Sutures of the skull & Frontanelle

Sutures:

• Immobile joints that unites the several separate bones of the skull.
• The connective tissue between the bones is called a sutural ligament.
• The mandible is an exception to this rule, for it is united to the skull by the mobile temporomandibular joint
• Sutures of the skull:
• Coronal suture: btwn frontal & parietal bone
• Squamousal suture: btwn parietal & temporal bone
• Lamboidal suture: btwn parietal & occipital bone
• Sagittal suture: btwn 2 parietal bones

The bones of the skull can be divided into those of the cranium and those of the face. The vault is the upper part of the cranium, and the base of the skull is the lowest part of the cranium.

The skull bones are made up of external and internal tables of compact bone separated by a layer of spongy bone called the diploe. The internal table is thinner and more brittle than the external table. The bones are covered on the outer and inner surfaces with periosteum.

The cranium consists of the following bones, two of which are paired.

• Frontal bone
• Parietal bones (paired)
• Occipital bone
• Temporal bones (paired)
• Sphenoid bone
• Ethmoid bone

The facial bones consist of the following, two of which are single:

• Zygomatic bones

• Maxillae

• Nasal bones

• Lacrimal bones

• Vomer (single)

• Palatine bones

• Inferior conchae

• Mandible (single)

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Frontanelle:

• Anatomical feature on an infant’s skull
• Soft spots on a baby’s head which, during birth, enable the bony plates of the skull to flex, allowing the child’s head to pass through the birth canal
• The ossification of the bones of the skull cause the fontanelles to close over by a child’s second birthday
• The closures eventually form the sutures of the neurocranium
• Clinical significance:
• Sunken frontanelle
• indicates dehydration
• Buldging anterior frontanelle
• increased intracranial pressure