Chapter I: Part 1

MEDICAL AND SURGICAL LANDMARKS

_By the same Author._

MANUAL OF DISSECTION OF THE HUMAN BODY.

With numerous Illustrations.

HUMAN OSTEOLOGY.

Comprising a Description of the Bones with Delineations of the Attachments of the Muscles. _Sixth Edition in the press._

LANDMARKS

MEDICAL AND SURGICAL

BY

LUTHER HOLDEN

EX-PRESIDENT, MEMBER OF COUNCIL, AND MEMBER OF THE COURT OF EXAMINERS
OF THE ROYAL COLLEGE OF SURGEONS OF ENGLAND: CONSULTING SURGEON
TO SAINT BARTHOLOMEW’S AND THE FOUNDLING HOSPITALS

_assisted by_

JAMES SHUTER, M.A.CAMB., F.R.C.S.

ASSISTANT SURGEON TO THE ROYAL FREE HOSPITAL: LATE DEMONSTRATOR
OF PHYSIOLOGY, AND LATE ASSISTANT DEMONSTRATOR OF
ANATOMY, AT SAINT BARTHOLOMEW’S HOSPITAL

_THIRD EDITION_

LONDON
J. & A. CHURCHILL, NEW BURLINGTON STREET
1881

[_All rights reserved_]

TO
THE STUDENTS
PAST AND PRESENT
OF
SAINT BARTHOLOMEW’S HOSPITAL
THESE ‘LANDMARKS’ ARE
Dedicated
BY THEIR SINCERE FRIEND
THE AUTHOR

PREFACE TO THE THIRD EDITION.

In the present Edition the author adheres to his decision not to introduce Diagrams. Additional experience more than ever convinces him that they would frustrate his original object, which is to teach Students the habit of making the eye and the hand work together, and to educate the ‘touch’ upon the normal living body.

Without such practical training, how can we reasonably expect to form a correct diagnosis when called upon to examine an injury or to detect a disease? In truth, the work is intended only for those who are desirous of acquiring the habit recommended.

LONDON: _May, 1881_.

PREFACE TO THE FIRST EDITION.

These ‘Landmarks’ have already appeared in Saint Bartholomew’s Hospital Reports. They are now republished, with some additions, in the hope that they may be useful to others besides those for whom they were originally intended.

My object has been to collect into a compact form the leading landmarks which help practical surgeons in their daily work. Those relating to the chest and abdomen have been ascertained, with as much precision as natural variations permit, by needles introduced in various directions.

I have to express my acknowledgments to Mr. WALSHAM and to Dr. GODSON for their contributions.

65 GOWER STREET: _March 1876_.

CONTENTS.

PAGE

THE HEAD 3

THE FACE 6

THE NECK 14

THE CHEST 19

THE BACK 25

THE ABDOMEN 29

THE PERINEUM 40

THE THIGH 43

THE BUTTOCKS 48

THE KNEE 49

THE LEG AND ANKLE 52

THE FOOT 56

THE ARM 59

THE FOREARM AND WRIST 64

THE HAND 67

PALPATION BY THE RECTUM 70

EXAMINATION PER VAGINAM 72

‘CHIRURGUS MENTE PRIUS ET OCULIS AGAT QUAM MANU ARMATA.’

LANDMARKS MEDICAL AND SURGICAL.

1. In clinical teaching, we often have occasion to point out, on the surface of the living body, what may be called ‘medical and surgical landmarks.’ By ‘landmarks’ we mean surface-marks, such as lines, eminences, depressions, which are guides to, or indications of, deeper-seated parts. This practice is not only most useful but absolutely necessary; because many, even advanced students of anatomy, are not so ready as they ought to be in their recognition of parts when covered by skin. Students who may be familiar enough with bones, muscles, blood-vessels, or viscera in the dissected subject, are often sadly at fault when they come to put this knowledge into practice in the living.

For instance, ask a student to put his finger on the exact place where he would feel for the head of the radius, the coracoid process of the scapula, the tubercle of the scaphoid bone in the foot; ask him to compress effectually one of the main arteries; to chalk the line of its course; to map on the chest the position of the heart and the several valves at its base; to trace along the walls of the chest the outline of the lungs and pleura; to point out the bony prominences about the joints, and their relative position in the different motions of the joints; test him about the muscles and tendons which can be seen or felt as they stand out in relief or remain in repose; let him introduce his finger into the several orifices of the body, and say what parts are accessible to the touch:--questions such as these, even a good anatomist, unaccustomed to deal with the living subject, might possibly find himself at a loss to answer.

2. =Object in view.=--Our main object, therefore, is to induce in students the habit of looking at the living body with anatomical eyes, and with eyes too at their fingers’ ends. The value of this habit cannot be too highly estimated. Is it not of the utmost importance to an operating surgeon that he should have in his mind’s eye the various structures of the body as they lie grouped, connected, and working together? Should he not try at least to see them with the same clearness and accuracy as if they were perfectly transparent?

Moreover, the habit of examining the living body with ‘anatomical eyes’ and ‘surgical fingers’ teaches the eye and the hand to act together, and trains that delicate sense of touch which every surgeon should possess.

This habit is within easy reach of any one who has carefully dissected for himself, and learned what to feel for. Plates will not give him this knowledge. Let a student examine his own body with a skeleton before him. Better still that two should work thus together, each serving as a model to the other.

