Elements of osteology, or, The minute anatomy of the bones, intended for the use of students

Front matter

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Preface

TO THE SECOND EDITION.

The flattering reception this little Work

has met with ever since its publication^ and

more particularly from the Webb Street

School, has encouraged the author to send forth a Second Edition ; which has been carefully corrected and enlarged, and the description in many parts altered.

The study of Anatomy, easy as it is of acquirement, cannot be too simplified ; and prolix and incomprehensive descriptions serve only to perplex and confound the student, in this most noble and interesting of professional sciences. The organization of man, viewed in all its extensive and diversified forms, finds no parallel, and opens to us a wide field both for anatomical, physiological, and pathological research.

There is no part, however, of the human body more particularly deserving our attention than the Osseous Structure; where, if we examine the various arrangements of the bones, the manner in which they defend the vital organs, either by enclosing them within their cavities, or by affording them support: the diversity of mechanical principles, which are exemplified in their articulation, and the infinite variety of functions, which, by the addition of cartilages, ligaments, and muscles, (more immediately under voluntary controul) they are destined to perform, — we shall find an endless subject for contemplative admiration, and

Ill be led to exclaim with the immortal Shakespeare,

“ What a piece of work is Man !

An accurate acquaintance with the bones, as has been stated in the first edition, is as indispensable to the study of the ligaments and muscles, as the knowledge of these are to that of the vessels and nerves. Osteology is indeed so intimately connected with every other branch of anatomy, that the acquirement of the one is necessary to that of the other.

V

Nor is it less indispensable to the practice of Surgery ! From a defective knowledge of the human fabric, arise those deformities of limbs after fractures, which even in this great metropolis are almost daily presented to our notice ; not always resulting from the severity of those accidents, but from their having fallen into the

IV hands of individuals, who, from their ignorance of Osteology, and of the various relations the bones have with each other, are unable to treat them scientifically.

The sole intention of the author, in the publication of this edition, is to afford the Student, if possible, a still more clear and familiar guide to the study of Osteology; one, which it is hoped will enable him, with the assistance of the bones themselves, to obtain a complete knowledge of their peculiar characters. For this purpose he has avoided in toto, a tabular arrangement, and has preferred describing the parts in the order that they present themselves to the eye ; so that the student may be enabled to trace them out unaided by a demonstrator. This was the method constantly followed by the late Edward Grainger, who in the morning of life, fell an untimely sacrifice to the intense ardour with which he devoted himself to the

V cultivation of his profession ; and likewise to the jyresent momeiit^ hy the celebrated anatomist to whom this ivork is dedicated ; whose happy method of communicating the knowledge he possesses, constitutes one amonirst the least of those excellencies which render him so distinguished and valuable a teacher.

But while, at the same time, the author has been anxiously desirous of affording the student as clear and as succinct a description as possible, he trusts that it will be found to comprise all the anatomical peculiarities of each individual bone ; stiff he is far from arrogating to himself the idea that he has fully accomplished his task; on the contrary, he is sensible that it has fallen into very imperfect hands. The hope, however, of being able to put the student in possession of such a guide, as may enable him to gain a knowledge of Osteology in

VI his closet, has overcome his own feelings of insufficiency to its performance, and he will therefore content himself with its resting, a second time upon its own merits.

To the articled apprentice he flatters himself that it will be found highly useful, inasmuch as it may forward him considerably in the commencement of his dissections ; and thus a great deal of valuable time will be saved. And if on examination, it should prove worthy of attention, and calculated to assist in removing those difficulties, with which it is too frequently thought to be surrounded ; and to excite that interest which to an unreflecting mind, it appears at first sight divested of, he will consider his labour sufficiently rewarded ; and led to indulge the hope, that his exertions have not been altogether useless or inefiPectual.

liotherhithey May 1831.

THE

OSSEOUS SYSTEM.

