band of ligament, which passes forwards from the anterior and inner border of the os calcis to the edge of the scaphoid bone. Besides connecting the os calcis

FIG. 147.

and scaphoid, it supports the astragalus, and forms part of the cavity in which the round head of the latter bone is received. It is lined on its upper surface by the synovial membrane of the astragalo-scaphoid articulation.

The firm connexion of the os calcis with the scaphoid bone, and the feebleness of the astragalo-scaphoid articulation, are conditions favorable to the occasional dislocation of the head of the astragalus.

The long calcaneo-cuboid, or ligamentum longum plantæ, is a long band of ligamentous fibres, which proceeds from the under surface of the os calcis to the rough surface on the under part of the cuboid bone, its fibres being continued onwards to the base of the third and fourth metatarsal bones.

This ligament forms the inferior boundary of a canal in the cuboid bone, through which the tendon of the peroneus longus passes to its insertion into the base of the metatarsal bone of the great toe.

The short calcaneo-cuboid, or ligamentum breve plantæ, is situated closer to the bones than the long plantar ligament, from which it is separated by adipose tissue; it is broad and extensive, and ties the under part of the os calcis and cuboid bone firmly together.

The interosseous ligaments are five in number; neo-cuboid ligament. 5. Part they are short and strong ligamentous fibres, situated

of the short calcaneo-cuboid ligament. 6. Calcaneo-scaphoid ligament. 7. Plantar tarsal ligaments. 8, 8. Tendon of the peroneus longus muscle. 9, 9. Plantar tarso-metatarsal ligaments. 10. Plantar ligament of the metatarso-phalangeal articulation of the great toe: the same ligament is seen on the other toes. 11, 11, 11. Lateral ligaments of the metatarso-phalangeal articulations. 12. Transverse ligament. 13. Lateral ligaments of the phalanges of the great toe; the same ligaments are seen on the other toes.

between adjoining bones, and firmly attached to their rough surfaces. One of these, calcaneo-astragaloid, is lodged in the groove between the upper surface of the os calcis and the lower of the astragalus. It is large and very strong, consists of vertical and oblique fibres, and serves to unite the os calcis and astragalus solidly together. The second interosseous ligament, also very strong, is situated between the sides of the scaphoid and cuboid bone; the three remaining interosseous ligaments connect strongly together the three cuneiform bones and the cuboid.

The synovial membranes of the tarsus are four in number one, for the posterior calcaneo-astragaloid articulation; a second, for the anterior calcaneoastragaloid and astragalo-scaphoid articulation; occasionally an additional small synovial membrane is found in the anterior calcaneo-astragaloid joint; a third, for the calcaneo-cuboid articulation; and a fourth, the large tarsal synovial membrane, for the articulations between the scaphoid and three cuneiform bones, the cuneiform bones with each other, the external cuneiform bone with the cuboid, and the two external cuneiform bones with the bases of the second and third metatarsal bones. The prolongation which reaches the metatarsal bones passes forwards between the internal and middl cuneiform bone. A small synovial membrane is sometimes met with between the contiguous surfaces of the scaphoid and cuboid bone.

Actions. The movements permitted by the articulation between the astragalus and os calcis, are a slight degree of gliding, in the direction forwards and back

wards, and laterally from side to side. The movements of the second range of tarsal bones are very trifling, being greater between the scaphoid and three cuneiform bones than in the other articulations. The movements occurring between the first and second range are the most considerable; they are adduction and abduction; and, in a minor degree, flexion, which increases the arch of the foot, and extension, which flattens the arch.

The dorsal ligaments connect the metatarsal to the tarsal bones, and the metatarsal bones with each other. The base of the second metatarsal bone, articulating with the three cuneiform bones, receives a ligamentous slip from each, while the rest articulating with a single tarsal bone receive only a single tarsal slip.

The plantar ligaments have a similar disposition on the plantar surface.

The interosseous ligaments are situated between the bases of the metatarsal bones of the four lesser toes; also between the base of the second and third metatarsal bones and the internal and external cuneiform bone.

The metatarsal bone of the second toe being implanted by its base between the internal and external cuneiform bone, is the most strongly articulated of all the metatarsal bones. This disposition must be recollected in amputation at the tarso-metatarsal articulation [Hey's operation].

The synovial membranes of the tarso-metatarsal articulation are three in number; one for the metatarsal bone of the great toe; one for the second and third metatarsal bone, which is continuous with the great tarsal synovial membrane; and one for the fourth and fifth metatarsal bones.

Actions. The movements of the metatarsal on the tarsal bones and on each other are very slight; they are such only as contribute to the strength of the foot, by permitting a certain degree of yielding to opposing forces.

7. Metatarso-phalangeal Articulation. The ligaments of this articulation, like those between the first phalanges and metacarpal bones of the hand, are,

Inferior or plantar,

Two lateral,

Transverse.

