FRONTAL

Cranial Anatomy: Frontal Bone Overview

Introduction to the Frontal Bone

• The frontal bone occupies the anterior and medial part of the skull, classified as an unpaired bone with two portions: a vertical portion and a horizontal portion resembling an "L" shape.

Vertical Portion Characteristics

• The vertical portion features a central prominence known as the median frontal eminence, which is visible above remnants of the metopic suture.

• This vertical section is predominantly convex except at the temples where it becomes slightly concave, covering about 20% of its surface area.

Orbital and Nasal Features

• The nasal and orbital borders are defined by the naso-orbital crest, which includes both orbital and nasal parts; it contains openings for nerves such as the supraorbital nerve.

• The nasal notch articulates with structures of the nose while also featuring a bony projection called the nasal spine.

Articulations with Adjacent Structures

• The internal orbital process connects to various facial bones including the ascending ramus of the maxilla in front and zygomatic bone behind.

• A notable feature is that this region includes temporal fossae, representing 20% of its vertical structure.

Horizontal Portion Insights

• Observing from below reveals a horseshoe-shaped structure containing several cells related to ethmoidal sinuses; this area supports other cranial components.

• The horizontal section forms part of the roof for orbital cavities, articulating with adjacent bones like lesser wings of sphenoid laterally.

Additional Anatomical Details

• Two depressions are noted: one larger (lacrimal fossa), another smaller (true lacrimal fossa), where ligaments attach for muscle function.

• The oblique muscle's path is described as moving from back to front while refracting around a ligamentous pulley system.

Internal View Analysis

• From an internal perspective, we see how both portions articulate with surrounding structures like lesser wings of sphenoid bones.