Section I

Ill commencing the study of Osteology it is necessary that we should first make a few observations upon the general characters of the bones and their mode of connexion with each other, before we pass on to a minute anatomical description. In so doing, a rude heap of materials will present themselves to our notice, so irregular in their appearance, and so varied in their form, that a transitory glance might convey to the inijid, the idea of the impossibility of their subserviency to any

B thing like symmetrical order. In no part of the body, however, shall we find more perfect symmetry of arrangement than in the osseus structure (the Skeleton) ; where we observe those apparently inorganic fragments fitted to each other with an almost inimitable degree of exactness, constituting, on the one hand, cavities for the reception and defence of the more important and vital organs ; and on the other, a varied series of articulations, which in combination with those loco-motive agents, the muscles, are so necessary to the performance of a variety of graceful movements; and which, independently of the rational and intellectual powers bestowed upon man, so pre-eminently distinsruish him in the scale of creation. The further we pursue this interesting study, our attention cannot fail of being struck w'ith the incomparable adaptation of parts to their particular uses, the wisdom, the order, and regularity of the whole — and our minds impressed with the most reverential feelings of wonder and admiration. rZ^^The number of bones thus constituting the frame-work of the body is subject to variety, and is differently stated by anatomists. Monro, Soemmering, and others, maintain that they amount to two hundred and sixty ; Meckel only to two hundred and fifty-three. Mr. Grainger, in his excellent work on General Anatomy, enu- • ' merates but two hundred and fifty-two, ^ which may be regarded as the most accurate. He describes them as follows; ‘‘the head contains sixty- two bones, viz. eight of the cranium, fourteen of the face, eight of the ear, and thirty-two teeth. The trunk contains fifty-four, viz. twenty-four moveable vertebras, four bones of the pelvis, twenty-four ribsj a sternum belonging to the chest, and one os hyoides, placed in the neck. The upper extremities contain seventy bones, viz. four of the shoulders, two of the upper arms, four of the forearms, and sixty of the hands, including sixteen of the carpus, eight of the metacarpus, thirty phalanges, and six ossa sesamoidea. The lower extremities contain sixty-six, viz. two of the thighs, six of the legs, and fifty-eight of the feet,

B 2 including fourteen of the tarsus, ten of the metatarsus, twenty-eight phalanges, and six ossa sesamoidea.”

62 of the head,

70 - - upper extremities,

66 - - lower extremities,

252 Total of the body.

The difference in the number is owing to the period of life at w^hich the enumeration is taken. Thus, we find that in childhood it is greatest, and vice versa in old age, when, from the long continuance of the process of ossification, many previously distinct pieces become consolidated into one.

The irregularity in the figure, length, and density of the various bones, when viewed in their separate and disarticulated state, has given rise to four distinct classifications, which are adopted by almost all modern writers on Anatomy. These classifications are arranged in the following order : 1. ossa longa vel cylindrica ; 2. ossa lata j 3. ossa crassa ; 4. ossa mixta.

1. Ossa loiiga vel cylindrica, or long bones, are, as their name implies, distinguished by their length. They are divided into a body and two extremities, and belong, in general, to the parts destined for loco-motion j and are in fact so many levers, subjected to the various actions of the muscles. Hence we find them constituting the limbs in which we observ^e them decreasing in size from above, downwards; but at the same time increasing in number: a disposition which, as an excellent author * of descriptive anatomy scientifically remarks, gives to the superior division of each limb the great extent of motion it enjoys, whilst it allows to the inferior and terminal ones, a variety of rapid movements, within restricted limits.”

2. Ossa lata, or broad bones, are generally nearly as broad as they are long, but vary in thickness. The greater part of them are hollowed ; in other words, are convex on one side, and concave on the other ; on which account they are better adapted for the purposes for which they were destined, viz. that of forming cavities for the reception

* Qiiain.

mid protection of vital organs. The circumstance too, of their arched shape, increases their strength, and affords additional security to the parts they inclose. A few of the bones of the cranium and pelvis belong to this division.

3. Ossa crassa, or short and thick bones, are nearly equal in their dimensions. Their figure, which varies, is usually rounded or cuneiform, and is generally determined by that of the parts into whose composition they enter. They present a great number of articular surfaces, by which they are adapted to themselves and to other bones. Those of the vertebrae, carpus, and tarsus, are referable to this class.

