In anatomy, the atlas (C1) is the most superior (first) cervical vertebra of the spine and is located in the neck.
In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine.
The obliquus capitis superior muscle is a small muscle in the upper back part of the neck. It is one of the suboccipital muscles. It attaches inferiorly at the transverse process of the atlas ; it attaches superiorly at the external surface of the occipital bone. The muscle is innervated by the suboccipital nerve.
The semispinalis muscles are a group of three muscles belonging to the transversospinales. These are the semispinalis capitis, the semispinalis cervicis and the semispinalis thoracis.
The splenius capitis is a broad, straplike muscle in the back of the neck. It pulls on the base of the skull from the vertebrae in the neck and upper thorax. It is involved in movements such as shaking the head.
The rectus capitis posterior major is a muscle in the upper back part of the neck. It is one of the suboccipital muscles. Its inferior attachment is at the spinous process of the axis ; its superior attachment is onto the outer surface of the occipital bone on and around the side part of the inferior nuchal line. The muscle is innervated by the suboccipital nerve. The muscle acts to extend the head and rorate the head to its side.
In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint. Each joint capsule has two parts: an outer fibrous layer or membrane, and an inner synovial layer or membrane.
The occipital artery is a branch of the external carotid artery that provides arterial supply to the back of the scalp, sternocleidomastoid muscles, and deep muscles of the back and neck.
The posterior triangle is a region of the neck.
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 squamous part of occipital bone is situated above and behind the foramen magnum, and is curved from above downward and from side to side.
The atlanto-axial joint is a joint in the upper part of the neck between the atlas bone and the axis bone, which are the first and second cervical vertebrae. It is a pivot joint.
The tectorial membrane of atlanto-axial joint is a tough membrane/broad, strong band representing the superior-ward prolongation of the posterior longitudinal ligament.
The occipital triangle, the larger division of the posterior triangle, is bounded, in front, by the Sternocleidomastoideus; behind, by the Trapezius; below, by the Omohyoideus.
The anterior atlantooccipital membrane is a broad, dense membrane extending between the anterior margin of the foramen magnum (superiorly), and the anterior arch of atlas (inferiorly).
The posterior atlantooccipital membrane is a broad but thin membrane extending between the to the posterior margin of the foramen magnum above, and posterior arch of atlas below. It forms the floor of the suboccipital triangle.
The articular capsule of the knee joint is the wide and lax joint capsule of the knee. It is thin in front and at the side, and contains the patella, ligaments, menisci, and bursae of the knee. The capsule consists of an inner synovial membrane, and an outer fibrous membrane separated by fatty deposits anteriorly and posteriorly.
The posterior branches of cervical nerves branch from the dorsal rami of the cervical nerves.
The following outline is provided as an overview of and topical guide to human anatomy:
