COLLECTIVE INVESTIGATION IN THE AlqATO- MICAL DEPARTMENT OF TRINITY COLLEGE, DUBLIN.

REPOltTEI) Bu W. t i . THOMPSON, M.D., F.R.C.S. ENG.

[Read in the Section of Anatomy ~nd Physiology, M:arch i 4, 1890.]

Formation of tke Portal Veiu. Investigated by Dr. gr. H. Thompson.

IN issuing this a s a subject for collective investigation, the Anato- mical Society asked for information regarding the three great trunks

which join to form the portal vein. But the investigator con- sidered the matter would be imperfect were the coronary or superior gastric vein not also included~ and so the results have proved.

The points noted were--(1) the order of union of the four great vessels ; (2) the levels at which they joined; and (3) the presence or absence of valves in their tributaries.

(1) The order of union of the four great trunks.---Taking ir a s a fact that the splenic vein always unites with the superior mesenteric vein, there are then only two other veins whose terminations have to be dealt with--viz., the inferior mesenteric and coronary veins. l~ow, of these the inferior mesenteric was examined in 58 subjects (26 males and 32 females), and was found to end as follows : 0

(a) In the splenic vein, in 33 subjects , o19 males and 14 females ;

(b) In the inferior mesenteric vein, in 22 subjects ...... 18 females

and 4 males; (c) In the angle of union between these two veins~ in 3 subjects,

all of whom were males.

The coronary vein~ however~ was examined only in 48 subjects (32 males and 26 females), and was found to terminate--

(a) In the portal vein, in 29 subjects--15 males and 14 females ; (b) In the splenic vein, in 19 subjects---7 males and 12 females.

Collective InvestŸ in Anatomical Department. 517

Thus the complete formation of the portal vein, so far as these four great trunks are concerned, was examined in 48 subjects. This brought out the result that there are four. chief ways in which the vessel may be formed---

(1) That which is usually described as normal, where the inferior mesenteric vein enters the splenic vein, while the coronary, or superior gastric, enters the portal vein (Fig. 1). This condition existed in 18 out of the 48 subjects examined. Nine of these were males and nine females.

(2) That in which exactly the reverse condition obtains, where

the inferior mesenteric vein joins the superior, while the coronary vein enters the splenic--where, in other words, the inferior mesen- teric and coronary veins have, so to speak, changed places (regarding,

for the moment~ the superior mesenteric and portal veins as one continuous trunk) (Fig. 2). This condition occurred in 11 out of the 48 subjects examined~ nine being females~ while onIy two were males.

Fig. 1. Fig. 2.

v

(3) That in which both inferior mesenteric and coronary veins pour their blood into the splenic vein (Fig. 3). In 8 out of the 48 subjects examined this was the mode of ending of these veins, 4 being males and 4 females.

(4.) That in which neither the inferior mesenteric nor coronary veins enter the splenic, but both of these, together with the splenic vein, successively join the continuous trunk formed by the superior

518 Collective Investigation in A natomŸ Department.

mesenteric and portal veins (Fig. 4). This group also included 8

cases---4 males and 4 females.

leig. 8. Fig. 4.

U Those cases (3 in number) in which the inferior mesenteric vein

joined exactly at the angle of union between the splenic and

superior mesenteric veins were too few to make into a separate

group. Most cases can be referred to one or other of the above

groups. Though not inclined to lay much stress upon it, the investigator would like to point out the much greater relative fre-

quency with which the second mode of formation occurred in

females.

2. T/te levels at which the Portal Vein was formed. This was

observed in 47 subjects. In 4 the level was that of the lower part of the first lumbar

vertebra ;

In 4 the disc between first and second lumbar vertebrm; in 33,

opposite the second lumbar vertebra ;

In 5 the disc between second and third lumbar vertebrm; and in

1 instance opposite the upper part of the thŸ lumbar

vertebra. With regard to the exact distances between the vessels at their

termination, it was found that the inferior mesenteric vein entered

the splenie between one half and three-quarters of an inch from

its termination in 19 cases ; about one inch from its termination in

10 tases ; a quarter of an inch of under in 4 cases, three of these

By DR. W. H. T~o~vsoN. 519

being exactly at the angle of union of the splenic and superior

mesenteric veins.

In all cases the portal vein was formed behind the head of the pancreas.

3. The presence of valves was sought for in 12 subjects. In none of these were any found.

Abnormalities of the Renal A rtery. Investigated by A. ff. O'Sullivan, .F.T.C.D., and O. L. Robi~~sou, M.R.C.S.

The arterial supply to the kidneys was examined in 5:?,) subjects-

In one of these, however~ the condition could only be noted on one

side. 103 kidneys were therefore examined. As regards number,

it was found that in 76 cases there was only one artery present;

in 23 instances there were two; in 3 cases there were three; and in 1 instance there were four arteries present.

