Anatomy of the Frontal Bone

Frontal Bone

• Located in the base of the skull, anterior cranial fossa, and articulates with the ethmoid bone posteriorly and the sphenoid bone wings
• Forms a great portion of the roof of the orbit
• Thickening of the frontal bone in the anterior region forms the superciliary arches (supraorbital ridges)
• Supraorbital notch or foramen transmits the frontal vessels and nerves (supraorbital and supra-trochlear nerves)
• Contains the frontal air sinuses (paranasal sinus), two hollow spaces lined with mucous membrane, located above the orbital margins

Ethmoid Bone

• A single bone located in the mid-area of the anterior cranial fossa
• Constitutes part of the nasal structure, medial orbital walls, and anterior cranial fossa
• Crista galli (bony projection) gives attachment to Falx cerebri (meningeal layer of dura mater)
• Perpendicular plate of ethmoid descends downward in the midline of the nasal cavity to form the superior and anterior portions of the nasal septum
• Articulates with the vomer and septal cartilage to form the nasal septum
• Cribriform plate (perforated bony plate) articulates with the frontal bone and posteriorly with the sphenoid bone, and transmits the filaments of the olfactory nerve (cranial nerve I)

Nasal Bones

• Rectangular bones that form the bridge of the nose
• Articulate with the frontal bone superiorly and with each other at the midline
• Thicker at the superior articulation, but thinner inferiorly
• Most fractures occur at the inferior articulation
• Articulate posteriorly with the frontal process of the maxilla

Facial Bones

Maxillary Bones

• Form the upper jaw, anterior part of the hard palate, part of the lateral walls of the nasal cavities, and part of the floors of the orbital cavities
• Meet in the midline at the intermaxillary suture and form the lower margin of the nasal aperture
• Infraorbital foramen perforates the maxilla below the orbit
• Alveolar process projects downward and forms the alveolar arch, which carries the upper teeth
• Contain a large pyramid-shaped body, the maxillary sinus (antrum of Highmore), and four prominent processes—the frontal, alveolar, zygomatic, and palatine processes
• Body of the maxilla is hollow and contains the maxillary sinus (pyramid-shaped)

Zygoma

• Paired bone that forms the essence of the cheek prominence
• Thick, strong, diamond-shaped bone that forms the lateral and anterior projections to the midface
• Composed of four processes: frontal, temporal, maxillary, and medial
• Frontal process forms the lateral orbital wall and articulates with the frontal bone at the frontozygomatic suture
• Temporal process forms the zygomatic arch and articulates with the temporal bone
• Maxillary process articulates with the maxilla to form the infraorbital rim and part of the floor of the orbit
• Medial process joins the maxilla on the lateral wall, producing the zygomatic eminence
• Articulates with the sphenoid bone on the posterior aspect of the frontal process

Vomer

• Plow-shaped bone that forms the posterior portion of the nasal septum
• Articulates with the palatine, maxillary, and ethmoid bones

Palatine Bones

• Irregularly shaped paired bones, composed of a major horizontal portion and vertical perpendicular plates
• Horizontal plate articulates anteriorly with the maxilla and with the palatine bone of the opposite side in the midline to form the posterior aspect of the hard palate
• Vertical plate passes superiorly behind the maxilla and articulates posteriorly with the lateral pterygoid plate of the sphenoid bone
• Vertical plate terminates in a small contribution to the orbital floor at the posteromedial aspect

Inferior Nasal Concha

• Paired bone that forms the bony support of the inferior turbinate bilaterally
• Obstructs the inferior meatus and the nasolacrimal duct

Lacrimal Bones

• Paired bone situated at the front part of the medial wall of the orbit
• Articulates anteriorly with the frontal process of the maxilla, posteriorly with the lamina papyracea of the ethmoid, superiorly with the frontal bone, and inferiorly with the orbital plate of the maxilla
• Lacrimal groove is a groove for the nasolacrimal duct, situated in the anterior part of the lateral surface of the lacrimal bone

Mandible

• Largest and strongest facial bone, composed of the body and two rami, with their junction at the angle
• Body is U-shaped, has mental foramen which transmits the mental nerve (terminal branch of inferior alveolar nerve) and vessels
• Symphysis menti is a shallow ridge on the external midline surface of the body of the mandible, indicating the line of fusion of the two halves of the mandible during development
• Mental spines (genial tubercles) are on the midline medial surface of the body of the mandible, giving origin to the genioglossus muscles above and the geniohyoid muscles below

Learn about the structure and functions of the frontal bone, including its location, articulations, and features such as the superciliary arches and frontal air sinuses.