There are fourteen, _viz._ four Common, and ten Proper. The first Pair of the Common is the _Sternothyroideus_ or _Bronchycus_, which proceeding from the inside, and the top of the _Sternum_, ascends along the Cartilages of the Wind-Pipe, and is terminated in the bottom of the {29} _Scutiformis_ or Buckler-like Cartilage, which it draws downward. The second is the _Hyothyroideus_, which ariseth from the Root of the _Os Hyoides_, and is inserted in that of the _Scutiforme_. This Muscle serves to lift up the _Larynx_, as also to dilate the bottom of the _Scutiformis_, and to close its top.
The first Pair of the Proper is the _Cricothyroideus Anticus_, which deriving its Original from the hinder and upper part of the _Cricoides_, or Ring-like Cartilage, is fixt in the upper and lateral part of the _Scutiformis_, to close or shut it up.
The second is the _Thyroides_.
The third is the _Cricoarytenoideus Lateralis_, which proceeds from the side of the _Cricoides_ within, and is fasten"d to the bottom and side of the _Arytenoides_, which it removes to dilate the Mouth of the _Larynx_.
The fourth is the _Thyroarytenoideus_, which arising from the fore-part on the inside of the _Scutiformis_, is terminated on the side of the _Arytenoides_, to close the Orifice of the _Larynx_.
The fifth is the _Arytenoideus_, which having its Source in that place where the _Cricoides_ is united to the _Arytenoides_ is inserted in its upper and lateral part, to close the _Larynx_.
_How many Muscles hath the _Pharynx_?_
It hath seven, the first whereof is the _Oesophagieus_, which takes its rise from the side of the _Scutiformis_ or Buckler-like Cartilage, and pa.s.sing behind the _Oesophagus_ or Gullet, is fasten"d to the other side of the Cartilage. It thrusts the Meat down by locking up the _Pharynx_ as a _Sphincter_.
The second named _Stylopharingaeus_, springs from within the Acute _Apophysis_ of the _Os Sphenoides_, or _Cuneiforme_, and is inserted obliquely {30} in the side of the _Pharynx_, which it dilates by drawing it upward.
The third, call"d _Sphenopharyngaeus_, proceeds from the _Apophysis Styliformis_, and is terminated in the side of the _Pharynx_, which it dilates by drawing its sides.
The fourth Pair is the _Cephalopharyngaeus_ which ariseth from the articulation of the Head with the first _Vertebra_, and closeth the _Larynx_.
_How many Muscles are there in the Neck, and which be they?_
There are four Muscles in the Neck on each side, _viz._ two Flexors, and two Extensors. The _Flexors_ are the _Scalenus_ and the _Rectus_ or _Longus_; and the Extenders are the _Spinatus_ and the _Transversalis_.
The _Scalenus_ or _Triangularis_ hath two remote Sources, _viz._ one in the first Rib, and the other in the Clavicle, and is fasten"d to the third and fourth _Vertebra_ of the Neck.
The _Rectus_ or _Longus_ begins in the side of the four upper _Vertebra"s_ of the Back, and is join"d to the upper _Vertebra"s_ of the Neck, and the hinder part of the Head.
The _Spinatus_ hath its Origine in the fourth and fifth upper _Vertebra"s_ of the Back, and is fasten"d to all the six lower _Vertebra"s_ of the Neck.
The _Transversalis_ springs forth out of the upper _Vertebra"s_ of the Back, and cleaves to the Extremity of the four _Vertebra"s_ of the Neck.
{31}
CHAP. VIII.
_Of the Myology or Anatomy of the Muscles of the Chest; or of the Breast Belly, and Back._
_How many Muscles are there in the Breast, and which be they?_
The Breast hath fifty seven Muscles, that is to say, thirty that serve to dilate it, twenty six whose Office is to contract it, and the _Diaphragm_ or Midriff, which partakes of both Actions.
The thirty which dilate the Breast are equally plac"d to the number of Fifteen, _viz._ the _Subclavius_, the _Serratus Major Anticus_, the two _Serrati Postici_, and the eleven external _Intercostals_.
The twenty six which contract the Breast are likewise equally rank"d to the Number of thirteen on each side, _viz._ the _Triangularis_, the _Sacrolumbus_, and eleven internal _Intercostals_.
The _Subclavian_ takes up the whole s.p.a.ce between the Clavicle and the first Rib: Its Original being in the internal and lower part of the _Clavicula_, and its insertion in the upper part of the first Rib.
The _Serratus Major_ is a large Muscle having seven or eight Indentings or Jaggs. It takes its rise in the interior Basis of the _Omoplata_ or Shoulder-Blade, and its Jaggings are inserted in {32} the five lower true Ribs, as also in the two upper spurious Ribs.
The _Serratus Posticus Superior_, begins with a large _Aponeurosis_ in the _Apophyses_ of the three lower _Vertebrae_ of the Neck, and of the first of those of the Back; then pa.s.sing under the _Rhomboid_, it is join"d obliquely by four Indentings to the four upper Ribs.
