backe-bone. By the head we understand the narrower part thereof, in which it re∣ceives the head of the Arme in a cavity, indifferently hollow, which it produces both by it selfe, as also by certaine gristles, which there fastened encompasse that cavity. This kinde of cavity is called Glene.
This receives and containes the bone of the arme, by a certaine strong ligament en∣compassing & strengthening the joynt, which kind of ligament is common to all other joints; this ligament arises from the bottome of the cavity of the shoulder-blade, and circularly encompasses the whole joynt, fastening it selfe to the head of the arme; there are also other ligaments besides this, which encompasse & strengthen this arti∣culation. By the spine is ment a processe, which rising by little and little upon the gib∣bous part of the blade, from the basis thereof where it was low and deprest, becomes higher untill it ends in the Acromion, or upper part thereof. Nature hath made two productions in this bone (that is to say, the Acromion from the spine, and the Coracoi∣des from the upper side) for the strengthening of the articulation of the arme and shoulder-blade, that is, left the arme should be easily strained upward or forwards; besides, it is fastened to the clavicle, by the processe Acromion.
The muscles which move the shoulder-blade are sixe in number, of which foure are proper, and two common. The first of the foure proper seated in the forepart, ascends from the bones of five or sixe of the upper ribbs, to the Coracoides, which it drawes forwards, and is called Serratus minor, that is, the Lesser saw-muscle; which that you may plainely shew, it is fit you pull the pectorall muscle from the collar-bone, almost to the middle of the Sternon. The other first opposite against it, is pla∣ced on the fore side, and drawes its originall from the three lower spines of the necke, and the three upper of the Chest, from whence it extends it selfe, and ends into all the gristly basis of the shoulder-blade, drawing it backwards; it is called the Rhom∣boides. The third from its action, is called the Levator, or the heaver, or lifter up, seated in the upper part, it descends from the transverse processes of the foure first Vertebrae of the necke into the upper angle and spine of the blade. The fourth called Trapezius, or the Table-muscle, is seated in the backe part, and is membranous at the originall, but presently becoms fleshy: it arises from almost all the backe-part of the head, from all the spines of the necke, and the eight upper Vertebrae of the chest, and then is inserted by his nervous part, almost into the whole basis of the blade, exten∣ding it selfe above the muscles thereof, even to the midst of its spine, where being fleshy it is inserted even to the Acromion, the upper part of the calvicle, and in some sort to the upper ribbe. This muscle hath a threefold action, by reason of its triple originall. The first is to draw the shoulder-blade towards its originall, that is, to the nowle, and spine of the necke; the other is to draw it towards the backe, because of the contraction of the middle or transverse fibers which leade it directly thither; and the other is to draw it downewards by reason of the originall it hath from the fifth, sixth, seventh, and eight spine of the Vertebrae of the Chest.
But we must note that these diverse actions are not performed by this muscle, by the assistance of one onely nerve, but by more, which come into it by the spinall marrow, by the holes of the Vertebrae, as well of the necke as the chest, from whence it takes the originall. For the two other which are the common muscles of the blade, and arme, or shoulder, we will describe them with the muscles of the shoulder or arme: for one of these which is called the Latissimus, that is, the broadest, ascends from the holy-bone to the shoulder-blade and arme.
The other named the Pectoralis coms from the Sternon and collar-bone to the shoulder-blade and arme.