I N T 



with the principal rocks and minerals of fucli di{lri£ls, hava 

 long been made by Mr. White Watfon of Bakewell, in 

 Derbyfhire, Mr. Elias Hall of Caftlcton, Brown and Co. 

 of Derby, and others, but it lias jullly been objected to all 

 the tablets or feftions of this kiud which wc have feen, that 

 they reprefent fome imaginary hill or mountain, intlead of 

 being in any way proportioned to, or made to reprefent, the 

 aftual lirata ajid outhne of any diilrid. Now that mineral 

 furveying, or the methods of obtaining a knowledge of the 

 interior of ftratificd diilricl.^, as well as of afcertaining 

 whether they are fo (Iratiiied, has been fully explained m 

 the Report to tlie Board of Agriculture on the County of 

 Derby, by Mr. .John Farcy, fenior, and illuftrated by a lur- 

 vey of that intcrcilnig and difficult county, we hope that 

 the making of accurate and natural reprefentations or tablets 

 of the interior, or fedions of different dillrifts, will be at- 

 tempted. A very neat and interelling way of difpofing a 

 tablet of a gentleman's mineral ftrata in his eltate, is in the 

 front of his chimney-piece, iiiftead of the flat or carved mar- 

 ble flab now generally ufed. Mr. William Milnes of the 

 Butts in Afhover, in Derbyfliire, has employed Mr. W. 

 Watfon to make him fuch a chimney-piece, wliich forms a 

 very intereiling objedl as well as a fubjeil of contemplation to 

 his friends and viiitors. 



INTERNODIUM, in Jimlomy, the fpace between two 

 articulations. It is only applied to the fingers, where it is 

 employed in naming fome of the mufcles ; at prefent it is 

 iifcd enly in the extenfors of the thumb, which are called 

 extenfor primi, and fecundi internodii polhcis. 



iNTiiUNODIu.M, in Botany, the fpace that is between two 

 knots, or join's, of the ftalk of a plant ; e.gr. of the ftalk 

 or flraw of wheat, or other corn. 



INTERNUS Mallei, in Anatomy, one of the mufcles 

 ef the oJlicula auditus, called more commonly tenfor tym- 

 pani. See E.\u. 



INTEROSSEI, a number of fmall mufcles of the hands 

 and feet, fo named from being fituated in tlie intervals of the 

 metacarpal and metatarfal bones. 



The tnterojii of the hai;d are feven ; wa. two for each of 

 the three middle fingers, and one for the little finger. The 

 abduftors and the adduclor of the thumb fupply the places 

 of the interofiei in that member ; and the adduitor oflis meta- 

 carpi iiidicis holds the place of an internal interoffeous miif- 

 cle in the httle finger. The interofiei produce the lateral 

 motions of the fingers to which they correfpond ; they may 

 therefore be moft conveniently arranged as abduttors and 

 adductors of their refpective fingers. More commonly, 

 however, tliey are divided into two clafTes, according as they 

 are placed towards the palm or the back of the hand, and 

 •Jiftinguifhed by the names of interofiei intcrni priores or 

 palmares, and externi polleriores or dorfales. In this diftri- 

 liution, the internal clafs contains four mufcles, which are 

 named by Albinus, i, indicis prior, and 2, pofterior; 3, prior 

 annularis ; 4, prior auricularis ; the external has only three ; 

 viz. 1 and 2, prior et pollerior digiti mcdii ; 3, pofterior 

 annularis. .Sometimes they are dillinguiflied numerically, 

 begiiming from the thumb. The abductor indicis, or fcn.i- 

 interofiVus, (fee Abductor,) forms the firft external in- 

 teroffeus of Soemmerring ; who therefore enumerates four 

 external iuterofTei. This anatomift makes only three in- 

 ternal interofiei; the lil, internal interoflcus of Albinus, 

 being one of the heads of Soenimerring's firll external inte- 

 rofieus. Both clafies are called by fome French writers 

 metacarpo-fus-phalangiens. 