4. Ossa mixta, or mixed and irregular bones, are so named from their not being distinguished by any particular form, but from their partaking of the characters of the two preceding classes. We shall hereafter, for convenience of description, speak of these bones as being divisible into a central portion, or body, and processes. Some of the bones of the cranium, as the sphenoid, temporal, ethmoid, and occipital, and those of the vertebrje and pelvis, belong to this class.

This, then, is the arrangement usually followed by anatomists, in reference to the bones in an unarticulated state. Before we proceed to their mode of junction, it will be necessary to make a few observations on the various projections and depressions, their external surfaces present.

The projections are distinguished by the terms of apophyses and epiphyses. The latter only exist in the earlier periods of life, when the process of ossification is incomplete.

The apophyses, or processes, are divided into the articular and non-articular. v The former are designated according to their particular figures ; thus, if they approach more or less to the hemispherical shape, they are called heads ; if flattened and elongated, condyles ; and, when assuming the form of teeth, serrae or dentations.

The non-articular processes present great variety in form and size; some of them project very considerably from the superficies of the bones, and are named from their supposed resemblance to particular bodies, from their relative position, or from their uses. Hence, in describing the bones, we shall frequently have occasion to speak of the coronoid, mastoid, styloid, coracoid, spinous, odontoid, transverse, pterygoid, orbitary, and trochanteric processes.

Those processes which are short, thick, and rough, are called tuberosities. Others which project but little from the bones, and are distinguished by their narrowness and length, are termed lines, ridges, and spines.

The principal uses of the apophyses are, to afford security and firmness to the joints, and points for the attachment of muscles. The more prominent they are, the greater will be the degree of muscular power exerted upon the bones, in consequence of the angle at which the muscle is inserted into the bone being increased, and the parallelism of the former with the axis of the latter, diminished.

The cavities of the bones, like the processes, are divided into the articular and non- articular. The articular vary in depth and form. Those which are deep and have large brims, are termed cotyloid, and those which are shallow, glenoid cavities. When the depression has the form of a pulley it is designated trochlea, and the cavities which are conical are called alveoli.

The non-art icular cavities are of two kinds, viz. the superficial and the deep. The former are only confined to the surface, but are numerous and various in their appearance. Those which are larger superiorly than interiorly, are called fossae, and are intended for the reception of soft parts, as the digastric and laclirymal fossae. Some are formed for vessels and nerves, and these are termed furrows, grooves, &c.

The deep cavities, like the superficial, are in great variety and number, since they are met with in all parts of the bones. Some pass completely through the bones. These are called foramina, or holes, if the bones are thin, and canals or conduits if their passage is of great extent. These foramina are frequently formed by the union of two or more bones, as for example the foramen incisivum, the foramen lacerum basis, cranii posterius, and caualis palato maxillaris, passages for the transmission of blood-vessels and nerves. There are other cavities which, although they pass deeply, do not perforate the bones ; and of these there are also two kinds. The first includes those which are found in the substance of the bones, having small apertures ; hence they are called sinuses, as we observe in the frontal and sphenoid bones. Or if they are partitioned off into small spaces, they are denominated cells, as in the ethmoid bone, and mastoid process of the temporal bone. In the second kind are included the cavities formed for the transmission of the nutrient vessels of the bones; and of these, which differ in their capacities, there are three varieties. The first variety is common to the long bones, in which they form canals, commencing near the middle of the shaft by an aperture which is called the medullary foramen ; they then take an oblique course into the interior or cancellated structure. They are also observed in the large irregular bones, as the ossa innominata, &c. The second variety is confined to the extremities of the long, and surfaces of the short bones, which are rendered lighter and (jiiite porous by the immense number of small openings leading into their internal spongy structure. In the third variety are included a vast number of minute pores, which are visible to the naked eye, even upon the surface of the compact structurcp These, as well as those of the second variety are for the transmission of the vessels derived from the periosteum. The, medullary foramina only give passage to vessels nourishing the interior of the bones, and derived from some neighbouring arterial trunk. The best specimens of the latter openings are seen in the femur, tibia^ and humerus.

