Squama temporalis
Encyclopedia
The squama of the temporal bone
forms the anterior and upper part of the bone, and is scale-like, thin, and translucent.
, and forms part of the temporal fossa
; on its hinder part is a vertical groove for the middle temporal artery. A curved line, the temporal line, or supramastoid crest, runs backward and upward across its posterior part; it serves for the attachment of the temporal fascia
, and limits the origin of the temporalis muscle. The boundary between the squama and the mastoid portion of the bone, as indicated by traces of the original suture, lies about 1 cm. below this line.
Projecting from the lower part of the squama is a long, arched process, the zygomatic process
. This process is at first directed lateralward, its two surfaces looking upward and downward; it then appears as if twisted inward upon itself, and runs forward, its surfaces now looking medialward and lateralward. The superior border is long, thin, and sharp, and serves for the attachment of the temporal fascia; the inferior, short, thick, and arched, has attached to it some fibers of the masseter. The lateral surface is convex and subcutaneous; the medial is concave, and affords attachment to the masseter. The anterior end is deeply serrated and articulates with the zygomatic bone
. The posterior end is connected to the squama by two roots, the anterior and posterior roots. The posterior root, a prolongation of the upper border, is strongly marked; it runs backward above the external auditory meatus, and is continuous with the temporal line. The anterior root, continuous with the lower border, is short but broad and strong; it is directed medialward and ends in a rounded eminence, the articular tubercle
(eminentia articularis).
This tubercle forms the front boundary of the mandibular fossa
, and in the fresh state is covered with cartilage. In front of the articular tubercle is a small triangular area which assists in forming the infratemporal fossa
; this area is separated from the outer surface of the squama by a ridge which is continuous behind with the anterior root of the zygomatic process, and in front, in the articulated skull, with the infratemporal crest
on the great wing of the sphenoid
. Between the posterior wall of the external acoustic meatus and the posterior root of the zygomatic process is the area called the suprameatal triangle (Macewen), or mastoid fossa, through which an instrument may be pushed into the tympanic antrum.
At the junction of the anterior root with the zygomatic process is a projection for the attachment of the temporomandibular ligament
; and behind the anterior root is an oval depression, forming part of the mandibular fossa, for the reception of the condyle of the mandible. The mandibular fossa (glenoid fossa) is bounded, in front, by the articular tubercle; behind, by the tympanic part of the bone, which separates it from the external acoustic meatus; it is divided into two parts by a narrow slit, the petrotympanic fissure (Glaserian fissure). The anterior part, formed by the squama, is smooth, covered in the fresh state with cartilage
, and articulates with the condyle of the mandible. Behind this part of the fossa is a small conical eminence; this is the representative of a prominent tubercle which, in some mammals, descends behind the condyle of the mandible, and prevents its backward displacement. The posterior part of the mandibular fossa, formed by the tympanic part
of the bone, is non-articular, and sometimes lodges a portion of the parotid gland
.
The petrotympanic fissure
leads into the middle ear
or tympanic cavity
; it lodges the anterior process of the malleus
, and transmits the tympanic branch of the internal maxillary artery
. The chorda tympani
nerve passes through a canal (canal of Huguier), separated from the anterior edge of the petrotympanic fissure by a thin scale of bone and situated on the lateral side of the auditory tube, in the retiring angle between the squama and the petrous portion of the temporal.
The internal surface of the squama is concave; it presents depressions corresponding to the convolutions of the temporal lobe of the brain, and grooves for the branches of the middle meningeal vessels.
, forming with it the squamosal suture. Posteriorly, the superior border forms an angle, the parietal notch, with the mastoid portion of the bone.
The antero-inferior border is thick, serrated, and bevelled at the expense of the inner table above and of the outer below, for articulation with the great wing of the sphenoid
.
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...
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 muscleTemporalis muscle
The temporal muscle is one of the muscles of mastication.-Structure:It arises from the temporal fossa and the deep part of temporal fascia...
, and forms part of the temporal fossa
Temporal fossa
The temporal fossa is a shallow depression on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.-Boundaries:...
; on its hinder part is a vertical groove for the middle temporal artery. A curved line, the temporal line, or supramastoid crest, runs backward and upward across its posterior part; it serves for the attachment of the temporal fascia
Fascia
A fascia is a layer of fibrous tissue that permeates the human body. A fascia is a connective tissue that surrounds muscles, groups of muscles, blood vessels, and nerves, binding those structures together in much the same manner as plastic wrap can be used to hold the contents of sandwiches...
, and limits the origin of the temporalis muscle. The boundary between the squama and the mastoid portion of the bone, as indicated by traces of the original suture, lies about 1 cm. below this line.
Projecting from the lower part of the squama is a long, arched process, the zygomatic process
Zygomatic process of temporal bone
The zygomatic process of the temporal bone is a long, arched process projecting from the lower part of the squamous portion of the temporal bone...