Teachers of anatomy should follow the example of Sir C. Bell, who was in the habit of introducing, from time to time, a powerful muscular fellow to his class, ‘in order to show how much of the structure of the body, such as the articulations and the muscles, might be learned without actual dissection.’[A][1]

At the same time, it is only fair to say that ‘landmarks’ cannot always be defined with precision. A considerable latitude must be allowed for natural variations in different persons. In some, their anatomy stands out beautifully clear; in others, it is masked by obesity. Selecting, therefore, for study a moderately lean person, let us begin with the head.

[A] The references throughout are to Notes at the end of the book.

_THE HEAD._

3. =Scalp: its density.=--The great toughness of the scalp, more especially at the back of the head, is owing to its intimate connection with the cranial aponeurosis, the scalp vessels and hair bulbs intervening. This density often obscures the diagnosis of tumours on the cranium. A tumour growing upon the head may be either above or below the aponeurosis of the scalp. If below, it will have a firm resisting feel, being bound down by the aponeurosis. Nevertheless its firmness and resistance may depend not simply on its confinement beneath the aponeurosis, but on its having its origin within the skull. Look with suspicion, then, on every tumour on the head that will not readily permit you to move it about, so as to be sure of its connections prior to an attempt at extirpation.

The scalp moves freely over the pericranium, to which it is very loosely connected by areolar tissue. When suppuration takes place in this tissue free incisions through the dense scalp must be made to let the pus out.

4. =Arteries of scalp.=--The supra-orbital artery can be felt beating just above the supra-orbital notch, and traced for some way up the forehead; the temporal (anterior branch) ascends tortuously about one inch and a quarter behind the external angular process of the frontal bone; the occipital can be felt near the middle of a line drawn from the occipital protuberance to the mastoid process; the posterior auricular, near the apex of the mastoid process. All these arteries can be effectually compressed against the subjacent bone.

5. =Skull-cap.=--The skull-cap is rarely quite symmetrical. This want of symmetry is often obvious. It may occur in men highly gifted, as in the celebrated French anatomist Bichat. As to shape and relative dimensions, no two heads are exactly alike, any more than are two faces. It is beside my present purpose to go into the question of craniology more than to say that, although the cranium does not exactly follow the brain in all its eminences and depressions so as to be like a cast of its surface, yet it certainly indicates the dimensions of the great cerebral masses. The prominence of the frontal and parietal ‘eminences’ and of the occipital region may be taken as a general indication of the development of the corresponding lobes of the brain. To ascertain the relative proportions of these three regions, let a thread be passed from one meatus auditorius to the other, across the frontal, parietal and occipital eminences respectively.

=Frontal sinuses.=--The ‘frontal sinuses’ formed by the separation of the two tables of the skull vary much in size in different persons and at different periods of life. This fact has an important bearing on wounds in the forehead and on trephining in this situation. These ‘bumps’ do not exist in children, because the tables of the skull do not begin to separate before puberty. From an examination of many skulls in the Hunterian Museum, I find that the absence of the ‘bumps,’ even in middle age, does not necessarily imply the absence of the sinuses, since they may be formed by a retrocession of the inner wall of the skull. In old persons, as a rule, when the sinuses enlarge, it is by the encroachment of the inner table on the brain case. The inner wall of the skull here follows the shrinking brain. It is, therefore, important to bear in mind that an adult, and more especially an elderly person, may have a large frontal sinus without any external indication of it.

Neither does a very prominent bump necessarily imply the existence of a large sinus, or indeed of even a small one. The ‘bump’ may be a mere heaping up of bone, a degradation, as in some Australian skulls.

=Mastoid process.=--The mastoid process, which can be felt behind the ear, contains air-cells, to which the above observations may also be applied.

=Occipital protuberance.=--The occipital protuberance, and the superior curved line, can be distinctly felt at the back of the head. The protuberance is always the thickest part of the skull-cap, and more prominent in some than in others.

The posterior inferior angle of the parietal bone, grooved by the lateral sinus, is on a level with the zygoma, and a trifle more than one inch behind the front border of the mastoid process.

=Lines of cerebral sinuses.=--A line drawn over the head from the root of the nose to the occipital protuberance corresponds with the superior longitudinal sinus. Another line drawn from the occipital protuberance to the front border of the mastoid process corresponds with a part of the lateral sinus.

=Middle meningeal artery.=--The trunk of the middle meningeal artery runs along the front lower corner of the parietal bone, about one inch and a half behind, and half an inch above, the external angular process of the frontal.

A straight line drawn from the front of one mastoid process to the other would pass through the middle of the condyles of the occiput, showing how nearly the skull is balanced on the top of the spine in the erect posture.

6. =Thickness of skull-cap.=--The average thickness of the cap of an adult skull is about ⅕ of an inch. The thickest part is at the occipital protuberance, where it is often ¾ of an inch or more, even in an otherwise thin skull. The thinnest part is at the temple, where it may be almost as thin as parchment. Everyone in the habit of making post-mortem examinations knows how much the skull-cap differs in thickness in different persons and in different parts of the same skull. In old persons it is often in some parts not thicker than a shilling, owing to absorption of the diploë. Another point of interest is that the inner plane of the cap is not always parallel with the outer. Hence, in applying the trephine this is not a bad rule--‘Think that you are operating on the thinnest skull ever seen, and thinner in one half of the circle than the other.’

