fossae (Subarcuate fossa, Jugular fossa) - canaliculi (Inferior tympanic, Mastoid) - Styloid process - Petrosquamous suture This article is about the skeletal organs. ... An MRI scan of the head. ... In humans, the adult skull is normally made up of 22 bones. ... The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself. ... The squama of the occipital bone, situated above and behind the foramen magnum, is curved from above downward and from side to side. ... The inion is the most prominent projection of the occipital bone at the lower rear part of the skull. ... The inion is the most prominent projection of the occipital bone at the lower rear part of the skull. ... The nuchal lines are four curved lines on the external surface of the occipital bone: The upper, often faintly marked, is named the highest nuchal line, and to it the galea aponeurotica is attached. ... The internal surface of the occipital bone is deeply concave and divided into four fossæ by a cruciform eminence ( or cruciate eminence). ... In the occipital bone, at the point of intersection of the four divisions of the cruciate eminence is the internal occipital protuberance. ... The internal surface of the squama frontalis of the frontal bone is concave and presents in the upper part of the middle line a vertical groove, the sagittal sulcus, the edges of which unite below to form a ridge, the frontal crest; the sulcus lodges the superior sagittal sinus, while... In the occipital bone, the lower division of the cruciate eminence is prominent, and is named the internal occipital crest; it bifurcates near the foramen magnum and gives attachment to the falx cerebelli; in the attached margin of this falx is the occipital sinus, which is sometimes duplicated. ... The lateral parts of the occipital bone are situated at the sides of the foramen magnum; on their under surfaces are the condyles for articulation with the superior facets of the atlas. ... The lateral parts of the occipital bone are situated at the sides of the foramen magnum; on their under surfaces are the occipital condyles for articulation with the superior facets of the atlas. ... Behind either condyle of the lateral parts of occipital bone is a depression, the condyloid fossa (or condylar fossa), which receives the posterior margin of the superior facet of the atlas when the head is bent backward; the floor of this fossa is sometimes perforated by the condyloid canal, through... In the lateral parts of occipital bone, behind either condyle is a depression, the condyloid fossa, which receives the posterior margin of the superior facet of the atlas when the head is bent backward; the floor of this fossa is sometimes perforated by the condylar canal (or condyloid canal), through... The hypoglossal canal is a bony canal in the occipital bone of the skull that transmits the hypoglossal nerve from its point of entry near the medulla oblongata to its exit from the base of the skull near the jugular foramen. ... In the lateral part of the occipital bone, extending lateralward from the posterior half of the condyle is a quadrilateral plate of bone, the jugular process, excavated in front by the jugular notch, which, in the articulated skull, forms the posterior part of the jugular foramen. ... The upper surface of the lateral parts of occipital bone presents an oval eminence, the jugular tubercle, which overlies the hypoglossal canal and is sometimes crossed by an oblique groove for the glossopharyngeal, vagus, and accessory nerves. ... The basilar part of the occipital bone extends forward and upward from the foramen magnum, and presents in front an area more or less quadrilateral in outline. ... On the lower surface of the basilar part of occipital bone, about 1 cm. ... In anatomy, in the occipital bone, the foramen magnum (Latin: great hole) is one of the several oval or circular apertures in the base of the skull (the foramina), through which the medulla oblongata (an extension of the spinal cord) enters and exits the skull vault. ... The parietal bones (os parietale) are bones in the human skull and form, by their union, the sides and roof of the cranium. ... The external surface of the parietal bone is convex, smooth, and marked near the center by an eminence, the parietal eminence (parietal tuber), which indicates the point where ossification commenced. ... Crossing the middle of the parietal bone in an arched direction are two curved lines, the superior and inferior temporal lines; the former gives attachment to the temporal fascia, and the latter indicates the upper limit of the muscular origin of the Temporalis. ... At the back part of the parietal bone and close to the upper or sagittal border is the parietal foramen, which transmits a vein to the superior sagittal sinus, and sometimes a small branch of the occipital artery; it is not constantly present, and its size varies considerably. ... The frontal bone (os frontale, TA: A02. ... There are two surfaces of the squama of the frontal bone: the external surface, and the internal surface. ... The frontal suture (sutura frontalis) is a dense connective tissue structure that divides the two halves of the frontal bone of the skull in infants and children. ... On the frontal bone, on either side of the frontal suture, about 3 cm. ... On the squama frontalis of the frontal bone, below the frontal eminences, and separated from them by a shallow groove, are two arched elevations, the superciliary arches; these are prominent medially, and are joined to one another by a smooth elevation named the glabella. ... The glabella is the space between the eyebrows and above the nose. ... Arching transversely below the superciliary arches is the upper part of the margin of the orbit, thin and prominent in its lateral two-thirds, rounded in its medial third, and presenting, at the junction of these two portions, the supraorbital notch or foramen for the supraorbital nerve and vessels. ... The frontal crest of the frontal bone ends below in a small notch which is converted into a foramen, the foramen cecum, by articulation with the ethmoid. ... The supraorbital margin of the frontal bone ends laterally in the zygomatic process, which is strong