Which muscle inserts on the transverse processes of the thoracic vertebrae and ribs 3-12?

Which muscle inserts on the transverse processes of the thoracic vertebrae and ribs 3-12?

• A. Longissimus thoracis
• B. Spinalis cervicis
• C. Quadratus lumborum
• D. Latissimus dorsi

Answer: (A)

The key idea here is recognizing the insertion pattern of the thoracic part of the erector spinae group. The longissimus thoracis, as the middle member of this group, extends across the thoracic region from the lower spine up to the higher thoracic levels and attaches to the transverse processes of the thoracic vertebrae as well as to the ribs—specifically ribs 3 through 12. This arrangement makes it well suited to extend the thoracic spine and contribute to rib elevation during breathing, while also helping stabilize the spine. Other muscles listed have different attachment sites: spinalis cervicis attaches mainly to cervical spinous processes; quadratus lumborum attaches to the iliac crest and the lower ribs and lumbar transverse processes; latissimus dorsi attaches to the humerus and to the thoracolumbar fascia with attachments along the lower ribs but not to the thoracic vertebral transverse processes and ribs 3–12.

The key idea here is recognizing the insertion pattern of the thoracic part of the erector spinae group. The longissimus thoracis, as the middle member of this group, extends across the thoracic region from the lower spine up to the higher thoracic levels and attaches to the transverse processes of the thoracic vertebrae as well as to the ribs—specifically ribs 3 through 12. This arrangement makes it well suited to extend the thoracic spine and contribute to rib elevation during breathing, while also helping stabilize the spine.

Other muscles listed have different attachment sites: spinalis cervicis attaches mainly to cervical spinous processes; quadratus lumborum attaches to the iliac crest and the lower ribs and lumbar transverse processes; latissimus dorsi attaches to the humerus and to the thoracolumbar fascia with attachments along the lower ribs but not to the thoracic vertebral transverse processes and ribs 3–12.