The general doctrine about muscles

THE MUSCLES are related with the bones, cartilages, ligaments, and pores and skin, both instantly, or via the intervention of fibrous constructions known as tendons or aponeuroses. The place a muscle is connected to bone or cartilage, the fibers finish in blunt extremities upon the periosteum or perichondrium, and don’t come into direct relation with the osseous or cartilaginous tissue. The place muscle groups are related with its pores and skin, they lie as a flattened layer beneath it, and are related with its areolar tissue by bigger or smaller bundles of fibers, as within the muscle groups of the face.   

The muscle groups differ extraordinarily of their type. Within the limbs, they’re of appreciable size, particularly the extra superficial ones; they encompass the bones, and represent an essential safety to the varied joints. Within the trunk, they’re broad, flattened, and expanded, and help in forming the partitions of the trunk cavities. Therefore the rationale of the phrases, lengthy, broad, quick, and so forth., used within the description of a muscle.   

There’s appreciable variation within the association of the fibers of sure muscle groups close to the tendons to which they’re connected. In some muscle groups the fibers are parallel and run instantly from their origin to their insertion; these are quadrilateral muscle groups, such because the Thyreohyoideus. A modification of those is discovered within the fusiform muscle groups, wherein the fibers usually are not fairly parallel, however barely curved, in order that the muscle tapers at both finish; of their actions, nonetheless, they resemble the quadrilateral muscle groups. Secondly, in different muscle groups the fibers are convergent; arising by a broad origin, they converge to a slender or pointed insertion. This association of fibers is discovered within the triangular muscle groups—e. g., the Temporalis. In some muscle groups, which in any other case would belong to the quadrilateral or triangular sort, the origin and insertion usually are not in the identical airplane, however the airplane of the road of origin intersects that of the road of insertion; such is the case within the Pectineus. Thirdly, in some muscle groups (e. g., the Peronei) the fibers are indirect and converge, just like the plumes of a quill pen, to 1 facet of a tendon which runs the whole size of the muscle; such muscle groups are termed unipennate. A modification of this situation is discovered the place indirect fibers converge to each side of a central tendon; these are known as bipennate, and an instance is afforded within the Rectus femoris. Lastly, there are muscle groups wherein the fibers are organized in curved bundles in a number of planes, as within the Sphincters. The association of the fibers is of appreciable significance in respect to the relative power and vary of motion of the muscle. These muscle groups the place the fibers are lengthy and few in quantity have nice vary, however diminished power; the place, then again, the fibers are quick and extra quite a few, there’s nice energy, however lessened vary.  

The names utilized to the varied muscle groups have been derived: (1) from their scenario, because the Tibialis, Radialis, Ulnaris, Peronæus; (2) from their course, because the Rectus abdominis, Obliqui capitis, Transversus abdominis; (3) from their makes use of, as Flexors, Extensors, Abductors, and so forth.; (4) from their form, because the Deltoideus, Rhomboideus; (5) from the variety of their divisions, because the Biceps and Triceps; (6) from their factors of attachment, because the Sternocleidomastoideus, Sternohyoideus, Sternothyreoideus.   

Within the description of a muscle, the time period origin is supposed to indicate its extra mounted or central attachment; and the time period insertion the movable level on which the pressure of the muscle is utilized; however the origin is totally mounted in solely a small variety of muscle groups, akin to these of the face that are connected by one extremity to immovable bones, and by the opposite to the movable integument; within the better quantity, the muscle could be made to behave from both extremity.   

