"former is attached to the basilar part of the occipital bone, in close relation with the membrana tectoria; the latter is fixed to the posterior surface of the body of the axis; hence, the whole ligament is named the cruciate ligament of the atlas. The transverse ligament divides the ring of the atlas into two unequal parts: of these, the posterior and larger serves for the transmission of the medulla spinalis and its membranes and the accessory nerves; the anterior and smaller contains the odontoid process. The neck of the odontoid process is constricted where it is embraced posteriorly by"
"Atlas (anatomy) In anatomy, the atlas (C1) is the most superior (first) cervical vertebra of the spine. It is named for the Atlas of Greek mythology, because it supports the globe of the head which is the skull. The atlas is the topmost vertebra and with the axis forms the joint connecting the skull and spine. The atlas and axis are specialized to allow a greater range of motion than normal vertebrae. They are responsible for the nodding and rotation movements of the head. The atlanto-occipital joint allows the head to nod up and down on the vertebral column. The"
"the atlas near the foramen magnum, a large hole () at the base of the skull. The atlas joins with the occipital condyle above and the axis below. The spinal cord passes through the foramen magnum. The head and neck is covered in skin and its appendages, termed the integumentary system. These include hair, sweat glands, sebaceous glands, and sensory nerves. The skin is made up of three microscopic layers: epidermis, dermis, and hypodermis. The epidermis is composed of stratified squamous epithelium and is divided into the following five sublayers or strata, listed in order from outer to inner: The"
"Axial skeleton The axial skeleton is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate. In the human skeleton, it consists of 80 bones and is composed of six parts; the skull bones, the ossicles of the middle ear, the hyoid bone, the rib cage, sternum and the vertebral column. The axial skeleton together with the appendicular skeleton form the complete skeleton. Another definition of axial skeleton is the bones including the vertebrae, sacrum, coccyx, ribs, and sternum. Flat bones house the brain and other vital organs. This article mainly deals"
"their anterior and posterior tubercles are fused into one mass; the foramen transversarium is directed from below, upward and backward. The atlas is usually ossified from three centers. Of these, one appears in each lateral mass about the seventh week of fetal life, and extends backward; at birth, these portions of bone are separated from one another behind by a narrow interval filled with cartilage. Between the third and fourth years they unite either directly or through the medium of a separate center developed in the cartilage. At birth, the anterior arch consists of cartilage; in this a separate center"
"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"
"Head and neck anatomy This article describes the anatomy of the head and neck of the human body, including the brain, bones, muscles, blood vessels, nerves, glands, nose, mouth, teeth, tongue, and throat. The head rests on the top part of the vertebral column, with the skull joining at C1 (the first cervical vertebra known as the atlas). The skeletal section of the head and neck forms the top part of the axial skeleton and is made up of the skull, hyoid bone, auditory ossicles, and cervical spine. The skull can be further subdivided into: The occipital bone joins with"
"the respiratory airway (trachea) open. Head and neck anatomy This article describes the anatomy of the head and neck of the human body, including the brain, bones, muscles, blood vessels, nerves, glands, nose, mouth, teeth, tongue, and throat. The head rests on the top part of the vertebral column, with the skull joining at C1 (the first cervical vertebra known as the atlas). The skeletal section of the head and neck forms the top part of the axial skeleton and is made up of the skull, hyoid bone, auditory ossicles, and cervical spine. The skull can be further subdivided into:"
"of the bones in the human body with the highest percentage of its surface area covered by articular cartilage. Additionally, it is also unusual in that it has a retrograde blood supply, i.e. arterial blood enters the bone at the distal end. In humans, no muscles attach to the talus, unlike most bones, and its position therefore depends on the position of the neighbouring bones. Though irregular in shape, the talus can be subdivided into three parts. Facing anteriorly, the head carries the articulate surface of the navicular bone, and the neck, the roughened area between the body and the"
"or ""coccygeal bone"" as unit. The sacral bone makes up the junction between the vertebral column and the pelvic bones. The word ""Axial"" is taken from the word ""axis"" and refers to the fact that the bones are located close to or along the central ""axis"" of the body. The axial skeleton consists of 80 bones: Axial skeleton The axial skeleton is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate. In the human skeleton, it consists of 80 bones and is composed of six parts; the skull bones, the ossicles"
"plexus. The cervical spinal nerves emerge from above the cervical vertebrae. For example, the cervical spinal nerve 3 (C3) passes above C3. The atlas (C1) and axis (C2) are the two topmost vertebrae. The atlas, C1, is the topmost vertebra, and along with the axis; forms the joint connecting the skull and spine. Its chief peculiarity is that it has no body because the body of the atlas has been fused with that of the axis. The axis, C2, forms the pivot on which the atlas rotates. The most distinctive characteristic of this bone is the strong odontoid process (dens)"