7. =Levels of the brain.=--The level of the anterior lobes in front corresponds with a straight line drawn across the forehead, just above the eyebrows. The lower level of the anterior and middle lobes of the cerebrum corresponds with a line drawn from the external angular process of the frontal bone to the upper part of the meatus auditorius. Another line drawn from the meatus to the occipital protuberance corresponds with the lower level of the posterior lobe. The lower level of the cerebellum cannot be defined by external examination. It depends upon the extent to which the occipital fossæ bulge into the nape of the neck; and this bulge varies in different skulls.

_THE FACE._

8. The approaches to the organs of the senses, their ever-varying expression, their numerous muscles, and their rich profusion of vessels and nerves, give the face great anatomical importance, which has a most valuable bearing, not only on the practice of surgery, but on the physiognomy of health, and in the diagnosis of disease.

9. =Foramina for branches of fifth nerve.=--As a surgeon may be called upon to divide any one of the three chief branches of the fifth nerve upon the face, he looks with interest to the precise situations where they leave their bony foramina with their corresponding arteries. The supraorbital notch or foramen can be felt about the junction of the inner with the middle third of the supraorbital margin. From this point a perpendicular line drawn with a slight inclination outwards, so as to cross the interval between the two bicuspid teeth in both jaws, passes over the infraorbital and the mental foramina. The direction of these two lower foramina looks towards the angle of the nose.

10. =Pulley for superior oblique muscle.=--By pressing the thumb beneath the internal angular process of the frontal bone, the cartilaginous pulley for the tendon of the superior oblique muscle can be distinctly felt. We should be careful not to interfere with this pulley in any operation about the orbit.

11. =Lower jaw.=--The working of the condyle of the jaw vertically and from side to side can be distinctly felt in front of the ear. When the mouth is opened wide, the condyle advances out of the glenoid cavity on to the eminentia articularis, and returns into its socket when the mouth is shut. The muscle which causes this advance is the external pterygoid; and it gives the jaw a greater freedom of grinding motion.

The posterior margin of the ramus of the lower jaw corresponds with a line drawn from the condyle to the angle. In opening abscesses in the parotid region, the knife should not be introduced behind this line for fear of wounding the external carotid artery. Punctures to any depth may be safely made in front of it. They are often necessary where inflammation of the parotid gland ensues after eruptive fevers, and runs on to suppuration. The swelling, tension, and pain are most distressing. Owing to the fibrous framework of the gland, the matter is not circumscribed, but diffused. One puncture is not enough. Three or more may be requisite. The blade of the knife should be held horizontally, so as to be less likely to injure the branches of the facial nerve. We are not to be disappointed if no matter flows. The punctures give relief, and matter will probably exude the next day.

12. =Parotid duct.=--A line drawn from the bottom of the lobe of the ear to midway between the nose and the mouth gives the course of the parotid duct. Opposite the second upper molar, the duct opens by a papilla into the mouth. The branch of the facial nerve which supplies the buccinator runs with the duct.

13. =Temporal and facial arteries.=--The pulsation of the trunk of the temporal artery can be felt, between the root of the zygoma and the ear. This should be well known to and used by chloroformists. It is also a convenient pulse to feel in a sleeping patient. The facial artery can be distinctly felt as it passes over the body of the jaw at the anterior edge of the masseter; again near the corner of the mouth close to the mucous membrane: and, lastly, by the side of the ala nasi, up to the inner side of the tendo oculi. By holding the lips between the finger and thumb the coronary arteries are felt under the mucous membrane. The facial vein does not accompany the tortuous artery, but runs a straight course from the inner angle of the eye to the front border of the masseter, just behind the artery.

14. =Eyelids and eyes.=--The opening between the eyelids varies in size in different persons; hence more of the eyeball is seen in some than in others, and the eye appears larger. Although human eyes do vary a little in size, yet the actual difference is by no means so great as is generally supposed. The size of the fissure has much to do with the apparent size of the eye. Contrast the narrow fissure of the Chinese and Mongolian races, and the apparent smallness of their eyes with those of Europeans. As a rule the external angle of the lid is higher than the internal. When not exaggerated, it gives the face an arch and pleasing expression.

Evert the lids to see the Meibomian glands; observe their perpendicular arrangement, in the substance of the tarsal cartilages.

The free borders of the lids are not bevelled, as described by J. L. Petit and most anatomists, ‘so as to form with the globe of the closed eye a triangular canal for the flow of the tears.’ On the contrary, it is easily seen that the lid margins, when closed, come into accurate contact. Their plane is not exactly horizontal, but slightly inclined upwards.

Every time the eye is shut, the ball turns upwards and inwards, so that the cornea is completely covered by the upper lid. This may be well seen by raising the lid of a sleeping infant; also in cases of low fever when the lid is not completely closed. This up-turning of the eye obviously clears the cornea, and protects it from the light.

A careful examination of the motion of the lower lid in the act of shutting the eye proves that it is a double motion. The lid is not only slightly raised, but drawn inwards about ¹⁄₁₂ of an inch. This second movement sweeps any particles of dust as well as moisture towards the inner canthus.

15. =Puncta lachrymalia.=--The puncta lachrymalia are distinctly visible at the inner angles of the lids. The lower punctum is larger and a little more external than the upper, so that they are not exactly opposite. The direction, too, of the puncta deserves notice. Their open mouths look a little backwards, ready to imbibe the tears. When their proper bearing is lost, as in facial paralysis or by a cicatrix near the lid, the tears overflow the cheek. The length of the lachrymal canals is from three to four lines. The lower is a little shorter and wider than the upper. As each makes a little angle in its course, about a line from its orifice, the lid should be drawn outwards to straighten the canal when we introduce a probe.