Within the dissection of the muscle groups, consideration must be directed to the precise origin, insertion, and actions of every, and to its extra essential relations with surrounding components. Whereas correct information of the factors of attachment of the muscle groups is of nice significance within the willpower of their actions, it’s not to be considered conclusive. The motion of the muscle deduced from its attachments, and even by pulling on it within the lifeless topic, will not be essentially its motion within the residing. By pulling, for instance, on the Brachioradialis within the cadaver the hand could also be barely supinated when within the susceptible place and barely pronated when within the supine place, however there isn’t any proof that these actions are carried out by the muscle throughout life. It’s inconceivable for a person to throw into motion anybody muscle; in different phrases, actions, not muscle groups, are represented within the central nervous system. To hold out a motion a particular mixture of muscle groups known as into play, and the person has no energy both to go away out a muscle from this mixture or so as to add one to it. One (or extra) muscle of the mixture is the chief shifting pressure; when this muscle passes over a couple of joint different muscle groups (synergic muscle groups) come into play to inhibit the actions not required; a 3rd set of muscle groups (fixation muscle groups) repair the limb—i. e., within the case of the limb-movements—and likewise stop disturbances of the equilibrium of the physique typically. For example, the motion of the closing of the fist could also be thought of: (1) the prime movers are the Flexores digitorum, Flexor pollicis longus, and the small muscle groups of the thumb; (2) the synergic muscle groups are the Extensores carpi, which stop flexion of the wrist; whereas (3) the fixation muscle groups are the Biceps and Triceps brachii, which regular the elbow and shoulder. An additional level which should be borne in thoughts in contemplating the actions of muscle groups is that in sure positions a motion could be effected by gravity, and in such a case the muscle groups appearing are the antagonists of these which could be purported to be in motion. Thus in flexing the trunk when no resistance is interposed the Sacrospinales contract to manage the motion of gravity, and the Recti abdominis are relaxed.

By a consideration of the motion of the muscle groups, the surgeon is ready to clarify the causes of displacement in varied types of fracture, and the causes which produce distortion in varied deformities, and, consequently, to undertake applicable remedy in every case. The relations, additionally, of among the muscle groups, particularly these in instant apposition with the bigger bloodvessels, and the floor markings they produce, must be remembered, as they type helpful guides within the software of ligatures to these vessels.   

Mechanics of Muscle.   In learning the mechanical motion of muscle groups the person muscle can not all the time be handled as a single unit, since totally different components of the identical muscle could have fully totally different actions, as with the Pectoralis main, the Deltoid, and the Trapezius the place the nerve impulses management and stimulate totally different parts of the muscle in succession or at totally different instances. Most muscle groups are, nonetheless, in a mechanical sense models. However in both case the muscle fibers represent the elementary motor parts.  

The Course of the Muscle Pull.—In these muscle groups the place the fibers all the time run in a straight line from origin to insertion in all positions of the joint, a straight line becoming a member of the center of the floor of origin with the center of the insertion floor will give the course of the pull. If, nonetheless, the muscle or its tendon is bent out of a straight line by a bony course of or ligament in order that it runs over a pulley-like association, the course of the muscle pull is of course bent out of line. The course of the pull in such circumstances is from the center level of insertion to the center level of the pulley the place the muscle or tendon is bent. Muscle tissue or tendons of muscle groups which cross over a couple of joint and cross via a couple of pulley could also be resolved, as far as the course of the pull is worried, into two or extra models or single-joint muscle groups. The tendons of the Flexor profundus digitorum, for instance, cross via a number of pulleys shaped by fibrous sheaths. The course of the pull is totally different for every joint and varies for every joint in accordance with the place of the bones. The course is decided in every case, nonetheless, by a straight line between the facilities of the pulleys on both facet of the joint. The course of the pull in any of the segments wouldn’t be altered by any change within the place or origin of the muscle stomach above the proximal pulley. 

The Motion of the Muscle Pull on the Tendon.—The place the muscle fibers are parallel or practically parallel to the course of the tendon the whole power of the muscle contraction acts within the course of the tendon.  

In pinnate muscle groups, nonetheless, solely a portion of the power of contraction is environment friendly within the course of the tendon, since a portion of the pull would have a tendency to attract the tendon to 1 facet, that is largely annulled by strain of surrounding components. In bipinnate muscle groups this lateral pull is counterbalanced. If, for instance, the muscle fibers are inserted into the tendon at an angle of 60 levels, it’s straightforward to find out by the parallelogram of forces that the power of the pull alongside the course of the tendon is the same as one-half the muscle pull.   

