SPLEEN. 



771 



opposed sides of the third and ourth toes, 

 having previously communicated with the ex- 

 ternal plantar. 



These different divisions of the internal 

 plantar nerve give off, in their course, fila- 

 ments to those portions of the cuticle with 

 which they are in relation ; and also small 

 twigs for the metatarso-phalangeal and pha- 

 langeal articulations, and muscular branches 

 to the flexor digitorum brevis, over the ten- 

 dons of which the different divisions of the 

 external portion of the nerve are obliquely 

 and superficially directed. 



The external plantar nerve, smaller than 

 the internal, is directed forwards and out- 

 wards between the musculus accessorius and 

 flexor digitorum brevis, giving filaments to 

 either, and, having reached the inner border of 

 the abductor minimi digiti, which muscle it sup- 

 plies, divides into a deep and superficial branch. 



The deep branch passes from between the 

 first and second layer of muscles to place it- 

 self between the latter and the third, passing 

 in company with the exterual plantar artery. 

 It describes a curve, the concavity of which 

 looks towards the heel and inner malleolus. 

 Filaments are sent off for the two outer lum- 

 bricales, for the transversalis pedis, the ad- 

 ductor pollicis, the interossei, and the tarsal 

 and metatarsal articulations. 



The superficial branch passes obliquely for- 

 wards and outwards between the flexor brevis 

 digitorum and abductor minimi digiti, to both 

 of which it gives filaments, and soon divides 

 into an external and internal branch. 



The external branch reaches the outer border 

 of the foot, and terminates at the extremity 

 of the outer aspect of the little toe ; giving 

 filaments to the flexor brevis minimi digiti 

 and the articulations. The internal, larger, com- 

 municates with the most external division of 

 the internal plantar, and bifurcates at the ex- 

 tremity of the fourth interosseous space, for 

 the supply of the contiguous sides of the 

 fourth and fifth toes. The divisions of the 

 superficial branch of the external plantar 

 nerve, like those of the internal, supply the 

 portions of the integument with which they 

 are in relation, as also the articulations over 

 which they pass. 



The internal and external plantar nerves 

 are, in reference to size, directly the reverse 

 of the corresponding arteries : the former 

 giving off seven filaments for the supply of 

 the three inner toes, and half of the fourth ; 

 and being analogous in its distribution to the 

 median in the hand : the latter giving off only 

 three filaments for the fifth and half of the 

 fourth toe, and corresponding with the distri- 

 bution of the termination of the ulnar nerve. 

 (Nathaniel Ward.} 



SPLEEN. (Lien sen Splen, Lat. ; 

 Gr. ; die MHz, Germ. ; la Rate, Fr.) Nor- 

 mal anatomy. The spleen is a single so-called 

 "vascular gland," which is attached to the 

 cardiac extremity of the stomach, and appears 

 to possess some intimate connection with the 

 renovation of the blood. 



Situation and form. The spleen has a 

 roundish elongated form, or almost the shape 

 of half an egg, and lies in the left hypochon- 

 driac region. We recognise on it two sur- 

 faces, two borders, and two extremities. The 

 outer surface (superficies externa sen convexd) 

 is completely free and smooth, and often ex- 

 hibits a more or less deep, long, and oblique 

 incision : it looks outwards, upwards, and back- 

 wards ; and is in contact with the left costal 

 portion of the diaphragm, corresponding to 

 the tenth and eleventh ribs. The inner surface 

 (superficies interna sen concava) is directed 

 inwards and forwards; is for the most part 

 slightly concave, and presents, in a prolonged 

 elevation which occupies its middle, a vertical 

 furrow, the fissure for the vessels, or hilus 

 lienalis, which contains many holes and de- 

 pressions, through which pass the nerves and 

 vessels to and from the spleen. This fissure 

 separates the concave surface into an anterior 

 and larger, and a posterior and smaller por- 

 tion ; and it is connected by the broad, but 

 short gastro-splenic omentum (ligamentum 

 gastro-lienale), with the fundus of the stomach, 

 to which the remainder of the concave surface 

 is opposed. The upper extremity or head of 

 the spleen (caput lienis), is the thicker and 

 more obtuse of the two ; it occupies the ele- 

 vated hinder part of the eighth rib, and is con- 

 nected by a suspensory ligament (ligamentum 

 phrenico-lienale seu suspensioruni) with the 

 diaphragm. The lower extremity or cauda 

 lienis, is thinner and more pointed, and is 

 directed downwards and forwards. The an- 

 terior border (margo anterior) is the thinner 

 and sharper, and is free. The posterior border 

 (margo obtustis) is thick and rounded, and 

 is in contact with the lumbar portion of the 

 diaphragm, and the anterior surface of the left 

 suprarenal capsule. The spleen is thus least 

 moveable, where it is limited by the diaphragm ; 

 but much more so at the site of its attach- 

 ment to the stomach. But its situation changes 

 with the variable positions of the diaphragm 

 and stomach : thus, on the one hand, it de- 

 scends and rises in the states of in- and ex- 

 spiration respectively ; and, on the other hand, 

 becomes more superficial or deeper, according 

 as the stomach is empty or full. 



Varieties of the spleen. It is not un- 

 common to find the anterior border of the 

 spleen, presenting one or more separate deep 

 fissures. Also supplementary spleens (lienculi, 

 seu lienes succenturiati} are now and then ob- 

 served : according to Rosenmiiller and Giesker, 

 more frequently in the Southern than in the 

 Northern Germans. These are situated in 

 the gastrosplenic ligament, and rarely in 

 the great omentum (Morgagni, Huschke) ; 

 they are red, of the ordinary splenic structure, 

 and of a size which varies from a linseed to a 

 walnut. They are generally one or two in 

 number, less frequently four or seven, and in 

 a misdeveloped foetus have even amounted 

 to twenty-three. 



The size and weight of the spleen experience 

 great variation, not only in different indi- 

 viduals, but even in one and the same person : 



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