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THE FIFTEENTH TABLE.
Fig. 1.
DIVERS Muscles of the Lower Jaw, and Os Hyoides in Situ, the Skin, and Musculus Quadratus Colli being Remov'd.
A B C, The Musculus Digastricus or Bi∣venter; B, its Fleshy Origination from the Processus Mammillaris; C, its Middle Ten∣don passing thro' the Musculus Stylocerato∣hyoideus (N), and an Annular Ligament arising from the Os Hyoides, to its Fleshy Termination A, in the Lower Jaw (D).
The Middle Tendon of this Digastric Muscle, and its Part∣ner, passing thro' Two Annular Ligaments Fixt to the Os Hyoides, as the Ropes thro' a Double Pully, is a necessary Contrivance in Nature to render them capable of pulling the Lower Jaw Down; which, had their Progress been di∣rect from their Originations, they could not have per∣form'd; nor is there any Processes, whether of the Vertebrae of the Neck, or Neighbouring Parts, that could give Origina∣tions to these Muscles below their Insertions, as in some Qua∣drupedes: Wherefore the Divine Architect, in Humane Bo∣dies, has plac'd this Double-Pully below their Terminations, by which means they are made capable of performing their design'd Office. Hence Deglutition is Hindred, when these Muscles are in Action, they at that Time preventing the Ascent of the Tongue, and Larynx; neither can we in the Time of Swallowing, draw the Lower Jaw down, because the Center of Direction is pull'd up; wherefore we are oblig'd to keep the Jaws close in that Action. But in Dogs, and other Voracious Animals, (wherein these Muscles Arise from the Transverse Processes of the First Vertebra of the Neck) these Actions do not Depend upon each other; whence it is they devour their Aliment so Quick
D, The Inferior Edge of the Lower Jaw Bone made bare.
E E, The Musculus Mylohyoideus, which derives its Fleshy Origin from the Internal Part of the Lower Jaw, partly under the Inferior Maxillary Glands, and partly at the Insertions of the Musculus Digastricus; whence Descending with a Dou∣ble Order of Fibres, here elegantly Exprest, is inserted to the Superior and Forepart of the Os Hyoides. Immediate∣ly under this Muscle lie the Glandulae Sublinguales, and Sali∣val Ducts of the Inferior and Maxillary Gland; both which are Comprest by it, and their contain'd Saliva driven Fore∣wards into the Mouth when this Muscle Acts, as in Deglu∣tition, &c.
F F, The Musculi Sternohyoidei, Arising from the Internal and Superior Part of the Claviculae, and not from the Ster∣num, as it's Vulgarly suppos'd, and are inserted to the Infe∣rior, and Forepart of the Os Hyoides.
G G, Parts of the Ceracohyoidei, coming from under the Mastoid Muscles (II).
H H, Parts of the Sternothyroidei, which spring from the Superior and Internal Part of the Sternum, and march under the Sternohyoidei to their Terminations in the Thyroide Carti∣lage, as appears in the following Figure.
I I, The Mastoidei.
K, Part of the Masseter on the Right Side.
L, Part of the Parotid Gland on the same Side.
M M, The Glandulae Maxillae Inferioris.
N, That Part of the Musculus Stylohyoideus, that is Perfo∣rated to transmit the Middle Tendon of the Biventral Muscle of the Lower Jaw; which together with an Annular Liga∣ment, springing from the Os Hyoides, in like manner invol∣ving the last mention'd Middle Tendon of that Muscle, do's like a Pully render it capable of pulling the Lower Jaw down, as above Noted.
O, Part of the Internal Jugular Vein.
P, Part of the Carotid Artery.
Q, A Blood-Vessel cut off and ti'd.
Fig. 2.
Divers Muscles lying under those exprest in the former Figure.
A A A, The Lower Edge of the Inferior Jaw-Bone laid bare.
B B, The Musculi Sternohyoidei free'd from their Insertions, and left at their Originations.
C C C C, The Coracohyoidei are a Pair of Digastrick Mus∣cles; they Arise Fleshy from the Processus Coracoides Scapulae, and Ascend under the Musculi Mastoidei where they become Tendinous, but Growing Fleshy again, are Inserted at the Ba∣sis of the Fore-Bone of the Os Hyoides; this draws the Os Hy∣oides downwards, and pulls it somewhat inwards.
D, Part of the Musculus Stylohyoideus at its Termination.
E E, The Musculus Mylohyoideus; on the Right Side not quite Free'd from its Origination; on the Left, so Rais'd, as that the Glandula Sublingualis W, do's Appear; this Bidloo calls Geniohyoidei.
F F, The Geniohyoidei, by Bidloo call'd Anthereohyoidei; they Arise Fleshy from the Internal Part of the Lower Jaw, which composes the Chin, and are Inserted to the Superior, and Forepart of the Os Hyoides: When these Muscles Act, the Os Hyoides is pull'd Upwards, and Forewards, and Assist the Genioglossi in Thrusting the Tongue out of the Mouth.
G G, The Digastrick Muscles of the Lower Jaw cut from their Insertions.
H H, The Mastodei Muscles; that of the Right Side being cut from its Origination and left at its Insertion, that of the Left remaining in Situ.
I, The Scutiformal Cartilage of the Larynx, which makes what they call, the Pomum Adami.
K, The Aspera Arteria or Wind-Pipe.
L L, The Glandulae Thyroidaeae.
M, The Musculus Masseter in Situ.
N, The Musculus Pterygoideus Internus in Situ; it A••••es partly Tendinous, and partly Fleshy, from the Cavity of the Winglike Process of the Os Sphenoides. Tab. 29. Fig. 2. K. whence it Descends to its Implantation at the Internal and Inferior Part of the Lower Jaw-Bone, opposite to the Ter∣mination of the Masseter: Either this, or its partner Acting, draws the Jaw to the contrary Side; if both Act, they Assist the Musculi Temporales, and Masseteres.
O, Part of the Parotid Gland.
P, The Musculus Hyothyroideus; it Arising from the Os Hyoides, is Inserted to the Lower Part of the Scutiformal Car∣tilage; this draws the Larynx Upwards in an Acute Tone of the Voice.
Q, The Cricothyroideus. See Tab. 24. Fig. 5. H H.
R, The Sternothyroideus ending in the Scutiformal Carti∣lage.
S, The Internal Jugular Vein, whose Lower Part is at some distance plac'd under that Part of the Mastoid Muscle, (App. Fig. 1.14.) which springs from the Clavicle, which Part of that Muscle is most commonly Contracted in those who are said to have Wry Necks, which the Operator in that Case ought to Observe, least in too boldly Thrusting in his Knife to divide the contracted Part, he also Wounds this large Blood-Vessel, and the Flux of Blood prove Destructive to the Patient; for tho' its Flux may easily be restrain'd out∣wardly, yet the Vein lying in so large an Interstice, defended by the Clavicle, and Adjacent Muscles, the Blood will ne∣vertheless pass out of the Vessel between the Muscles, and Neighbouring Parts. When such a Mischief is done, we ought to divide the External Integuments largely, and clear the Part of the Coagulated Blood, and apply a moderate Compress on the Wounded Vessel: An Instance of which Practice we had once Occasion to make in a Wound between the Pectoral, and Deltoid Muscles, immediately under the Clavicula, where the Subclavian Vein was Wounded. In such like Cases, how can those Ignorant in Anatomy, Practice without Fear and Trembling?
T, The Carotid Artery.
V, A large Vein proceeding from the Thyroide Gland to the Ramus Subclavius.
W, The Glandula Sublingualis lying immediately under the Musculus Mylohyoideus.