Levatores Costarum Breves 1–12

Thorax · Trunk

The Levatores Costarum Breves 1–12 is found among the Thorax muscles of the Trunk. It arises from Transverse processes of C7–T11 and attaches to Outer surface of the rib immediately below, between the tubercle and angle. Its chief action is that it elevates the ribs (aiding inspiration) and assists lateral flexion of the vertebral column. Innervation is provided by the Posterior (dorsal) rami of C8–T11 spinal nerves.

Origin, Insertion, Action & Nerve

Origin

Transverse processes of C7–T11

Insertion

Outer surface of the rib immediately below, between the tubercle and angle

Action

Elevates the ribs (aiding inspiration) and assists lateral flexion of the vertebral column

Nerve

Posterior (dorsal) rami of C8–T11 spinal nerves

Attachments explained

The Levatores Costarum Breves 1–12 is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.

Origin

Transverse processes of C7–T11

Insertion

Outer surface of the rib immediately below, between the tubercle and angle

Action & function

When the Levatores Costarum Breves 1–12 contracts, it produces the following movement: Elevates the ribs (aiding inspiration) and assists lateral flexion of the vertebral column.

As part of the Thorax group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.

Nerve supply & clinical relevance

The Levatores Costarum Breves 1–12 receives its nerve supply from the Posterior (dorsal) rami of C8–T11 spinal nerves. This nerve carries fibres from spinal segment(s) C8, T11.

Because a muscle can only contract when its nerve is intact, injury to the Posterior or to its spinal roots (C8, T11) can weaken or paralyse the Levatores Costarum Breves 1–12, impairing the movements it normally produces (elevates the ribs (aiding inspiration) and assists lateral flexion of the vertebral column). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Levatores Costarum Breves 1–12 (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Levatores Costarum Breves 1–12, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.

Most students remember the Levatores Costarum Breves 1–12 fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.