. This process is at first directed lateralward, its two surfaces looking upward and downward; it then appears as if twisted inward upon itself, and runs forward, its surfaces now looking medialward and lateralward. The superior border is long, thin, and sharp, and serves for the attachment of the temporal fascia; the inferior, short, thick, and arched, has attached to it some fibers of the masseter. The lateral surface is convex and subcutaneous; the medial is concave, and affords attachment to the masseter. The anterior end is deeply serrated and articulates with the zygomatic bone
Zygomatic bone
The zygomatic bone is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. The zygomatic is homologous to the jugal bone of other tetrapods...
. The posterior end is connected to the squama by two roots, the anterior and posterior roots. The posterior root, a prolongation of the upper border, is strongly marked; it runs backward above the external auditory meatus, and is continuous with the temporal line. The anterior root, continuous with the lower border, is short but broad and strong; it is directed medialward and ends in a rounded eminence, the articular tubercle
Articular tubercle
The anterior root of the posterior end of the outer surface of the Squama temporalis, continuous with the lower border, is short but broad and strong; it is directed medialward and ends in a rounded eminence, the articular tubercle .This tubercle forms the front boundary of the mandibular fossa,...
(eminentia articularis).
This tubercle forms the front boundary of the mandibular fossa
Mandibular fossa
The mandibular fossa is the depression in the temporal bone that articulates with the mandibular condyle. In the temporal bone, the mandibular fossa is bounded, in front, by the articular tubercle; behind, by the tympanic part of the bone, which separates it from the external acoustic meatus; it is...
, and in the fresh state is covered with cartilage. In front of the articular tubercle is a small triangular area which assists in forming the infratemporal fossa
Infratemporal fossa
The infratemporal fossa is an irregularly shaped cavity, situated below and medial to the zygomatic arch.* anteriorly, by the infratemporal surface of the maxilla and the ridge which descends from its zygomatic process...
; this area is separated from the outer surface of the squama by a ridge which is continuous behind with the anterior root of the zygomatic process, and in front, in the articulated skull, with the infratemporal crest
Infratemporal crest
The lateral surface of the great wing of the sphenoid is convex, and divided by a transverse ridge, the infratemporal crest, into two portions....
on the great wing of the sphenoid
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
. Between the posterior wall of the external acoustic meatus and the posterior root of the zygomatic process is the area called the suprameatal triangle (Macewen), or mastoid fossa, through which an instrument may be pushed into the tympanic antrum.
At the junction of the anterior root with the zygomatic process is a projection for the attachment of the temporomandibular ligament
Temporomandibular ligament
The temporomandibular ligament consists of two short, narrow fasciculi, one in front of the other, attached, above, to the lateral surface of the zygomatic arch and to the tubercle on its lower border; below, to the lateral surface and posterior border of the neck of the mandible.It is broader...
; and behind the anterior root is an oval depression, forming part of the mandibular fossa, for the reception of the condyle of the mandible. The mandibular fossa (glenoid fossa) is bounded, in front, by the articular tubercle; behind, by the tympanic part of the bone, which separates it from the external acoustic meatus; it is divided into two parts by a narrow slit, the petrotympanic fissure (Glaserian fissure). The anterior part, formed by the squama, is smooth, covered in the fresh state with cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
, and articulates with the condyle of the mandible. Behind this part of the fossa is a small conical eminence; this is the representative of a prominent tubercle which, in some mammals, descends behind the condyle of the mandible, and prevents its backward displacement. The posterior part of the mandibular fossa, formed by the 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....
of the bone, is non-articular, and sometimes lodges a portion of the parotid gland
Parotid gland
The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...
.
The petrotympanic fissure
Petrotympanic fissure
The petrotympanic fissure is a fissure in the temporal bone that runs from the temporomandibular joint to the tympanic cavity....
leads into 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...
or tympanic cavity
Tympanic cavity
The tympanic cavity is a small cavity surrounding the bones of the middle ear.It is formed from the tubotympanic recess, an expansion of the first pharyngeal pouch....
; it lodges the anterior process of the malleus
Malleus
The malleus or hammer is a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum...
, and transmits the tympanic branch of the internal maxillary artery
Internal maxillary artery
The maxillary artery is an artery that supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible.-Structure:...
. The chorda tympani
Chorda tympani
The chorda tympani is a nerve that branches from the facial nerve inside the facial canal, just before the facial nerve exits the skull via the Stylomastoid foramen...
nerve passes through a canal (canal of Huguier), separated from the anterior edge of the petrotympanic fissure by a thin scale of bone and situated on the lateral side of the auditory tube, in the retiring angle between the squama and the petrous portion of the temporal.
The internal surface of the squama is concave; it presents depressions corresponding to the convolutions of the temporal lobe of the brain, and grooves for the branches of the middle meningeal vessels.
Borders
The superior border is thin, and bevelled at the expense of the internal table, so as to overlap the squamous border of the parietal boneParietal bone
The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....
, forming with it the squamosal suture. Posteriorly, the superior border forms an angle, the parietal notch, with the mastoid portion of the bone.
The antero-inferior border is thick, serrated, and bevelled at the expense of the inner table above and of the outer below, for articulation with the great wing of the sphenoid
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
.