In the following two graphs :i.first graph shows: twitch→→...
Graph 1 shows muscle fiber tension with time. Which occurs in order as : twitch→→summation→→tetanus→→fatigue. Graph 2 shows complete and incomplete tetanus. Tetanus is also known as lockjaw, which is a infection characterized by muscle spasm.
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In the following two graphs :i.first graph shows: twitch→→...
Movable joint between the atlas and axis
The movable joint between the atlas and axis is known as a pivot joint. It is a type of synovial joint that allows rotational movement between two bones.
Anatomy of the atlas and axis
The atlas (C1 vertebra) is the first cervical vertebra and is located at the top of the vertebral column. It is a ring-like structure that supports the skull and allows for the nodding movement of the head. The axis (C2 vertebra) is the second cervical vertebra and is situated just below the atlas. It has a unique structure called the odontoid process or dens, which projects upward and fits into the atlas, forming the pivot joint.
Pivot joint
A pivot joint is a type of synovial joint that allows rotational movement around a central axis. It consists of a rounded or pointed surface of one bone fitting into a ring-like structure or notch of another bone. In the case of the atlas and axis, the odontoid process of the axis fits into the anterior arch of the atlas, forming a pivot joint.
Movement at the pivot joint between the atlas and axis
The pivot joint between the atlas and axis allows for the rotational movement of the head. This movement is responsible for the shaking of the head to indicate 'no'. The atlas acts as the pivot point, while the axis and the rest of the vertebral column rotate around it. This rotation is facilitated by the smooth surface of the odontoid process and the ligaments that hold the atlas and axis together.
Importance of the pivot joint
The presence of the pivot joint between the atlas and axis is crucial for the movement and stability of the head and neck. It allows for the necessary range of motion for various activities such as tilting the head, shaking the head, and rotating the head from side to side.
In conclusion, the type of movable joint present between the atlas and axis is a pivot joint. This joint allows for the rotational movement of the head and is important for the stability and functionality of the neck and upper cervical spine.