In the 23 instances where there were two arteries~ the extra trunk was distributed as follows : .... In 10 cases ir entered the upper

border of the kidney, the main trunk entering the hilum. In 5 it entered the lower border of the kidney, the main trunk also

entering the hilum. In 4 of these the accessory trunk arose from the aorta below the main trunk~ the remaining one arising from

the right common iliac artery.

In regard to the relations of the artery of arteries to the vein

and ureter at the hilum of the kidney, it was found convenient to divide them into six groups.

Group 1.--This was taken as the normal arrangement, in which

the arterial trunk arising from the aorta passed outwards behind

the vein, its branches entering the hilum between the vein and

ureter. This condition existed in 52 out of the 103 kidneys ex-

amined. Group 2. ~Itere the trunk of the artery also passed outwards

behind the vein, but its branches enclosed the ureter at the hilum.

This condition was observed in 21 instances. Group 3. ..... The artery here also passed out behind the vein~ but

its terminal branches enclosed that vessel on entering the hilum.

12 instances of this variety were note&

520 CoUective Investigation in Anatomical ,Department.

Group 4.---In this the artery, passing outwards behind the vein, broke up into branches which enclosed both the vein and ureter at

the hilum. 8 cases of this variety were noted~ in 5 of which there

was also a branch pass~ng between the vein and ureter. Group 5 . In which the artery passed inwards wholly Ÿ front

of the vein, its branches entering the hilum in the same position. Of this variety 8 cases were also noted.

Group 6.. .... In this the artery passed outwards behind the vean,

breaking up into branches which entered the hilum altogether be- hind the ureter. Only 2 instances of this were note&

The Relation of the lnternal ,)[axillary Artery to the External .Pterygoid 3luscle. Investigated by J. ,L Zong, JB.A. (Dub.).

Fifty-one subjects were examined~ and in these the position of 93

arterieswas noted---9 of the subjectsbeing examined on one side only.

The artery lay superficial to the external pterygoid muscle in 47

of the 93 cases examined. This condition did not show any de-

cided preference for one side more than the other--thus 22 were on

the right side and 25 on the left. In all these cases the artery p~ssed into the spheno-maxillary

fossa between the two heads of the external pterygoid muscle. The

only other structure which bote any special relation to the artery

was the long buccal nerve. This invariably came out between the

heads of the muscle~ in 13 cases appearing above the artery to pass

down superficial to it~ while in 31 cases it passed out below and

deeper than the vessel. The artery 1ay deeper than the external pterygoid muscle in 43

cases~ and here it seemed to have a slight preference for the right

side. Thus~ of the 43 cases~ 25 were on the right side and 18 were

on the left. When taking this position moreover it was found to have a very

variable relation to the branches of the inferior maxillary nerve.

This is shown as follows : (a) The inferior dental nerve in 19 instances passed down super-

ficial to the artery, in 19 instances also ir lay deeper than

the vessel and in 5 ir was perforated by ir.

By Dn. W. H. T~oMeso~. 521

(b) The lingual nerve in 36 cases passed deeper than the artery, while in the remaining 7 cases it passed down superficial to

ir. In all these 7 cases the inferior dental nerve also passed

down superficial to the artery.

There were two instances in which the artery pursued an inter-

mediate course as regards the external pterygoid muscle by piercing

its lower head of origin and then becoming superficial to ir.

A few cases of special irregularities in the origin and course of

the artery occurred to which it is only necessary to allude.

The Tuberculum .Laterale of the Astragalus, or Os Trigonum. In- vestigated by C. E. Stokes, .B.A. ( Cantab. et .Dub.).

One hundred and eight lower limbs were examined. Amongst these there were 3 well-marked examples of the os trigonum~ while in a fourth case there were evidences which seemed to point to the

original separate existence of the tubercle. In each of the 3 cases the ossicle articulated by means of a synovial joint with the

main bone, the interior of the joint communicating with the pos- terior calcaneo-astragaloid articulation. In each of these cases also

it gave attachment to a few fibres of the posterior fasciculus of the

external lateral ligament of the ankle-joint.

The Superior Tibio.Fibular Articulatiou. Investigated by J. Bar- croft A~~derson~ tLL.

This joint was examined with the object of determining in what proportion of cases a communication existed between i~ and the knee-joint. 100 legs were examined~ and in 18 of these a com- munication between the two joints was found. In 3 of the others

some anchylosis from disease existed. The communication was invariably between the so-called bursal

prolongation of the synovial sac which underlies the popliteal tendon

on the external tuberosity of the tibia and the immediately subjacent synovial cavity of the tibia-fibular joint. The opening varŸ from a centimetre to a centimetre a n d a half in length.