Ultimately, efficient human movement is dependent on the coordinated activity of whole groups of muscles and will involve varying combinations of different muscle actions. In an attempt to distinguish between the diverse roles of muscle during movement, muscles can be placed into the following categories:
• agonist/prime mover: the muscle(s) that causes a desired action. e. g. the bicep brachii during a bicep curl or the quadriceps during a leg extension
• antagonist: the opposing muscle(s) to the agonist e.g. the triceps during a bicep curl or the hamstrings during a leg extension
• synergist: the muscle(s) that assist or modify the movement of the prime mover e.g. during hip extension the hamstrings act as synergists for the gluteus maximus
• fixators: the muscle(s) that stabilises the part of the body that remains fixed e.g. shoulder girdle muscles stabilise the scapula to allow efficient movement at the shoulder joint
Level 2 : Black
Level 3 : Orange Location Origin Insertion Primary concentric actions
Deltoids Shoulder Clavicle and scapula Humerus Abduction, flexion and extension of shoulder
Rotator cuff
Teres minor
Shoulder
Lateral border
of scapula Greater tuberosity of humerus
Abduction, lateral rotation and stabilisation of shoulder joint
Supraspinatus Superior to spine of scapula Greater tuberosity of humerus (superior) Abduction and stabilisation of shoulder joint Infraspinatus Posterior surface below spine of scapula Greater tuberosity of humerus (posterior) Abduction, horizontal extension, lateral rotation and stabilisation of shoulder joint
Subscapularis Anterior surface of scapula Lesser tuberosity of humerus
Medial rotation, adduction, extension and stabilisation of shoulder joint Teres major Shoulder Inferior angle of scapula Medial lip of bicipital groove of
upper humerus
Extension, adduction and medial rotation of shoulder
Levator scapulae Upper back and neck Transverse processes of C1-C4
Superior angle of scapula
Elevation of shoulder girdle and lateral flexion of neck Biceps brachii Front of upper arm Scapula Radius Flexion of elbow, supination of forearm
and flexion of shoulder Triceps brachii Back of upper arm Humerus and scapula Ulna Extension of elbow and extension of
shoulder Latissimus dorsi Sides of the back
Lower thoracic vertebrae, lumbar vertebrae, ilium
Humerus Adduction, extension and medial rotation of shoulder
Trapezius Upper back
Base of skull, cervical and thoracic vertebrae Clavicle and scapula Elevation, retraction and depression of shoulder girdle
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Level 2 : Black
Level 3 : Orange Location Origin Insertion Primary concentric actions
Rhomboids
Major Mid back Spinous processes of T2-T5
Medial border and inferior angle of scapula
Retraction and elevation of scapula
Minor Mid back Spinous processes of C7-T1
Medial border of
scapula Retraction and elevation of scapula
Pectoralis major Chest Clavicle and sternum Humerus
Horizontal flexion, adduction and medial rotation of the shoulder
Pectoralis minor Chest Anterior surface of 3rd-5th rib Coracoid process of scapula Depression and protraction of scapula Serratus anterior Side of the torso Surface of upper 8 or 9
ribs
Anterior surface of medial border
of scapula Protraction of scapula Erector spinae Either side of spine Sacrum, ilium, ribs, vertebrae Ribs, vertebrae, occipital bone Extension and lateral flexion of spine
Iliocostalis (3 erector spinae
muscles) Either side of spine
Sacrum, iliac crest and spinous processes of lumbar and lower thoracic vertebrae Ribs and transverse processes of cervical vertebrae
Lateral flexion of the neck and extension of the vertebral column
Longissimus (3 erector spinae
muscles) Either side of spine
Transverse processes of the lumbar and thoracic vertebrae Ribs and transverse processes of the thoracic and cervical vertebrae and mastoid process
Lateral flexion of the neck and extension of the vertebral column
Spinalis (2 erector spinae
muscles) Either side of spine
Spinous processes of lumbar and thoracic vertebrae Spinous processes of the upper thoracic and cervical vertebrae
Lateral flexion of the neck and extension of the vertebral column
Multifidus Either side of spine
Posterior superior iliac spine (PSIS), transverse processes of lumbar, thoracic and C4-C7 vertebrae Spinous processes of 2nd-4th vertebrae above each origin
