Iliocostalis thoracis muscle
Musculus iliocostalis thoracis
Iliocostalis thoracis is the middle part of the outer erector spinae column, joining the lower rib angles to the upper rib angles.
At a glance
- English
- Iliocostalis thoracis muscle
- Latin (TA2)
- Musculus iliocostalis thoracis
- System
- Muscle
- Region
- Back
- Side
- Paired, left and right
About the iliocostalis thoracis muscle
Iliocostalis is the most lateral of the three columns of erector spinae, and it is divided into lumbar, thoracic and cervical parts that overlap like a relay. Iliocostalis thoracis is the middle link. It lies along the back of the chest over the rib angles, lateral to longissimus thoracis and deep to serratus posterior and the scapular muscles.
Unlike the lumbar part, it does not begin on the pelvis. Its origin is a row of flat tendons on the top edges of the rib angles of ribs 7 to 12, placed just medial to the tendons by which iliocostalis lumborum ends on those ribs. These become fleshy and climb to insert on the top edges of the rib angles of ribs 1 to 6 and on the posterior face of the C7 transverse process. At its upper end the cervical part takes over, starting medial to these insertions.
Working on one side, the muscle bends the thoracic spine to the same side. Working on both sides, it extends the thoracic spine and helps to keep the upper back from rounding forward. Its pull on the ribs is small but may help to stiffen the chest wall during heavy lifting.
Iliocostalis thoracis is supplied by lateral branches of the dorsal rami of the thoracic spinal nerves, and blood reaches it from the dorsal branches of the posterior intercostal arteries. Pain from strain of this part is felt along the rib angles and between the shoulder blades, and the muscle is involved with its neighbours in postural pain of the thoracic region.
Attachments, action and supply
- Origin
- Top edges of the rib angles of ribs 7 to 12, medial to the insertions of iliocostalis lumborum.
- Insertion
- Top edges of the rib angles of ribs 1 to 6, and the posterior face of the C7 transverse process.
- Action
- Bends the thoracic spine to the same side on one side; extends it on both sides.
- Nerve supply
- Lateral branches of the dorsal rami of the thoracic spinal nerves.
- Blood supply
- Dorsal branches of the posterior intercostal arteries.
Anthromica
See the iliocostalis thoracis muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
