Muscle Function

The main framework of the body (skeleton) is covered by muscles, whose function is to permit movement and maintain posture. Sensory receptors in the muscles monitor the tension and length of the muscles and provide the nervous system with crucial information about the position of the body parts, thereby enabling posture to be maintained. Muscle tissue has four main properties: Excitability (ability to respond to stimuli), Contractibility (is ability to contract), Extensibility (the ability of a muscle to be stretched without tearing) and Elasticity (the ability to return to its normal shape).

Movement Definitions

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

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. Extends head
• 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 arm
• Teres major - Extends arm, assists in adduction and medial rotation of arm

Muscles which move the forearm and wrist and their action

• 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

• 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

• 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

• 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

• 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

• 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

Associated Pages

The following Sports Coach pages should be read in conjunction with this page:

• Articles on Physiology
• Blood Pressure
• Body Fat
• Body Type
• Energy Pathways
• Ideal Weight
• Lactic Acid
• Maximum Heart Rate
• Movement Analysis
• Muscle Types
• Protein
• Range of Movement
• Vitamins
• VO2 max

• Training Books
• Training Products

Associated Books

The following books provide more information related to this topic:

• Principles of Anatomy and Physiology, G.J. Tortora et al., ISBN 0 06 046704 5
• Strength Training Anatomy, F. Delavier, ISBN 0 7360 4185 0
• Atlas of Skeletal Muscles, R.J. Stone et al., ISBN 0 697 13790 2
• The Muscle Book, P. Blakey, ISBN 1 873017 00 6
• Advanced Studies in Physical Education and Sport, P Beashel et al., ISBN 0 17 4482345
• Physical Education and the Study of Sport, B. Davis et al., ISBN 0 7234 31752
• Essentials of Exercise Physiology, W.D. McArdle et al., ISBN 0 683 30507 7
• Physical Education and Sport Studies, D. Roscoe et al., ISBN 1 901424 20 0
• The World of Sport Examined, P. Beashel et al., ISBN 0 17 438719 9
• Advanced PE for Edexcel, F. Galligan et al., ISBN 0 435 50643 9
• Examining Physical Education, K. Bizley, ISBN 0 435 50660 9
• Sport and PE, K Wesson et al., ISBN 0 340 683821
• PE for you, J. Honeybourne, ISBN 0 7487 3277 2