The Axis (C2 vertebra) also known as epistropheus forms the pivot upon which the first cervical vertebra
What type of bones are the atlas and axis?
The atlas and axis vertebrae are the two most superior bones in the vertebral column, and they are part of the seven cervical vertebrae. The atlas is the top-most bone, sitting just below the skull; it is followed by the axis. Together, they support the skull, facilitate neck movement, and protect the spinal cord.
Where is the axis bone?
In anatomy, the axis (from Latin axis, “axle”) or epistropheus, is the second cervical vertebra (C2) of the spine, immediately inferior to the atlas, upon which the head rests. The axis’ defining feature is its strong odontoid process (bony protrusion) known as the dens, which rises dorsally from the rest of the bone.
Is the axis a joint?
The axis is the second cervical vertebra; it has what is called the odontoid process about which the atlas rotates. The joint between the atlas and axis is a pivot type of joint. It allows the head turn from side to side. It is also called the atloaxoid joint.What type of bone is the axis C2 vertebrae?
The axis is the second cervical vertebra, commonly called C2. It is an atypical cervical vertebra with unique features and important relations that make it easily recognisable. Its most prominent feature is the odontoid process (also know as the dens or peg), which is embryologically the body of the atlas (C1) 1,2.
Why is C2 called axis?
Axis: The axis is the second cervical vertebra (symbol: C2). It is called the “axis” because the uppermost cervical vertebra (called the atlas) rotates about the odontoid process of C2. The joint between the axis and atlas is a pivot type of joint. It allows the head turn.
Which two bones does the axis articulate with?
Introduction to Axis Bone Anatomy: articulates with the anterior arch of the atlas bone, where they form a pivot joint. rotates side-to-side, the atlas bone rotates around the peg-like odontoid process. This is the reason why the second cervical vertebra is also called the axis bone.
What are dens of axis?
Description. The odontoid process (also dens or odontoid peg) is a protuberance (process or projection) of the Axis (second cervical vertebra). It exhibits a slight constriction or neck, where it joins the main body of the vertebra.Is the axis an irregular bone?
An irregular bone is one of the types of bones classified by shape. … Axis bone and other vertebrae. Hyoid bone. Sphenoid bone.
Is the dens anterior or posterior?The dens or odontoid process exhibits a slight constriction or neck, where it joins the body. On its anterior surface is an oval or nearly circular facet for articulation with that on the anterior arch of the atlas.
Article first time published onHow many axis bones are there?
The 80 bones of the axial skeleton form the vertical axis of the body. They include the bones of the head, vertebral column, ribs and breastbone or sternum. The appendicular skeleton consists of 126 bones and includes the free appendages and their attachments to the axial skeleton.
Does the axis have a transverse foramen?
The axis. The second cervical vertebra is the axis (Fig. … Both transverse processes have a transverse foramen for the vertebral arteries. The superior articular facets of the axis articulate with the inferior articular facets of the atlas.
Where is C1 and C2 on the spine?
The C1 and C2 vertebrae are the first two vertebrae at the top of the cervical spine. Together they form the atlantoaxial joint, which is a pivot joint. The C1 sits atop and rotates around C2 below. More of the head’s rotational range of motion comes from C1-C2 than any other cervical joint.
What is Jefferson fracture?
A Jefferson fracture is a bone fracture of the vertebra C1. The vertebra C1 is a bony ring, with two wedge-shaped lateral masses, connected by relatively thin anterior and posterior arches and a transverse ligament. The lateral mass on vertebra C1, who is taller, is directed laterally.
What are alar ligaments?
In anatomy, the alar ligaments are ligaments which connect the dens (a bony protrusion on the second cervical vertebra) to tubercles on the medial side of the occipital condyle.
Which bone articulates with the dens quizlet?
Correct. The prominent projection known as dens on the axis forms a pivot joint with the atlas, allowing the atlas to rotate around the axis. The axis is a very sensible name for C2 since it serves as a central axis for rotation of the atlas. Identify the region of the skull that articulates with the atlas.
What is atlas bone?
The atlas is the topmost vertebra and, with the axis (the vertebra below it), 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.
What articulates with the dens?
Inferiorly the atlas articulates with the dens which acts as a pivot that allows the atlas and attached head to rotate on the axis. This is the Atlanto-axial joint.
What is Flavum?
One of a series of bands of elastic tissue that runs between the lamina from the axis to the sacrum, the ligamentum flavum connects the laminae and fuses with the facet joint capsules. … As we age, the ligament loses elastin, and this allows the ligament to encroach on the canal.
What bones are sesamoid bones?
A sesamoid bone is a small round bone that is imbedded within a tendon, whose purpose is to reinforce and decrease stress on that tendon. You will mostly find sesamoid bones in the knee, thumb, and big toe1. Others in the hand and feet are much smaller.
What are pneumatic bones?
Pneumatic bones are those bones which contain an air filled cavity within them. In humans, they are seen in relation to the the nasal cavity – they enclose the paranasal sinuses. Pneumatic bones are – maxilla, frontal bone, sphenoid and ethmoid.
Is the kneecap a sesamoid bone?
The patella is a sesamoid bone located in the major extensor tendon of the knee joint, in the hindlimb of many tetrapods.
What is the transverse foramen?
The transverse foramen (foramen transversarium) of cervical vertebrae is an opening that is occupied by the vertebral artery and vein in the first six vertebrae and only the vertebral vein in the seventh. The vertebral artery is of particular importance because it serves the brain and spinal cord.
What is thoracic vertebra?
Thoracic vertebrae are the twelve vertebral segments (T1-T12) that make up the thoracic spine. These structures have very little motion because they are firmly attached to the ribs and sternum (breastbone).
Which vertebrae have dens?
The odontoid process, or dens, is a superior projecting bony element from the second cervical vertebrae (C2, or the axis). The first cervical vertebrae (atlas) rotates around the odontoid process to provide the largest single component of lateral rotation of the cervical spine.
In what type of bones does kneecap belong?
Sesamoid bones function to protect tendons from stress and wear. The patella, commonly referred to as the kneecap, is an example of a sesamoid bone.
Which type of bones forms the arms and legs?
The skeleton of the arms and legs are made up of mostly long bones. Long bones are so-called because they are longer than they are wide. Long bones in the arm include the humerus, radius, ulna, metacarpals, and phalanges.
Where is maxillary?
The maxilla is the bone that forms your upper jaw. The right and left halves of the maxilla are irregularly shaped bones that fuse together in the middle of the skull, below the nose, in an area known as the intermaxillary suture.
Does axis have a Centrum?
The axis has an elongated centrum, the dens, which extends into the large neural canal of the atlas. The shape of the dens restricts motions between the first two vertebrae to rotations parallel to the long axis of the body.
What are the 3 types of vertebrae and how are they different?
The vertebral column can be divided into three segments: Cervical. … Each of the three segments of the spine has a curve. The cervical spine and the lumbar curve both are convex anteriorly, while the thoracic spine curves the opposite way, convex posteriorly.
What is the normal curve of the thoracic spine?
Thoracic Kyphosis: Forward Curvature of the Upper Back. The normal spine, when viewed from the side, is not a straight line as it is when viewed from the front or back. The thoracic (rib cage) portion of the spine has a normal forward curvature, called “kyphosis,” which has a normal range (20 to 50 degrees).