The Power of Muscle tissue.—The power of a muscle relies upon upon the variety of fibers in what is called the physiological cross-section, that’s, a bit which passes via virtually all the fibers. In a muscle with parallel or practically parallel fibers which have the identical course because the tendon this corresponds to the anatomical cross-section, however in unipinnate and bipinnate muscle groups the physiological cross-section could also be practically at proper angles to the anatomical cross-section. Since Huber has proven that muscle fibers in a single fasciculus of a given muscle differ significantly in size, in some fasciculi from 9 mm. to 30.4 mm., it’s unlikely that the physiological cross-section will cross via all of the fibers. Estimates have been made from the power of muscle groups and it’s possible that coarse-fibered muscle groups are considerably stronger per sq. centimeter of physiological cross-section than are the fine-fibered muscle groups. Fick estimates the common power as about 10 kg. per sq. cm. This is called absolutely the muscle power. The whole power of a muscle could be equal to the variety of sq. centimeters in its physiological cross-section x 10 kg.   

If we take into account now the motion of a single muscle extending over a single joint wherein one bone is mounted and the opposite movable, we are going to discover that muscle pull could be resolved into two parts.

Growth of the Muscle tissue. Each the cross-striated and easy muscle groups, except for just a few which might be of ectodermal origin, come up from the mesoderm. The intrinsic muscle groups of the trunk are derived from the myotomes whereas the muscle groups of the pinnacle and limbs differentiate instantly from the mesoderm.   

The Myotomic Muscle tissue.—The intrinsic muscle groups of the trunk that are derived instantly from the myotomes are conveniently handled in two teams, the deep muscle groups of the again and the thoraco-abdominal muscle groups.   

The deep muscle groups of the again lengthen from the sacral to the occipital area and differ a lot in size and measurement. They act mainly on the vertebral column. The shorter muscle groups, such because the Interspinales, Intertransversarii, the deeper layers of the Multifidus, the Rotatores, Levatores costarum, Obliquus capitis inferior, Obliquus capitis superior and Rectus capitis posterior minor which lengthen between adjoining vertebræ, retain the primitive segmentation of the myotomes. Different muscle groups, such because the Splenius capitis, Splenius cervicis, Sacrospinalis, Semispinalis, Multifidus, Iliocostalis, Longissimus, Spinales, Semispinales, and Rectus capitis posterior main, which lengthen over a number of vertebræ, are shaped by the fusion of successive myotomes and the splitting into longitudinal columns.   

The fascia lumbo-dorsalis develops between the true myotomic muscle groups and the extra superficial ones which migrate over the again such because the Trapezius, Rhomboideus, and Latissimus.  

The anterior vertebral muscle groups, the Longus colli, Longus capitis, Rectus capitis anterior and Rectus capitis lateralis are derived from the ventral a part of the cervical myotomes as are most likely additionally the Scaleni.  

The thoraco-abdominal muscle groups come up via the ventral extension of the thoracic myotomes into the physique wall. This course of takes place coincident with the ventral extension of the ribs. Within the thoracic area the primitive myotomic segments nonetheless persist because the intercostal muscle groups, however over the stomach these ventral myotomic processes fuse right into a sheet which splits in varied methods to type the Rectus, the Obliquus externus and internus, and the Transversalis. Such muscle groups because the Pectoralis main and minor and the Serratus anterior don’t belong to the above group.   

The Ventrolateral Muscle tissue of the Neck.—The intrinsic muscle groups of the tongue, the Infrahyoid muscle groups and the diaphragm are derived from a kind of steady premuscle mass which extends on all sides from the tongue into the lateral area of the higher half of the neck and into it early lengthen the hypoglossal and branches of the higher cervical nerves. The 2 halves which type the Infrahyoid muscle groups and the diaphragm are at first broadly separated from one another by the center. Because the latter descends into the thorax the diaphragmatic portion of every lateral mass is carried with its nerve down into the thorax and the laterally positioned Infrahyoid muscle groups transfer towards the midventral line of the neck.   