The _Serratus Posticus Inferior_, commences in like manner with a large _Aponeurosis_ in the _Apophyses_ of the three lower _Vertebra"s_ of the Back, and of the first of those of the Loins, and is afterwards fasten"d by four Digitations to the four lower Ribs.
The eleven _External Intercostal_ Muscles are situated in the s.p.a.ces between the twelve Ribs pa.s.sing obliquely and on the outside from the back part to the fore part. They take their rise below the Upper Rib, and have their Insertion above the lower Rib.
The _Triangularis_ is the first of those that contract the Breast, and possesseth the inward part of the _Sternum_: Its Original is in its lower part, and its Insertion in the top of the Cartilages of the two upper Ribs.
The _Sacrolumbus_ hath its Source in the hinder part of the _Os Sacrum_, as also in the _Vertebra"s_ of the Loins, and ascending from thence, insinuates it self into the hinder part of the Ribs, to every one of which it imparts two _Tendons_, one whereof sticks on the outside, and the other on the inside. This Muscle is fleshy within, and fibrous without.
The Eleven _Internal Intercostals_, contrary to the External, derive their Original from the {33} top of every lower Rib, and ascend obliquely from the back-part to the fore-part, till they are join"d to the lower Lip of every upper Rib: Thus these Internal Muscles, with the External, form, by the opposition of their Fibres, a Figure resembling a _Burgundian_ Cross.
The Diaphragm or Midriff is esteem"d as the fifty seventh Muscle of the Breast, and serves as well for its dilatation as contraction. It separates the _Thorax_ or Chest from the lower Belly, and is tied circularly to all the Extremities of the b.a.s.t.a.r.d Ribs, immediately under the _Xiphoides_, or Sword-like Cartilage.
Modern Anatomists have discover"d that the Diaphragm is compos"d of two Muscles, _viz._ one Upper, and the other Lower; so that the Upper cleaves to the Extremities of the Spurious Ribs, and is terminated in a flat _Tendon_ in the middle, which hath been always taken for its Nervous part.
The Lower begins with two Productions, the longest whereof being on the right side, ariseth from the three upper _Vertebra"s_ of the Loins, and the other on the Left from the two _Vertebra"s_ of the Back, till it is lost in the _Aponeurosis_ of the Upper Muscle.
_How many Muscles are there in the Back and the Loins, and which be they?_
There are three in each side, _viz._ one for Flection, and the other for Extension.
The _Triangularis_ is the _Flexor_, taking its rise in the hinder part of the Rib of the _Os Ilion_, and the inner part of the _Os Sacrum_, in pa.s.sing from whence it is joined to the last of the {34} b.a.s.t.a.r.d Ribs, and to the transverse Productions of the _Vertebra"s_ of the Loins.
The _Extensors_ are the _Sacer_, and the _Semi-spinatus_, which make the Waste streight, and are so interwoven along the Back-Bone, that one would imagine that there were as many Pairs of Muscles as _Vertebra"s_, affording _Tendons_ to all.
The _Sacer_ springs from behind the _Os Sacrum_, as also from the hinder and upper Extremity of the _Os Ilium_, and is inserted in the Spines of the _Vertebra"s_ of the Loins and Back.
The _Semi-spinatus_ hath its Source in the Spines of the _Os Sacrum_, and is join"d to all the transverse Productions of the _Vertebra"s_ from the Back to the Neck, being exactly situated between the _Sacer_ and the _Sacrolumbus_.
CHAP. IX.
_Of the Myology, or Anatomy of the Muscles of the lower Belly._
_How many Muscles are there in the lower Belly, and which be they?_
There are generally ten, five on each side, that is to say, two _Obliqui_, one ascending, and the other descending; one _Transversus_, one _Rectus_, and two Pyramidal, of which last, nevertheless, there is sometimes only one, and sometimes none at all. {35}
The _Obliquus Descendens_, which is the first, hath its Original by digitation in the sixth and seventh of the true Ribs, in all the spurious Ribs, and in the transverse _Apophyses_ of the _Vertebra"s_ of the Loins, and comes near to the _Serratus Major Anticus_ of the Breast; from whence it proceeds to the external Rib of the _Os Ilion_, and is terminated by a large _Aponeurosis_ in the _Linea Alba_ or _White Line_, which separates the Muscles that are on each side of the _Abdomen_ or lower Belly.
The _Obliquus Ascendens_ ariseth from its Source in the upper part of the _Os Pubis_, and in the Ridge of the Hip-Bone, till it cleaves to the _Apophyses_ of the _Vertebra"s_ of the Loins in the Extremities of all the Ribs, and in the _Xiphoides_ or Sword-like Cartilage, and is terminated in the White Line by a large _Aponeurosis_.
The _Rectus_ being situated between the _Aponeuroses_ of the _Obliquus_, takes its rise in the Cartilages of the Ribs, in the _Xiphoides_ and the _Sternum_, and enters into the _Os Pubis_, having many nervous parts to corroborate it in its length.