The inferior or plantar ligaments, thick and fibro-cartilaginous, form part of the articulating surface of the joint.

The lateral ligaments, short and very strong, are situated one on each side of the joint.

The transverse ligament is a strong band, which passes transversely between the plantar ligaments.

The expansion of the extensor tendon supplies the place of a dorsal ligament. Actions. The movements of the first phalanges on the rounded heads of the metatarsal bones, are flexion, extension, adduction, and abduction.

8. Articulation of the Phalanges. The ligaments of the phalanges are the same as those of the fingers, and have the same disposition; their actions are also similar. They are,

Inferior or plantar, and, Two lateral.

CHAPTER IV.

OF THE MUSCLES.

MUSCLES are the moving organs of the animal frame; they constitute by their size and number 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 a principal protection. In the trunk they are spread out to inclose cavities and constitute a defensive wall, capable of yielding to internal pressure, and again returning to its original position.

Their color presents the deep red which is characteristic of flesh, and their form is variously modified, to execute the varied range of movements which they are required to effect.

Muscle is composed of a number of parallel fibres placed side by side, and supported and held together by a delicate web of areolar tissue; so that, if it were possible to remove the muscular substance, we should have remaining a beautiful reticular framework, possessing the exact form and size of the muscle without its color and solidity. Towards the extremity of the organ the muscular fibre ceases, and the fibrous structure becomes aggregated, and modified, so as to constitute those glistening fibres and cords by which the muscle is tied to the surface of bone, and which are called tendons. Almost every muscle in the body is connected with bone [through the medium of the periosteum], either by tendinous fibres, or by an aggregation of those fibres constituting a tendon; and the union is so firm, that, under extreme violence, the bone itself breaks rather than permit the separation of the tendon from its attachment. In the broad muscles the tendon is spread out so as to form an expansion, called aponeurosis (axò, longè; εupov, nervus, a nerve widely spread out).

Muscles present various modifications in the arrangement of their fibres in relation to their tendinous structure. Sometimes they are longitudinal, and terminate at each extremity in tendon, the entire muscle being fusiform in shape; in other situations they are disposed like the rays of a fan, converging to a tendinous point, as the temporal, pectoral, glutei, &c., and constitute a radiate muscle. Again, they are penniform, converging like the barbs of a feather to one side of a tendon, which runs the whole length of the muscle, as in the peronei; or bipenniform, converging to both sides of the tendon. In other muscles the fibres pass obliquely from the surface of a tendinous expansion spread out on one side, to that of another extended on the opposite side, as in the semi-membranosus; or, they are composed of penniform or bipenniform fasciculi, as in the deltoid, and constitute a compound muscle.

The nomenclature of muscles is defective and confused, and is generally derived from some prominent character which the muscle presents; thus, some are named from their situation, as the tibialis, peroneus, brachialis, temporalis; others from their uses, as the flexors, extensors, adductors, abductors, levators, tensors, sphincters, &c. Some again from their form, as the trapezius, triangularis, deltoid, rhomboideus, scalenus, orbicularis, &c.; and others from their direction, as the rectus, obliquus, transversalis, &c. Certain muscles have received names expressive of their attachments, as the sterno-mastoideus, sterno-hyoideus, &c.; and others, of their divisions, as the biceps, triceps, digastricus, complexus, &c. In the description of a muscle we express its attachment by the words “origin” and insertion"; the term origin is generally applied to the more fixed or central 1 The ancients named all the white fibres of the body vevpá: the term has since been limited to the nerves.

attachment, or to the point towards which the motion is directed, while insertion is assigned to the more movable point, or to that most distant from the centre; but there are exceptions to this principle, and as many muscles pull equally towards both extremities, the use of such terms must be regarded as arbitrary

FIG. 148.

In structure, muscle is composed of bundles of fibres of variable size called fasciculi, which are inclosed in an areolar membranous investment or sheath, and the latter is continuous with the areolar framework of the fibres. Each fasciculus is composed of a number of smaller bundles, and these of single fibres, which, from their minute size and independent appearance, have been distinguished by the name of ultimate fibres. The ultimate fibre is found by microscopic investigation to be itself a fasciculus (ultimate fasciculus), made up of a number of ultimate fibrils inclosed in a delicate sheath, the myolemma inclosed in its myoor sarcolemma.' Two kinds of ultimate muscular fibre exist in the animal economy; viz., that of voluntary or animal life, striated muscle; and that of involuntary or organic life, smooth muscle.

A MUSCULAR FIBRE OF ANIMAL LIFE

lemma; the transverse and longitudinal striæ are seen.

The ultimate fibre of animal life is known by its size, by its uniformity of calibre, and especially by the transverse markings which occur at minute and regular distances. It also presents other markings or striæ, having a longitudinal direction, which indicate the existence of fibrilla within the myolemma. The myolemma, or sarcolemma, the investing sheath of the ultimate fibre, is thin, homogeneous, transparent, and elastic.

