Insertion of Splenius capitis.

Insertion of Splenius capitis.

• A. Transverse processes C1-C3
• B. Spinous processes C7-T4
• C. Inferior borders of ribs 8-12
• D. Mastoid process and superior nuchal line

Answer: (D)

Splenius capitis is a superficial deep neck muscle that attaches to the skull, so its insertion sits on the head rather than the vertebrae or ribs. It anchors to the mastoid process of the temporal bone and to the superior nuchal line of the occipital bone. From this position, when both sides contract, the head extends; when it contracts on one side, it rotates and laterally flexes the head to the same side. The mastoid process and superior nuchal line are the landmarks aligned with the muscle’s pull, making this the correct insertion. In contrast, attachments to the transverse processes C1-C3 would relate to the splenius cervicis region, not the capitis; spinous processes C7-T4 are part of the origin rather than the insertion; and the inferior borders of ribs 8-12 belong to other muscles altogether.

Splenius capitis is a superficial deep neck muscle that attaches to the skull, so its insertion sits on the head rather than the vertebrae or ribs. It anchors to the mastoid process of the temporal bone and to the superior nuchal line of the occipital bone. From this position, when both sides contract, the head extends; when it contracts on one side, it rotates and laterally flexes the head to the same side.

The mastoid process and superior nuchal line are the landmarks aligned with the muscle’s pull, making this the correct insertion. In contrast, attachments to the transverse processes C1-C3 would relate to the splenius cervicis region, not the capitis; spinous processes C7-T4 are part of the origin rather than the insertion; and the inferior borders of ribs 8-12 belong to other muscles altogether.