Chap. 8. Of the Muscles of the Cubitus and Radius.
THe Muscles of the CUBIT, according* 1.1 to the arbitrary Method of Dissecti∣on follow. Yet I do advise the Dissector, that the Muscles of the Radius are not to be shewed immediately after those, but last of all; but after the Muscles of the Cubit, those of the fingers, thumb and wrist; because the Muscles of these parts being shewn and removed, the Insertions of the Muscles of the Ra∣dius, are more couveniently discerned. Otherwise the Brachium may follow next after the demonstration of the Muscles of the Cubitus and Radius, by an Or∣der free for any one to follow.
The Muscles of the Cubit are four, and of the RA∣DIUS as many.
There are two Benders of the Cubit, as the Biceps and Brachiaeus: two Extenders, viz. the Longus and the Brevis.
There are two Pronators of the Radius, the Rotun∣dus and the Quadratus, and two Supinators, the Lon∣gior and Brevior.
For the proper Motion of the Cubit is flexion and extension. But the Radius makes the whole Arm prone or supine.
The first of the Cubit is termed BICEPS; because of its double distinct Beginning, which is from the Scapu∣la, the one tendinous and round, from the upper lie of the Acerabulum, the other broader and less tendi∣nous, from the Processus ancoriformis. And it is inserted with the Head of the Radius, and possesses the in∣ner part of the Arm with its Body. The tendon of this Muscle ought in Blood-letting to be taken heed of.
The second lying under this, and spred out upon the bone it self, being short, is called BRACHIAEUS; 'tis all fleshy, less then the former; artses from the middle bone of the Brachium, and is before inserted into the common beginning of the Cubitus and Radius, and the Ligament of the Joynt.
The third is the EXTENDENS primus and LONGUS, it arises with a double beginning, from the lower Rib of the Scapula, is ended being fleshy in the Olecra∣num.
The fourth is the EXTENDENS secundus and BRE∣VIS; it arises from the Neck of the Humerus, is be∣hind mixed with the precedent, and occupies the Os Humeri; and it ends into the part of the Olecranum on which we lean.
Casserius adds a fift called tertius extendens, which o∣thers count a portion of the fourth Muscle; but he counts it a distinct Muscle, as later Anatomists Riola∣nus and Veslingus do, which they term Anconeus. But he would have it to be a portion of his Brachiaeus, be∣cause it sticks sometimes close to the fleshy Extremity thereof, and to answer to the Poplitaeus, that an equali∣ty may be maintained between the foot and the hand. It springs out of the hinder extremity of the Shoulder, by the end of the fourth and third Muscle, and passing beyond the Joynt of the Cubir, it is also inserted by its hinder and lateral part, yet not above a fingers bredth beyond the Olecranum, into the Os Cubiti.
Moreover Galen seems to add a sixt, which is the fourth Extender, viz. a fleshy Lump hudled up of the two former, which Riolanus calls Brachiaeus externus, to difference it from the Brachiaeus intern is flectens, be∣cause being spred out upon the outside of the Brachi∣um, it is placed under the two former.
The first Muscle of the Radius is termed ROTUN∣DUS, or Teres; from the inner Apophysis of the Arm by a strong and fleshy beginning, it ends obliquely ve∣ry near into the middle of the Radius, with a fleshy end, and likewise a membranous tendon, which Spige∣lius writes, does go again to the middle of the Radius, and is knit to the outward side of the said Radius.
The second QUADRATUS, reaching from the lowest part of the Cubita, into the lowest of the Radiu••s, wholly fleshy, every where two fingers broad; it goes above that Ligament common to the Radius and Cu∣bitus. These are the Manus pr••natores.
The third is the SUPINATOR PRIMUS, from the lo∣wer part of the Brachium growing sharp, till it reach into the lower part of the Radius, fleshy, where it is inserted with a tendinous End.
The fourth is the SUPINATOR ALTER, growing from the outward Apophysis of the Arm, fleshy, membra∣nous without, fleshy within, and is inserted into the middle wel-near of the Radius.
Among the Muscles of the Radius Casserius once found two little ones, and very small, about the Joynt Cubit, and proceeding in an opposite fashion, and moving the Radius Prone and Supine like a Pulley. Howbeit, I found them not as yet. I have somtimes seen in their place, in a musculous man, one triangular