HUESO ETMOIDES. PROF. DR. MARCELINO BRÍTEZ CABRERA

Study of the Ethmoid Bone

Overview of the Ethmoid Bone

• The ethmoid bone is a unique, medium-sized symmetrical bone located in front of the sphenoid bone and behind the ethmoidal notch of the frontal bone. It contributes to forming orbital and nasal cavities.

• It consists of a perpendicular or vertical plate and a horizontal plate known as the cribriform plate, which intersects with the perpendicular plate near its upper end.

Structure and Features

• The cribriform plate extends from one lateral mass to another, having an elongated rectangular shape from front to back. This structure is crucial for olfactory functions due to its numerous perforations that connect the anterior cranial fossa with nasal cavities.

• The crista galli divides this surface into anterior and posterior portions, providing attachment points for membranes covering the brain. Each side features olfactory bulbs adjacent to this structure.

Anatomical Relationships

• The cribriform plate articulates anteriorly with the frontal bone's notch and contains various foramina for nerves passing through it, including branches from the nasociliary nerve that innervate nasal mucosa.

• The perpendicular plate forms part of the bony nasal septum, separating left and right nasal cavities; it articulates with both cartilaginous structures and other bones like vomer and sphenoid at different borders.

Nasal Septum Formation

• The perpendicular plate's lower portion connects with cartilage forming part of the nasal septum while also articulating with surrounding bones such as vomer posteriorly, contributing significantly to overall nasal cavity structure.

• Observations highlight how these anatomical relationships create a functional division between both sides of the nasal passages essential for respiratory processes.

Innervation Details

• Key nerves involved include branches from nasociliary nerve (anterior) that pass through specific foramina into cranial spaces before descending into nasal cavities; they play vital roles in sensory innervation within these areas.

• Internal branches provide sensory input primarily focused on mucosal surfaces along anterior sections of the septum, ensuring effective communication between neural pathways and respiratory functions in this region.

Anatomy of the Nasal Cavity and Related Structures

Overview of Nasal Anatomy

• The nasal cavity's anatomy includes the orbits on either side, with the perpendicular plate of the ethmoid bone situated centrally.

• The nasal septum is lined with mucosa, showcasing the anterior ethmoidal nerve and its branches, as well as olfactory bulbs positioned above.

• Key structures include branches from the anterior ethmoidal nerve and nasopalatine nerve, which are significant for sensory innervation in this region.

Ethmoid Bone Features

• The lateral masses (labyrinths) of the ethmoid bone hang from the cribriform plate, contributing to both structural support and sinus formation.

• The external surface of these lateral masses forms part of the orbit's wall, characterized by a smooth and flat appearance known as the orbital plate.

Sinus Cavities and Articulations

• Observations reveal cavities termed "ethmoidal cells" that articulate with adjacent bones like the lacrimal bone, forming complex air spaces within a connected cranial structure.

• The superior view shows various anatomical features including irregularities that contribute to sinus drainage pathways.

Meatuses and Cornetes

• Within this anatomy, meatuses are identified: superior meatus beneath superior nasal concha; middle meatus below middle concha; these facilitate airflow and drainage.

• Notably, there exists variability in cornet structures such as an occasional supreme nasal concha above the superior concha.

Posterior Structures

• The posterior aspect articulates with sphenoid bones while also housing important structures like inferior nasal conchae that influence airflow dynamics.

• Overall observations highlight multiple surfaces (anterior, posterior, superior, inferior), emphasizing their roles in respiratory function through intricate anatomical relationships.

Anatomy of Nasal Structures

Overview of Nasal Anatomy

• The speaker discusses the connection between nasal structures, specifically mentioning how the superior nasal concha is related to the inferior nasal concha, highlighting their independent nature as facial bones.

• The relationship between the superior and middle nasal conchae is explained, emphasizing their anatomical positioning within the nasal cavity and their role in respiratory function.

• The speaker notes that the inferior nasal conchae are distinct from other structures, reinforcing their classification as independent bones rather than part of a larger mold.

• Observations are made regarding the presence of ethmoidal cells located between various nasal conchae, which play a significant role in sinus drainage and airflow regulation.

• The discussion includes an analysis of lateral aspects of the nasal fossae, indicating areas for further exploration in understanding overall nasal anatomy.