Squamosal bone: Difference between revisions

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'''Squamosal bone''' is a bone found in the skull of most reptiles, birds, and mammals. It is named for its somewhat flattened or squamous shape. The squamosal bone forms part of the temporal bone in mammals.
== Squamosal Bone ==


==Etymology==
[[File:Skull_synapsida_1.png|thumb|right|Diagram of a synapsid skull showing the location of the squamosal bone.]]
The term "squamosal" is derived from the Latin word "squama", meaning "scale", due to the bone's flat, scale-like appearance.


==Anatomy==
The '''squamosal bone''' is a part of the [[skull]] found in most [[vertebrates]]. It is a component of the [[temporal bone]] in humans and plays a crucial role in the structure of the [[cranium]]. The squamosal bone is located in the lateral part of the skull and is involved in forming the [[temporal fossa]], which is an important area for muscle attachment.
The squamosal bone is located at the side of the skull, forming a part of the cranium. It is situated near the [[temporal bone]], and in mammals, it is often fused with the temporal bone to form a single structure. The squamosal bone is typically flat and somewhat rectangular in shape, and it plays a crucial role in forming the [[temporal fossa]] and the [[zygomatic arch]].


==Evolution==
== Anatomy ==
In early tetrapods, the squamosal bone was a separate element that, along with the [[quadratojugal]], made contact with the [[quadrate bone]] to form the upper part of the jaw joint. In mammals, the squamosal has become part of the temporal bone, and the quadrate has become the [[incus]], one of the [[ossicles]] of the middle ear.


==Clinical significance==
In [[mammals]], the squamosal bone is fused with other bones to form the temporal bone. It articulates with the [[parietal bone]] superiorly, the [[zygomatic bone]] anteriorly, and the [[occipital bone]] posteriorly. The squamosal bone contributes to the formation of the [[zygomatic arch]], which is a bony arch on the side of the skull that provides an attachment point for the [[masseter muscle]], a major muscle involved in [[mastication]].
While the squamosal bone is generally robust and not prone to injury, fractures can occur as a result of severe trauma to the skull. Such fractures may lead to complications including [[intracranial hemorrhage]], [[cerebrospinal fluid leak]], and [[cranial nerve injury]].
 
== Evolution ==
 
The squamosal bone has an interesting evolutionary history. In early [[synapsids]], the squamosal bone was a separate element of the skull. Over time, as synapsids evolved into mammals, the squamosal bone became more integrated into the skull structure. This integration is part of the transition from the [[reptilian]] jaw structure to the mammalian jaw structure, where the squamosal bone plays a role in the formation of the [[temporomandibular joint]].
 
== Function ==
 
The primary function of the squamosal bone is to provide structural support to the skull and serve as an attachment site for muscles. It also plays a role in protecting the [[brain]] by forming part of the cranial cavity. In addition, the squamosal bone is involved in the articulation of the jaw, particularly in mammals, where it forms part of the temporomandibular joint, allowing for complex movements necessary for chewing.
 
== Clinical Significance ==
 
In humans, the squamosal part of the temporal bone can be involved in various medical conditions. Fractures of the temporal bone can affect the squamosal region, leading to complications such as [[hearing loss]] or [[facial nerve]] damage. Additionally, the squamosal bone is a site where [[temporal arteritis]] can occur, an inflammatory condition affecting the blood vessels in the area.
 
== Related Pages ==


==See also==
* [[Cranial bones]]
* [[Temporal bone]]
* [[Temporal bone]]
* [[Zygomatic arch]]
* [[Cranium]]
 
* [[Synapsid]]
==References==
* [[Mastication]]
<references />
* [[Temporomandibular joint]]


[[Category:Anatomy]]
[[Category:Anatomy]]
[[Category:Skull]]
[[Category:Skull]]
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Latest revision as of 11:20, 15 February 2025

Squamosal Bone[edit]

Diagram of a synapsid skull showing the location of the squamosal bone.

The squamosal bone is a part of the skull found in most vertebrates. It is a component of the temporal bone in humans and plays a crucial role in the structure of the cranium. The squamosal bone is located in the lateral part of the skull and is involved in forming the temporal fossa, which is an important area for muscle attachment.

Anatomy[edit]

In mammals, the squamosal bone is fused with other bones to form the temporal bone. It articulates with the parietal bone superiorly, the zygomatic bone anteriorly, and the occipital bone posteriorly. The squamosal bone contributes to the formation of the zygomatic arch, which is a bony arch on the side of the skull that provides an attachment point for the masseter muscle, a major muscle involved in mastication.

Evolution[edit]

The squamosal bone has an interesting evolutionary history. In early synapsids, the squamosal bone was a separate element of the skull. Over time, as synapsids evolved into mammals, the squamosal bone became more integrated into the skull structure. This integration is part of the transition from the reptilian jaw structure to the mammalian jaw structure, where the squamosal bone plays a role in the formation of the temporomandibular joint.

Function[edit]

The primary function of the squamosal bone is to provide structural support to the skull and serve as an attachment site for muscles. It also plays a role in protecting the brain by forming part of the cranial cavity. In addition, the squamosal bone is involved in the articulation of the jaw, particularly in mammals, where it forms part of the temporomandibular joint, allowing for complex movements necessary for chewing.

Clinical Significance[edit]

In humans, the squamosal part of the temporal bone can be involved in various medical conditions. Fractures of the temporal bone can affect the squamosal region, leading to complications such as hearing loss or facial nerve damage. Additionally, the squamosal bone is a site where temporal arteritis can occur, an inflammatory condition affecting the blood vessels in the area.

Related Pages[edit]