Muscles-action and location

We will now examine the major muscles in the body. As a fitness leader you will be expected to know these names of these muscles, their location and their action as they move different joints in the body. You will need this knowledge to explain exercises to clients. You will also need to know the names of muscles as you communicate with other health professionals.

1. Major muscles of the anterior chest

• Pectoralis Major• Pectoralis minor• Serratus anterior

Where are these muscles?

Summary of actions and locationMuscle Action Location

Pectoralis major Flexes adducts and medially rotates the arm

Anterior chest wall

Pectoralis Minor Adducts and medially rotates the arm

Anterior chest deep to

pectoralis major

Serratus anterior Holds scapula against ribs rotates scapula upwards an laterally

Lies beneath and inferior to pectoralis major and has a serrated appearance.

Summary of muscles and jointsMuscle Joints which move

Pectoralis major The shoulder joint

Pectoralis Minor The shoulder joint

Serratus anterior The scapulo-thoracic region ( no specific joint)

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles What exercises can you think of that would

strengthen these muscles?

2. Major Muscles of the posterior trunk and back Latissimus dorsi Trapezius (lower fibres) Rhomboid major and minor Quadratus lumborum Erector spinae

Where are these muscles?

Where are these muscles?

Summary of actions and locationMuscle Action Location

Latissimus Dorsi Extends, adducts and medial rotates the arm

Lower trunk extending up to the arm

Trapezius (lower fibres)

Retracts and depresses the scapula

The posterior trunk from the tip of the shoulder down to the lumbar spine

Rhomboids Retracts the scapula

Medial border of the scapula to the spine

Summary of actions and location cont…Muscle Action Location

Quadratus Lumborum

Side bending of the trunk

Hitching of the pelvis

Between the lowest rib and iliac crest

Erector Spinae-

(made up of three muscles)

Iliocostalis, Longissimus,

Spinales,

Trunk extension and some trunk side flexion

On either side of the spine, with some extensions

out onto the ribs

Summary of muscles and joints

Muscles Joint action

Latissimus Dorsi The shoulder joint

Trapezius (lower fibres)

The scapulo-thoracic region ( no specific joint)

Quadratus Lumborum

The lumbar spine intervertebral/facet joints and the sacro-liac joint

Erector Spinae Spine intervertebral/facet joints

Rhomboids The scapulo-thoracic region ( no specific joint)

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles. How would you strengthen these muscles?

3. Major muscles of the neck

Sternocleidomastoid Trapezius

Where are these muscles?

Where are these muscles?

Summary of actions and location

Muscle Action Location

Sternocleido-mastoid

Head flexion, rotation and lateral flexion

Front of neck

Trapezius Head and neck side flexion

Hitching scapula and shoulder

Side of neck down to the tip of the shoulder

Muscles and Joint Action

Muscle Joint Action

Sternocleido-mastoid

Cervical intervertebral/ facets joints

Trapezius Cervical intervertebral/ facets joints

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles How would you strengthen these muscles?

4. Major muscles of the upper limb

Deltoid Biceps brachii Triceps brachii Forearm flexors Forearm extensors

Where are these muscles?

Where are these muscles?

Where are these muscles?

Where are these muscles?

Summary of actions and locationMuscle Action Location

Deltoid Abduction of the arm

Tip of the shoulder

Biceps brachii Flexion of the elbow and shoulder

Front of the arm between shoulder and elbow

Triceps brachii Extension of the elbow and shoulder

Back of the arm between the shoulder and elbow

Summary of actions and location

Muscle Action LocationForearm flexors( The major ones are -Flexor carpi radialis, flexor carpi ulnaris, flexor digitorum, palmaris longus)

Flexing the wrist and fingers

From the medial epicondyle down the anterior or palmar side of the forearm

Forearm extensors(The major ones are- Extensor carpi radialis longus &brevis, extensor carpi ulnaris, extensor digitorum)

Extending the wrist and fingers

From the lateral epicondyle down the posterior or dorsal side of the forearm.