16. =Lachrymal sac.=--To find the lachrymal sac, draw outwards the eyelids to tighten the tendo oculi, which crosses the sac a little above its middle. A knife introduced just below the tendon close to the edge of the orbit would enter the sac. The angular artery and vein would be on the inner side of the incision. A probe directed in a line with the inner edge of the orbit, _i.e._ downwards, outwards, and backwards, would pass down the nasal duct, and appear in the inferior meatus of the nose.

The tendo oculi serves many purposes besides giving attachment to the cartilages and muscles of the lids. One purpose is said to be to pump the tears into the lachrymal sac. Place a finger on the tendon, and feel that it tightens every time the lids are closed. The tendon, being intimately connected to the sac, draws, as it tightens, the sac wall outwards and forwards, and in this way it may pump along the lachrymal canals any fluid collected at the angle of the eye.

17. =Nasal duct.=--The nasal duct is from six to eight lines long, and narrowest in the middle of its course. Its termination in the inferior meatus lies under the inferior spongy bone, about a quarter of an inch behind the bony edge of the nostril. The appearance of the orifice in the dry bone conveys no idea of its size and shape in life; for it is diminished by a valve-like fold of mucous membrane, so that it becomes, in most cases, a mere slit, not exceeding a line in diameter.

The facility with which instruments can be introduced into the nasal opening of the duct depends upon its position as well as its size. This position varies in different instances. Sometimes it opens directly into the roof of the inferior meatus, in which case the hole is large and round, so that tears readily run into the nose. In other instances the opening is situated on the outer wall of the meatus, and is then always such a narrow fissure as to be hardly discernible. The practical conclusion then is, that a probe can be easily introduced when the opening is in the roof of the meatus, but not without difficulty and laceration of the mucous membrane when on the outer wall. This difficulty indeed may be increased by the narrowness of the meatus, arising from an unusual curvature of the spongy bone.

18. =Nose and nasal cavities.=--The line where the cartilages of the nose are attached to the nasal and superior maxillary bones can be traced with precision. The close connection of the skin to the cartilages admits of no stretching; hence the acute pain felt in erysipelas and boils on the nose. The external aperture of the nose is always placed a little lower than the floor of the nostril, so that the nose must be pulled up before we can inspect its cavities.

Looking into the nostrils, we find that the left is, in the majority of cases, narrower than the right, owing to an inclination of the septum towards the left. A communication sometimes exists between them, through a hole in the septum, as in the case of the celebrated anatomist Hildebrandt. By stretching open the anterior nares we can get a view of the end of the inferior spongy bone. The middle spongy bone cannot be seen: its attachment to the ethmoid is high up, nearly opposite the tendo oculi. The cavities are so much narrowed transversely by the spongy bones, that in the extraction of polypi it is better to dilate the blades of the forceps perpendicularly, and near the septum.

19. =Mouth.=--What can be seen and felt through the mouth? The upper surface of the tongue, ‘_speculum primarum viarum_,’ is a study in itself. We notice, on its under surface, a median furrow, on each side of which stands out the ranine vein, lying upon the prominent fibres of the lingualis. In the middle line of the floor of the mouth is the ‘frenum linguæ,’ with the orifice of the duct of the submaxillary gland on each side of it. The gland itself can be detected immediately beneath the mucous membrane by feeling further back near the angle of the jaw, at the same time pressing the gland upwards from below.

The long ridge of mucous membrane on each side of the floor contains the sublingual glands.

We can feel the attachment of the ‘genio-hyo-glossi’ behind the symphysis of the jaw. The division of this attachment would enable a surgeon to draw the tongue more freely out of the mouth in any attempt to remove carcinoma extending far back into its root.

There is great difference in the shape of the hard palate; this difference depends upon the depth of the alveolar processes. In some it forms a broad arch; in others it is narrow, and rises almost to a point like a Gothic arch, and materially impairs the tone of the voice.

=Throat.=--To examine the throat well, the nose should be held so as to compel breathing through the mouth. Thus the soft palate will be raised, the palatine arches widened, and the tonsils and the back of the pharynx fairly exposed. Pressing the tongue downwards, provided it be done very gently, is also of advantage. Rude treatment the tongue at once resists. The forefinger can be passed into the throat, beyond the epiglottis, as low as the bottom of the cricoid cartilage, and thus search the pharynx down to the top of the œsophagus, and the hyoid space (on each side) where foreign bodies are so apt to lodge. The greater cornu of the hyoid bone can be felt as a distinct projection on either side. In introducing a tube into the œsophagus the finger should keep the instrument well against the back of the pharynx so as to prevent its slipping into the larynx.

Pass the finger between the teeth and the cheek and feel the anterior border of the coronoid process of the jaw. On the inner side of this process, between it and the tuberosity of the upper jaw, is a recess, where a deeply-seated temporal abscess might burst, or might be opened. Behind the last molar on the inner side of the upper jaw we can distinctly feel the hamular process of the sphenoid bone; also the lower part of the pterygoid fossa, and the internal pterygoid plate. Behind, and on the outer side of the last molar, can be felt part of the back of the antrum and of the lower part of the external pterygoid plate.

