the peroneus brevis. In my experience the peroneus tertius has been, where separable in its origin from the extensor longus digitorum, almost always connected much more extensively with the fibula. The extent of surface of the fibula occupied by the muscle has usually exceeded the lower half of the bone, not including however the part below the tibio-fibular articulation. Not infrequently the origin of the muscle has occupied the lower two-thirds of its anterior surface, and then the proportionate length of attachment of the extensor longus and of the peroneus tertius has been a matter of surprise to the student. I have also frequently been able to trace the lower muscular fibre of the extensor as lying on a plane internal to those of the peroneus, and attached under cover of the latter to the anterior surface of the fibula down to just above the tibio-fibular articulation.

Sacrolumbalis. This portion of the erector spinæ is usually described as passing upwards to be attached to the lower ribsQuain says six or seven, Ellis the same, and Gray the lower six, My respected colleague, Mr Rainey, has, however, for years taught in the Dissecting Room at St Thomas's that slips can without difficulty be traced from the muscle into every one of the ribs; and this I have verified in almost every subject in which I have examined the attachments of this muscle carefully. It is well known that the muscles of the back vary very much in the number of slips of which they are composed, but it can be demonstrated readily that the Sacrolumbalis has a much larger extent of attachment to ribs than is described in our text-books of Anatomy.

Transversalis colli et capitis. Under this head Mr Ellis proposed to include the transversalis colli and trachelomastoid, and it is a matter of surprise that in the last edition of Quain's Anatomy advantage is not taken of this means of simplifying the very complicated description of the muscles of the back. One of our objects as teachers of Anatomy should undoubtedly be to render the explanation of these muscles more intelligible to students, and more easily retained in their memory. As it is, students rather shirk the dissection of the muscles of the back on account of the difficulty of remembering the attachments, the formidable array of names, and the number of

so-called separate muscles; and they are hindered also very materially by reason of the difficulty of distinguishing them as separate structures. The transversalis colli and transversalis capitis (trachelomastoid) are commonly one muscle at their origin, but divide towards their insertion into a neck portion (tr. colli) and a head portion (tr. capitis), resembling in this respect the splenius: and the analogy between these two muscles can be traced even further. The splenius arises from spinous processes in the dorsal region down to about the sixth, from the vertebra prominens, and from the ligamentum nucha in the neck about as high as opposite the third cervical vertebra. The transversalis arises from transverse processes in the dorsal region down to about the sixth, and from articular processes in the neck about as high as the third.

It will be useful to notice here the attachment of the complexus as compared with that of the above two muscles. The complexus, including the biventer cervicis, which is practically a part of the complexus, arises from transverse processes in the dorsal region as low as about the sixth (though it not infrequently receives fibres from much lower down) and from articular processes in the neck about as high as the third cervical vertebra. It will thus be seen that a comparison of these three muscles, grouped in the manner I have indicated, simplifies the description usually given. The extent of origin of each is about the same, but the splenius arises from spinous processes or their equivalent, the ligamentum nucha, while the transversalis and complexus rise from transverse processes or their equivalents, articular processes. The splenius and transversalis are single. muscles at their origin but divide into head and neck portions, which receive names indicating their destination (spl. capitis, spl. colli, transv. capitis, transv. colli).

Supinator radii longus. The action of this muscle is so little that of supination that it does not deserve the name given to it. In Quain's Anatomy it is admitted that its chief use is to flex the forearm, but it is stated that supination having commenced by other muscles the movement is assisted by the supinator longus. In Gray's Anatomy it is stated that the supinator longus and brevis are the supinators of the forearm and hand, the longus more especially acting where the limb

is pronated: when supination has been produced the further action of this muscle is to flex the forearm.

