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.
What are axis characteristics?
An axis is an invisible line around which an object rotates, or spins . The object can be a tiny particle, smaller than a single atom. Or it could be a star with the mass of a thousand suns. In either case, an object’s axis runs through its center of mass, or barycenter.
What is unique about the axis?
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 (or dens) , which is embryologically the body of the atlas (C1) 1 , 2 .
What makes the axis different from the rest of the vertebrae?
The axis is somewhat analogous to the other cervical vertebrae in shape, but it differs slightly for two reasons: its spinous process isn’t as obviously bifid, and the presence of the dens .
What movement does the axis allow?
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 .
What are the two main characteristics of the Earth’s axis?
- Direction — The earth completes one rotation from west to east on its axis in 23 hours, 56 minutes, 4.09 seconds.
- Inclination of axis — The earth is always tilted in the same direction as it moves round the sun. The angle at which the earth is tilted is known as the inclination of the earth’s axis.
What is axis in simple words?
The definition of an axis is a real or imaginary line on which something rotates , or a straight line around which things are evenly arranged. An example of axis is an imaginary line running through the earth on which the earth rotates. ... A main line of motion, development, etc.
Does axis have a body?
The axis is composed of a vertebral body , heavy pedicles, laminae, and transverse processes, which serve as attachment points for muscles.
Why is C2 called axis?
C2 is called the “axis” because it enables the head’s rotation around a longitudinal axis with left and right rotation as when shaking the head “no” (Figure 2, C2 – Axis). To accomplish this feat, the axis has a unique feature among the vertebrae: the dens (or odontoid process).
What does axis mean in anatomy?
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. The Latin word “axis” means axle or pole.
What is the main axis of the body?
Explanation: 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.
Why should you maintain S shape in back?
A healthy spine is S-shaped with three natural curves and requires strong and flexible muscles in the back, leg and abdomen in order to maintain good alignment. When the back is bent, the weight of the upper body alone puts extra pressure on the lower discs in the spine. ... Standing is a natural posture for the spine.
What is true regarding the axis?
In anatomy, the axis (from Latin axis, “axle”) or epistropheus, is the second cervical vertebra (C2) of the spine, immediately posterior 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.
What is the middle of your neck called?
The Latin-derived term cervical means “of the neck.” The neck supports the weight of the head and is highly flexible, allowing the head to turn and flex in different directions. The midline in front of the neck has a prominence of the thyroid cartilage termed the laryngeal prominence , or the so-called “Adam’s apple.”
What are the two characteristics of protraction?
What are two characteristics of protraction? An anterior movement of the bone. Movement along the transverse plane . What are the two articulations of the elbow joint?
How is the skull attached to the body?
The neurocranium is a protective shell surrounding the brain and brain stem. The viscerocranium (or facial skeleton) is formed by the bones supporting the face. Except for the mandible, all skull bones are joined together by sutures —synarthrodial (immovable) joints.