On the roof of the mouth we can feel the pulsation of the posterior palatine artery. Hæmorrhage from this vessel can be arrested by plugging the orifice of the canal, which lies (not far from the surface) on the inner side of the last molar, about 1/3 of an inch in front of the hamular process.

When the mouth is wide open, the pterygo-maxillary ligament forms a prominent fold readily seen and felt beneath the mucous membrane, behind the last molar teeth. A little below the attachment of this ligament to the lower jaw we can easily feel the gustatory nerve, as it runs close to the bone below the last molar tooth. The exact position of the nerve can be ascertained in one’s own person by the acute pain on pressure. A division of the nerve, easily effected by a small incision, gives much temporary relief in cases of advanced carcinoma of the tongue.

To feed a patient in spasmodic closure of the jaw, it is well to know that there is behind the last molar teeth a space sufficient for the passage of a small tube into the mouth.

=Antrum.=--Lift up the upper lip and examine the front wall of the antrum. The proper place in which to tap it is above the second bicuspid tooth, about one inch above the margin of the gum.

20. =Posterior nares.=--A surgeon’s finger should be familiar with the feel of the posterior nares, and of all that is within reach behind the soft palate. This is important in relation to the attachment of polypi, to plugging the nostrils, and to the proper size of the plug. In the examination of this part of the back of the throat it is necessary to throw the head well back, because, in this position, nearly all the pharynx in front of the basilar process comes down below the level of the hard palate, and can be seen as well as felt. But when the skull is horizontal, _i.e._ at a right angle with the spine, the hard palate is on a level with the margin of the foramen magnum, and the parts covering the basilar process are concealed from view.

The head then being well back, introduce the forefinger behind the soft palate, and turn it up towards the base of the skull. You feel the strong grip of the superior constrictor. Hooking the finger well forwards, you can feel the contour of the posterior nares. Their size depends upon the anterior, but rarely exceeds a small inch in the vertical diameter, and a small half-inch in the transverse. The plug for the posterior nares should not be larger than this. Their plane is not perpendicular, but slopes a little forwards. You can feel the septum formed by the vomer, and also the posterior end of the inferior spongy bone in each nostril.

21. =Tonsils.=--Before taking leave of the throat, look well at the position of the tonsils between the anterior and posterior half arches of the palate. In a healthy state they should not project beyond the level of these arches. In all operations upon the tonsils, we should remember the close proximity of the internal carotid artery to their outer side. Nothing intervenes but the pharyngeal aponeurosis, and the superior constrictor of the pharynx. Hence the rule in operating on the tonsils, always to keep the point of the knife inwards.

In troublesome hæmorrhage from the tonsils, after an incision or removal, it is well to know that they are accessible to pressure if necessary by means of a padded stick, or even a finger.

22. =Features.=--A word or two on the lines of the face as indicative of expression. Everyone pays unconscious homage to the study of physiognomy when, scanning the features of a stranger, he draws conclusions concerning his intelligence, disposition, and character. Without discussing how much physiognomy is really worth, there can be no doubt that it is a mistake to place it in the same category as phrenology, since the latter lacks that sound basis of physiology which no one can deny to the former.

A person fond of observing cannot fail to have arrived at the conclusion that a man’s daily calling moulds his features. Place a soldier, a sailor, a compositor, and a clergyman side by side, and who will not immediately detect a marked difference in their physiognomies?

The muscles of the features are generally described as arising from the bony fabric of the face, and as inserted into the nose, the corners of the mouth, and the lips. But this description gives a very inadequate idea of their true insertion. They drop fibres into the skin all along their course, so that there is hardly a point of the face which has not its little fibre to move it. The habitual recurrence of good or evil thoughts, the indulgence in particular modes of life, call into play corresponding sets of muscles which, by producing folds and wrinkles, give a permanent cast to the features, and speak a language which all can understand, and which rarely misleads. Schiller puts this well when he says that ‘it is an admirable proof of infinite wisdom that what is noble and benevolent beautifies the human countenance; what is base and hateful imprints upon it a revolting expression.’

_THE NECK._

23. =Subcutaneous veins.=--Notice first the direction of the subcutaneous veins. The chief subcutaneous vein is the external jugular. Its course corresponds with a line drawn from the angle of the jaw to the middle of the clavicle, where it joins the subclavian. It is made more prominent by putting the sterno-mastoid into action, or by gentle pressure on the lower end of the vein. It is exceptionally joined by a branch which runs over the clavicle, and is termed ‘jugulo-cephalic.’ The anterior jugular generally runs along the front border of the sterno-mastoid.

24. =Parts in central line. Os-hyoides.=--Immediately below and nearly on a level with the lower jaw we feel the body of the os-hyoides, and can trace backwards on each side the whole length of the cornua. They might easily be broken by the grasp of a garotter. Below the body of the os-hyoides is the gap above the thyroid cartilage. This gap corresponds with the anterior thyro-hyoid ligament and the apex of the epiglottis; so that in cases of cut throat in this situation, nearly the whole of the epiglottis lies above the wound.

=Thyroid cartilage.=--The projection and depth of the notch in the thyroid cartilage, or ‘pomum Adami,’ varies in different persons. Between the notch and the hyoid bone there is a large bursa, which facilitates the play of the cartilage beneath the bone in deglutition. The notch does not appear till puberty, and is throughout life much less distinct in the female than the male. The finger can trace the upper borders and cornua of the thyroid cartilage: its lower cornua can be felt by the side of the cricoid.

