|
Occiput
The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cerebrum. At the base of skull in the occipital bone, there is a large oval opening called the foramen magnum, which allows the passage of the spinal cord. Like the other cranial bones, it is classed as a flat bone. Due to its many attachments and features, the occipital bone is described in terms of separate parts. From its front to the back is the basilar part, also called the basioccipital, at the sides of the foramen magnum are the lateral parts, also called the exoccipitals, and the back is named as the squamous part. The basilar part is a thick, somewhat quadrilateral piece in front of the foramen magnum and directed towards the pharynx. The squamous part is the curved, expanded plate behind the foramen magnum and is the largest part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parietal Bone
The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin ''paries'' (''-ietis''), wall. Surfaces External The external surface ig. 1is convex, smooth, and marked near the center by an eminence, the parietal eminence (''tuber parietale''), which indicates the point where ossification commenced. Crossing the middle of the 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 temporal muscle. Above these lines the bone is covered by a tough layer of fibrous tissue – the epicranial aponeurosis; below them it forms part of the temporal fossa, and affords attachment to the temporal muscle. At the back part an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squamous Part Of Occipital Bone
The squamous part of occipital bone is situated above and behind the foramen magnum, and is curved from above downward and from side to side. External surface The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance and inion. Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the epicranial aponeurosis is attached. The lower is termed the superior nuchal line. That area of the squamous part, which lies above the highest nuchal lines is named the occipital plane ''(planum occipitale)'' and is covered by the ''occipitalis muscle''. That below, termed the nuchal plane, is rough and irregular for the attachment of several muscles. From the external occipital protuberance, an often faintly marked ridge or crest, the median nuchal line, descends to the foram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuchal Plane
The squamous part of occipital bone is situated above and behind the foramen magnum, and is curved from above downward and from side to side. External surface The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance and inion. Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the epicranial aponeurosis is attached. The lower is termed the superior nuchal line. That area of the squamous part, which lies above the highest nuchal lines is named the occipital plane ''(planum occipitale)'' and is covered by the ''occipitalis muscle''. That below, termed the nuchal plane, is rough and irregular for the attachment of several muscles. From the external occipital protuberance, an often faintly marked ridge or crest, the median nuchal line, descends to the forame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occipital Plane
The squamous part of occipital bone is situated above and behind the foramen magnum, and is curved from above downward and from side to side. External surface The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance and inion. Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the epicranial aponeurosis is attached. The lower is termed the superior nuchal line. That area of the squamous part, which lies above the highest nuchal lines is named the occipital plane ''(planum occipitale)'' and is covered by the ''occipitalis muscle''. That below, termed the nuchal plane, is rough and irregular for the attachment of several muscles. From the external occipital protuberance, an often faintly marked ridge or crest, the median nuchal line, descends to the forame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuchal Line
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, but is sometimes referred to as the Mempin line or linea suprema, and it attaches to the epicranial aponeurosis. * Below the highest nuchal line is the superior nuchal line. To it is attached, the splenius capitis muscle, the trapezius muscle, and the occipitalis. * From the external occipital protuberance a ridge or crest, the external occipital crest also called the median nuchal line, often faintly marked, descends to the foramen magnum, and affords attachment to the nuchal ligament The nuchal ligament is a ligament at the back of the neck that is continuous with the supraspinous ligament. Structure The nuchal ligament extends from the external occipital protuberance on the skull and median nuchal line to the spinous proc .... * Running from the middle of this line is the inferior nuchal line. Attached are the obliquus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuchal Ligament
The nuchal ligament is a ligament at the back of the neck that is continuous with the supraspinous ligament. Structure The nuchal ligament extends from the external occipital protuberance on the skull and median nuchal line to the spinous process of the seventh cervical vertebra in the lower part of the neck. From the anterior border of the nuchal ligament, a fibrous lamina is given off. This is attached to the posterior tubercle of the atlas, and to the spinous processes of the cervical vertebrae, and forms a septum between the muscles on either side of the neck. The trapezius and splenius capitis muscle attach to the nuchal ligament. Function It is a tendon-like structure that has developed independently in humans and other animals well adapted for running. In some four-legged animals, particularly ungulates, the nuchal ligament serves to sustain the weight of the head. Clinical significance In Chiari malformation treatment, decompression and duraplasty with a harvest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Occipital Crest
The external occipital crest is part of the external surface of the squamous part of the occipital bone. It is a ridge along the midline, beginning at the external occipital protuberance and descending to the foramen magnum The foramen magnum ( la, great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblonga ..., that gives attachment to the nuchal ligament. It is also called the median nuchal line. References External links Bones of the head and neck {{musculoskeletal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Occipital Protuberance
Near the middle of the squamous part of occipital bone is the external occipital protuberance, the highest point of which is referred to as the inion. The inion is the most prominent projection of the protuberance which is located at the posterioinferior (rear lower) part of the human skull. The nuchal ligament and trapezius muscle attach to it. The inion (ἰνίον, iníon, Greek for the occipital bone) is used as a landmark in the 10-20 system in electroencephalography (EEG) recording. Extending laterally from it on either side is the superior nuchal line, and above it is the faintly marked highest nuchal line. A study of 16th-century Anatolian remains showed that the external occipital protuberance statistically tends to be less pronounced in female remains. Additional images See also * Internal occipital protuberance Along the internal surface of the occipital bone, at the point of intersection of the four divisions of the cruciform eminence, is the internal occipital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cruciform Eminence
The cruciform eminence (or cruciate eminence) divides the deeply concave internal surface of the occipital bone into four fossae: * The upper two fossae are called the cerebral fossae, are triangular and lodge the occipital lobes of the cerebrum. * The lower two are called the cerebellar fossae, are quadrilateral and accommodate the hemispheres of the cerebellum. The upper fossae are separated from the lower fossae by a groove for the transverse sinuses The transverse sinuses (left and right lateral sinuses), within the human head, are two areas beneath the brain which allow blood to drain from the back of the head. They run laterally in a groove along the interior surface of the occipital bone. .... At the point of intersection between all four fossae is the internal occipital protuberance. Additional images File:Cerebral fossa of occipital bone04.png, Cerebral fossa (shown in red) File:Cerebellar fossa of occipital bone01.png, Cerebellar fossa (shown in red) References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occipital Condyles
The occipital condyles are undersurface protuberances of the occipital bone in vertebrates, which function in articulation with the superior facets of the atlas vertebra. The condyles are oval or reniform (kidney-shaped) in shape, and their anterior extremities, directed forward and medialward, are closer together than their posterior, and encroach on the basilar portion of the bone; the posterior extremities extend back to the level of the middle of the foramen magnum. The articular surfaces of the condyles are convex from before backward and from side to side, and look downward and lateralward. To their margins are attached the capsules of the atlanto-occipital joints, and on the medial side of each is a rough impression or tubercle for the alar ligament. At the base of either condyle the bone is tunnelled by a short canal, the hypoglossal canal. Clinical significance Fracture of an occipital condyle may occur in isolation, or as part of a more extended basilar skull fracture ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diploë
Diploë ( or ) is the spongy cancellous bone separating the inner and outer layers of the cortical bone of the skull. In the cranial bones, the layers of compact cortical tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the ''vitreous table''. The intervening cancellous tissue is called the diploë. In certain regions of the skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ... this becomes absorbed so as to leave spaces filled with liquid between the two tables. Etymology From Ancient Greek διπλόη (''diplóē'', “literally, a fold”), noun use of feminine of διπλόος (''diplóos'', “double”) References External links Skull {{musculoskelet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
