Abdominal Pressure Model

Abdominal Pressure Model#

This model introduces intra-abdominal and intra-thoracic pressure, along with the diaphragm, which balance pressure balance between them.

The abdominal model consists of five layers connected to L1–L5, and layers connected to the pelvis and the diaphragm. Each layer contains multiple segments, constrained by averaging measures to maintain anatomical accuracy. Multiple nodes are defined on each layer, forming meshes that create volumes. These volumes can hold pressure and transfer forces to surrounding structures. As a result of the layer constraints, the volumes can compress or expand as the body moves. The detailed explanation of the model will be available in the forthcoming paper (Shayestehpour, H., Tørholm, S., Damsgaard, M., Lund, M., Wong, C., Rasmussen, J.: A generic detailed multibody abdominal and diaphragm model. Multibody Syst. Dyn.​).

Here are some examples of different postures of the abdominal pressure model.

../_images/Abdomen_postures.png

Pressure model#

The transversus abdominis, obliquus, and rectus abdominis muscles wrap around the abdominal volumes, exerting posterior pressure. The diaphragm muscles support upward pressure transmission to the ribcage, while the pelvic floor absorbs downward pressure. This pressure model generates an extensor moment on the ribcage, integrating detailed muscle configurations.

Muscles configurations#

New diaphragm muscles were introduced, and the abdominal muscles were updated. Below are figures of the new muscle configuration.

../_images/Abdomen_muscles.png

Example Configuration#

The abdominal pressure model can be controlled using the BM_* statements like the rest of the body models.

#define BM_TRUNK_CAVITY_MODEL _CAVITY_MODEL_BUCKLE_  //Enables the old buckle model
#define BM_TRUNK_CAVITY_MODEL _CAVITY_MODEL_VOLUME_  //Enables the new abdominal pressure model with the volumes

Resources#

References#

Will be available once the paper is published.

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