Having thus hastily glanced at the bones in an unconnected state, and spoken of their division, arrangement, and appearances, as usually given by anatomists, we shall reserve our observations on the exemplification of the advantages derived from their various forms, as displayed in the construction of the osseous frame, till we have described them individually, and considered their mode of junction and connection with each other, either directly or indirectly, so as to constitute the skeleton.

OP THE ARTICULATIONS.

The junction of any two bones, of whatever form or character it may be, is generally distinguished by the term of articulation. If we carefully examine the skeleton we shall find that its articulations are almost as varied as they are numerous, and are all of them subservient to the different movements of the body. This part of anatomical investigation demands the most undeviating attention of the student, in consequence of its important relation to dislocation and fracture : and no man sliould think of commencing his practical caredlr till he is perfectly acquainted with it, inasmuch as his ignorance may entail upon him irretrievable infamy and disgrace.

The articulations of the skeleton have been variously arranged bj^ different writers. That arrangement however will be found the most useful which has reference to the mobility and immobility of the joints and form of the articular surfaces. Accordingly the articulations have been divided into three classes, as follows ; A. synathrosis, or the immoveable; B. diarthrosis, or moveable; C. amphi-arthrosis, or mixed. Two out of the three classes admit of subdivisions, which latter possess two or more varieties and modifications. This arrangement wdll be better understood by referring to the annexed diagram taken from Mr. Grainger’s Elements of General Anatomy, 381.

TABLE OF THE ARTICULATIONS.

Synarthrosis

■ji

o H a;

c or

Immoveable

Articulation o . L Serrata >

OUtllFtl ^ J

J Squamosa

Gompliosis

Schiiiflvlesis

Symphysis

Dentata

liarmonia

Diarthrosis "I Enarthrosis ] Arthrodia

or moveable Articulation J

^ Ginglymus

^ Angular j Lateral 1

Double e

Amphi-arthrosis

or

.Mixed Articulation

This Table comprises all the articulations of the skeleton. It will now be for us cursorily to point out the circumstances under which they are found.’ Their practical illustration will be further dwelt upon after having described the anatomical characters of the individual bones, and the manner in which they constitute the various joints.

A. Synarthrosis, or the first species of articulation, is met with in the head and pelvis. It admits, as is exemplified by the foregoing diagram, of four sub-divisions,— 1. Sutura; 2. Gomphosis ; 3. Schindylesis ; 4. Symphysis.

I. Sutura, the suture or seam, exists, M'ith a few exceptions, between the facial and cranial bones, and is formed by numerous eminences and depressions. It pos^- sesses two varieties, viz. the sutura serrata and sutura squamosa. The first characterized by alternate projections and recessions like the teeth of a saw, and hence the term sutura serrata, or true suture ; abundant examples of which are seen in the union of the frontal, parietal, and occipitul bones. Some slight modifications of this suture have received the names *of sutura dentata from the projections being tooth-shaped \ and harmonia, . when the surfaces are merely placed in apposition, as in the superior maxillary bones, vide table. The second variety is distinguished by the bones being bevil-edged, which has given rise to the appellation of sqimmous or false suture, as in the junction of the os temporis with the os parietale.

2. Gomphosisy is that mode of connexion in which a conical surface is received into a cavity, and is best exemplified by the manner in which the teeth are lodged in the alveoli.

3. Sc/iindi/lesis, is the union by furrowing, in which the ridge of one bone is received into the groove of another, as in the connexion of the vomer with the nasal lamella of the os ethmoides.

4. Si/mp/)^sis, by some authors classed wdth the moveable or mixed articulations. It is however more correct to place it amongst the immoveable joints, inasmuch as the slight yielding motion it permits is entirely depending upon the intervention of an elastic structure. The best examples of it are in the pubic and sacro iliac symphyses.

13. Diarthrosis, or the moveable articulations, are those in which the extremities only of the bones are in contact with each other} their contiguity being maintained by ligaments and fibrous structures. This is the most frequent and important kind of articulation in the whole skeleton. It principally exists between the cylindrical bones, both where they are united to each other, and to the trunk; also in the junction of the lower jaw and cranium, between the skull and . vertebral column, between the articulating processes of the vertebra? ; and lastly in the union of the ribs with the spine and with the sternum. In most instances of the moveable articulations the articulating surfaces are mutually adapted to each other, being either convex or concave ; but there are modifications in their configuration which may be reduced to the three following varieties, 1. Enarthrosis ; 2. Arthrodia; 3. Ginglymus.