"Axis (anatomy) In anatomy, the second cervical vertebra (C2) of the spine is named the axis (from Latin ""axis"", ""axle"") or epistropheus. By the atlanto-axial joint, it forms the pivot upon which the first cervical vertebra (the atlas), which carries the head, rotates. The most distinctive characteristic of this bone is the strong odontoid process known as the dens which rises perpendicularly from the upper surface of the body. That peculiar feature gives to the vertebra a rarely used third name: vertebra dentata. In some judicial hangings the odontoid process may break and hit the medulla oblongata, causing death. The"
"of vertebrae, except for the first cervical segment, the ""atlas"". The ""atlas"" is a ring around the roughly cone-shaped extension of the ""axis"" (second cervical segment). The axis acts as a post around which the atlas can rotate, allowing the neck to swivel. There are 23 discs in the human spine: 6 in the neck (cervical region), 12 in the middle back (thoracic region), and 5 in the lower back (lumbar region). For example, the disc between the fifth and sixth cervical vertebrae is designated ""C5-6"". During development and at birth, vertebral discs have some vascular supply to the cartilage"
"seen in humans, with the bar between the orbit and fenestra vanishing entirely, and only the lower boundary of the fenestra remaining, as the zygomatic arch. The term ""zygomatic"" derives from the Greek Ζυγόμα ""zygoma"" meaning ""yoke"". The zygomatic bone is occasionally referred to as the zygoma, but this term may also refer to the zygomatic arch. Zygomatic bone In the human skull, the zygomatic bone (cheekbone or malar bone) is a paired irregular bone which articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It is situated at the upper and lateral part of"
"cases the sclerites are fused to various degrees. Thorax The thorax or chest (from the Greek θώραξ ""thorax"" ""breastplate, cuirass, corslet"" via ) is a part of the anatomy of humans and various other animals located between the neck and the abdomen. The thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain. In humans and other hominids, the thorax is the chest region of the"
"bone and the prefrontal bone. The posterior part of the bone articulates with the postorbital bone and the parietal bone. This bone defines all of part of the upper margin of the orbit. Frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions. These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, part of the bony orbital cavity holding the eye, and part of the bony part of the nose respectively. The name comes from the Latin word ""frons"" (meaning"
"or twelfth cerebral nerve, and entrance to a meningeal branch of the ascending pharyngeal artery. 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 condyloid canal, through which an emissary vein passes from the transverse sinus. 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"
"themselves, the atlas and axis are fused, albeit with a visible suture. In front of the atlas is a small, rudimentary proatlas, which is symmetrical, platelike, and has a projection at the front. Corresponding to the spherical occipital condyle is the cup-like joint of the atlas. The atlas had a prominent neural spine, but the neural spine on the axis is not exposed. At the back of the axis, on the neural arch, is the postzygapophysis, which would have connected to the next cervical vertebra. There is one specimen of ""Liaodactylus"" known, namely the holotype PMOL-AP00031, which is stored at"
"Atlanto-axial joint The atlantoaxial joint is a joint in the upper part of the neck between the first and second cervical vertebrae; the atlas and axis. It is a pivot joint. The atlantoaxial joint is of a complicated nature. It consists of no fewer than four distinct joints. There is a pivot articulation between the odontoid process of the axis and the ring formed by the anterior arch and the transverse ligament of the atlas. There are three atlantoaxial joints: one median and two lateral: The ligaments connecting these bones are: The atlantoaxial joint in common terminology is actually a"
"the transverse process of the atlas and the mastoid process of the temporal bone, and passes horizontally backward, grooving the surface of the latter bone, being covered by the sternocleidomastoideus, splenius capitis, longissimus capitis, and digastricus, and resting upon the rectus capitis lateralis, the obliquus superior, and semispinalis capitis. It then changes its course and runs vertically upward, pierces the fascia connecting the cranial attachment of the trapezius with the sternocleidomastoideus, and ascends in a tortuous course in the superficial fascia of the scalp, where it divides into numerous branches, which reach as high as the vertex of the skull"
"Vertex (anatomy) In arthropod and vertebrate anatomy, the vertex (or ""cranial vertex"") is the upper surface of the head. In humans, the vertex is formed by four bones of the skull: the frontal bone, the two parietal bones, and the occipital bone. These bones are connected by the coronal suture between the frontal and parietal bones, the sagittal suture between the two parietal bones, and the lambdoid suture between the parietal and occipital bones. ""Vertex baldness"" refers to a form of male pattern baldness in which the baldness is limited to the vertex, resembling a tonsure. In childbirth, ""vertex birth"""
"Craniocervical junction misalignment is also suspected as a factor in neurodegenerative diseases where altered CSF flow plays a part in the pathological process. Atlas (anatomy) In anatomy, the atlas (C1) is the most superior (first) cervical vertebra of the spine. It is named for the Atlas of Greek mythology, because it supports the globe of the head which is the skull. The atlas is the topmost vertebra and with the axis forms the joint connecting the skull and spine. The atlas and axis are specialized to allow a greater range of motion than normal vertebrae. They are responsible for the"
