Intercostal muscle
Deep muscles of the chest and front of the arm, with the boundaries of the axilla.
Gray's	subject #117 403
Origin	ribs 1-11
Insertion	ribs 2-12
Artery	intercostal arteries
Nerve	intercostal nerves
Actions	Elevation or Depression of the Ribs
MeSH	Intercostal+Muscles

Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall.

There are three principal layers;

• the external intercostal muscles, which aid in quiet and forced inhalation. They originate on ribs 1-11 and have their insertion on ribs 2-12. The external intercostals are responsible for the elevation of the ribs, and expanding the transverse dimensions of the thoracic cavity.

Located around the ribs

• the internal intercostal muscles, which aid in forced expiration (quiet expiration is a passive process). They originate on ribs 2-12 and have their insertions on ribs 1-11. The internal intercostals are responsible for the depression of the ribs decreasing the transverse dimensions of the thoracic cavity.
• the innermost intercostal muscle, the deep layers of the internal intercostal muscles which are separated from them by the neurovascular bundle.

Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves), and are provided by the intercostal arteries and intercostal veins. Their fibers run in opposite directions.

[edit] External links

• -294977459 at GPnotebook
• SUNY Figs 18:03-03
• UCC

v • d • e List of muscles of torso (TA A04.3-5, GA 4.397) Back splenius (capitis, cervicis) · erector spinae (iliocostalis, longissimus, spinalis) · latissimus dorsi transversospinales: (semispinalis dorsi, semispinalis cervicis, semispinalis capitis, multifidus, rotatores) · interspinales · intertransversarii Vertebral column: trapezius · latissimus dorsi · rhomboid (major, minor) · levator scapulae fascia: Thoracolumbar fascia Thorax intercostales (external, internal, innermost) · subcostales · transversus thoracis · levatores costarum · serratus posterior (inferior, superior) · diaphragm Thoracic cavity: pectoralis major · pectoralis minor · subclavius · serratus anterior fascia: Pectoral fascia · Clavipectoral fascia Abdominopelvic Abdomen/ wall Anterior/ lateral Abdominal external oblique · Transversus abdominis/Conjoint tendon · Rectus sheath (rectus abdominis, pyramidalis) · Arcuate line · Tendinous intersection Cremaster · Abdominal internal oblique Fascia/abdominal fascia: panniculus adiposus (Fascia of Camper) · stratum membranosum (Fascia of Scarpa) · Transversalis fascia (Interfoveolar ligament) Linea alba · Linea semilunaris · Inguinal triangle Inguinal canal (Deep inguinal ring, Superficial inguinal ring, Intercrural fibers, Crura of superficial inguinal ring) Inguinal ligament (Pectineal ligament, Lacunar ligament, Reflected ligament) Posterior quadratus lumborum · psoas major/psoas minor · iliacus  · iliopsoas fascia (Iliac fascia/Iliopectineal arch) Pelvis levator ani (iliococcygeus, pubococcygeus, puborectalis) · coccygeus fascia/pelvic fascia visceral (Rectovaginal fascia, Rectoprostatic fascia) · parietal (Obturator fascia/Tendinous arch, Piriformis fascia) floor/diaphragm: Superior fascia of pelvic diaphragm (Pubovesical ligament, Puboprostatic ligament) · Inferior fascia of pelvic diaphragm Anococcygeal body

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