1. JLnarthrosis^ or the connexion by ball and socket, the head or rounded process of one bone being received into the cavity of another, is better calculated for extensive motion than any other articulation. The best examples of it are in the hip and shoulder joints.

2. Arthrodia, or the connexion by flat surfaces, frequently a slight modification of enarthrosis, is best exemplified in the articulations of the carpus and tarsus.

3. Ginglymus, or the hinge joint, the most complicated of the three, is of two kinds, viz. the angular and the lateral.

The angular is that in which one bone has a pulley-like surface, called trochlea, into which another bone is received; the'purest examples of it are the elbow and knee joints. The lateral or rotatory ginglymus is formed by the cavity of one bone receiving the convex process of another. It admits, as we shall afterwards find, of a sub-division into double and single', it is double when one bone turns upon another in two distinct places, as in

the radius rolling upon the ulna; and single rrftiryh-*

c when the motion is performed at a single point, as in the articulation of the atlas or first vertebra of the neck, with the odontoid process of the second. The motions permitted in the diarthrodial joints are considerably modified by these varieties, in the form of the articular surfaces which Ave have described. All the motions, hoAvever, according to Bichat, may be referred to four species : 1 . The motions of angular opposition; 2. of circumduction; 3. of rotation ; 4. of gliding.

1 . The motion of opposition, or the angular movement, can only take place betAveen the long bones ; and the angles they describe with one another, Avhen made to move in opposite directions, as from flexion to extension, or from abduction to adduction, vary in size, according to the degree of separation and approximation. In some joints, as in the elboAV and knee, only flexion and extension are permitted; in others, as the hip, shoulder, and thumb, it is more general, allowing not only of the two former kinds of motion, but also of abduction and adduction, and of various degrees of motion intermediate to them.

2. Circumduction is the movement which is performed when the shaft of a bone describes a cone, the apex of which is placed superiorly ; the base being at the distal extremity of the bone. During the execution of this movement, which is most extensively permitted at the shoulder joint, the limb passes successively through the states of elevation, abduction, depression, adduction, and all the intermediate points.

3. Rotation is entirely different from circumduction, and is that movement in which the bone remains in the same place and merely turns on its axis. It is best developed in the ileo-femoral articulation.

4. The motion of gliding is more or less common to all the diarthrodial articulations ; but there are some joints as those of the carpus and tarsus, which have no other action.

C. Amphi- ARTHROSIS, or the mixed form of articulation, resembles the synarthrosis, inasmuch as the bones are united by an intervening substance, and the diarthrosis by permitting sensible movements. The only true examples of this form of articulation

c2 are the fibro-cartilaginous connexions of the bodies of the vertebrae. The amphi-arthrosis may be said to be intermediate to the synarthrosis and diarthrosis.

Having briefly considered the general characters and peculiarities of the bones, and their mode of connexion with each other, we now pass on to a minute anatomical description. In so doing, we shall carefully endeavour to illustrate the principles we have advanced, and to render our demonstration of their anatomical features as clear and as accurate as possible.

Section II. Description Of The Bones Op Thp: Skeleton

There are two kinds of Skeletons, viz, the natural and the artificial. In both the animal frame is deprived of all its soft parts, with the exception in the former of its ligaments and cartilages, which v surround and envelope its articulations, and which are quite sufficient to preserve the contiguity of the bones. In the latter they are completely denuded of those appendages, and their articulating processes and surfaces exposed by long continued maceration in water. They are then fastened to each other, by means of wires, pieces of tin, cork, leather, &c. and by various mechanical contrivances. The articulations and their different motions are equally preserved^ and hence its superiority over the natural skeleton for the purposes of anatomical description.

The Skeleton is divided into three parts, viz. the head) trunk, and extremities.

BONES OF THE HEAD.

The head of the adult varies both in size and shape, but is generally of a spheroidal figure. It is broader posteriorly than anteriorly, compressed laterally, and is placed upon the superior part of the trunk, resting upon the vertebral column. Inferiorly it has a great many processes which render its appearance extremely irregular. It is divided into two parts, the cranium and face ; the former consisting of eight bones, the latter of fourteen.

