Atlas (C1) vs Deltoid
| Property | Atlas (C1) | Deltoid |
|---|---|---|
| Latin Name | Atlas | Musculus deltoideus |
| Type | Bone | Muscle |
| Body System | Skeletal | Muscular |
| Body Region | Spine | Shoulder |
| Function | The first cervical vertebra that supports the skull. Allows nodding movements (flexion and extension) of the head at the atlanto-occipital joint. | The primary abductor of the shoulder joint. The anterior fibers flex and medially rotate the arm. The posterior fibers extend and laterally rotate the arm. Gives the shoulder its rounded … |
| Clinical Significance | Jefferson fractures (burst fractures of the atlas) result from axial loading. Atlanto-occipital dislocation is usually fatal. Congenital anomalies include atlas assimilation (occipitalization). | Deltoid paralysis from axillary nerve injury prevents arm abduction. The deltoid is a common site for intramuscular injections. Rotator cuff tears may cause compensatory deltoid overuse. |
| FMA ID | 12519 | 32521 |