coronal

**Definition:** The coronal (frontal) plane is a vertical plane running side-to-side that splits the body into anterior (front/ventral) and posterior (back/dorsal) halves. It is perpendicular to both the sagittal plane (left/right division) and the transverse/axial (horizontal) plane (superior/inferior division). The name derives from the Latin *corona* ("crown"), because it parallels the line of a crown/diadem across the head.

**Movements in the coronal plane (about an anterior-posterior axis):** - Abduction and adduction (e.g., shoulder, hip) - Lateral flexion (side bending) of the spine/neck - Inversion/eversion of the foot (primarily frontal-plane motion) - Radial/ulnar deviation of the wrist

(Contrast: flexion/extension occur in the sagittal plane; rotation occurs in the transverse plane.)

**Imaging significance:** - Coronal CT/MRI slices show anterior-to-posterior "slices" of the body, viewed as if facing the patient. - Particularly useful for: sinuses (osteomeatal complex), pituitary/sellar lesions, temporal lobe and hippocampus (mesial temporal sclerosis in epilepsy), brainstem and ventricles, kidneys/adrenals, spinal curvature (scoliosis, Cobb angle on coronal-plane radiographs), and hip/pelvis alignment. - A standard PA/AP chest X-ray is a coronal projection.

**Coronal suture (skull):** - Fibrous joint between the frontal bone and the two parietal bones. - Premature fusion (craniosynostosis) of the coronal suture causes **brachycephaly** (short, wide head) if bilateral, and **anterior plagiocephaly** if unilateral. It is associated with syndromes such as Crouzon, Apert, Pfeiffer, Saethre-Chotzen (FGFR2/FGFR3/TWIST1 mutations). - Sagittal suture synostosis (most common) causes scaphocephaly/dolichocephaly (long, narrow head). - The bregma is the junction of the coronal and sagittal sutures (anterior fontanelle, closes ~18-24 months); the lambda is the junction of the sagittal and lambdoid sutures (posterior fontanelle, closes ~2-3 months).

**Other uses:** - Coronal section in neuroanatomy/histology: used to view the basal ganglia, thalamus, internal capsule, and amygdala relationships. - "Coronary" is a different term (from the same Latin root, referring to vessels encircling the heart like a crown); do not confuse the two.

**Board pearls:** - Know the three cardinal planes (sagittal, coronal, transverse) and which movements occur in each. - Midsagittal = midline plane dividing the body into equal left/right halves; parasagittal = any plane parallel to it. - Craniosynostosis patterns (which suture is fused → which head shape) are commonly tested.