Of the bones of the cranium five are termed proper, and three common. The five proper, consist of the os occipitis placed posteriorly j two ossa parietalia upon the upper part and sides ; and the ossa temporum upon the sides of the ossa parietalia,

and at the same time beneath them. They

•

are called proper because they are considered as belonging to the head alone. The three common are the os frontis, placed anteriorly, and forming the whole of the fore-part of the cranium, and the os spenoides and os ethmoides, which are completely hidden in the base of the skull. They are termed common as constituting a part of both the head and face. All these bones are connected together by various seams, or sutures, the principal of which, eight in number, are named from their figure, situation, and course, and are as follow :

1. The Coronal 5. The Sjjhenoidal

2. — Sagittal 6. — Ethmoidal

3. — Lamhdoidal 7* — Transverse

4. — Tejnporal, or 8. — Zygomatic

Squamous

1. The Coronal is so named from the ancients wearing their garlands over that part. It commences about an inch behind the external angular process of the os frontis, ascends upwards and backwards, till it reaches the top of the head ; then descends downwards and forwards to the same point on the opposite side from which we began to trace it. It connects the back part of the os frontis to the fore-part of the ossa parietalia.

2. The Sagittal commences from the centre of the coronal ; it passes in a straight direction, backwards, to the centre of the lambdoidal. It has been named sagittal from its’lving between the two sutures like an arrow between the string and the bow’. It connects the ossa parietalia to each other.

3. The Lambdoidal, so named from its resemblance to the Greek letter A, commences at the root of the mastoid process of the temporal bone ; it passes obliquely upwards and backwards till it reaches the termination of the sagittal, it then descends downwards and forwards to the same point upon the opposite side. It connects the upper part and sides of the occipital to the hack part of the parietal bones. The continuation of this suture to the base of the skull has been called additamentum sutio'cc lambdoidalis. This addition to the lambdoidal suture commences at the root of the mastoid process, that is, at the point from which the lambdoidal suture itself begins ; it then descends upon the inner and posterior side of that process, and passes forwards and inwards till it reaches the base of the skull; and it there terminates at the foramen lacerum basis cranii posterius. It connects the inferior and anterior part of the occipital bone to the posterior part of the temporal bone upon each side.

4. The Temporal or Squamous, commences also at the root of the mastoid process, at the point common to the origins of the lambdoidal suture, and its continuation, the additamentum suturrn lambdoidalis; it "ascends in an arched direction above the temporal bone, then descends underneath the zygoma, passing backwards and inwards upon the inner side of the glenoid cavity of the os temporis, and terminates in its continuation at the base of the skull; this continuation receiving the name of additamentum suturce squamosa. It connects the temporal bone on either side to the parietal and sphenoid. It has received the additional name of squainous, from the upper edges of the temporal overlapping the inferior edges of the parietal bones, like the scales of fishes.

5. The Sphenoidal, which is very irregular in its course, is so named from its surrounding the sphenoid bone. It connects it to all the other bones of the cranium.

6. The Ethmoidal also surrounds the ethmoid bone, and connects it to the frontal and sphenoid hones.

7. The Transverse connects the frontal bone with the nasal, superior maxillary, ossa unguis, the ethmoid, sphenoid, and malar bones. It commences at the external angular process of the os frontis, crosses first one orbit between the bones of the head and those of the face ; runs over the root of the nose, then traverses in a similar manner the other orbit, and finally terminates at the opposite external angular process of the os frontis.

8. The Zygomatic is a little suture which merely connects the zygomatic process of the os temporis to the same process of the os male; forming an arch called the zygoma or yoke, under which the temporal muscle descends to its insertion into the lower jaw. There is another suture which is seldom mentioned, and is rarely seen in the adult, though always in the foetus and frequently in the female and in young persons. It has been denominated the frontal. It divides the os frontis into two equal portions. Commencing at the nasal process of that bone, it passes in a straight direction upwards and backwards to the sagittal suture, of which the latter may be said to be its continuation.