Levatores longi costarum

The levatores longi costarum are slender slips beside the thoracic spine that pass from a vertebra over one rib to the next.

At a glance

English: Levatores longi costarum
Latin (TA2): Levatores longi costarum
System: Muscle
Region: Trunk
Side: Paired, left and right
Inserts on: The eighth rib, eleventh rib, fifth rib, fourth rib, ninth rib, seventh rib, sixth rib, tenth rib, third rib and twelfth rib

About the levatores longi costarum

The rib elevators, levatores costarum, form a series of small triangular muscles on either side of the thoracic spine, under the erector spinae. Each elevator has a short member that reaches the rib just below its vertebra. In the lowest part of the series a second bundle separates off and runs further: this is the long levator, levator costae longus, which crosses one rib to land on the second rib below.

Each long levator begins on the tip of a transverse process of a thoracic vertebra, alongside the origin of the short member. Its fibres run steeply downward and slightly outward, parallel to the spine, and attach to the outer surface of the rib two levels down, between the tubercle and the angle. In standard descriptions this long slip is regular only in the lower part of the thorax, roughly for the last four ribs; higher up it is absent or small. The model shows attachments for these slips along much of the thoracic cage.

Like the short levators, the long ones can raise the ribs slightly, aiding inspiration, but they lie so close to the rib joints that their pull is small. Their more likely role is to help steady and move the thoracic spine, assisting extension, side bending and rotation, and to signal posture and movement to the nervous system. They work together with the deep rotator and multifidus muscles lying alongside them.

The long levators are supplied by dorsal rami of the thoracic spinal nerves, and their blood comes from the dorsal branches of the posterior intercostal arteries. They are rarely singled out in the clinic, but as part of the deep layer of back muscles they may share in localised pain and stiffness beside the spine.

Attachments, action and supply

Origin: Tips of the transverse processes of the thoracic vertebrae, chiefly the lower ones.
Insertion: Outer surface of the second rib below the vertebra of origin, between its tubercle and angle.
Action: Weakly elevate the ribs; assist extension, side bending and rotation of the thoracic spine.
Nerve supply: Dorsal rami of the thoracic spinal nerves.
Blood supply: Dorsal branches of the posterior intercostal arteries.

Parts of the levatores longi costarum

Each number is marked on the model. Press one, here or on the model, to see it named in place.

Insertion on the eighth ribThe long slip from the sixth thoracic transverse process reaches the outer back surface of the eighth rib here.
Insertion on the eleventh ribAttachment on the back of the eleventh rib for the slip from the ninth thoracic vertebra, within the lower group where long levators are most regular.
Insertion on the fifth ribThe slip ending on the outer surface of the fifth rib near its angle, coming from the third thoracic transverse process. Long slips this high are often small.
Insertion on the fourth ribAttachment on the back of the fourth rib, between tubercle and angle, for a slip from the second thoracic vertebra. It is variable in size.
Insertion on the ninth ribWhere the slip from the seventh thoracic transverse process ends on the back of the ninth rib, lateral to its tubercle.
Insertion on the seventh ribThe attachment on the outer surface of the seventh rib for the slip that started two levels higher, on the fifth thoracic vertebra.
Insertion on the sixth ribThe slip from the fourth thoracic vertebra lands here, on the back of the sixth rib between its tubercle and angle.
Insertion on the tenth ribAttachment on the tenth rib for the slip from the eighth thoracic transverse process, one of the regular long levators.
Insertion on the third ribThe highest attachment shown, on the back of the third rib, for a slip from the first thoracic vertebra.
Insertion on the twelfth ribThe lowest attachment, on the back of the twelfth rib, for the slip from the tenth thoracic transverse process.

Anthromica

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At a glance

About the levatores longi costarum

Attachments, action and supply

Related structures

See the levatores longi costarum where it really sits, with every layer of the body around it.