Overview
This lecture covers the major bones, sutures, and unique soft spots (fontanelles) of the fetal skull, including their names and locations.
Major Bones of the Fetal Skull
- The frontal bones are located at the front of the skull and are paired in the fetus.
- Parietal bones are found on the sides and top of the skull.
- The maxilla and mandible form the upper and lower jaws, respectively.
- Nasal bones form the bridge of the nose.
- Temporal bones are on the sides of the skull.
- The sphenoid bone is at the base of the skull, visible from the side.
- The occipital bone is at the back and base of the skull.
Sutures of the Fetal Skull
- The coronal suture separates the frontal and parietal bones.
- The sagittal suture runs between the two parietal bones.
- The squamous suture is found between the parietal and temporal bones.
- The lambdoid suture separates the parietal bones from the occipital bone.
- The frontal suture divides the two frontal bones in the fetal skull.
Fontanelles (Soft Spots) of the Fetal Skull
- Fontanelles are soft spots where skull bones have not yet fused in infants.
- The anterior fontanelle is found at the meeting of the frontal and parietal bones.
- The sphenoidal fontanelle is located near the sphenoid bone.
- The mastoid fontanelle is where the squamous and lambdoid sutures meet.
- The posterior fontanelle is at the meeting point of parietal and occipital bones and the sagittal and lambdoid sutures.
Key Terms & Definitions
- Frontal bones — paired bones at the front of the fetal skull.
- Parietal bones — two bones forming the sides and roof of the skull.
- Suture — immovable joint between skull bones.
- Fontanelle — soft spot on an infant’s skull where bones are not yet fused.
- Anterior fontanelle — large soft spot at the top front of the skull.
- Sphenoidal fontanelle — soft spot near the sphenoid bone.
- Mastoid fontanelle — soft spot where squamous and lambdoid sutures meet.
- Posterior fontanelle — soft spot at the back of the skull.
Action Items / Next Steps
- Review the locations and names of the major bones and sutures on a diagram of the fetal skull.
- Memorize the positions and names of all four major fontanelles.