Muscle tissue of the Shoulder Girdle and Arm.—The Trapezius and Sternocleidomastoideus come up from a standard premuscle mass within the occipital area simply caudal to the final branchial arch; because the mass will increase in measurement it spreads downward to the shoulder girdle to which it later turns into connected. It additionally spreads backward and downward to the spinous processes, gaining attachment at a nonetheless later interval.  

The Levator scapulæ, Serratus anterior and the Rhomboids come up from premuscle tissue within the decrease cervical area and endure in depth migration. 

The Latissimus dorsi and Teres main are related of their origin from the premuscle sheath of the arm as are additionally the 2 Pectoral muscle groups when the arm bud lies within the decrease cervical area.   

The intrinsic muscle groups of the arm develop in situ from the mesoderm of the arm bud and doubtless don’t obtain cells or buds from the myotomes. The nerves enter the arm bud when it nonetheless lies within the cervical area and because the arm shifts caudally over the thorax the decrease cervical nerves which unite to type the brachial plexus, purchase a caudal course.  

The Muscle tissue of the Leg.—The muscle groups of the leg like these of the arm develop in situ from the mesoderma of the leg bud, the myotomes apparently taking no half of their formation.   

The Muscle tissue of the Head.—The muscle groups of the orbit come up from the mesoderm over the dorsal and caudal sides of the optic stalk. The muscle groups of mastication come up from the mesoderm of the mandibular arch. The mandibular division of the trigeminal nerve enters this premuscle mass earlier than it splits into the Temporal, Masseter and Pterygoideus. The facial muscle groups (muscle groups of expression) come up from the mesoderm of the hyoid arch. The facial nerve enters this mass earlier than it begins to separate, and because the muscle mass spreads out over the face and head and neck it splits kind of incompletely into the varied muscle groups. The early differentiation of the muscular system apparently goes on independently of the nervous system and solely later does it seem that muscle groups are depending on the useful stimuli of the nerves for his or her continued existence and progress. Though the nervous system doesn’t affect muscle differentiation, the nerves, owing to their early attachments to the muscle rudiments, are in a common means indicators of the place of origin of most of the muscle groups and likewise in lots of cases the nerves point out the paths alongside which the growing muscle groups have migrated throughout improvement. The muscle of the diaphragm, for instance, has its origin within the area of the fourth and fifth cervical segments. The phrenic nerve enters the muscle mass whereas the latter is on this area and is drawn out because the diaphragm migrates via the thorax. The Trapezius and Sternocleidomastoideus come up within the lateral occipital area as a standard muscle mass, into which at a really early interval the nervus accessorius extends and because the muscle mass migrates and extends caudally the nerve is carried with it. The Pectoralis main and minor come up within the cervical area, obtain their nerves whereas on this place and because the muscle mass migrates and extends caudally over the thorax the nerves are carried alongside. The Latissimus dorsi and Serratus anterior are glorious examples of migrating muscle groups whose nerve provide signifies their origin within the cervical area. The Rectus abdominis and the opposite stomach muscle groups migrate or shift from a lateral to a ventrolateral or stomach place, carrying with them the nerves.  

The facial nerve, which early enters the frequent facial muscle mass of the second branchial or hyoid arch, is dragged about with the muscle because it spreads over the pinnacle and face and neck, and because the muscle splits into the varied muscle groups of expression, the nerve is correspondingly break up. The mandibular division of the trigeminal nerve enters at an early time the muscle mass within the mandibular arch and as this mass splits and migrates aside to type the muscle groups of mastication the nerve splits into its varied branches. The nerve provide then serves as a key to the frequent origin of sure teams of muscle groups. The muscle groups provided by the oculomotor nerve come up from a single mass within the eye area; the lingual muscle groups come up from a standard mass provided by the hypoglossal nerve.  