Extension and rotation of vertebral column
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Level 2 : Black
Level 3 : Orange Location Origin Insertion Primary concentric actions
Quadratus
lumborum Lower back Iliac crest
12th rib and transverse processes of L1-L4
Lateral flexion and extension of spine
Rectus abdominis centre of the Along the
abdomen Pubis Sternum
Flexion of spine, lateral flexion of spine
Internal obliques Sides of the abdomen Ribs, ilium Ilium, pubis, ribs, linea alba Rotation and lateral flexion of spine
External obliques Sides of the abdomen Ribs Ilium, pubis Rotation andlateral flexion of spine Transversus
abdominis Abdomen Iliac crest and lumbar fascia
Pubis and
linea alba Support of internal organs and forced expiration
Diaphragm Beneath rib cage
Sternum, costal cartilages and lumbar vertebrae
Central tendon of
diaphragm Depresses and aids in expiration Intercostals Between ribs Ribs and costal cartilages Superior border of next rib below Elevates ribs and aids in expiration
Hip flexors
Iliacus
Through the pelvis and onto
the femur
Iliac fossa Lesser trochanter of femur Flexion and lateral rotation of hip
Psoas major Transverse processes of T12 –L5
Lesser trochanter
of femur Flexes and laterally rotates hip Gluteus maximus Bottom Ilium Femur Extension and external rotation of the hip
Abductors Gluteus medius Outside of upper thigh Lateral and posterior ilium Posterior and lateral surface of greater trochanter of femur
Abduction and medial rotation of hip
Gluteus minimus Lateral ilium Anterior surface of greater trochanter of femur
Abduction and medial rotation of hip
Piriformis Posterior hip Anterior sacrum Upper surface of greater trochanter of femur
Abduction and lateral rotation of hip
Tensor fascia latae Outer thigh Anterior iliac crest Lateral upper tibia via iliotibial band (ITB)
Flexion and abduction of hip
Adductors
Magnus
Inner thigh Pubis, ischium Femur Adduction of hip
Longus Brevis
Pectineus Inner thigh Anterior pubis Lesser trochanter and upper femur Adduction and flexion of hip
Gracilis Inner thigh Ischio-pubic ramus Medial tibia below condyle Adduction of hip and flexion of knee
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Level 2 : Black
Level 3 : Orange Location Origin Insertion Primary concentric actions
Sartorius Front and inner thigh Anterior superior iliac spine (ASIS)
Medial condyle of tibia
Flexion, abduction and lateral rotation of hip, flexion and medial rotation of knee Quadriceps Rectus femoris Front of thigh Anterior inferior iliac spine (AIIS) Tibial tuberosity
via patella Flexion of hip and extension of knee
Vastus lateralis Lateral femur and greater trochanter
Tibial tuberosity
via patella Extension of knee
Vastus intermedius Medial femur Tibial tuberosity via patella Extension of knee
Vastus medialis Anterior femur Tibial tuberosity via patella Extension of knee, especially last 20° motion Hamstrings Biceps femoris Back of thigh Ischial tuberosity and posterior femur Head of fibula and lateral condyle of tibia
Extension of hip and flexion of knee
Semitendinosus Ischial tuberosity Medial condyle of tibia Extension of hip and flexion of knee Semimembranosus Ischial tuberosity Anterior medial surface of tibia Extension of hip and flexion of knee
Gastrocnemius Calf Femur Calcaneus (heel bone) Plantarflexion of ankle,flexion of knee Soleus gastrocnemius TibiaCalf, beneath Calcaneus (heel bone) Plantarflexion of ankle Tibialis anterior Front of lower limb (shin) Tibia Metatarsal and tarsal Dorsiflexion and inversion of ankle
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The nervous and endocrine systems are the means by which the body maintains homeostasis (a stable internal environment). The nervous system does so via a complex web of nerves, whereas the endocrine system supports homeostasis through a series of glands and hormones (chemical messengers).
As exercise activity represents one of the biggest challenges to the internal environment of the body, it is important to understand how these two systems help regulate this environment. Although clearly distinct from one another, the two systems work closely together, one often triggering a response in the other. However, for the purposes of clarity each will be addressed separately here.