On each side of the thyroid cartilage we can recognise the lateral lobes of the thyroid gland. On the upper and front part of the gland we can distinctly feel the pulsation of the superior thyroid artery. This pulsation, coupled with the fact that the gland rises and falls with the larynx in deglutition, gives the best means of distinguishing a bronchocele from other tumours resembling it.

Below the angle of the thyroid cartilage we feel the interval between it and the cricoid, which is occupied by the cricothyroid membrane. In laryngotomy we cut through this membrane transversely close to the upper edge of the cricoid cartilage, in order that the incision may be as far as possible from the attachment of the vocal cords.

25. =Cricoid cartilage.=--The projection of the cricoid cartilage is a point of great interest to the surgeon, because it is his chief guide in opening the air-passages, and can always be felt even in infants, however young or fat. It corresponds to the interval between the fifth and sixth cervical vertebræ. The commencement of the œsophagus lies behind it: here, therefore, a foreign substance too large to be swallowed would probably lodge, and might be felt externally.

Again, a transverse line drawn from the cricoid cartilage horizontally across the neck would pass over the spot where the omo-hyoid crosses the common carotid. Just above this spot is the most convenient place for tying the artery.

26. Those who have not directed their attention to the subject are hardly aware what a little distance there is between the cricoid cartilage and the upper part of the sternum. In a person of the average height sitting with the neck in an easy position, the distance is barely one inch and a half. When the neck is well stretched, about three-quarters of an inch more is gained. Thus, we have (generally) not more than seven or eight rings of the trachea above the sternum. None of these rings can be felt externally. The second, third, and fourth are covered by the isthmus of the thyroid gland. The trachea, it should be remembered, recedes from the surface more and more as it descends, so that, just above the sternum in a short fat-necked adult, the front of the trachea would be quite one inch and a half from the skin.

27. =Trachea.=--In the dead subject nothing is more easy than to open the trachea: in the living, this operation may be attended with the greatest difficulties. In urgent dyspnœa you must expect to find the patient with his head bent forward, and the chin dropped, so as to relax as much as possible the parts. On raising his head, a paroxysm of dyspnœa is almost sure to come on, threatening instant suffocation. The elevator and depressor muscles draw the trachea and larynx up and down with a rapidity and a force which may bring the cricoid cartilage within half an inch of the sternum. The great thyroid veins which descend in front of the trachea are sure to be distended. There may be a middle thyroid artery. In children the lobes of the thymus may extend up in front of the trachea, and the left vena innominata may cross it unusually high. Thus the air-tube may be covered by important parts which ought not to be cut. Considering all these possible complications, the least difficult and the best mode of proceeding is to open the trachea just below the cricoid cartilage; and if more room be requisite, to pull down the isthmus of the thyroid gland, or in children to divide the cricoid itself. It is important that all the incisions be made strictly in the middle line, the ‘line of safety.’

28. =Sterno-mastoid muscle.=--The sterno-mastoid muscle is the great surgical landmark of the neck. It stands out in bold relief when the head turns towards the opposite shoulder. Its inner border overlaps the common carotid, which can be easily compressed for a short time against the spine about the level of the cricoid cartilage. The artery extends (generally) as high as the upper border of the thyroid cartilage and corresponds with a line drawn from the sterno-clavicular joint to midway between the angle of the jaw and the mastoid process.

Between the sternal origins of the sterno-mastoid is the fossa above the sternum, more or less perceptible in different necks. As it heaves and sinks alternately, especially in distressed breathing, it was called by the old anatomists ‘fonticulus gutturis.’ In beautiful necks, as seen in the ‘Venus,’ it is filled up by fat.

Notice the interval between the sternal and clavicular origins of the sterno-mastoid. A knife introduced a very little way into this interval would wound, slanting inwards, the common carotid, slanting outwards, the internal jugular vein. These facts are of importance in performing the subcutaneous section of the tendon of this muscle.

29. =Sterno-clavicular joint.=--Many important parts lie behind the sterno-clavicular joint. There is the commencement of the vena innominata; behind this comes the common carotid on the left side, and the division of the arteria innominata on the right. Deeper still, the apex of the lung rises into the neck.

In a child the arteria innominata often lies in front of the trachea and divides a little higher than the joint: a point to be remembered in tracheotomy (27).

30. =Apex of lung in the neck.=--The extent to which the apex of the lung rises into the neck is greater than is generally supposed. Many observations in reference to this point lead to the conclusion that the lung rises behind the sterno-mastoid, on an average, one inch and a half above the clavicle; in persons with long necks, as much as two inches. The apex of the lung and pleura is covered by the clavicular origin of the sterno-mastoid, the sterno-thyroid, and a part of the scalenus anticus. It is also crossed by the subclavian vessels in the first part of their course. As this cervical portion of lung is peculiarly liable to tubercular disease, it should always be carefully examined. Its condition may be ascertained by percussion near the sternal end of the clavicle.

31. =Supra-clavicular fossa.=--The hollow above the clavicle, between the sterno-mastoid and the trapezius, is very manifest in emaciation and old age. Notice the termination here of the external jugular vein. In some necks only a small depression is visible, particularly when the trapezius has a broad insertion into the clavicle, and comes well forwards, so that its front border gives a graceful contour to the base of the neck.