Striped or Voluntary Muscle.—Striped or voluntary muscle consists of bundles of fibers every enclosed in a fragile net known as the perimysium in contradistinction to the sheath of areolar tissue which invests the whole muscle, the epimysium. The bundles are termed fasciculi; they’re prismatic in form, of various sizes in numerous muscle groups, and are for essentially the most half positioned parallel to 1 one other, although they generally tend to converge towards their tendinous attachments. Every fasciculus is made up of a strand of fibers, which additionally run parallel with one another, and are separated from each other by a fragile connective tissue derived from the perimysium and termed endomysium. This doesn’t type the sheath of the fibers, however serves to assist the bloodvessels and nerves ramifying between them.   

 A muscular fiber could also be mentioned to encompass a gentle contractile substance, enclosed in a tubular sheath named by Bowman the sarcolemma. The fibers are cylindrical or prismatic in form, and are of no nice size, not exceeding, as a rule, 40 mm. Huber  78 has not too long ago discovered that the muscle fibers within the adductor muscle of the thigh of the rabbit differ significantly in size even in the identical fasciculus. In a fasciculus 40 mm. in size the fibers assorted from 30.4 mm. to 9 mm. in size. Their breadth varies in man from 0.01 to 0.1 mm. As a rule, the fibers don’t divide or anastomose; however often, particularly within the tongue and facial muscle groups, they could be seen to divide into a number of branches. Within the substance of the muscle, the fibers finish by tapering extremities that are joined to the ends of different fibers by the sarcolemma. On the tendinous finish of the muscle the sarcolemma seems to mix with a small bundle of fibers, into which the tendon turns into subdivided, whereas the muscular substance ends abruptly and could be readily made to retract from the purpose of junction. The areolar tissue between the fibers seems to be extended kind of into the tendon, in order to type a form of sheath across the tendon bundles for an extended or shorter distance. When muscular fibers are connected to pores and skin or mucous membranes, their fibers grow to be steady with these of the areolar tissue.   

The sarcolemma, or tubular sheath of the fiber, is a clear, elastic, and apparently homogeneous membrane of appreciable toughness, in order that it typically stays whole when the included substance is ruptured. On the inner floor of the sarcolemma in mammalia, and likewise within the substance of the fiber in frogs, elongated nuclei are seen, and in reference to these is somewhat granular protoplasm.  Upon examination of a voluntary muscular fiber by transmitted gentle, it’s discovered to be marked by alternate gentle and darkish bands or striæ, which cross transversely throughout the fiber. When examined by polarized gentle the darkish bands are discovered to be doubly refracting (anisotropic), whereas the clear stripes are singly refracting (isotropic). The darkish and light-weight bands are of practically equal breadth, and alternate with nice regularity; they differ in breadth from about 1 to 2&mu. If the floor be fastidiously focussed, rows of granules will likely be detected on the factors of junction of the darkish and light-weight bands, and really nice longitudinal strains could also be seen operating via the darkish bands and becoming a member of these granules collectively. By treating the specimen with sure reagents (e. g., chloride of gold) nice strains could also be seen operating transversely between the granules and uniting them collectively. This look is believed to be resulting from a reticulum or community of interstitial substance mendacity between the contractile parts of the muscle. The longitudinal striation offers the fiber the looks of being made up of a bundle of fibrils which have been termed sarcostyles or muscle columns, and if the fiber be hardened in alcohol, it may be damaged up longitudinally and the sarcostyles separated from one another. The reticulum, with its longitudinal and transverse meshes, known as sarcoplasm.

In a transverse part, the muscular fiber is seen to be divided into a lot of areas, known as the areas of Cohnheim, kind of polyhedral in form and consisting of the transversely divided sarcostyles, surrounded by clear sarcoplasm.

