44 O B S E R V A T I O N S ON THE
C H A P T E R XVII.
Of the Connexion of the feveral Cords which compofe each
of the Nerves.
T .
F T E R finding, that, in the plexufes and net-works, the fibrils of
different nei-ves were intimately intermixed, and that, almoil all
our organs, whether aftivc or paiiivc, received branches of nerves from
various trunks^ I was naturally led to inveftigate, whether the cords, into
which the fibrils of the particular nerves are coUefted, run parallel to each
other in a common ilieath, without connedlion, fo that their number is the
fame at the end as at the origin of each nerve, which we lhall find is fuppofed
by authors * ; or whether thefe, in their progrefs, formed new combinations.
I foon found, that, in the whole extent of the nervous fyftem,
the fubordinate cords, of which the particular nerves confift, formed within
their proper iheaths a fuccelTion of plexufes, in which their fibrils were intermixed
and combined again, in nearly the fame manner as in the axillaiy
plexus formed by the trunks of the cervical nerves : Thus, when I flit open
the fheath of the brachial nerve, callcd Radial, by my father, or Median
by
• Haller, E!em. Phyf. Tab. 4- L. lo- S. 6. S 3- P- 187- and 188. « Nullus nervus adeo exiguus
' eft ut non ex pluribus conftet funiculis . . . . hi funiculi . . . . facile ofteuduntur cylindrici aut
' aliquantum compreiE, reSi, fibique paralleli et fiiniles, nufquam (fi a gangliis recefferis) confufi,
' nufquam ramofi, fed ab ipfo cerebro aut a fpinali medulla, ;id fuum ufque fmem di(tin£li, ut non
' piures in fine funt quam in principio. Numerus eorum funiculorun» iniri vix poteft. Saepe centum
' in uno nervo C^uinto funt, in ifchiadico plurcs.
' Deindc, fi microfcopium adhibuens, funiculi iJli, qui nudo oculo fimplices videntur, i
' alios difccduat,' &c.
N E R V O U S S Y S T E M . 45
by Winflow, which, after fupplying various mufcles, terminates in the
thumb and three next fingers, inftead of finding the fame number of fubordinate
cords at the lower end of the nerve, which I found at its upper part,
and, inflcad of finding that thefe were placed parallel and contiguous to
each other, but unconnefled, and that the outermoft of them ended in the
thumb, the next in the fore-finger, and fo on, I found a very different
number of fubordinate cords at the upper and under ends ; and the fibres
of thefe cords were, in theu- whole courfe, fo often feparated from each other,
then blended together, and afterwards combined into other cords,
that each of the cords, at the lower end, feemed to have received fibrils
from all the cords at tlie upper end
In like manner, I have difcovered, in the ear, that the branches of the
portio mollis form, upon the membrane and fcala of the cochlea, a mofl 6-=
legant plexus; in which the nervous filaments are fo intermixed as to form
new combinations, fo far as they can be traced with glaffes, and feem at laft
to terminate in a retina or web, fomewhat refembling that formed in the
eye by the optic nerve f .
S E C T 11 .
T chief intention of Nature, in this very foUicitous intermixture of the
nervous fibrils, is, I apprehend, to leffen the danger wi th which accidents
or difeafes, affeding the trunks of the nerves, would, without thefe combinations,
have been attended.
Thus, let us fuppofe that two nei-ves are fufficient to fupply the flexors
M and
• See Tab. XVin.
f I firfl traced the portio mollis on the membrane of the cochlea of an adult at Berlin, in the end
of the year 1756. In Table XXX. fee very accurate figures of this firft preparation, which I have annually,
fince that time, demonftrated in my anatomical courfes, and which feveral good judges have
had the curiofiry to examine with glalfes, particularly Dr Soemmering, Dr Meckel junior, Mr Luther^
P r Smith from Oxford, Dr Rutherford, Dr Black, Dr Hutton.