Muscle Function
The body's main framework (skeleton) is covered by muscles that permit movement and maintain posture. Sensory receptors in the muscles monitor the muscles' tension and length and provide the nervous system with information about the position of the body parts, thereby enabling posture to be maintained.
Movement Definitions
Each of the muscles' movements for the various parts of the body is described by multiple 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
Muscles which move the shoulder and their action
- 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
- 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 the arm
- Teres major - Extends arm, assists in adduction and medial rotation of the arm
Muscles which move the forearm and wrist and their action
- Biceps brachii - Flexes and supinates forearm. Flexes arm
- Brachialis - Flexes the forearm
- Brachioradialis - Flexes, semi-supinates and semi-pronates the forearm
- Triceps brachii - Extends forearm. Extends arm
- Pronator teres - Pronates and flexes the forearm
- Pronator quadratus - Pronates the forearm and hand
- Supinator - Supinates forearm and hand
Muscles which move the abdominal wall and their action
- Rectus abdominis - Compresses abdomen and flexes the 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
- 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 the 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
- Psoas major - Flexes and rotates thigh medially and flexes the vertebral column
- Iliacus - Flexes and rotates thigh medially and flexes the 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
- Rectus femoris - Extends knee and flexes hip
- Vastus lateralis - Extends the knee
- Vastus medialis - Extends the knee
- Vastus intermedius - Extends the knee
- Sartorius - Flexes knee. Flexes hip and rotates femur laterally
- Biceps femoris - Flexes leg and extends the thigh
- Semitendinosus - Flexes leg and extends the thigh
- Semimembranosus - Flexes leg and extends the thigh
Muscles which move the foot and their action
- Tibialis anterior - Dorsiflexes and inverts the foot
- Peroneus tertius - Dorsiflexes and everts foot
- Gastrocnemius - Plantar flexes the foot and knee
- Soleus - Plantar flexes the foot
- Plantaris - Plantar flexes the 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
Page Reference
If you quote information from this page in your work, then the reference for this page is:
- MACKENZIE, B. (2006) Muscle Function [WWW] Available from: https://www.brianmac.co.uk/musclefun.htm [Accessed