Skull

• Skull


  Formed by two sets of bones
• Cranium


  • Encloses and protects the fragile brain tissue
• Facial bones


  • Form a cradle for the eyes that is open to the anterior and allow the facial muscles to show our feelings through smiles or frowns
• All but one of the bones of the skull are joined together by sutures, which are interlocking, immovable joints
• Mandible


  The only bone of the skull that is attached to the rest of the skull by a freely movable joint
• Bones of the cranium

  • Frontal bone
  • Parietal bones
  • Temporal bones
  • Occipital bone
  • Sphenoid bone
  • Ethmoid bone
• Frontal bone


  • Forms the forehead, the bony projections under the eyebrow's, and the superior part of each eye's orbit
• Parietal bones


  • Form most of the superior and the lateral walls of the cranium. They meet in the midline of the skull at the sagittal suture and form the coronal suture where they meet the frontal bone
• Temporal bones


  • Lie inferior to the parietal bones; they join them at the squamous sutures; important bone markings: external auditory meatus, styloid process, zygomatic process, mastoid process
• Occipital bone


  • Most posterior bone of the cranium; forms the floor and back wall of the skull; join the parietal bones anteriorly at the lambdoid suture; has the foramen magnum which surrounds the lower part of the brain and allows the spinal cord to connect with the brain; has the occipital condyles which rest on the first vertebra of the spinal column
• Sphenoid bone


  • Spans the width of the skull and forms part of the floor of the cranial cavity; has the sella turcica which holds the pituitary gland, the foramen ovale which allows fibers of cranial nerve V to pass, the optic canal which allows the optic nerve to pass, and the superior orbital fissure which allows cranial nerves III, IV, and VI to pass; has the sphenoidal sinuses
• Ethmoid bone


  • Lies anterior to the sphenoid; forms the roof of the nasal cavity and part of the medial walls of the orbits; has the crista galli and the cribriform plates which allow nerve fibers carrying impulses from the olfactory receptors to reach the brain; has the superior nasal conchae and middle nasal conchae
• Facial bones


  • Maxillae
  • Palatine bones
  • Zygomatic bones
  • Lacrimal bones
  • Nasal bones
  • Vomer bone
  • Inferior nasal conchae
  • Mandible
• Maxillae


  • Fuse to form the upper jaw; all facial bones except the mandible join the maxillae; carry the upper teeth in the alveolar process; have the palatine processes which form the anterior part of the hard palate; contain paranasal sinuses
• Palatine bones


  • Lie posterior to the palatine process of the maxillae; form the posterior part of the hard palate
• Zygomatic bones


  • Commonly referred to as the cheekbones; form a good-sized portion of the lateral walls of the orbits
• Lacrimal bones


  • Fingernail-sized bones forming part of the medial wall of each orbit; have a groove that serves as a passageway for tears
• Nasal bones


  • Small rectangular bones forming the bridge of the nose
• Vomer bone


  • Single bone in the median line of the nasal cavity; forms the inferior part of the bony nasal septum
• Inferior nasal conchae


  • Thin, curved bones projecting medially from the lateral walls of the nasal cavity
• Mandible


  • Largest and strongest bone of the face; joins the temporal bones forming the only freely movable joints in the skull; the horizontal part (body) forms the chin; the two upright bars of bone (rami) extend from the body to connect the mandible with the temporal bone; the lower teeth lie in alveoli in the alveolar process at the superior edge of the mandibular body