what is the most posterior structure of the atlas c1 vertebra
posterior arch
dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side. The atlas's chief peculiarity is that it has no body. It is ring-like and consists of an anterior and a posterior arch and two lateral masses. The atlas and axis are important neurologically because the brain stem extends down to the axis. The anterior arch forms about one-fifth of the ring: its anterior surface is convex, and presents at its center the anterior tubercle for the attachment of the "Longus colli" muscles and the anterior longitudinal ligament; posteriorly it is
Atlas (anatomy)
called nuclei. Axons within the CNS are grouped into tracts. There are 33 spinal cord nerve segments in a human spinal cord: 8 cervical segments forming 8 pairs of cervical nerves (C1 spinal nerves exit spinal column between occiput and C1 vertebra; C2 nerves exit between posterior arch of C1 vertebra and lamina of C2 vertebra; C3-C8 spinal nerves through IVF above corresponding cervica vertebra, with the exception of C8 pair which exit via IVF between C7 and T1 vertebra) 12 thoracic segments forming 12 pairs of thoracic nerves (exit spinal column through IVF below corresponding vertebra T1-T12) 5 lumbar
Neuromere
6th cervical vertebrae (C6), or occasionally (in 7.5% of cases) at the level of C7. They then proceed superiorly, in the transverse foramen of each cervical vertebra. Once they have passed through the transverse foramen of C1 (also known as the atlas), the vertebral arteries travel across the posterior arch of C1 and through the suboccipital triangle before entering the foramen magnum. Nunziante Ippolito, a Neapolitan physician, identified the "angle of Nunziante Ippolito" to find the vertebral artery, between the anterior scalene muscle and the longus colli muscle. Inside the skull, the two vertebral arteries join to form the basilar
Vertebral artery
capitis posteriores minores and Obliqui capitis superiores and is superficial to the dura mater of the vertebral canal to which it is closely associated. In 2015, Scali et al. revisited the anatomy of the posterior atlantooccipital membrane via plastination. Their findings revealed that the PAO membrane superiorly consisted of periosteum of the occiput, whereas inferiorly it formed part of the dura at the cerebrospinal junction, terminating at the level of the third cervical vertebra (rather than attaching to the posterior arch of the atlas). It is believed that this anatomical arrangement permits a superiorly located anchor point for epidural bridging
Posterior atlantooccipital membrane
often bifurcated (the spinous process of C7, however, is not bifurcated, and is substantially longer than that of the other cervical spinous processes). The atlas differs from the other vertebrae in that it has no body and no spinous process. It has instead a ring-like form, having an anterior and a posterior arch and two lateral masses. At the outside centre points of both arches there is a tubercle, an anterior tubercle and a posterior tubercle, for the attachment of muscles. The front surface of the anterior arch is convex and its anterior tubercle gives attachment to the longus colli
Vertebra
emerges from the foramen transversarium of the sixth cervical vertebra, and opens at the root of the neck into the back part of the innominate vein near its origin, its mouth being guarded by a pair of valves. On the right side, it crosses the first part of the subclavian artery. Vertebral vein The vertebral vein is formed in the suboccipital triangle, from numerous small tributaries which spring from the internal vertebral venous plexuses and issue from the vertebral canal above the posterior arch of the atlas. They unite with small veins from the deep muscles at the upper part
Vertebral vein
refined by the relatively small suboccipital triangle muscles. Suboccipital triangle The suboccipital triangle is a region of the neck bounded by the following three muscles of the suboccipital group of muscles: (Rectus capitis posterior minor is also in this region but does not form part of the triangle) It is covered by a layer of dense fibro-fatty tissue, situated beneath the semispinalis capitis. The floor is formed by the posterior atlantooccipital membrane, and the posterior arch of the atlas. In the deep groove on the upper surface of the posterior arch of the atlas are the vertebral artery and the
Suboccipital triangle
Suboccipital triangle The suboccipital triangle is a region of the neck bounded by the following three muscles of the suboccipital group of muscles: (Rectus capitis posterior minor is also in this region but does not form part of the triangle) It is covered by a layer of dense fibro-fatty tissue, situated beneath the semispinalis capitis. The floor is formed by the posterior atlantooccipital membrane, and the posterior arch of the atlas. In the deep groove on the upper surface of the posterior arch of the atlas are the vertebral artery and the first cervical or suboccipital nerve. In the past,
Suboccipital triangle
artery, which, after ascending through the foramen in the transverse process, winds around the lateral mass in a direction backward and medially to enter the vertebrobasilar circulation through the foramen magnum; it also transmits the suboccipital nerve (first spinal nerve) On the under surface of the posterior arch, behind the inferior articular facets, are two shallow grooves, the inferior vertebral notches. The lower border gives attachment to the posterior atlantoaxial ligament, which connects it with the axis. The lateral masses are the most bulky and solid parts of the atlas, in order to support the weight of the head. Each
Atlas (anatomy)
Posterior atlantooccipital membrane The posterior atlantooccipital membrane (posterior atlantooccipital ligament) is a broad but thin membrane. It is connected above to the posterior margin of the foramen magnum and below to the upper border of the posterior arch of the atlas. On each side of this membrane there is a defect above the groove for the vertebral artery which serves as an opening for the entrance of the artery. The suboccipital nerve also passes through this defect. The free border of the membrane arches over the artery and nerve and is sometimes ossified. The membrane is deep to the Recti
Posterior atlantooccipital membrane
