Two several Motions are perform"d by the Wrist, _viz._ one of Flection, and the other of Extension, three Muscles being appropriated to the former, and as many to the later: But it ought to be observed, that a strong Ligament, call"d the _Annular_, appears here, which, surrounding all the _Tendons_ of the Muscles as it were a Bracelet, holds them together, and elsewhere serves to unite the two Bones of the Elbow. The three Flexors or Bending Muscles of the Wrist are the _Cubitaeus Internus_, the _Radiaeus Internus_, and the _Palmaris_.
The _Cubitaeus Internus_ derives its Original from the part of the Arm-Bone, pa.s.seth under the Annular Ligament, and is ty"d by a thick _Tendon_ to the small Bone of the Wrist, which is plac"d above the others.
The _Radiaeus Internus_ proceeds from the same place with the _Cubitaeus_, and is fasten"d to the first Wrist-Bone which supports the Thumb. It lies along the _Radius_, and pa.s.seth under the _Annular_ Ligament.
The _Palmaris_ is reckon"d among the Flexors of the Wrist, although situated in the Palm of the Hand. It ariseth from the inner Process or k.n.o.b {44} of the Arm-Bone, and is united by a large _Tendon_ to the first _Phalanges_ of the Fingers, slipping under the Transverse or _Annular_ Ligament and sticking under the Skin of the Palm of the Hand.
The three extending Muscles of the Wrist are the _Cubitaeus Externus_, and the _Radiaeus Externus_ or the _Longus_, and the _Brevis_.
The _Cubitaeus Externus_ taking its rise from the hinder-part of the Elbow, pa.s.seth under the _Annular_ Ligament, and adheres to the upper and outward-part of the Bone of the _Metacarpus_ that stayeth the little Finger.
The _Radiaeus Externus_, or the _Longus_, having its Origine in the edge of the lower part of the Arm-Bone, slides from thence along the _Radius_ on the outside, extends it self under the _Annular_ Ligament, and cleaves to the Wrist-Bone, which stayeth the Fore-Finger.
The _Brevis_ or _short_ Muscle of the Wrist springs from the lower part of the same Edge; afterwards it runs along the _Radius_, pa.s.seth under the _Annular_ Ligament, and is terminated in the Bone of the _Carpus_ or Wrist, which stayeth the Middle Finger. But we must take notice, that besides these six Muscles, there is also _Caro quaedam quadrata_, or a square piece of Flesh under the _Palmaris_, which seems to arise from the _Thenar_, and sticks to the eighth Wrist-Bone. It is supposed that this Musculous piece of Flesh serves with the _Hypothenar_ of the little Finger, to make that which is call"d _Diogenes"s Cup_.
_How many Motions are there in the Fingers, and what are their Muscles_?
{45}
The Fingers are bent, extended, and turn"d from one side to the other by the means of twenty-three Muscles, whereof ten are proper, and thirteen common: The former are those that serve all the Fingers in general, and the other those that are particularly serviceable to some of them: The Common are the _Sublimis_, the _Profundus_, the common _Extensor_, the four _Lumbricales_, and the six _Interossei_.
The _Sublimis_ or _Perforatus_, arising from the internal part of the lower Process of the _Humerus_ or Shoulder-Bone is divided into four _Tendons_, which run below the _Annular_ Ligament of the Wrist, and are inserted in the second _Phalanx_ of the Bones of the four Fingers, after having stuck in pa.s.sing to those of the first _Phalanx_, to help to bend it. It is also observed that every one of these _Tendons_ hath a small cleft in its length, to let in the _Tendons_ of the _Profundus_.
The _Profundus_ or _Perforans_ lies under the _Sublimis_, deriving its Original from the top of the _Cubitus_ and _Radius_. It creeps along these two Bones, and is divided into four _Tendons_, which pa.s.s under the _Annular_ Ligament, and slip into the Fissures of the _Tendons_ of the _Sublimis_, to adhere to the third _Phalanx_ of the Fingers, which they bend with the _Sublimis_: So that these two Muscles make together the bending of the Fingers.
The _Extensor Magnus_ is that which extends the four Fingers. It springs from the external and lower Process of the Arm-Bone, and is divided into four flat _Tendons_, which pa.s.s under the _Annular_ Ligament, and cleave {46} to the second and third _Phalanx_ of the Fingers.
The four _Lumbricales_ or _Vermiculares_ are in the Palm of the Hand, to draw the Fingers to the Thumb: They proceed from the _Tendons_ of the _Profundus_, and the _Annular_ Ligament, extend themselves along the sides of the Fingers and are inserted in their second Articulation, to cause the drawing toward the Thumb.
The three _Interossei Interni_, and the three _Externi_, are situated between the four Bones of the _Metacarpium_, as well on the inside of the Hand as without: They have their beginning in the Intervals or s.p.a.ces between the Bones of the _Metacarpium_, are united with the _Lumbrical_, and fixt in the last Articulation of the Bones of the Fingers, to produce the Motion of drawing back or removing from the Thumb.
The Thumb is mov"d by five particular Muscles; one whereof serves to bend it, two to extend it, one to remove it from the Fingers, and another to draw it to them.
The _Flexor_ of the Thumb takes its rise from the upper and inner part of the _Radius_, pa.s.ses under the _Annular_ Ligament, as also under the _Thenar_, and adheres to the first and second Bones of the same Thumb to bend it.
