rotation

Examples of rotation in the following topics:

• Rotator Cuff Injury and Dislocated and Separated Shoulder

  • Rotator cuff tears are the most common conditions affecting the shoulder .
  • The tears occur in one or more of the four tendons of the rotator cuff muscles.
  • The tendons of the rotator cuff, not the muscles, are most commonly torn.
  • Once a tear happens in the rotator cuff, it is much more likely to recur.
  • After injury, it is hard to do a 180 degree rotation.

• Muscles that Cause Movement at the Hip Joint

  • Actions – Extends of the thigh and assists with rotation.
  • The muscles of the lateral rotator group are deeply located and as the name suggests, act to laterally rotate the thigh at the hip.
  • Actions - Lateral rotation and abduction of the thigh at the hip.
  • Actions - Lateral rotation and abduction of the thigh at the hip.
  • Actions: Extends and laterally rotates at the hip.

• Muscles of the Shoulder

  • Actions – The superior region supports the arm and elevates and rotates the scapula, the intermediate region retracts the scapula, and the inferior region rotates and depresses the scapula.
  • It retracts and rotates the scapula.
  • There are six intrinsic muscles, four of which form the rotator cuff.
  • Actions – Adducts the shoulder and assists in rotation of the arm.
  • Muscles of the rotator cuff and presented with the triceps brachii.

• Posterior Muscles

  • Actions – The superior region supports the arm and elevates and rotates the scapula, the intermediate region retracts the scapula, and the inferior region rotates and depresses the scapula.
  • Rhomboid Minor – Sits between the levator scapulae and rhomboid major, with which it is paired in action and function, this retracts and rotates the scapula.
  • Two muscles in the superficial layer are responsible for rotation of the head.
  • Two muscles in the deep layer are responsible for maintenance of posture and rotation of the neck.

• Neck Muscles

  • Two muscles in the superficial layer are responsible for rotation of the head.
  • Two muscles in the deep layer are responsible for maintenance of posture and rotation of the neck.
  • Actions – The superior region supports the arm and elevates and rotates the scapula.
  • It controls adduction, abduction and rotation of the head, the intermediate region retracts the scapula, and the inferior region rotates and depresses the scapula.
  • Actions – Abduction, adduction, extension, flexion, and rotation of the neck depending on intra and inter-muscle contractions.

• Impingement Syndrome

  • Shoulder impingement syndrome occurs when the tendons of the rotator cuff muscles become irritated and inflamed.
  • The rotator cuff muscle tendons pass through a narrow space between the acromion process of the scapula and the head of the humerus.
  • Loss of function of the rotator cuff muscles, due to injury or loss of strength, may cause the humerus to move superiorly, resulting in impingement.
  • Ultrasonography, arthrography, and MRI can be used to detect rotator cuff muscle pathology .
  • Also damaged rotator cuff muscles can be surgically repaired.

• Muscles that Cause Movement at the Knee Joint

  • When the knee is fully extended the femur rotates slightly on the tibia to lock the joint into place, allowing for efficient load bearing.
  • The rectus femoris additionally facilitates rotation at the hip.
  • Actions: Extends and laterally rotates at the hip, main action is flexing of the lower leg at the knee.
  • Actions: Laterally rotates the femur on the tibia “unlocking” the knee joint so that flexion can occur.
  • The knee joint allows for slight rotation when flexed, which is produced by the biceps femoris, semitendinosus, semimembranosus, gracilis, and sartorius.

• Synovial Joint Movements

  • Rotation is a circular movement around a fixed point.

• Lever Systems

  • Internal or medial rotation is specific to the shoulder or hip and brings the distal portions of the limbs inwards towards the midline.
  • Internal rotation can also move the humerus and femur inward.
  • External or lateral rotation is the opposite movement, pointing the distal portion of limbs as well as the humerus and femur away from the mid-line.

• How Skeletal Muscles Produce Movements

  • The muscles of the rotator cuff are also synergists in that they fix the shoulder joint allowing the bicepps brachii to exert a greater force.
  • The brachioradialis and brachialis are synergist muscles, and the rotator cuff (not shown) fixes the shoulder joint allowing the biceps brachii to exert greater force.