Uncinate process of ethmoid bone

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Uncinate process of ethmoid bone
Processus uncinatus ossis ethmoidalis.PNG
Lateral wall of nasal cavity, showing ethmoid bone in position.(Uncinate process of ethmoid labeled at left.)
Gray152.png
Ethmoid bone from the right side. (Uncinate process labeled at bottom right.)
Details
Identifiers
Latin processus uncinatus ossis ethmoidalis
TA98 A02.1.07.016
TA2 737
FMA 57455
Anatomical terms of bone

In the ethmoid bone, a sickle shaped projection, the uncinate process, projects posteroinferiorly from the ethmoid labyrinth. Between the posterior edge of this process and the anterior surface of the ethmoid bulla, there is a two-dimensional space, resembling a crescent shape. This space continues laterally as a three-dimensional slit-like space - the ethmoidal infundibulum. This is bounded by the uncinate process, medially, the orbital lamina of ethmoid bone (lamina papyracea), laterally, and the ethmoidal bulla, posterosuperiorly. This concept is easier to understand if one imagine the infundibulum as a prism so that its medial face is the hiatus semilunaris. The "lateral face" of this infundibulum contains the ostium of the maxillary sinus, which, therefore, opens into the infundibulum.

Contents

Variations

The uncinate process can be attached to either the lateral nasal wall, on the lamina papyracea (50%), the anterior cranial fossa, on the ethmoidal roof (25%), or the middle concha (25%). The superior attachment of the uncinate process determines the drainage pattern of the frontal sinus. In the first case, the infundibulum and the frontal recess are separated from each other, forcing the frontal sinus to drain directly into the middle meatus and not into the ethmoidal infundibulum. With the other configurations, the sinus will drain, firstly, into the infundibulum.

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<span class="mw-page-title-main">Ethmoid bone</span> Bone in the human skull

The ethmoid bone is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that make up the orbit of the eye.

<span class="mw-page-title-main">Lacrimal bone</span> Smallest and most fragile bone of the human skull and face

The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of the lacrimal bone function in the process of lacrimation or crying. Specifically, the lacrimal bone helps form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of the bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears or lacrimal fluid, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways.

<span class="mw-page-title-main">Inferior nasal concha</span>

The inferior nasal concha is one of the three paired nasal conchae in the nose. It extends horizontally along the lateral wall of the nasal cavity and consists of a lamina of spongy bone, curled upon itself like a scroll,. The inferior nasal conchae are considered a pair of facial bones. As the air passes through the turbinates, the air is churned against these mucosa-lined bones in order to receive warmth, moisture and cleansing. Superior to inferior nasal concha are the middle nasal concha and superior nasal concha which both arise from the ethmoid bone, of the cranial portion of the skull. Hence, these two are considered as a part of the cranial bones.

<span class="mw-page-title-main">Nasal cavity</span> Large, air-filled space above and behind the nose in the middle of the face

The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract.

<span class="mw-page-title-main">Orbit (anatomy)</span> Cavity or socket of the skull in which the eye and its appendages are situated

In anatomy, the orbit is the cavity or socket/hole of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is 30 millilitres, of which the eye occupies 6.5 ml. The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves.

<span class="mw-page-title-main">Orbital part of frontal bone</span>

The orbital or horizontal part of the frontal bone consists of two thin triangular plates, the orbital plates, which form the vaults of the orbits, and are separated from one another by a median gap, the ethmoidal notch.

<span class="mw-page-title-main">Ethmoid sinus</span> Air-filled space near the nasal cavity

The ethmoid sinuses or ethmoid air cells of the ethmoid bone are one of the four paired paranasal sinuses. Unlike the other three pairs of paranasal sinuses which consist of one or two large cavities, the ethmoidal sinuses entail a number of small air-filled cavities. The cells are located within the lateral mass (labyrinth) of each ethmoid bone and are variable in both size and number. The cells are grouped into anterior, middle, and posterior groups; the groups differ in their drainage modalities, though all ultimately drain into either the superior or the middle nasal meatus of the lateral wall of the nasal cavity.