Upon nearer examination, and by considerably altering the main target, the appearances grow to be extra difficult, and are vulnerable of varied interpretations. The transverse striation, which in seems as a mere alternation of darkish and light-weight bands, is resolved into the looks seen in, which reveals a sequence of broad darkish bands, separated by gentle bands, every of which is split into two by a darkish dotted line. This line is termed Dobie’s line or Krause’s membrane, as a result of it was believed by Krause to be an precise membrane, steady with the sarcolemma, and dividing the sunshine band into two compartments. Along with the membrane of Krause, nice clear strains could also be made out, with a sufficiently excessive energy, crossing the middle of the darkish band; these are generally known as the strains of Hensen.   Schäfer has labored out the minute anatomy of muscular fiber, notably within the wing muscle groups of bugs, that are peculiarly tailored for this objective on account of the big quantity of interstitial sarcoplasm which separates the sarco-styles. Within the following description that given by Schäfer will likely be intently adopted.  A sarcostyle could also be mentioned to be made up of successive parts, every of which is termed a sarcomere. The sarcomere is located between two membranes of Krause and consists of (1) a central darkish half, which kinds a portion of the darkish band of the entire fiber, and is called a sarcous component. This sarcous component actually consists of two components, superimposed one on the highest of the opposite, and when the fiber is stretched these two components grow to be separated from one another on the line of Hensen. (2) On both facet of this central darkish portion is a transparent layer, most seen when the fiber is prolonged; that is located between the darkish heart and the membrane of Krause, and when the sarcomeres are joined collectively to type the sarcostyle, constitutes the sunshine band of the striated muscular fiber.  When the sarcostyle is prolonged, the clear intervals are well-marked and plainly to be seen; when, then again, the sarcostyle is contracted, that’s to say, when the muscle is in a state of contraction, these clear parts are very small or they could have disappeared altogether. When the sarcostyle is stretched to its full extent, not solely is the clear portion well-marked, however the darkish portion—the sarcous component—is separated into its two constituents alongside the road of Hensen. The sarcous component doesn’t lie free within the sarcomere, for when the sarcostyle is stretched, in order to render the clear portion seen, very nice strains, that are most likely septa, could also be seen operating via it from the sarcous component to the membrane of Krause.    Schäfer explains these phenomena within the following means: He considers that every sarcous component is made up of a lot of longitudinal channels, which open into the clear half towards the membrane of Krause however are closed on the line of Hensen. When the muscular fiber is contracted the clear a part of the muscular substance is pushed into these channels or tubes, and is subsequently hidden from sight, however on the similar time it swells up the sarcous component and widens and shortens the sarcomere. When, then again, the fiber is prolonged, this clear substance is pushed out of the tubes and collects between the sarcous component and the membrane of Krause, and offers the looks of the sunshine half between these two constructions; by this implies it elongates and narrows the sarcomere.   If this view be true, it’s a matter of nice curiosity, and, as Schäfer has proven, harmonizes the contraction of muscle with the ameboid motion of protoplasm. In an ameboid cell, there’s a framework of spongioplasm, which stains with hematoxylin and comparable reagents, enclosing in its meshes a transparent substance, hyaloplasm, which won’t stain with these reagents. Below stimulation the hyaloplasm passes into the pores of the spongioplasm; with out stimulation it tends to cross out as within the formation of pseudopodia. In muscle there is similar factor, viz., a framework of spongioplasm staining with hematoxylin—the substance of the sarcous component—and this encloses a transparent hyaloplasm, the clear substance of the sarcomere, which resists staining with this reagent. Throughout contraction of the muscle—i.e., stimulation—this clear substance passes into the pores of the spongioplasm; whereas throughout extension of the muscle—i.e., when there isn’t any stimulation—it tends to cross out of the spongioplasm.   On this means the contraction is caused: underneath stimulation the protoplasmic materials (the clear substance of the sarcomere) recedes into the sarcous component, inflicting the sarcomere to widen out and shorten. The contraction of the muscle is merely the sum whole of this widening out and shortening of those our bodies.   30 Vessels and Nerves of Striped Muscle.—The capillaries of striped muscle are very ample, and type a type of rectangular community, the branches of which run longitudinally within the endomysium between the muscular fibers, and are joined at quick intervals by transverse anastomosing branches. Within the pink muscle groups of the rabbit dilatations happen on the transverse branches of the capillary community. The bigger vascular channels, arteries and veins, are discovered solely within the perimysium, between the muscular fasciculi. Nerves are profusely distributed to striped muscle. Their mode of termination is described on web page 730. The existence of lymphatic vessels in striped muscle has not been ascertained, although they’ve been present in tendons and within the sheaths of the muscle groups.   31  Ossification of muscular tissue on account of repeated pressure or damage will not be rare. It’s oftenest discovered concerning the tendon of the Adductor longus and Vastus medialis in horsemen, or within the Pectoralis main and Deltoideus of troopers. It might take the type of exostoses firmly mounted to the bone—e.g., “rider’s bone” on the femur—or of layers or spicules of bone mendacity within the muscle groups or their fasciæ and tendons. Busse states that these bony deposits are preceded by a hemorrhagic myositis resulting from damage, the effused blood organizing and being lastly transformed into bone. Within the rarer illness, progressive myositis ossificans, there’s an unexplained tendency for virtually any of the voluntary muscle groups to grow to be transformed into stable and brittle bony lots that are fully inflexible.