32. =Subclavian artery.=--In the supra-clavicular fossa, near the outer border of the sterno-mastoid, and about one inch above the clavicle, we feel the pulsation of the subclavian artery. Here the artery lies upon the first rib, and can be effectually compressed. A little pressure is sufficient. But the pressure must be made in the right direction, or the artery will be pressed off the rib instead of against it. The plane of the rib is such that the pressure, to be effectual, must be made in a direction downwards and a little inwards. It is best to stand behind the shoulder and make the pressure with one thumb.

It is worth remembering that the outer border of the sterno-mastoid corresponds pretty nearly with the outer edge of the scalenus anticus, which is the surgical guide to the subclavian artery.

By pressing deeply at the upper part of the supra-clavicular fossa, the transverse process of the seventh cervical vertebra can be distinctly felt.

In long and thin necks, a thin cord is perceptible, running nearly parallel with and just above the clavicle. It is the posterior belly of the omo-hyoideus. See it rising and falling in breathing, and making tense during inspiration that part of the cervical fascia which lies over the cervical portion of the lung. Thus it may be said to be in all respects a muscle of inspiration, co-operating with the sterno-mastoid and scaleni. In the language of transcendental anatomy, we may say that the central tendon of the omo-hyoid represents a rudimentary cervical rib. Its posterior belly is analogous to a serration of the serratus magnus; its anterior belly to a sterno-hyoid.

_THE CHEST._

33. As a rule, the right half of the chest is slightly larger than the left. Of ninety-two persons of the male sex and good constitutions, seventy-one had the right side the larger; eleven the left; ten had both sides equal. The maximum of difference in favour of the right was one inch and a quarter. The measurements were made on a plane with the nipple.

34. =Peculiarities in the female.=--The chest of the female differs from that of the male in the following points:--Its general capacity is less; the sternum is shorter; the upper opening is larger in proportion to the lower; the upper ribs are more movable, and therefore permit a greater enlargement of the chest at its upper part, in adaptation to the requirements of pregnancy.

35. The top of the sternum is on a level with the second dorsal vertebra; and the available space between the top of the sternum and the spine is hardly more than two inches.[2]

36. =Parts behind first bone of sternum.=--There is little or no lung behind the first bone of the sternum, the space being occupied by the trachea and large vessels as follows:--

The left vena innominata crosses the sternum just below the upper border. Next come the great primary branches of the arch of the aorta. Deeper still is the trachea dividing into its two bronchi opposite the junction of the first and second bones of the sternum. Deepest of all is the œsophagus.

About one inch from the upper border of the sternum is the highest part of the arch of the aorta, which lies on the bifurcation of the trachea.

37. The course of the arteria innominata corresponds with a line drawn from the middle of the junction of the first with the second bone of the sternum, to the right sterno-clavicular joint. When the artery rises higher than usual into the neck, its pulsation can be felt in the fossa above the sternum.

38. =Rules for counting the ribs.=--In fat persons it is often difficult to count the ribs; hence the following rules may be useful:--

_a._ The finger passed down from the top of the sternum soon comes to a transverse projection, slight, but always to be felt, at the junction of the first with the second bone of the sternum. This corresponds with the level of the cartilage of the second rib.

_b._ The nipple of the male is placed, in the great majority of cases, between the fourth and the fifth ribs, about three-quarters of an inch external to their cartilages.

_c._ The lower external border of the pectoralis major corresponds with the direction of the fifth rib.

_d._ A line drawn horizontally from the nipple round the chest cuts the sixth intercostal space midway between the sternum and the spine. This is a useful rule in tapping the chest.

_e._ When the arm is raised, the highest visible digitation of the serratus magnus corresponds with the sixth rib. The digitations below this correspond respectively with the seventh and eighth ribs.

_f._ The scapula lies on the ribs from the second to the seventh, inclusive.

_g._ The eleventh and twelfth ribs can be felt even in corpulent persons, outside the erector spinæ, sloping downwards.

_h._ One should remember the fact that the sternal end of each rib lies on a lower level than its corresponding vertebra. For instance, a line drawn horizontally backwards from the middle of the third costal cartilage at its junction with the sternum, to the spine, would touch the body, not of the third dorsal vertebra, but of the sixth. Again, the end of the sternum would be on about the level of the tenth dorsal vertebra. Much latitude must be allowed here for variation in the length of the sternum, especially in women.

39. =Interval below clavicle.=--Immediately below the clavicle we recognise the triangular interval between the pectoralis major and the deltoid. This space varies in different cases, depending on the distance between the muscles. It is important as a guide to the coracoid process and the axillary artery. In a case of injury to the shoulder, to ascertain whether the coracoid process is broken, carry the arm outwards, to put the deltoid and pectoral muscles on the stretch, and make manifest the space between their opposite borders. Pressing the thumb into the space we can feel the inner side of the coracoid process, the apex being under the fibres of the deltoid; thus it is easy to ascertain whether it be broken. Moreover, this space corresponds with the line of the axillary artery; here its pulsation can be distinctly felt, and here it can be compressed (but not easily, or for long) against the second rib.

40. =Internal mammary artery.=--The line of the internal mammary artery runs perpendicularly behind the cartilages of the ribs, about half an inch from the sternum. The perforating branch through the second intercostal space is generally the largest.

41. =Outline of heart on chest-wall.=--To have a general idea of the form and position of the heart, map its outline on the wall of the chest, as follows:--

_a._ To define the base draw a transverse line across the sternum corresponding with the upper borders of the third costal cartilages: continue the line half an inch to the right of the sternum and one inch to the left.

