lateral rotator group

Examples of lateral rotator group in the following topics:

• Muscles that Cause Movement at the Hip Joint

  • The four main groups of hip muscles are gluteal, adductor, iliopsoas, and lateral rotator, defined by the type of movement they mediate.
  • The muscles of the lateral rotator group are deeply located and as the name suggests, act to laterally rotate the thigh at the hip.
  • All of the lateral rotator group muscles originate from the pelvis and attach to the femur.
  • Piriformis - The piriformis is the most superior of the lateral rotator group muscles.
  • It is the most inferior of the lateral rotator group muscles, located below the gemelli and obturator internus.

• Anterior Muscles

  • Serratus Anterior – The serratus anterior is located in the lateral wall of the chest.
  • Five muscles form the abdominal wall, divided into vertical and flat groups.
  • The flat muscles act to flex, laterally flex, and rotate the trunk.

• Muscles of the Shoulder

  • Upper arm muscles will be discussed in a later section since they primarily promote forearm movement.
  • It retracts and rotates the scapula.
  • The lateral region assists in shoulder flexion when the shoulder is rotating, although it also assists the transverse abduction of the shoulder.
  • The rotator cuff is a group of four muscles that pull the ball of the humerus into the shallow socket of the scapula, adding required stability.
  • Serratus Anterior – The serratus anterior is located in the lateral wall of the chest.

• Posterior Muscles

  • Posterior muscles are split into three groups depending on their physiological location.
  • 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.
  • Two muscles in the superficial layer are responsible for rotation of the head.
  • Iliocostalis – The most laterally located of the three intermediate muscles.
  • Two muscles in the deep layer are responsible for maintenance of posture and rotation of the neck.

• Neck Muscles

  • Omohyoid – Located laterally to the sternohyoid, the omohyoid muscle is split in two parts attached by a tendon.
  • Two muscles in the superficial layer are responsible for rotation of the head.
  • Iliocostalis – The most laterally located of the three intermediate muscles.
  • It controls adduction, abduction and rotation of the head, the intermediate region retracts the scapula, and the inferior region rotates and depresses the scapula.
  • Suprahyoid and infrahyoid muscle groups are named based on their location relative to the hyoid bone.

• 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.
  • These muscles are sometimes termed the hamstring group.
  • 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.

• Femur (The Thigh)

  • Immediately lateral to the head is the neck, which connects the head with the shaft, narrower than the head the neck permits a greater range of movement at the hip joint.
  • Located superiorly on the main shaft, lateral to the joining of the neck, the greater trochanter is a projection to which the abductor and lateral rotator muscles of the leg attach.
  • Two rounded regions termed the medial and lateral condyles articulate with the tibia and at the most anterior projection the patella.
  • Finally, medial and lateral epicondyles lie immediately proximal to the condyles and are also regains where key internal knee ligaments attach.

• Lever Systems

  • For example, moving arms or legs laterally away from the body is abduction, and bringing the limbs back to the midline is adduction.
  • 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

  • Muscles are arranged in groupings of agonist, antagonist, and synergists that produce and modulate movement.
  • The biceps and triceps muscle groups are an example of an agonist/antagonist pair.
  • Muscles exist in groupings that work to produce movements by muscle contraction.
  • The majority of muscles are grouped in pairs, with an antagonist to each agonist muscle.
  • 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.

• Muscles of the Wrist and Hand

  • Actions – Rotates the thumb towards the palm, producing opposition and improving grip.
  • Actions - Rotates little finger towards the palm, producing opposition and improving grip.
  • Flexor Digiti Minimi Brevis – Located laterally to the digiti minimi.
  • The interossei muscles are located between the fingers; they can be split into two groups.
  • One other muscle in the hand is not easily grouped with the above categories.