<span class="mw-page-title-main">Semilunar hiatus</span>

The semilunar hiatus is a crescent-shaped/semicircular/ curved slit/groove upon the lateral wall of the nasal cavity at the middle nasal meatus just inferior to the ethmoidal bulla. It is the location of the openings for the frontal sinus, maxillary sinus, and anterior ethmoidal sinus. It is bounded inferiorly and anteriorly by the sharp concave margin of the uncinate process of the ethmoid bone, superiorly by the ethmoidal bulla, and posteriorly by the ethmoidal process of the inferior nasal concha. It leads into the ethmoidal infundibulum; it marks the medial limit of the ethmoidal infundibulum.

<span class="mw-page-title-main">Sphenoidal conchae</span>

The sphenoidal conchae are two thin, curved plates, situated at the anterior and lower part of the body of the sphenoid. An aperture of variable size exists in the anterior wall of each, and through this the sphenoidal sinus opens into the nasal cavity.

<span class="mw-page-title-main">Ethmoidal labyrinth</span>

The ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate forms part of the nasal cavity. In the disarticulated bone many of these cells are opened into, but when the bones are articulated, they are closed in at every part, except where they open into the nasal cavity.

<span class="mw-page-title-main">Anterior ethmoidal artery</span>

The anterior ethmoidal artery is a branch of the ophthalmic artery in the orbit. It exits the orbit through the anterior ethmoidal foramen alongside the anterior ethmoidal nerve. It contributes blood supply to the ethmoid sinuses, frontal sinuses, the dura mater, lateral nasal wall, and nasal septum. It issues a meningeal branch, and nasal branches.

The ethmoid bulla is a rounded elevation upon the lateral wall of the middle nasal meatus produced by one or more of the underlying middle ethmoidal air cells. It varies significantly based on the size of the underlying air cells.

<span class="mw-page-title-main">Maxillary hiatus</span>

The maxillary hiatus is the opening of a maxillary sinus into the middle nasal meatus of the nasal cavity. It is situated superoposteriorly upon the lateral nasal wall, opening into the nasal cavity at the posterior portion of the ethmoidal infundibulum. Its opening in the maxillary sinus is present upon the superior part of the medial wall of the sinus near the roof of the sinus; because of the position, gravity cannot drain the maxillary sinus contents when the head is erect.

<span class="mw-page-title-main">Anterior cranial fossa</span>

The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting frontal lobes of the brain. It is formed by the orbital plates of the frontal, the cribriform plate of the ethmoid, and the small wings and front part of the body of the sphenoid; it is limited behind by the posterior borders of the small wings of the sphenoid and by the anterior margin of the chiasmatic groove. The lesser wings of the sphenoid separate the anterior and middle fossae.

<span class="mw-page-title-main">Body of sphenoid bone</span>

The body of the sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal sinuses, which are separated from each other by a septum.

<span class="mw-page-title-main">Ethmoidal infundibulum</span>

The ethmoidal infundibulum is a funnel-shaped/slit-like/curved opening/passage/space/cleft upon the anterosuperior portion of the middle nasal meatus at the hiatus semilunaris. The anterior ethmoidal air cells, and (usually) the frontonasal duct open into the ethmoidal infundibulum. The ethmoidal infundibulum extends anterosuperiorly from its opening into the nasal cavity.

<span class="mw-page-title-main">Orbital lamina of ethmoid bone</span>

The orbital lamina of ethmoid bone is a smooth, oblong, paper-thin bone plate which forms the lateral wall of the labyrinth of the ethmoid bone. It covers the middle and posterior ethmoidal cells, and forms a large part of the medial wall of the orbit.

<span class="mw-page-title-main">Human nose</span> Feature of the human face

The human nose is the most protruding part of the human face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum which separates the nostrils and divides the nasal cavity into two.

<span class="mw-page-title-main">Nasal meatus</span> Nasal passage of the nasal cavity

In anatomy, the term nasal meatus can refer to any of the three meatuses (passages) through the skull's nasal cavity: the superior meatus, middle meatus, and inferior meatus.

References

PD-icon.svgThis article incorporates text in the public domain from page 155 of the 20th edition of Gray's Anatomy (1918)

G., Arun et alli (2017) - Anatomical variations in superior attachment of uncinate process and localization of frontal sinus outflow tract. International Journal of Otorhinolaryngology and Head and Neck Surgery, 3(2):176-179

P.S., Hechl et alli (1997) - The hiatus semilunaris and infundibulum. Endoscopic Anatomy of the Paranasal Sinuses. Springer, Vienna