Temporal bone
The temporal bones are situated at the sides and base of the skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

, and lateral to the temporal lobes of the cerebrum.

The temporal bone supports that part of the face known as the temple
Temple (anatomy)
Temple indicates the side of the head behind the eyes. The bone beneath is the temporal bone as well as part of the sphenoid bone.-Anatomy:Cladists classify land vertebrates based on the presence of an upper hole, a lower hole, both, or neither in the cover of dermal bone which formerly covered the...



The temporal bone consists of four parts:
  • Squama temporalis
    Squama temporalis
    The squama of the temporal bone forms the anterior and upper part of the bone, and is scale-like, thin, and translucent.- Surfaces :Its outer surface is smooth and convex; it affords attachment to the temporalis muscle, and forms part of the temporal fossa; on its hinder part is a vertical groove...

  • Mastoid portion
  • Petrous portion
    Petrous portion of the temporal bone
    The petrous portion of the temporal bone or pyramid is pyramidal and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents for examination a base, an apex, three surfaces, and three angles, and contains, in its...

     (Petrosal ridge)
  • Tympanic part
    Tympanic part
    The tympanic part of the temporal bone is a curved plate of bone lying below the squama, in front of the mastoid process, and surrounding the external acoustic meatus....


The structure of the squama is like that of the other cranial bones: the mastoid portion is spongy, and the petrous portion dense and hard.

In other animals

In evolutionary terms, the temporal bone is derived from the fusion of many bones that are often separate in non-human mammals:
  • The squamosal
    The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...

     bone, which is homologous
    Homology (biology)
    Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...

     with the squama, and forms the side of the cranium in many bony fish
    Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...

     and tetrapod
    Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...

    s. Primitively, it is a flattened plate-like bone, but in many animals it is narrower in form, for example, where it forms the boundary between the two temporal fenestrae of diapsid
    Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara...

  • The petrous and mastoid parts of the temporal bone, which derive from the periotic bone
    Periotic bone
    Periotic bone is the single bone that surrounds the ear of mammals. It is formed from the fusion of the pro-otic, epiotic, and opisthotic bones.- External links :* http://www.encyclopedia.com/doc/1O8-perioticbone.html...

    , formed from the fusion of a number of bones surrounding the ear of reptiles. The delicate structure of the middle ear
    Middle ear
    The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear has...

    , unique to mammals, is generally not protected in marsupial
    Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...

    s, but in placentals, it is usually enclosed within a bony sheath called the auditory bulla
    Auditory bulla
    The auditory bulla is a hollow bony structure on the ventral, posterior portion of the skull of placental mammals that encloses parts of the middle and inner ear. In most species, it is formed by the tympanic part of the temporal bone.In extant primates, the structure is found in tarsiers,...

    . In many mammals this includes a separate femer bone derived from the angular bone of the reptilian lower jaw, and, in some cases, an additional entotympanic bone. The auditory bulla is homologous with the tympanic part of the temporal bone.
  • Two parts of the hyoid arch: the styloid process. In the dog the styloid process is represented by a series of 4 articulating bones, from top down tympanohyal, stylohyal, epihyal, ceratohyal; the first two represent the styloid process, and the ceratohyal represents the anterior horns of the hyoid bone
    Hyoid bone
    The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

     and articulates with the basihyal which represents the body of the hyoid bone.

See also

  • Ossification of temporal bone
    Ossification of temporal bone
    The temporal bone is ossified from eight centers, exclusive of those for the internal ear and the tympanic ossicles: one for the squama including the zygomatic process, one for the tympanic part, four for the petrous and mastoid parts, and two for the styloid process. Just before the close of fetal...

  • Bone terminology
  • Terms for anatomical location
  • Temporal fenestrae
  • Temporomandibular joint
    Temporomandibular joint
    The temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on either side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium , and the lower jaw bone called the...

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