It may be seen, upon examining the action of the muscle in the dead body, that it cannot be considered more of a supinator than of a pronator. When the hand is made prone the supinator longus brings up the radius over the ulna to the semiprone position. When the hand is supinated it brings up the radius again over the ulna also to the semi-prone position. After this the muscle flexes the forearm. In other words, its tendency is to throw the forearm and hand into the position it readily occupies when placed across the chest as in a sling. Dr Duchenne has recently employed the interrupted current for the purpose of demonstrating upon the living subject the action of different muscles, and shewed that by placing the two poles of the battery over the body of the supinator longus when the hand was lying supine, complete pronation was produced; but there is no evidence that the stimulus did not affect other mus

cles besides the supinator. On the contrary, I am of opinion (having been the subject experimented on by Dr Duchenne at a recent demonstration at this hospital) that the stimulus was so powerful as to affect at least those lying directly under it, namely the radial extensors of the wrist. Now it will be seen, upon examining the attachments of these muscles, that their action will undoubtedly be that of pronation provided the hand be originally supine: for they pass downwards from the outer condyle to the back of the wrist, and will naturally tend when contracting to bring the back of the hand over and pronate the hand distinctly.

Popliteal space. In giving the boundaries of this space I am not aware of any notice being taken of the adductor magnus. This muscle is placed deeply on the inner side of the space above the condyle, and upon raising the semi-membranosus can be readily discovered. It is that portion of the great adductor especially which is passing down as a strong tendinous structure to the inner femoral condyle. The boundaries, as I have been in the habit of teaching them, are as follows: on the inner side above, the Adductor magnus, deeply placed and hidden by the Semi-membranosus, upon which is lying the long tendon of the Semi-tendinosus with some of the fleshy part of the muscle.

Superficial to these muscles, and not directly in relation with the popliteal space, are the Gracilis and Sartorius. On the outer side above is the Biceps, both its heads being visible. Below we have on the inner side Gastrocnemius, and on the outer side Gastrocnemius and Plantaris.

Acromio-thoracic artery. The description of the origin of this vessel in all our manuals of Anatomy is, I am inclined to believe, inaccurate. It is stated to arise from the axillary artery in its first part, from that portion which lies between the first rib and the upper border of the pectoralis minor, but in every subject in which I have examined the artery during the seven years I have been demonstrator in the anatomical department of this Hospital I have found it rising from the second part of the axillary artery. I am indebted to Mr Rainey for first pointing out this fact to me. It is given off from the front of the axillary artery a short distance under the pectoralis minor and then passes upwards to appear in the space above the muscle, where it gives off its pectoral and humeral branches as usually described.

TWO CASES SHOWING A PECULIAR ARRANGEMENT IN THE FIBRES OF THE EXTERNAL PTERYGOID MUSCLE IN MAN. By W. W. WAGSTAFFE, B.A., F.R.C.S., Demonstrator of Anatomy at St Thomas's Hospital.

Two similar cases of rather curious muscular abnormality have recently come under my notice in the Dissecting Room at St. Thomas's Hospital, and as they are of a character not hitherto described, it may be interesting to have them recorded.

Case 1.-Upon the outer surface of the right external pterygoid muscle, close to its origin from the margin of the sphenomaxillary fossa, I noticed, in demonstrating upon this subject, a number of vertical aponeurotic fibres. These aponeurotic fibres were connected above with the pterygoid ridge of the 19

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sphenoid along its anterior part, and ended below in well-defined muscular bundles. The muscular bundles were found to be attached below to the lower part of the outer surface of the external pterygoid plate. These superficial vertical fibres of the external pterygoid consequently ran a short distance from bone to bone without a possibility of movement of either extremity. It therefore became a matter for conjecture as to what function they could possess, and the further connections of this structure were carefully examined. At the anterior border of the muscle it was seen that the usual origin from the tuberosity of the upper maxilla and palate-bone was entirely deficient, and with this, and probably accounting in a measure for it, there was a rather larger spheno-maxillary fossa than is commonly observed. The most posterior of the superficial aponeurotic fibres gradually blended with the rest of the muscle in the manner shown in the accompanying sketch, and the uppermost of these passed directly into the anterior surface of the inter-articular fibro-cartilage of the joint. Upon turning back

Showing the vertical tendinous fibres on the external pterygoid, from the under surface of which a portion of the horizontal muscular fibres sprang. The band of vertical fibres is about half-an-inch broad. For the lower fourth of their length they usually became muscular.