"to these there is a secondary center for a thin epiphysial plate on the under surface of the body of the bone. Fractures of the dens, not to be confused with Hangman's fractures, are classified into three categories according to the Anderson–D'Alonso system: Axis (anatomy) In anatomy, the second cervical vertebra (C2) of the spine is named the axis (from Latin ""axis"", ""axle"") or epistropheus. By the atlanto-axial joint, it forms the pivot upon which the first cervical vertebra (the atlas), which carries the head, rotates. The most distinctive characteristic of this bone is the strong odontoid process known as"
"the odontoid process, and above to the lateral mass of the atlas near the transverse ligament. A widening of the atlanto-axial joint, as measured between the posterior surface of the anterior arch of atlas and the front of the odontoid process, indicates an injury to the transverse atlantal ligament. Normally, this atlanto-dental distance is less than 2 mm, sometimes a maximum of 3 mm is accepted in men and 2.5 mm in women. Atlanto-axial joint The atlantoaxial joint is a joint in the upper part of the neck between the first and second cervical vertebrae; the atlas and axis. It"
"Frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions. These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, part of the bony orbital cavity holding the eye, and part of the bony part of the nose respectively. The name comes from the Latin word ""frons"" (meaning ""forehead""). The frontal bone is made up of two main parts. These are the squamous part, and the orbital part. The squamous part marks the vertical, flat, and also the biggest part, and"
"to pass in front of the transverse process, and not through the foramen. The movement of nodding the head takes place predominantly through flexion and extension at the atlanto-occipital joint between the atlas and the occipital bone. However, the cervical spine is comparatively mobile, and some component of this movement is due to flexion and extension of the vertebral column itself. This movement between the atlas and occipital bone is often referred to as the ""yes joint"", owing to its nature of being able to move the head in an up-and-down fashion. The movement of shaking or rotating the head"
"Thorax The thorax or chest (from the Greek θώραξ ""thorax"" ""breastplate, cuirass, corslet"" via ) is a part of the anatomy of humans and various other animals located between the neck and the abdomen. The thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain. In humans and other hominids, the thorax is the chest region of the body between the neck and the abdomen, along"
"the number remains the same. The number of those in the cervical region however is only rarely changed. The vertebrae of the cervical, thoracic and lumbar spines are independent bones, and generally quite similar. The vertebrae of the sacrum and coccyx are usually fused and unable to move independently. Two special vertebrae are the atlas and axis, on which the head rests. A typical vertebra consists of two parts: the vertebral body and the vertebral arch. The vertebral arch is posterior, meaning it faces the back of a person. Together, these enclose the vertebral foramen, which contains the spinal cord."
"the dens of the axis, the second cervical vertebra. They span almost horizontally, creating an angle between them of at least 140°. The alar ligaments, along with the transverse ligament of the atlas, derive from the axial component of the first cervical sclerotome. The function of the alar ligaments is to limit the amount of rotation of the head, and by their action on the dens of the axis, they attach the skull to the axis, the second cervical vertebra. The alar ligaments are prone to tearing if a force is applied when the head is flexed and in rotation."
"has a helical margin that is pulled upward and towards the back. The anterior superior margins are rolled. Tragus and antitragus are small, lobulated and equal in size. The manus has a unique raided pads; the interdigital pads are separated from the palm by a structure called deep flex urge line. The palm consist of two elongated central pads, a hypothenar pad and a thenar pad. The skull is orthognathous, orbits are unfenestrated, balls are inflated ventrally, and a large sinus found above the nasal. The foramen magnum is located towards the front, and the atlas has shallow anterior articular"
"with the axial skeletons of humans; however, it is important to understand the evolutionary lineage of the axial skeleton. The human axial skeleton consists of 80 different bones. It is the medial core of the body and connects the pelvis to the body, where the appendix skeleton attaches. As the skeleton grows older the bones get weaker with the exception of the skull. The skull remains strong to protect the brain from injury. The human skull consists of the cranium and the facial bones. The cranium holds and protects the brain in a large space called the cranial vault. The"
"The condition, where the dens is separated from the body of the axis, is called os odontoideum, and may cause nerve and circulation compression syndrome. On its anterior surface is an oval or nearly circular facet for articulation with that on the anterior arch of the atlas. On the back of the neck, and frequently extending on to its lateral surfaces, is a shallow groove for the transverse atlantal ligament which retains the process in position. The apex is pointed, and gives attachment to the apical odontoid ligament; below the apex the process is somewhat enlarged, and presents on either"
"left and right happens almost entirely at the joint between the atlas and the axis, the atlanto-axial joint. A small amount of rotation of the vertebral column itself contributes to the movement. This movement between the atlas and axis is often referred to as the ""no joint"", owing to its nature of being able to rotate the head in a side-to-side fashion. Cervical degenerative changes arise from conditions such as spondylosis, stenosis of intervertebral discs, and the formation of osteophytes. The changes are seen on radiographs which are used in a grading system from 0-4 ranging from no changes (0),"