Trusted medical expertise in seconds.

Access 1,000+ clinical and preclinical articles. Find answers fast with the high-powered search feature and clinical tools.

Try free for 5 days
Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer.

Skull

Last updated: May 10, 2021

Summarytoggle arrow icon

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.

Overview

  • Protects the skull while permitting growth
  • Provides bony architecture to major neurovascular and lymphatic structures

Gross Anatomy

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”.

  • Posterior fontanelle
  • Anterior fontanelle
  • Sphenoidal fontanelles (not pictured)
  • Mastoid fontanelles (not pictured)

Superior surface of the base of the skull (cranial fossa)

Structures of the cranial fossa
Area Bones Foramina Penetrating structures
Anterior cranial fossa
  • Foramen cecum
  • Foramina of the cribriform plate
  • Anterior ethmoidal foramen
  • Anterior ethmoidal nerve (from V1)
  • Anterior ethmoidal artery and anterior ethmoidal vein
  • Posterior ethmoidal foramen
  • Posterior ethmoidal nerve (from V1)
  • Posterior ethmoidal artery and posterior ethmoidal vein
Middle cranial fossa
  • Lesser wing of sphenoid bone
  • Optic canal
  • Superior orbital fissure
    • Lies between the lesser and greater wing of sphenoid
  • Greater wing of sphenoid bone
  • Foramen rotundum
  • Foramen ovale (skull)
  • Foramen spinosum
  • Foramen lacerum
  • Carotid canal
  • Hiatus for greater petrosal nerve
  • Greater petrosal nerve (from VII)
  • Hiatus for lesser petrosal nerve
  • Lesser petrosal nerve (from IX)
  • Superior tympanic artery
Posterior cranial fossa
  • Internal acoustic meatus
  • Jugular foramen
  • Foramen magnum (largest opening of the skull)
  • Hypoglossal canal

Inferior surface of the base of the skull

Structures of the inferior surface of the base of the skull
Area Bones Foramina Penetrating structures
Anterior
  • Incisive foramen
  • Nasopalatine nerve (from V2)
  • Descending palatine artery
  • Greater palatine foramen
  • Greater palatine nerve (from V2)
  • Greater palatine artery and vein
  • Lesser palatine foramina
  • Lesser palatine nerve (from V2)
  • Lesser palatine artery and vein
Middle
  • Inferior orbital fissure
  • Petrotympanic fissure
  • Stylomastoid foramen
  • Mastoid canaliculus
  • Auricular branch (from X)
  • Inferior tympanic canaliculus
  • Tympanic nerve (from IX)
Posterior
  • Mastoid foramen
  • Condylar canal


Overview of the temporal, infratemporal, and pterygopalatine fossae
Location Connection to other cranial cavities Most important structures
Temporal fossa
  • Orbit via inferior orbital fissures

Infratemporal fossa

Pterygopalatine fossa

Jaw

  • Consists of the maxilla (upper jaw bone; composed of two maxillary bones fused at the intermaxillary suture) and the mandible (lower jaw bone), which are connected at the temporomandibular joints.
  • The mental foramen: two openings in the mandible through which pass the mental nerves (from V3)

Temporomandibular joints (TMJ)