and prominent, and articulates with the zygomatic bone. ... The internal surface of the squama frontalis of the frontal bone is concave and presents in the upper part of the middle line a vertical groove, the sagittal sulcus, the edges of which unite below to form a ridge, the frontal crest; the sulcus lodges the superior sagittal sinus, while... The internal surface of the squama frontalis of the frontal bone is concave and presents in the upper part of the middle line a vertical groove, the sagittal sulcus, the edges of which unite below to form a ridge, the frontal crest; the sulcus lodges the superior sagittal sinus, while... The ethmoidal notch separates the two orbital plates; it is quadrilateral, and filled, in the articulated skull, by the cribriform plate of the ethmoid. ... The lacrimal bone (Os Lacrimale), the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. ... Near the nasal part of the interior surface of the frontal bone is a depression, the trochlear fovea, or occasionally a small trochlear spine, for the attachment of the cartilaginous pulley of the Obliquus oculi superior. ... ... The frontal air sinuses are lined by mucous membrane, and each communicates with the corresponding nasal cavity by means of a passage called the frontonasal duct. ... The temporal bones (os temporales) are situated at the sides and base of the skull. ... The squama of the temporal bone forms the anterior and upper part of the bone, and is scale-like, thin, and translucent. ... 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 (eminentia articularis). ... In the temporal bone, between the posterior wall of the external acoustic meatus and the posterior root of the zygomatic process is the area called the suprameatal triangle, or mastoid fossa, through which an instrument may be pushed into the tympanic antrum. ... In the temporal bone, 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 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 divided into two parts by a narrow slit, the petrotympanic fissure (Glaserian fissure). ... 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. ... The outer surface of the temporal bone is perforated by numerous foramina; one of these, of large size, situated near the posterior border, is termed the mastoid foramen; it transmits a vein to the transverse sinus and a small branch of the occipital artery to the dura mater. ... The mastoid process (or mastoid bone) is a conical bump of the posterior portion of the temporal bone that is situated behind the ear in humans and many other vertebrates and serves as a site of neck muscle attachment (the Sternocleidomastoid, Splenius capitis, and Longissimus capitis). ... A section of the mastoid process shows it to be hollowed out into a number of spaces, the mastoid cells, which exhibit the greatest possible variety as to their size and number. ... On the medial side of the mastoid process is a deep groove, the mastoid notch (digastric fossa), for the attachment of the Digastricus. ... On the medial side of the mastoid process of the temporal bone is a deep groove, the mastoid notch (digastric fossa), for the attachment of the Digastricus; medial to this is a shallow furrow, the occipital groove, which lodges the occipital artery. ... The inner surface of the mastoid portion of the temporal bone presents a deep, curved groove, the sigmoid sulcus, which lodges part of the transverse sinus; in it may be seen the opening of the mastoid foramen. ... Mastoid antrum (or tympanic antrum) is a cavity in the petrous portion of the temporal bone, communicating posteriorly with the mastoid cells and anteriorly with the epitympanic recess of the middle ear via the aperture of the mastoid antrum. ... On the interior surface of the temporal bone, behind the rough surface of the apex, is the large circular aperture of the carotid canal, which ascends at first vertically, and then, making a bend, runs horizontally forward and medialward; it transmits into the cranium the internal carotid artery, and the... The facial canal is a canal running from the internal acoustic meatus to the stylomastoid foramen. ... A shallow groove, sometimes double, leading lateralward and backward to an oblique opening, the hiatus of the facial canal, for the passage of the greater superficial petrosal nerve and the petrosal branch of the middle meningeal artery. ... Near the center of the posterior surface of the temporal bone is a large orifice, the internal acoustic meatus (or internal auditory meatus), the size of which varies considerably; its margins are smooth and rounded, and it leads into a short canal, about 1 cm. ... Medial to the opening for the carotid canal and close to its posterior border, in front of the jugular fossa, is a triangular depression; at the apex of this is a small opening, the aquaeductus cochleae (or cochlear aqueduct, or aqueduct of cochlea), which lodges a tubular prolongation of the... Between the styloid and mastoid processes is the stylomastoid foramen; it is the termination of the facial canal, and transmits the facial nerve and stylomastoid artery. ... In the temporal bone, above and between the aquæductus vestibuli is an irregular depression which lodges a process of the dura mater and transmits a small vein; in the infant this depression is represented by a large fossa, the subarcuate fossa, which extends backward as a blind tunnel under... In the temporal bone, behind the openings for the carotid canal and the aquæductus cochleæ is a deep depression, the jugular fossa, of variable depth and size in different skulls; it lodges the bulb of the internal jugular vein. ... In the bony ridge dividing the carotid canal from the jugular fossa is the small inferior tympanic canaliculus for the passage of the tympanic branch of the glossopharyngeal nerve. ... In the lateral part of the jugular fossa of the temporal bone is the mastoid canaliculus for the entrance of the auricular branch of the vagus nerve. ... The styloid process is pointed piece of bone that extends down from the human skull, just below the ear. ... The Petrosquamous suture is a cranial suture between the petrous portion and the squama of the temporal bone. ...