Tendons, Aponeuroses, and Fasciæ Tendons are white, glistening, fibrous cords, various in size and thickness, typically spherical, typically flattened, and devoid of elasticity. They consist virtually fully of white fibrous tissue, the fibrils of which have an undulating course parallel with one another and are firmly united collectively. When boiled in water tendon is sort of fully transformed into gelatin, the white fibers being composed of the albuminoid collagen, which is commonly considered the anhydride of gelatin. They’re very sparingly provided with bloodvessels, the smaller tendons presenting of their inside no hint of them. Nerves supplying tendons have particular modifications of their terminal fibers, named organs of Golgi.   1  Aponeuroses are flattened or ribbon-shaped tendons, of a pearly white shade, iridescent, glistening, and comparable in construction to the tendons. They’re solely sparingly provided with bloodvessels.   

The tendons and aponeuroses are related, on the one hand, with the muscle groups, and, then again, with the movable constructions, because the bones, cartilages ligaments, and fibrous membranes (as an example, the sclera). The place the muscular fibers are in a direct line with these of the tendon or aponeurosis, the 2 are instantly steady. However the place the muscular fibers be a part of the tendon or aponeurosis at an indirect angle, they finish, in accordance with Kölliker, in rounded extremities that are obtained into corresponding depressions on the floor of the latter, the connective tissue between the muscular fibers being steady with that of the tendon. The latter mode of attachment happens in all of the penniform and bipenniform muscle groups, and in these muscle groups the tendons of which begin in a membranous type, because the Gastrocnemius and Soleus.   

The fasciæ are fibroareolar or aponeurotic laminæ, of variable thickness and power, present in all areas of the physique, investing the softer and extra delicate organs. Through the strategy of improvement most of the cells of the mesoderm are differentiated into bones, muscle groups, vessels, and so forth.; the cells of the mesoderm which aren’t so utilized type an funding for these constructions and are differentiated into the true pores and skin and the fasciæ of the physique. They’ve been subdivided, from the conditions wherein they happen, into superficial and deep.

The superficial fascia is discovered instantly beneath the integument over virtually the whole floor of the physique. It connects the pores and skin with the deep fascia, and consists of fibroareolar tissue, containing in its meshes pellicles of fats in various amount. Fibro-areolar tissue consists of white fibers and yellow elastic fibers intercrossing in all instructions, and united collectively by a homogeneous cement or floor substance, the matrix.

