Treatment of fracture of the jaw : with critical remarks / by Thos. Brian Gunning.

  • Gunning, Thomas Brian, -1889
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: Treatment of fracture of the jaw : with critical remarks / by Thos. Brian Gunning. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    upon the back of the head, and I have been unable to find any action in the clavicular portion, although the action of this part of the muscle is so delicate and prompt that it can be distinctly felt when the foot is raised in walking, the head and body being then thrown over to the other side to restore the balance. Further, when the sterno-cleido-mastoid and the splenius of the same side are acting in concert to pull the head down to the shoulder, no backward move- ment of the head is discoverable. This is conclusive, for both these muscles having similar insertions, if one rocks the head back the other must, and their combined action would be manifest if they exerted it. It has been shown that this muscle acts as a lateral flexor, in con- nection with the splenius of the same side, but only when the head is obstructed, and then generally by its clavicular portion, the sternal acting only in extreme necessity. It is now seen that it does not flex the head down in front, that is upon the atlas at all, and that its action as an extensor of the head cannot be demonstrated. The proper function of the sterno-clcido-inastoids when acting in concert is to give anterior support to the top of the spine, the splenii muscles giving posterior support. This may be easily proved by sitting- down and watching the tendons. When the head is back of its centre of support both the sternal and clavicular tendons are tightened, when rising they become tenser until the head is started, as it comes into balance they relax. On sitting down the tendons tighten to check the head as it goes back out of balance. Sudden forward movements tighten them until the head is in motion, they then slacken as the head is forward of the centre and the atlas supported by the splenii muscles. If the head is in balance any pressure upon the forehead brings the muscles into action to preserve it. The action of the muscles in these movements is but a modification of the service rendered by them in raising the head from the horizontal position, in doing which the muscles at first support more than the weight of the head ; for in supporting the mastoid processes they support the atlas, and make it a fulcrum between the bulk of the head and the counter- balance at the other end of the lever; but as the body comes upright and the head into balance, the strain upon the sterno-mastoid muscles gradually diminishes, until the head is held by the posterior muscles, when the spine bears all the weight. [A reference to the figure will render this explanation more apparent. The same figure also illustrates the action of the muscles of the lower jaw, and confirms the opinions expressed in the subsequent portions of this paper.]