Deltoid · spinal part

A scapular spine, not the backbone

The spinal part is the posterior portion of deltoid. Its name refers to the ridge on the back of the scapula.

Start with Back rather than assuming that the front camera shows every part clearly. A mesh can be present but concealed by neighboring structures.

Sources: Loyola anatomy · Arm anatomy tables

Scapular ridge to deltoid tuberosity

Its proximal attachment follows the scapular spine; distally it joins the deltoid attachment on the humerus.

Use the whole scapula for orientation. The source model does not supply a separate clickable ridge or a painted attachment border, so the written landmark remains important.

Sources: Loyola anatomy

A posterior shoulder action

Posterior deltoid fibers contribute to shoulder extension and lateral rotation.

The source pose is fixed. Turning the camera does not raise the arm or rotate the humerus within the socket; the viewer does not simulate muscle contraction or shoulder mechanics.

The long head of triceps is also available in this arm scene. Comparing the two meshes is a positional exercise, not a test of which muscle contributes more to a movement.

Sources: Loyola anatomy

Named supply, not a nerve map

The axillary nerve supplies deltoid. Arterial contributors include the posterior circumflex humeral artery and the deltoid branch of the thoracoacromial artery.

Nerves and vessels are not loaded in this subset, so the text describes connections you cannot select in the viewer.

Sources: Arm anatomy tables

Read the model

Explore deltoid · spinal part in 3D

1. Inspect the posterior part. Choose Back. Drag the isolated part to compare its surfaces; the selection color does not represent the appearance of living tissue.
2. Find the scapular ridge. Choose Show context, then select Scapula. Return to Deltoid · spinal part and use Fade others to compare the neighboring surfaces.
3. Compare rather than rename. Choose the clavicular part, then return to the spinal part from the list. Camera direction never changes which anatomical part is selected.

Sources and editorial status

This guide uses independently written explanations with links to the evidence behind them. Source checking and specialist anatomical review are separate steps; the latter is still pending.

1. Loyola University Chicago — LUMEN, Deltoid

   Deltoid attachments and part-specific actions. No source illustrations reproduced.

2. Texas Tech University Health Sciences Center El Paso — Axilla, Posterior Shoulder, & Arm

   Deltoid and coracobrachialis rows: actions, nerve and arterial supply; scapular landmarks.

3D geometry and its separate license are credited beneath the viewer. References do not imply endorsement of this site.