a fusiform, or spindle-shaped muscle. 2, In a radiated muscle. 3, In a penniform muscle. 4, In a bipenniform muscle. t, t, The tendons of a muscle.
152. Muscles present various modifications in the arrangement of their fibres, as relates to their tendinous structure. Sometimes they are completely longitudinal, and terminate, at each extremity, in a tendon, the entire muscle being spindle-shaped. In other situations, they are disposed like the rays of 66 a fan, converging to a tendinous point, and constituting a ra´di-ate muscle. Again they are pen´ni-form, converging, like the plumes of a pen, to one side of a tendon, which runs the whole length of the muscle; or they are bi-pen´ni-form, converging to both sides of the tendon.
How are tendons or cords formed? What is the expansion of a tendon called? How can the structure of muscles and their fibres be shown? What does fig. 36 represent? 152. Give the different arrangements of muscular fibres.
153. In the description of a muscle, its attachments are expressed by the terms “origin” and “insertion.” The term origin is generally applied to the more fixed or central attachment, or to the point toward which motion is directed; while insertion is assigned to the more movable point, or to that most distant from the centre. The middle, fleshy portion is called the “belly,” or “swell.” The color of a muscle is red in warm-blooded fish and animals; and each fibre is supplied with arteries, veins, lymphatics, and both sensitive and motor nervous filaments.
154. The FASCIA is of various extent and thickness, distributed through the different regions of the body, for the purpose of investing and protecting the softer and more delicate organs. An instance is seen in the membrane which envelopes a leg of beef, and which is observed on the edges of the slices when it is cut for broiling. When freshly exposed, it is brilliant in appearance, tough, and inelastic. In the limbs it forms distinct sheaths to all the muscles.
155. This tendinous membrane assists the muscles in their action, by keeping up a tonic pressure on their surface. It aids materially in the circulation of the fluids, in opposition to the laws of gravity. In the palm of the hand and sole of the foot, it is a powerful protection to the structures that enter into the formation of these parts. In all parts of the system, the separate muscles are not only invested by fascia, but they 67 are arranged in layers, one over another. The sheath of each muscle is loosely connected with another, by the cellular membrane.
153. What is meant by the origin of a muscle? The insertion? The swell? What is the color of muscles? With what is each muscular fibre supplied? 154. What is said of fascia? What is its appearance when freshly exposed? 155. What effect has it on the muscles? Give other uses of the fascia.
156. The interstices between the different muscles are filled with adipose matter, or fat. This is sometimes called the packing of the system. To the presence of this tissue, youth are indebted for the roundness and beauty of their limbs.
Fig. 37.
Fig. 37. A transverse section of the neck. The separate muscles, as they are arranged in layers, with their investing fasciæ, are beautifully represented. As the system is symmetrical, figures are placed only on one side. In the trunk the muscles are arranged in layers, surrounded by fasciæ, as in the neck. The same is true of the muscles of the upper and lower limbs.
12, The trachea, (windpipe.) 13, The œsophagus, (gullet.) 14, The carotid artery and jugular vein. 28, One of the bones of the spinal column. The figures that are placed in the white spaces represent some of the fasciæ; the other figures indicate muscles.
157. The muscles may be arranged, in conformity with the general division of the body, into four parts: 1st. Those of the Head and Neck. 2d. Those of the Trunk. 3d. Those of the Upper Extremities. 4th. Those of the Lower Extremities.
156. Give a reason why the limbs of youth are rounder than those of the aged. Describe fig. 37.
Fig. 38.
Fig. 38. The superficial layer of muscles on the face and neck. 1, 1, The occipito-frontalis muscle. 2, The orbicularis palpebrarum. 6, The levator labii superioris 7, The levator anguli oris. 8, The zygomaticus minor. 9, The zygomaticus major 10, The masseter. 11, The depressor labii superioris. 13, The orbicularis oris. 15, The depressor anguli oris. 16, The depressor labii inferioris. 18, The sterno-hyoideus. 19, The platysma-myodes. 20, The superior belly of the omo-hyoideus. 21, The sterno-cleido mastoideus. 20, The scalenus medius. 23, The inferior belly of the omo-hyoideus. 24, The trapezius.[5]
Practical Explanation. The muscle 1, 1, elevates the eyebrows. The muscle 2 closes the eye. The muscle 6 elevates the upper lip. The muscles 7, 8, 9, elevate the angle of the mouth. The muscle 10 brings the teeth together when eating. The muscle 11 depresses the upper lip. The muscle 13 closes the mouth. The muscle 15 depresses the angle of the mouth. The muscle 16 draws down the lower lip. The muscles 18, 19, 20, 23, depress the lower jaw and larynx and elevate the sternum. The muscle 21, when both sides contract, draws the head forward, or elevates the sternum; when only one contracts, the face is turned one side toward the opposite shoulder. The muscles 18, 19, 20, 21, 22, 23, 24, aid in respiration.