Jnferojfdoi the fore-finger. The abduftor (prior indicis 

 of Albinus, one of the heads of the firft external interofleus 

 of Socramerring and otherr,) is attached to tlie radial flat 



INT 



furface of the metacarpal bone of the fore-finger ; it forms 

 a tendon towards the finger, which is mferled, in con mon 

 with that of the abdu<Elor mdici?, into the radial lide of the 

 metacarpal end of the fint phalanx of that finger, having 

 alfo a flight connexion to the extenfor tendon ; the radial 

 artery dips into the palm of the hand between this mufcle 

 and the abduftor n:dicis. 



The adductor of the fore-finger (pofterior indicis, Aib.) 

 is placed towards the palm of the hand. It ariles from the 

 ulnar flat furface of the 2d metacarpal bone, and from the 

 ligaments which unite that to the trapezoid bone. At the 

 end of the metacarpus it forms a fmall flat tendon, pafii;s 

 over the articulation of the index and metacarpus, the fide 

 and back part of the firft phalanx, the articulation between 

 the firft and fecond phalanges, and the dorful furface of the 

 2d phalanx. On the middle of the latter bone, it meets at 

 an acute angle with a correfponding tendon of the lumbri- 

 calis, and the two tendons unite into a broader one, which 

 is flightiy contrafted and inferted into the middle prominence 

 of the back of the third phalanx. About the middle of the 

 firft phalanx, or rather fooncr, it becomes united to the 

 broad tendon of the extenfor, from which it feparates a little 

 before the termination of that tendon. 



This conneftion is formed by a thin and broad tendinous 

 expanfion, which clofely covers the articulation of the index 

 with the metacarpus. 



Interojci of the middle finger. The abduftor (prior di- 

 git! m.e«lii) is placed towards the back of the hand : it 

 arifes from the uhiar fide of tlie fecond, and radia! fide of 

 the third metacarpal bone ; and has a middle tendon, in 

 which two oblique rows of fibres terminate. The coiirfe 

 of its tendon correfponds exadiy to that of the preceding, 

 and is united, at its termination, to that of the fu»iceeding 

 tnufcle. 



The adduftor of the middle finger (pofterior medii digiti) 

 is placed alfo towards the back of the hand, and has a fimi- 

 lar form to the laft mufcle. It arii'es from the third ajjd 

 fourth metacarpal bones, and is inferted in the manner 

 alread(y defcribed. 



Jntiioff'A of the ring-finger. The abduftor, (prior annu- 

 larif,) placed towards the palm, is attached to the radial 

 fide lai the fourtJi metacarpal bone, and to the ligaments 

 which conneft it to the carpus. It terminates in a tendon 

 ending as already defcribed. The adduftor (pofterior an- 

 nularis) is placed towards the back of the hand, arifes from 

 the ulnar fide of the fourth, and from the radial fide of the 

 fifth metacarpal bone, and has a middle tendon placed be- 

 tween two planes of fibres, and inferted like the preceding 

 ones. 



The tnteroffius of the little finger. This finger has only 

 an abduAor (prior auricularis), which arifes from the radial 

 furface of the fifth metacarpal bone, and from the ligaments 

 joining it to the carpus. Its tendon has a courfe and infer- 

 tion like thofe of the former. 



The expanfions of the interofiei, where their tendons 

 begin to join thofe of the extenfors, arc conncdted by many 

 fibres to the capfules of the joints formed between the meta- 

 carpal bones and the firft phalanges : their aponeurofes are 

 alfo ftrengthcncd by the tendons of the lumbricales. The 

 relations of the interofiei to the funounding parts may be 

 confidered in a general view. On the fides. they correfpond 

 to the metacarpal bones, and they are reciprocally in contaA 

 with each other. They are coveied in .fi-orii by the tendons 

 of the flexor profundus, by the lumbricale's, and, fo for as 

 the three firft are concerned, by the adductor pollicis. They 

 are retained, towards the end of the metacarpus, by the an- 

 terior iranfvcrfe palmar ligament, at the level of \shich they 

 is are 



