Intercostal Muscle Group

Description

Schematic of the chest wall musculature indicating the location of muscles. Inspiratory muscles including scalenes, external intercostals, parasternal intercostals and diaphragm are drawn on the left. Expiratory muscles are drawn on the right

Intercostal muscles anatomy. A schematic picture of anatomy and function of internal and external intercostal muscles. Panel A: the figure represents the anatomical distribution of intercostal muscles. Panel B: the figure represents the schematic functional activity of intercostal muscles. In particular, the external intercostal connects the ribs in such a way that contraction of the muscles lift the ribs and the rib cage allowing to expand the anterior-posterior dimension of the chest wall. On the other hand, the contraction of the internal intercostal (oriented opposite to the external) determines the opposite effect such as lowering of the ribs and reducing the anterior-posterior dimension

Names

• Intercostal Muscle Group

General

• Group of intrinsic muscles of the thorax
• They occupy 11 intercostal spaces
• Divided into external, internal and innermost intercostals

Function

• Support the rib cage
• Accessory muscles of respiration

External Intercostal Muscles

• Most superficial intercostals
• Originate on inferior border of one rib, course inferomedial, insert on superior marge of rib immediately below
• Innervated by intercostal nerves of corresponding intercostal space
• Vascular supply: anterior and posterior intercostal arteries
• Function: elevate the ribs during forced expiration

Internal Intercostal Muscles

• Middle layer of the intercostal musculature
• Originate from costal groove of one rib, course inferolateral, insert on superior border of immediate below rib
• Innervated by intercostal nerves of corresponding intercostal space
• Vascular supply: posterior intercostal, costocervical trunk, internal thoracic, musculophrenic arteries
• Function: depress the ribs during forced expiration

Innermost Intercostal Muscles

• Deepest layer of the intercostal muscles
• Originate from posterior aspect of internal intercostals, insert on same border of immediate rib below
• Innervated by intercostal nerves of corresponding intercostal space
• Vascular supply: posterior intercostal, costocervical trunk, internal thoracic, musculophrenic arteries
• Function: assist in the depression of ribs during forced expiration

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Clinical Significance

• Needs to be updated

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See Also

• Chest Pain Main
• Physical Exam Chest
• Thoracic Anatomy Main

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