_b._ To find the apex, mark a point about two inches below the left nipple, and one inch to its sternal side. This point will be between the fifth and sixth ribs.

_c._ To find the lower border (which lies on the central tendon of the diaphragm), draw a line, slightly curved downwards, from the apex across the bottom of the sternum (not the ensiform cartilage) as far as its right edge.

_d._ To define the right border (formed by the right auricle), continue the last line upwards with an outward curve, so as to join the right end of the base.

_e._ To define the left border (formed by the left ventricle), draw a line curving to the left, but not including the nipple, from the left end of the base to the apex.

Such an outline (seen in the cut, page 22, with the angles rounded off) shows that the apex of the heart points downwards and towards the left, the base a little upwards and towards the right; that the greater part of it lies in the left half of the chest, and that the only part which lies to the right of the sternum is the right auricle. A needle introduced in the third, the fourth, or the fifth right intercostal space close to the sternum would penetrate the lung and the right auricle.

A needle passed through the second intercostal space, close to the right side of the sternum, would, after passing through the lung, enter the pericardium and the most prominent part of the bulge of the aorta.

A needle passed through the first intercostal space, close to the right side of the sternum, would pass through the lung and enter the superior vena cava above the pericardium.

42. The best definition of that part of the præcordial region which is less resonant on percussion, was given by Dr. Latham years ago in his ‘Clinical Lectures.’ ‘Make a circle of two inches in diameter round a point midway between the nipple and the end of the sternum. This circle will define, sufficiently for all practical purposes, that part of the heart which lies immediately behind the wall of the chest, and is not covered by lung or pleura.’

=Apex of the heart.=--The apex of the heart pulsates between the fifth and sixth ribs, two inches below the nipple, and one inch to its sternal side. The place and extent, however, of the heart’s impulse, vary a little with the position of the body. Of this anyone may convince himself by leaning forwards, backwards, on this side and on that, feeling, at the same time, the heart. Inspiration and expiration also alter the position of the heart. In a deep inspiration it may descend half an inch, and can be felt beating at the pit of the stomach.

43. =Valves of the heart.=--The aortic valves lie behind the third intercostal space, close to the left side of the sternum.

The pulmonary valves lie in front of the aortic behind the junction of the third costal cartilage, on the left side, with the sternum.

The tricuspid valves lie behind the middle of the sternum, about the level of the fourth costal cartilage.

The mitral valves (the deepest of all) lie behind the third intercostal space, about one inch to the left of the sternum.

Thus these valves are so situated that the mouth of an ordinary sized stethoscope will cover a portion of them all, if placed over the sternal end of the third intercostal space, on the left side. All are covered by a thin layer of lung; therefore we hear their action better when the breathing is for a moment suspended.

44. =Outline of the lungs.=--Now let us trace on the chest the outline of the lungs, with as much precision as their expansion and contraction in breathing permit. (See the cut.)

45. The apex of each lung rises into the neck behind the sternal end of the clavicle and sterno-mastoid muscle as much as an inch and a half: in females rather higher than in males (30). From the sternal ends of the clavicles the lungs converge, so that their thin edges almost meet in the mesial line on a level with the second costal cartilage. Thus there is little or no lung behind the first bone of the sternum. From the level of the second costal cartilage to the level of the fourth, the margins of the lungs run parallel, or nearly so, close behind the middle of the sternum: consequently their thin edges overlap the great vessels and valves at the base of the heart.

Below the level of the fourth costal cartilage the margins of the lungs diverge, but not in an equal degree. The margin of the right corresponds with the direction of the cartilage of the sixth rib: the margin of the left, being notched for the heart, runs behind the cartilage of the fourth. A line drawn perpendicularly from the nipple would find the lung margin about the lowest part of the sixth rib. Laterally, _i.e._ in the axillary line, the lung margin comes down as low as the eighth rib: posteriorly, _i.e._ in the dorsal or scapular line, it descends as low as the tenth.

It should be remembered that, in a deep inspiration, the lung margins descend about one inch and a half.

In children the lungs are separated in front by the thymus gland. Allowance should be made for this. About the approach of puberty the thymus disappears.

46. =Anterior mediastinum.=--The direction of the anterior mediastinum is not straight down the middle of the sternum, but slants a little to the left, owing to the position of the heart. The right pleural sac generally encroaches a little upon the left, behind the middle of the sternum. A needle introduced through the middle of the sternum opposite the third or the fourth rib would go through the right pleura.

47. =Reflection of pleura.=--The reflection of the pleura from the wall of the chest on to the diaphragm corresponds with a sloping line drawn from the bottom of the sternum over the cartilages of the ribs down to the lower border of the last rib.

Since the pleura lines the inside of the last rib, a musket ball or other foreign body, loose in the pleural sac, and rolling on the diaphragm, might fall to the lowest part of the sac, which would be between the eleventh and twelfth ribs. The ball might be extracted here. The chest might also be tapped here, but not with a trochar, since a trochar would penetrate both layers of pleura, and go through the diaphragm into the abdomen.

The operation should be done cautiously, by an incision beginning about two inches from the spine, on the outer border of the ‘erector spinæ,’ on a level between the spines of the eleventh and twelfth dorsal vertebræ. The intercostal artery will not be injured if the opening be made below the middle of the space, which is very wide.[3]

_THE BACK._