Skull

Summary

The human skull consists of approximately 30 bones, which can be anatomically divided into the cranial bones (neurocranium) and the facial bones (viscerocranium). The neurocranium consists of the frontal, the ethmoid, the sphenoid, the occipital, and the paired temporal and parietal bones. The cranial bones are connected by fibrous joints called sutures. The bones of the infant neurocranium are not fused but are instead connected by membranous gaps between the bone plates called fontanelles, which enable flexion of the skull to facilitate passage through the birth canal and accommodate the rapidly growing brain. The fontanelles, which comprise the anterior, posterior, and the paired mastoid and sphenoid fontanelles, close between the age of 2 months and 18 months. The viscerocranium consists of the unpaired mandible and vomer and the paired zygomatic bones, inferior nasal conchae, lacrimal bones, nasal bones, maxillary bones, and palatine bones. The temporomandibular joint connects the lower jaw to the temporal bone and enables movement for speech and mastication. The skull features numerous foramina through which pass the cranial nerves, the spinal cord, arteries, and veins.

Craniomaxillofacial bones

Viscerocranium (facial bones)

Neurocranium (cranial bones)

Calvaria (skullcap)

Adult skull

The calvaria (skullcap) comprises the superior portions of the frontal bone, the occipital bone, and the parietal bones.

Infant skull (fontanelles)

An infant's neurocranium consists of five separate bones (two frontal bones, two parietal bones, and one occipital bone) held together by connective tissue sutures. This allows for stretching and deformation of the skull to facilitate birth and accommodate the brain's growth at a faster rate than the surrounding bone. The larger areas of connective tissue that arise at the gaps between the bone plates are called “fontanelles”.

Base of the skull

Superior surface of the base of the skull

Area Bones Foramina Penetrating structures
Anterior cranial fossa
Middle cranial fossa
  • Nerve of pterygoid canal (consists of deep petrosal nerve and greater petrosal nerve)
  • Artery of pterygoid canal
  • Meningeal branch of ascending pharyngeal artery
  • Emissary vein
  • Greater petrosal nerve (from VII)
  • Lesser petrosal nerve (from IX)
  • Superior tympanic artery
Posterior cranial fossa

Inferior surface of the base of the skull

Area Bones Foramina Penetrating structures
Anterior
  • Nasopalatine nerve (from V2)
  • Descending palatine artery
  • Greater palatine nerve (from V2)
  • Greater palatine artery and vein
  • Lesser palatine nerve (from V2)
  • Lesser palatine artery and vein
Middle
  • Greater petrosal nerve (from VII)
  • Lesser petrosal nerve (from IX) through the sphenopetrosal fissure
  • Deep petrosal nerve (from the internal carotid plexus)
  • Auricular branch (from X)
  • Tympanic nerve (from IX)
Posterior
  • Mastoid emissary vein
  • Condylar emissary vein


Temporal, infratemporal, and pterygopalatine fossae

Location Connection to other cranial cavities Most important structures
Temporal fossa

Infratemporal fossa

Pterygopalatine fossa

Jaw

Jaw

Temporomandibular joints (TMJ)

last updated 02/26/2020
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