Muscles and joint actionMuscles Joint Action

Deltoid The shoulder joint

Biceps brachii

The elbow and shoulder joint

Triceps brachii

The elbow and the shoulder joint

Forearm flexors

The wrist joint and some move the finder joints

Forearm extensors

The wrist joints and some move the finder joint

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles

5. Major muscles of the abdominal region Rectus abdominis External and Internal oblique Transverse abdominis

Where are these muscles?

Summary of actions and location

Muscle Action Location

Rectus abdominis

(The six pack)

Trunk flexion Straight up and down from the ribs to the pelvis

External and Internal oblique

Trunk flexion, rotation and side flexion

Diagonal muscles on the side of the trunk

Transverse abdominis

Trunk and lumbar spine core stability

Circular muscle deep to other abdominal muscles.

Muscles and Joint ActionMuscle Joint Action

Rectus abdominis

Thoracic and lumbar spine intervertebral / facets joints

Sacro-iliac joint

External and Internal oblique

Thoracic and lumbar spine intervertebral / facets joints

Transverse abdominis

Lumbar spine intervertebral / facets joints

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles. How would you strengthen these muscles?

6. Major muscles of the lower limb Gluteals- maximus, medius and minimus Quadriceps- vastus medialis, lateralis,

intermedialis rectus femoris Hamstrings- biceps femoris,

semitendinosus, semimembranosus Calf- Gastrocnemius, soleus Tibialis anterior

Where are these muscles?

Summary of actions and locationMuscle Action Location

Gluteus maximus Hip extension Major muscle base of trunk covering the pelvis

Gluteus medius Hip abduction medial rotation and stabilisation of the hip

Lateral posterior pelvis, slightly lateral to the glut.max.

Gluteus minimus Hip abduction medial rotation and stabilisation of the hip

Sits deep to the glut max.

Muscles and joint action

Muscle Joint Action

Gluteus maximus

Hip joint

Gluteus medius Hip joint

Gluteus minimus

Hip joint

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles What exercises can you think of that would

strengthen these muscles?

Where are these muscles?

Summary of actions and locationMuscle Action Location

Biceps femoris Extends the hip and flexes the knee

The back of the thigh, the lateral side

Semitendinosus Extends the hip and flexes the knee

The back of the thigh, the medial side

Semimembranosus Extends the hip and flexes the knee

The back of the thigh, the medial side

Muscles and joint action

Muscle Joint Action

Biceps femoris Hip joint and knee joint

Semitendinosus Hip joint and knee joint

Semimembranosus Hip and knee joint

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles What exercises can you think of that would

strengthen these muscles?

Where are these muscles?

Summary of actions and locationMuscle Action Location

Rectus femoris Flexes the hip and extends the knee

Main muscle in the front of the thigh

Vasti lateralis Extends the knee Major muscle sitting slightly lateral to rectus femoris

Vasti medialis Extends the knee Major muscle sitting slightly medial to rectus femoris

Vasti intermedialis Extends the knee Sits under the rectus femoris

Muscles and joint action

Muscle Joint ActionRectus femoris Hip and knee joint

Vasti lateralis Knee joint

Vasti medialis Knee joint

Vasti intermedialis

Knee joint

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles What exercises can you think of that would

strengthen these muscles?

Where are these muscles?

Summary of actions and locationMuscle Action Location

Gastrocnemius Flexes the knee and plantaflexes (extends) the ankle

The major muscle in the calf

Soleus Plantaflexes the ankle

Sits deep to gastrconemius

Muscles and Joint Action

Muscle Joint Action

Gastrocnemius Knee joint and ankle joint

Soleus Ankle joint

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles What exercises can you think of that would

strengthen these muscles?

Where are these muscles?

Summary of actions and locationMuscle Action Location

Tibialis Anterior Ankle dorsiflexion

Below the knee , the just lateral to the shin.

Muscle and Joint Action

Muscle Joint Action

Tibialis Anterior Ankle joint

Learning Tools

Find the muscles you have just learnt on a fellow student or friend.

As you identify them review the names, actions of these muscles and joints which move as these muscles contract.

List the actions of these muscles What exercises can you think of that would

strengthen these muscles?