Muscle Function

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Movement Definitions[edit]

Each of the movements of the muscles for the various parts of the body is described by various terms.

  • Abductor - moves a limb away from the midline
  • Adductor - moves a limb towards the midline
  • Extensor - increase the angle at a joint - extends a limb
  • Flexor - decreases the angle at a joint - flexes a limb
  • Pronator - turns a limb to face downwards
  • Supinator - turns a limb to face upwards
  • Rotator - rotates a limb
  • Sphincter - closes an orifice of opening

Muscle actions[edit]

Muscles which move the shoulder and their action[edit]

  • Levator scapulae - Raises shoulder blade
  • Pectoralis minor - Lowers shoulder blade
  • Trapezius - Lifts clavicle. Adducts, elevates and rotates scapular outwards
  • Rhomboideus major - Adducts scapular and rotates it inwards
  • Serratus anterior - Stabilises scapula when hand exerts pressure on an object

Muscles which move the arm and their action[edit]

  • Pectoralis major - Flexes, adducts and rotates arm medially
  • Latissimus dorsi - Extends, adducts and rotates arm medially. Moves arm downward and backwards
  • Deltoid - Abducts, flexes, extends and medially and laterally rotates arm
  • Teres major - Extends arm, assists in adduction and medial rotation of arm

Muscles which move the forearm and wrist and their action[edit]

  • Biceps brachii - Flexes and supinates forearm. Flexes arm
  • Brachialis - Flexes the forearm
  • Brachoradialis - Flexes, semi-supinates and semi-pronates the forearm
  • Triceps brachii - Extends forearm. Extends arm
  • Pronator teres - Pronates and flexes forearm
  • Pronator quadratus - Pronates the forearm and hand
  • Supinator - Supinates forearm and hand

Muscles which move the abdominal wall and their action[edit]

  • Rectus abdominis - Compresses abdomen and flexes vertebral column
  • External obliques - Bends vertebral column laterally and rotates vertebral column
  • Transversus abdominis - Compresses abdomen
  • Quadratus lumborum - Side flexion

Muscles which move the vertebral column and their action[edit]

  • Iliocostalis lumborum - Extends lumbar region
  • Iliocostalis thoracis - Maintains the spine's erect position
  • Iliocostalis cervicis - Extends cervical region
  • Longissimus thoracis - Extends thoracis region
  • Longissimus cervicis - Extends cervical region
  • Longissimus capitis - Extends the head and rotates it to opposite side
  • Spinalis thoracis - Extends vertebral column
  • Spinalis cervicis - Extends vertebral column
  • Spinalis capitis - Extends vertebral column

Muscles which move the thigh and their action[edit]

  • Psoas major - Flexes and rotates thigh medially and flexes vertebral column
  • Iliacus - Flexes and rotates thigh medially and flexes vertebral column
  • Gluteus maximus - Extends and rotates thigh laterally.
  • Adductor longus - Adducts, medially rotates and flexes the thigh
  • Adductor brevis - Adducts, laterally rotates and flexes the thigh
  • Adductor magnus - Adducts, flexes, laterally rotates and extends the thigh

Muscles which act on the leg and their action[edit]

  • Rectus femoris - Extends knee and flexes hip
  • Vastus lateralis - Extends knee
  • Vastus medialis - Extends knee
  • Vastus intermedius - Extends knee
  • Sartorius - Flexes knee. Flexes hip and rotates femur laterally
  • Biceps femoris - Flexes leg and extends thigh
  • Semitendinosus - Flexes leg and extends thigh
  • Semimembranosus - Flexes leg and extends thigh

Muscles which move the foot and their action[edit]

  • Tibialis anterior - Dorsiflexes and inverts foot
  • Peroneus tertius - Dorsiflexes and everts foot
  • Gastrocnemius - Plantar flexes foot and flexes knee
  • Soleus - Plantar flexes foot
  • Plantaris - Plantar flexes foot
  • Tibialis posterior - Plantar flexes and inverts the foot
  • Peroneus longus - Plantar flexes and everts the foot
  • Peroneus brevis - Plantar flexes and everts the foot