The cells of areolar tissue are of 4 principal varieties: (1) Flattened lamellar cells, which can be both branched or unbranched. The branched lamellar cells are composed of clear cytoplasm, and include oval nuclei; the processes of those cells could unite in order to type an open community, as within the cornea. The unbranched cells are joined edge to edge just like the cells of an epithelium; the “tendon cells,” presently to be described, are examples of this selection. (2) Clasmatocytes, massive irregular cells characterised by the presence of granules or vacuoles of their protoplasm, and containing oval nuclei. (3) Granule cells (Mastzellen), that are ovoid or spheroidal in form. They’re shaped of a gentle protoplasm, containing granules that are basophil in character. (4) Plasma cells of Waldeyer, often spheroidal and distinguished by containing a vacuolated protoplasm. The vacuoles are crammed with fluid, and the protoplasm between the areas is obvious, with often just a few scattered basophil granules.  

Along with these 4 typical types of connective-tissue corpuscles, areolar tissue could also be seen to own wandering cells, i.e., leucocytes which have emigrated from the neighboring vessels; in some cases, as within the choroid coat of the attention cells crammed with granules of pigment (pigment cells) are discovered. 

The cells lie in areas within the floor substance between the bundles of fibers, and these areas could also be introduced into view by treating the tissue with nitrate of silver and exposing it to the sunshine. This may shade the bottom substance and depart the cell-spaces unstained.   8  Fats is fully absent within the subcutaneous tissue of the eyelids, of the penis and scrotum, and of the labia minora. It varies in thickness in numerous components of the physique; within the groin it’s so thick that it might be subdivided into a number of laminæ. Beneath the fatty layer there’s typically one other layer of superficial fascia, comparatively devoid of adipose tissue, wherein the trunks of the subcutaneous vessels and nerves are discovered, because the superficial epigastric vessels within the stomach area, the superficial veins within the forearm, the saphenous veins within the leg and thigh, and the superficial lymph glands. Sure cutaneous muscle groups are also located within the superficial fascia, because the Platysma within the neck, and the Orbicularis oculi across the eyelids. This fascia is most distinct on the decrease a part of the stomach, perineum, and extremities; it is extremely skinny in these areas the place muscular fibers are inserted into the integument, as on the facet of the neck, the face, and across the margin of the anus. It is extremely dense within the scalp, within the palms of the palms, and soles of the ft, forming a fibro-fatty layer, which binds the integument firmly to the underlying constructions. The superficial fascia connects the pores and skin to the subjacent components, facilitates the motion of the pores and skin, serves as a gentle nidus for the passage of vessels and nerves to the integument, and retains the heat of the physique, for the reason that fats contained in its areolæ is a foul conductor of warmth.  

The deep fascia is a dense, inelastic, fibrous membrane, forming sheaths for the muscle groups, and in some circumstances affording them broad surfaces for attachment. It consists of shining tendinous fibers, positioned parallel with each other, and related collectively by different fibers disposed in a rectilinear method. It kinds a powerful funding which not solely binds down collectively the muscle groups in every area, however offers a separate sheath to every, in addition to to the vessels and nerves. The fasciæ are thick in unprotected conditions, as on the lateral facet of a limb, and thinner on the medial facet. The deep fasciæ help the muscle groups of their actions, by the diploma of pressure and strain they make upon their surfaces; the diploma of pressure and strain is regulated by the related muscle groups, as, as an example, by the Tensor fasciæ latæ and Glutæus maximus within the thigh, by the Biceps within the higher and decrease extremities, and Palmaris longus within the hand. Within the limbs, the fasciæ not solely make investments the whole limb, however give off septa which separate the varied muscle groups, and are connected to the periosteum: these prolongations of fasciæ are often spoken of as intermuscular septa.  The Fasciæ and Muscle tissue could also be organized, in accordance with the final division of the physique, into these of the pinnacle and neck; of the trunk; of the higher extremity; and of the decrease extremity.

References:

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