Third layer
Serratus dorsalis anterior
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This muscle is thin, quadrilateral, flat muscle situated under the rhomboideus thoracis , serratus thoracis and latissimus dorsi. It consists of aponeurotic and fleshy portions.
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Origin: Lumbo-dorsal fascia .
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Insertion: By three fleshy digitations to the anterior borders and lateral surface of the ribs from the fifth to the seventh.
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Action: Inspiratory muscle.
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Nerve supply: 5th -7th dorsal spinal nerves.
Serratus dorsalis posterior
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This is a thin, elongated, quadrilateral muscle but wider than the preceding one. It also consists of aponeurotic and fleshy portions.
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Origin: Lumbo-dorsal fascia.
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Insertion: Posterior borders and lateral surface of the last three ribs.
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Action: Expiratory muscle.
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Nerve supply: 10th -13th dorsal spinal nerves.
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Last modified: Saturday, 15 October 2011, 8:25 AM