Serratus posterior inferior

Anatomy

Origin:
Spinous processes of T11 to L3 and supraspinous ligaments.

Insertion:
Lower border of the 9th to the 12th ribs just lateral to their angles.

Key Relations:
-Serratus posterior inferior shares it’s aponeurosis of origin with latissimus dorsi.
-Sometimes referred to as part of the respiratory group.

Functions

-Depresses 9th to the 12th ribs, aiding in forced expiration.
-May prevent elevation of the lower ribs when the diaphragm contracts.

Supply

Nerve Supply:
Anterior rami of T9 to T12 i.e. intercostals nerves 9 to 12.

Blood Supply:
Intercostal arteries.

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