a now-shelved film adaptation of John Kennedy Toole's Pulitzer Prize-winning novel "A Confederacy of Dunces". He had also expressed interest in portraying Atuk in a film adaptation of Mordecai Richler's "The Incomparable Atuk" and Roscoe "Fatty" Arbuckle in a biopic based on the silent film comedian's life. These three shelved projects have been referred to as "cursed" because Candy, John Belushi, Sam Kinison and Chris Farley were each attached to all three roles, and they all died before they could make any of these films. Candy was originally considered to play Alec Guinness's role in the remake of the 1950
John Candy
and physical examination. National Institute of Allergy and Infectious Diseases guidelines recommend that parent and patient reports of food allergy be confirmed by a doctor because "multiple studies demonstrate 50% to 90% of presumed food allergies are not allergies." Skin prick tests can be used to confirm specific food allergies. Skin prick tests are designed to identify specific IgE bound to cutaneous mast cells. During the test, a glycerinated allergen extract drop is placed on the patient's skin. The patient's skin is then pricked through the drop. This procedure is repeated with two controls: a histamine drop designed to elicit
Peanut allergy
RNA world, has been suggested. One of the difficulties for the study of the origins of viruses is their high rate of mutation; this is particularly the case in RNA retroviruses like HIV. A 2015 study compared protein fold structures across different branches of the tree of life, where researchers can reconstruct the evolutionary histories of the folds and of the organisms whose genomes code for those folds. They argue that protein folds are better markers of ancient events as their three-dimensional structures can be maintained even as the sequences that code for those begin to change. Thus, the viral
Abiogenesis
liturgical color is white. It is a tradition to celebrate such Rorate Masses in the early morning (before sunrise), accompanied by candle light in an otherwise dark church. In the ordinary form of the Roman Rite, it is often replaced by a Mass with the liturgical texts of the corresponding Advent weekday (consequently with violet vestments), or possibly the day's saint, but with the rest of the Rorate Mass traditions. The Rorate Mass originated during the course of the Middle Ages as one of the various popular Advent devotions to the Blessed Virgin Mary which were then developed. As one
Rorate caeli
pay claims in full. Before selling its domestic and international property and casualty business to the Bermuda-based ACE Insurance company in the late 1990s, Cigna was among the companies with a large international network comparable to those of AIG, Allianz, and Zurich. The strategy behind the sale was to concentrate on core business. ACE – at that time a key player at the Bermuda and Lloyds insurance market – on the other hand was interested on expanding the international network in the traditional insurance market. Cigna sold the majority of its life insurance operations to Lincoln National Corporation in 1997.
Cigna
Xenoposeidon Xenoposeidon (meaning "strange or alien Poseidon", in allusion to "Sauroposeidon") is a genus of rebbachisaurid sauropod dinosaur from the Early Cretaceous of England, living about 140 million years ago. It is known from a single partial vertebra with unusual features, unlike those of other sauropods. This bone was first discovered in the early 1890s but received little attention until it was found by University of Portsmouth student Mike Taylor, who formally described and named it in 2007 with Darren Naish. "Xenoposeidon" is based on BMNH R2095, a partial posterior back vertebra. The specimen lacks the anterior face of the
Xenoposeidon
of the head of the rib. The other costovertebral joint is that between the tubercle on the neck and the transverse process of the joining thoracic vertebra of the same rib number, and this is known as the costotransverse joint. The superior costotransverse ligament attaches from the non-articular facet of the tubercle to the transverse process of the vertebra. The neck of the rib is a flattened part that extends laterally from the head. The neck is about 3 cm long. Its anterior surface is flat and smooth, whilst its posterior is perforated by numerous foramina and its surface rough,
Rib
Adad baranto. Viewed in a lateral radiograph, it appears as a triangular shaped bone fragment, not unlike an anterior lip fracture, but with softer edges. Limbus vertebra is not always symptomatic, but severe cases may lead to more serious pathological conditions and chronic pain. In rare instances, a posterior limbus vertebra has been described causing radiculopathy due to nerve root compression. Limbus vertebra A limbus vertebra is a bone tubercle formed by bone trauma on a vertebral body, bearing a radiographic similarity to a vertebral fracture. The anterior-superior corner of a single vertebra is the common site for this defect
Limbus vertebra
4% of all spondylosis. The facet joints are formed by the superior and inferior processes of each vertebra. The first cervical vertebra has an inferior articulating surface but, as it does not restrict lateral or posterior translation, is not always considered a proper zygoma ("zygoma" is Greek for "yoke," i.e. something that restrains movement). In the lumbar spine, facets provide about 20 percent of the twisting stability in the low back. Each facet joint is positioned at each level of the spine to provide the needed support especially with rotation. Facet joints also prevent each vertebra from slipping over the
Facet syndrome
form than those at the front, and transmit the posterior divisions of the sacral nerves. On the side of the posterior sacral foramina is a series of tubercles, the transverse processes of the sacral vertebrae, and these form the lateral sacral crest. The transverse tubercles of the first sacral vertebra are large and very distinct; they, together with the transverse tubercles of the second vertebra, give attachment to the horizontal parts of the posterior sacroiliac ligaments; those of the third vertebra give attachment to the oblique fasciculi of the posterior sacroiliac ligaments; and those of the fourth and fifth to
Sacrum
posterior arch
Title: Atlas (anatomy). Content: dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side. The atlas's chief peculiarity is that it has no body. It is ring-like and consists of an anterior and a posterior arch and two lateral masses. The atlas and axis are important neurologically because the brain stem extends down to the axis. The anterior arch forms about one-fifth of the ring: its anterior surface is convex, and presents at its center the anterior tubercle for the attachment of the "Longus colli" muscles and the anterior longitudinal ligament; posteriorly it is
Posterior arch
Dens
posterior arch
posterior arch
posterior arch
posterior arch