The two _Extensors_ of the Thumb are the _Longior_ and the _Brevior_: The former proceeding from the upper and outward part of the _Cubitus_, ascends above the _Radius_, and is ty"d with a forked _Tendon_ to the second Bone of the Thumb. The _Brevior_ hath the same Origin with the _Longior_, keeps the same Track, pa.s.ses under the _Annular_ Ligament, and is terminated in the third Thumb-Bone. {47}
The _Thenar_ removes the Thumb from the Fingers, and forms that part which is call"d the _Mount of Venus_: It hath its Source in the first Bone of the _Carpus_ or Wrist, and the _Annular_ Ligament, and is inserted in its second Bone.
The _Ant.i.thenar_ draws the Thumb to the other Fingers, having its Origine in the Bone of the _Metacarpus_, that stayeth the middle Finger, and its Insertion is in the first Bone of the Thumb.
The Muscle which serves to extend the Fore-Finger, is call"d _Indicator_: It proceeds from the middle and outer part of the _Cubitus_, and is fixt by a double _Tendon_ in the second Articulation of the Fore-Finger, as also in the _Tendon_ of the great _Extensor_ of the Fingers.
That which draws the Fore-Finger to the Thumb is term"d _Adductor_: It commenceth in the fore-part of the first Thumb-Bone, and is terminated in the Bones of the Fore-Finger.
That which removes the Fore-Finger from the Thumb is known by the Name of _Abductor_, which arising out of the external and middle part of the Bone of the Elbow, and pa.s.sing under the _Annular_ Ligament, cleaves to the Lateral and outward part of the Bones of the Fore-Finger.
The Little-Finger hath two proper Muscles, _viz._ an _Extensor_ and an _Abductor_.
The _Extensor_ springs from the lower part of the _Condylus_ of the Arm-Bone, and is fasten"d by a double _Tendon_ in the second Articulation of the Little-Finger, and in the _Tendon_ of the _Extensor_ of all the others. {48}
The _Abductor_, call"d also _Hypothenar_, hath its beginning in the small Bone of the Wrist, which is situated over the others, and is terminated in the first Bone of the Little-Finger on the outside.
CHAP. XI.
_Of the Muscles of the Thighs, Legs, and Feet._
_What are the Motions of the Thighs?_
The Thigh performs five kinds of Motions; for it is bent, extended, drawn within side and without, and turn"d round: All these Motions are produc"d by the means of fourteen Muscles, _viz._ three _Flexors_, three _Extensors_, three _Adductors_, three _Abductors_, and two _Obturators_ for the Circular Motion.
The _Flexors_ of the Thigh are the _Psoas_, _Iliacus_, and _Pectineus_.
The _Psoas_ or _Lumbaris_ is situated inwardly in the _Abdomen_, on the side of the _Vertebra"s_. It proceeds from the transverse _Apophyses_ of the two lower _Vertebra"s_ of the Back, and of the upper of the Loins, and lying on the inner Face of the _Os Ilion_, sticks to the lesser _Trochanter_ or _Rotator_.
The _Iliacus Internus_ hath its Origine in all the Lips of the inner Cavity of the _Os Ilion_, and being joyn"d by a _Tendon_ to the _Lumbaris_, is inserted with it in the lesser _Trochanter_. {49}
The _Pectineus_ takes its rise from the fore-part of the _Os Pubis_, and is united before to the Thigh-Bone a little below the lesser _Trochanter_.
The _Extensors_ of the Thigh are the _Glutaeus Major_, _Medius_, and _Minimus_.
The _Glutaeus Major_ springs forth out of the lateral part of the _Os Sacrum_, as also the hinder and outer part of the _Os Ilion_ and _Coccyx_, and enters into the Thigh-Bone, four Fingers breadth below the great _Trochanter_ or _Rotator_, being the thickest of all the Muscles of the Body.
The _Glutaeus Medius_, deducing its Original from the hinder and outward part of the _Os Ilion_, is inserted three Fingers breadth below the great _Trochanter_.
The _Glutaeus Minimus_ ariseth from the bottom of the Cavity of the _Os Ilion_, and is fasten"d to a small Hole near the great _Trochanter_.
The _Adductors_ of the Thigh are the _Triceps Superior, Medius_, and _Inferior_.
The _Triceps Superior_ hath its beginning in the top of the _Os Pubis_, and is terminated in the top of a Line, which is on the inside of the Thigh.
The _Triceps Medius_ proceeding from the middle of the _Os Pubis_, is inserted in the Thigh-Bone a little lower than the _Triceps Superior_.
The _Triceps Inferior_ hath its Source in the bottom of the _Os Pubis_, and is implanted in the Thigh-Bone, a little lower than the _Triceps Medius_.
Some Anatomists make only one Muscle of these three, attributing thereto three Originals and three Insertions. These Muscles serve to draw the Thighs one against another.
The _Abductors_ of the Thigh are the _Iliacus Externus_, or _Pyriformis_, the _Quadratus_, and the _Gemelli_. {50}
The _Pyriformis_ arising from the upper and lateral part of the _Os Sacrum_, and the the _Os Ilion_ cleaves to the Neck of the great _Trochanter_.
The _Quadratus_ or square Muscle of the Thigh takes its Origine from the external Prominence of the _Os Ischion_, and adheres to the outward part of the great _Trochanter_.
The _Gemelli_ or Twin Muscles arise from two small k.n.o.bs in the hinder-part of the _Ischion_ and insinuate themselves into a small Cavity in the Neck of the great _Trochanter_.
The Circular Motion of the Thigh is performed by the means of two Muscles, named the _Obturatores Externi_ and _Interni_.
The _Obturator Internus_ springs from the inner Circ.u.mference of the Oval Hole of the _Ischion_ and its _Tendons_ pa.s.sing between the two _Gemelli_ are inserted in a small Cavity at the Root of the great _Trochanter_ or _Rotator_.