Diaphragm (anatomy)

From Freepedia

In the anatomy of mammals, the diaphragm is a shelf of muscle extending across the bottom of the ribcage. It separates the thoracic cavity (with lung and heart) from the abdominal cavity (with liver, stomach, intestines, etc.). In its relaxed state, the diaphragm is shaped like a dome. It is critically important in respiration: in order to draw air into the lungs, the diaphragm contracts, thus enlarging the thoracic cavity and reducing intra-thoracic pressure. (The muscles between the ribs also participate in this enlargement.) When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity.

The diaphragm also helps to expel vomit, feces, and urine from the body by increasing intra-abdominal pressure. A hiccup occurs when the diaphragm contracts periodically without voluntary control. A hiatal hernia is a tear in the diaphragm.

If the diaphragm is struck, or for other reasons, it may spasm briefly, making breathing difficult. This is called "being winded" or "having the wind knocked out of you". In some martial arts, practitioners are trained to do this.

There are three main apertures (or holes) in the diaphragm, one each for the inferior vena cava (the Foramen Venae Cavae), aorta (the Hiatus Aorticus) and oesophagus.

External links

• Gray's anatomy, muscles of the thorax

Muscles of the trunk

The deep muscles of the back: Interspinales muscle | Intertransversarii muscle | Multifidus muscle | Rotatores muscle | Sacrospinalis muscle | Semispinalis muscle | Splenius capitis muscle | Splenius cervicis muscle The suboccipital muscles: Obliquus capitis inferior muscle | Obliquus capitis superior muscle | Rectus capitis posterior major muscle | Rectus capitis posterior minor muscle The muscles of the thorax: Diaphragm | Intercostales externi muscle | Intercostales interni muscle | Levatores costarum muscle | Serratus posterior inferior muscle | Serratus posterior superior muscle | Subcostales muscle | Transversus thoracis muscle The muscles of the abdomen: Cremaster muscle | Obliquus externus abdominis muscle | Obliquus internus abdominis muscle | Psoas major muscle | Psoas minor muscle | Pyramidalis muscle | Quadratus lumborum muscle | Rectus abdominis muscle | Transversus abdominis muscle The muscles of the pelvis: Coccygeus muscle | Levator Ani muscle The muscles of the perineum: Bulbospongiosus muscle | Corrugator cutis ani muscle | Ischiocavernosus muscle | Sphincter ani externus muscle | Sphincter ani internus muscle | Sphincter urethrae membranaceae muscle | Transversus perinei profundus muscle | Transversus perinei superficialis muscle