FIG. 149.

TRANSVERSE SECTION OF ULTIMATE FIBRES OF THE BICEPS, after Bow

According to Bowman, the ultimate fibres or fasciculi are polyhedral in shape and various in size; the polyhedral form being due to mutual pressure, and the variety of size, besides being met with in a single muscle, being also characteristic of different classes, ge

man. In this figure the polyhedral era, and even sexes

form of the fibres is seen, and their composition of ultimate fibrils.

of animals: thus the
average diameter of
the ultimate fibre in

FIG. 150.

2

FIBRIL OF

1. ULTIMATE MUSCULAR FIBRE OF ANIMAL

LIFE, according to the views of Bowman. 2. MUSCULAR FIBRE OF ANIMAL LIFE, more

highly magnified. Its myolemma is so thin and transparent as to permit the ultimate fibrils to be seen.

the human female is, in the male, the average of both being in round numbers [of an inch]. The largest fibres are met with in fishes, in which they average; the next largest are found in man; while in other classes they range in the following order-insects; reptiles ; mammalia 7; birds [of an inch].

1

In the summer of 1836, while engaged with Dr. Jones Quain in the examination of animal tissues with a simple dissecting microscope, constructed by Powell, I first saw that the ultimate fibre of muscle was invested by a proper sheath, for which I proposed the term Myolemma;" a term which was adopted by Dr. Quain in the fourth edition of his "Elements of Anatomy." We at that time believed that the transverse folding of that sheath gave rise to the appearance of transverse striæ, an opinion which subsequent examination proved to be incorrect. Mr. Bowman has since employed the term " Sarcolemma," as synonymous with Myolemma.

On the Minute Structure and Movements of Voluntary Muscle. Philosophical Trans

actions, 1840.

The ultimate fibrils of animal life, according to Bowman, are beaded filaments, presenting a regular succession of segments and constrictions, the latter being narrower than the former, and the component substance probably less dense.

An ultimate fibre consists of a bundle of these fibrils, which are so disposed that all the segments and all the constrictions correspond, and in this manner

FIG. 151.

give rise to the alternate light and dark lines of the transverse striæ. The fibrils are connected together with very different degrees of closeness in different animals; in man they are but slightly adherent, and distinct longitudinal lines of junction may be observed between them; they also separate easily when macerated for some time. Besides the more usual separation of the ultimate fibre into fibrils, it breaks when stretched, into transverse segments, corresponding with the dark lines of the striæ, and consequently with the constrictions of the fibrillæ. Where this division occurs with the greatest facility, the longitudinal lines are indistinct, or scarcely perceptible. "In constrictions of the ultimate fact," says Bowman, "the primitive fasciculus seems to consist of primitive component segments or particles, arranged so as to form, in one sense, fibrillæ, and in another sense, disks: and which of these two may happen to present itself to the observer, will depend on the amount of adhesion, endways or sideways, existing between the segments. Generally, in a recent fasciculus, there are transverse striæ, showing divisions into disks, and longitudinal striæ, marking its composition by fibrilla."

ULTIMATE FIBRE, in which the transverse splitting into disks, in the direction of the

man.

Bowman has observed that in the substance of the ultimate fibre there exist minute "oval or circular disks, frequently concave on one or both surfaces, and

FIG. 152.

MASS OF ULTIMATE FIBRES

from the pectoralis major of the

human foetus, at nine months. These fibres have been immersed in a solution of tartaric

acid, and their "numerous corpuscles, turned in various directions, some presenting nu

cleoli," are shown. After Bow

man.

containing, somewhere near the centre, one, two, or three minute dots or granules." Occasionally they present irregularities of form, which he regards as accidental. They are situated between and connected with the fibrils, and distributed in pretty equal numbers through the fibre. These corpuscles are the nuclei of the nucleated cells out of which the muscular fibre was originally developed. Observing, however, that their "absolute number is far greater in the adult than in the foetus, while their number, relatively to the bulk of the fasciculi, at these two epochs, remains nearly the same," Mr. Bowman believes that, "during development, and subsequently, a further and successive deposit of corpuscles" takes place. The corpuscles are brought into view only when the muscular fibre is acted upon by a solution of "one of the milder acids, as the citric."

According to my investigations,' the ultimate fibril of animal life is cylindrical when isolated, and probably polyhedral from pressure when forming part of an ultimate fibre or fasciculus. It measures in diameter of an inch, and is composed of a succession of cells connected by their flat surfaces. The cells are filled with a transparent substance, which may be termed myoline. The myoline differs in density in different cells, and from this circumstance bestows a peculiarity of character on certain of the cells. For example, when a fibril in its passive state is examined, there will be seen a series

These were made on dissections of fresh human muscle, prepared for me by Mr. Lea. land, partner of the eminent optician, Mr. Powell.