NEUROCRANIUM

• The cranium, or skull, is the bony structure that protects the structures found inside our head, and it's divided into two parts: the viscerocranium and the neurocranium

  
• Brain case


  cranium = neurocranium

  
• Face


  splanchnocranium = viscerocranium
• The brain is almost entirely enclosed by the neurocranium with the exception of the foramen magnum and other foramina at the skull base which serve as entry and exit point for blood vessels and cranial nerves

  
• Neurocranium bones


  • Frontal bone (1)
  • Occipital bone (1)
  • Sphenoidal bone (1)
  • Ethmoidal bone (1)
  • Temporal bone (2)
  • Parietal bone (2)

  
• Frontal bone


  • The external surface above the supraorbital margin hosts a curved elevation known as the supraciliary arch
  • Between the two arches, there is a prominence known as the glabella
  • The orbital parts contain orbital plates
  • The anterolateral portion of the orbital part of the frontal bone presents with the lacrimal fossa (for the lacrimal gland)

  
• Occipital bone


  • They comprise two kidney-shaped prominences (occipital condyles) that articulate with the first cervical vertebra (atlanto-occipital joint)
  • Structures that pass through the foramen magnum include: The brainstem (medulla oblongata), The spinal branch of the accessory nerve, The anterior and posterior spinal arteries, The vertebral arteries, The tectorial membrane, The alar ligaments

  
• Sphenoid bone


  • The body of the sphenoid bone, The lesser wings, The greater wings, The pterygoid processes
  • Foramen rotundum: Allows passage for the maxillary nerve, the second branch of the trigeminal nerve (CN V)
  • Foramen ovale: Passageway for neurovascular structures which pass from the middle cranial fossa into the infratemporal fossa including the mandibular nerve (CN V3), the accessory meningeal artery, the lesser superficial petrosal nerve, the emissary vein
  • The mandibular nerve supplies the teeth and gums of the mandible, the skin of the temporal region, part of the auricle, the lower lip, and the lower part of the face, and innervates the muscles of mastication and the mucous membrane of the anterior two-thirds of the tongue
  • The articulations of the sphenoid are with the frontal, parietal, ethmoid, temporal, occipital, ethmoid

  
• Ethmoid bone


  • The cribriform plate, Two ethmoidal labyrinths, The perpendicular plate
  • The ethmoid articulates with 13 bones: the frontal, sphenoid, nasals, maxillae, lacrimals, palatines, inferior nasal conchae, and vomer

  
• Temporal bone


  • There is an anterior projection from the temporal bone, the zygomatic process
  • There is a downward conical projection called the mastoid process from the mastoid part
  • The inferior border is sharp, and forms the vaginal process of the styloid process
  • Concave posterior surface forms the anterior wall, floor and part of the posterior wall of the external acoustic meatus
  • The temporal bone also houses the structures forming the middle and inner ear
  • Mandibular fossa: The condyle of the mandible articulates with the temporal bone in the mandibular fossa, separated by an articular disc
  • The temporal bone articulates anteriorly with the sphenoid bone, above with the parietal bone, and posteriorly with the occipital bone

  
• Parietal bone


  • The parietal bones are bilateral skull bones that form the superior and lateral walls of the cranium
  • The parietal bones are part of the neurocranium, together with the frontal, ethmoid, sphenoid, temporal and occipital bones
  • The bulk of each parietal bone forms the calvaria (skull cap), while the remaining smaller part is a component of the cranial base (basicranium)

  
• The skull is divided into the neurocranium (8 bones) and the viscerocranium (14 bones)

  
• Viscerocranium bones

  • Zygomatic bone (2)
  • Lacrimal bone (2)
  • Nasal bone (2)
  • Vomer (1)
  • Concha nasalis inferior (2)
  • Palatin bone (2)
  • Maxilla (2)
  • Mandibula (1)

  
• Maxilla


  • Consists of five major parts: the body and four processes (frontal, zygomatic, palatine, alveolar)
  • The body of the maxilla is the largest part of the bone and shaped like a pyramid
  • It contributes to the anterior margin and floor of the bony orbit and the anterior wall of the nasal cavity
  • It contains the maxillary sinuses which extend from the orbital ridge to the alveolar process and drain to the middle meatus of the nose
  • The infraorbital foramen is located underneath the orbital ridge and serves as a pathway for the infraorbital nerve and vessels
  • The alveolar process forms the maxillary dental arch containing eight cavities where the upper teeth are held
  • Together with the palatine bone it forms the hard palate
  • The incisive foramen can be found on the median

  
• The skull has 22 bones in total: 8 neurocranium bones and 14 viscerocranium bones

  
• Maxilla


  • Involved in the formation of the orbit, nose and palate
  • Holds the upper teeth
  • Plays an important role for mastication and communication

  
• Maxilla structure


  1. Body

  2. Four projections named processes (frontal, zygomatic, palatine, alveolar)

  
• Maxilla body


  • Largest part of the bone
  • Shaped like a pyramid
  • Contributes to the anterior margin and floor of the bony orbit
  • Contributes to the anterior wall of the nasal cavity

  
• Maxilla sinuses


  • Extend from the orbital ridge to the alveolar process
  • Drain to the middle meatus of the nose

  
• Infraorbital foramen


  • Located underneath the orbital ridge
  • Serves as a pathway for the infraorbital nerve and vessels
• Maxilla alveolar process


  • Inferior extension of the maxilla
  • Porous structure
  • Forms the maxillary dental arch containing eight cavities where the upper teeth are held

  
• Hard palate


  • Formed by the maxilla and palatine bone
• Incisive foramen


  • Located on the median line just posteriorly to the incisor teeth
  • Where the nasopalatine nerve and greater palatine vessels pass through

  
• Maxilla articulation


  • Superiorly with the frontal bone
  • Posteriorly with the sphenoid bone, palatine and lacrimal bones and ethmoid bone
  • Medially with the nasal bone, vomer, inferior nasal concha
  • Laterally with the zygomatic bone

  
• Mandible


  • Largest of facial skeleton bones
  • Only movable bone of the facial skeleton

  
• Mandible articulation


  Doesn't articulate with surrounding bones via sutures, but via a synovial joint called the temporomandibular joint
• Temporomandibular joint


  • Allows the mandible to be attached to the skull while at the same time being capable of producing various translatory and rotatory movements
  • Enables complex actions like chewing and speaking
• Mandible structure


  1. Body

  2. Two rami
• Mandible body


  • Alveolar part
  • Base of mandible
• Mandible base


  • Mandibular symphysis
  • Mental protuberance
  • Mental tubercle
  • Oblique line
  • Mental foramen
• Internal surface of mandible base


  • Digastric fossa
  • Superior and inferior mental spines
  • Submandibular fossa
  • Sublingual fossa
  • Mylohyoid line
• Mandible ramus


  • Angle of mandible
  • Coronoid process
  • Condylar process
  • Mandibular notch
  • Masseteric tuberosity
  • Pterygoid tuberosity
• Mandibular foramen


  • Starting point of the mandibular canal which is traversed by the inferior alveolar nerve and its branches
• Bones articulating with maxilla

  • Frontal bone
  • Sphenoid bone
  • Palatine bone
  • Lacrimal bone
  • Ethmoid bone
  • Nasal bone
  • Vomer
  • Inferior nasal concha
  • Zygomatic bone

  
• Fossa cranii posterior