Muscle Theory: Part 1
This post is dedicated to some of the different muscles, their origins and insertions that we are primarily interested in when we train for Hypertrophy and/or Strength based on individual goals.
Certain specific fibers organised into bands or bundles that may contract and produce bodily movement are called muscle tissue. Upon contraction, muscles pull both ends towards the middle or belly of the muscle. The points at which a muscle attaches are known as the origin and insertion of the muscle. A muscle may have one or more origin and/or insertion point. Origin is the proximal attachment, the least moveable or closest to the midline or centre of the body. While, insertion is the distal attachment, the most moveable or farthest from the midline or centre of the body.
So, lets get started with the upper body muscles first and in a separate post we will look into the muscles of the lower body.
1. Trapezius (upper and middle):
Origin:
Upper: Base of skull, occipital protuberance and posterior ligaments of neck.
Middle: Spinous process of 7C and T1-T3.
Lower: Spinous process of T4-T12.
Insertion:
Upper: Posterior aspect of the lateral clavicle.
Middle: Medial border of the acromion process and upper boarder of acromion.
Lower: Base of Scapular Spine.
Actions:
Upper: Scapula elevation and extension of the head at neck.
Middle: Elevation, upward rotation and adduction of scapula.
Lower: Depression adduction, upward rotation of the scapula
Example Exercise/Movement:
Upper: Barbell Shrug, Dumbbell Shrug.
Middle: Bent-over Barbell or Dumbbell Row.
Lower: Bent-over Barbell or Dumbbell Row, Face Pull.
2. Deltoid (Anterior, Middle and Posterior):
Origin:
Anterior: Anterior Lateral third of Clavicle.
Middle: Lateral Aspects of acromion.
Posterior: Inferior edge of spine scapula.
Insertion:
Anterior: Deltoid tuberocity on lateral humerus.
Middle: Deltoid tuberocity on lateral humerus.
Posterior: Deltoid tuberocity on lateral humerus.
Action:
Anterior: Abduction, flexion, horizontal adduction and internal rotation of glenohumeral joint.
Middle: Abduction of the glenohumeral joint.
Posterior: Abduction, extension, horizontal abduction and external rotation of glenohumeral joint.
Example Exercise/Movement:
Anterior: Barbell Over Head Press.
Middle: Dumbbell lateral raise.
Posterior: Face Pull, Rear Delt Fly.
3. Latissimus Dorsi:
Origin: Posterior crest of illium, back of sacrum and spinious process of lumbar and lower T6-T12.
Insertion : Medial side of intertubercular groove of humerus.
Action:Adduction, extension and internal rotation of glenohumeral joint, transverse extension.
Example Exercise/Movement: Pull up, Seated machine row, Pull in.
4. Pectoralis Major:
Origin:
Clavicular: Medial half of anterior surface of clavicle.
Sternal: Anterior surfaces of costal cartilage of first 6 ribs and adjacent portion of sternum.
Insertion:
Clavicular: Flat tendon 2 or 3 inches wide to the outer lip of intertubercular.
Sternal: Groove of humerus.
Action:
Clavicular: Internal rotation, horizontal adduction, flexion abduction and adduction (when the arm is 90 degree of abduction of the glenohumeral joint).
Sternal: Internal rotation, horizontal adduction, extension, and adduction of the glenohumeral joint.
Example Exercise/Movement: Dumbbell incline bench chest press, pec-deck.
5. Biceps Brachii:
Origin:
Long Head: Supraglenoid tubercle above the superior lip of glenoid fossa.
Short Head: Coracoid process of scapula and upper lip of glenoid fossa.
Insertion:
Long Head and Short Head: Tuberosity of radius and bicipital aponeurosis.
Action:
Long Head and Short Head: Flexion of elbow, supination of forearm.
Example Exercise/Movement: Cable biceps curl, dumbbell hammer curl.
6. Brachioradialis:
Origin:Distal 2/3 of lateral condyloid ridge of humerus.
Insertion:Lateral surface, distal end of the radius at styloid process.
Action:Flexion of elbow, pronation from supinated to neutral position, supination from pronation to neutral position.
Example Exercise/Movement: Dumbbell hammer curl.
7. Triceps Brachii:
Origin:
Long Head: Infraglenoid tubercle below inferior lip of glenoid fossa of scapula.
Medial Head: Distal 2/3 of posterior surface of humerus.
Lateral Head: Upper half of posterior surface of humerus.
Insertion:Long, Medial and Lateral Head: Olecranon process of the ulna.
Action:
Long Head: Adduction of the shoulder joint, extension of the elbow.
Long Medial and Lateral Head: Extension of the elbow.
Example Exercise/Movement: Triceps cable extension with rope, French Press.
8. Rectus Abdominus:
Origin: Superior surface of pubis around syphysis
Insertion:Inferior surfaces of costal cartilages (ribs 5 – 7) and xiphoid process of sternum.
Action:Depresses ribs, flexes vertebral column.
Example Exercise/Movement: Hanging leg raise.
9. External and Internal Oblique:
Origin:
External: External and inferior borders of ribs 5 – 12.
Internal: Lumbodorsal fascia and iliac crest
Insertion:
External: Linea alba and iliac crest.
Internal: Inferior surface of ribs 9-12, costal cartilage 8-10, linea alba and pubis.
Action:
External and Internal: Compresses abdomen; depresses ribs; flexes, bends to side, or rotates spine.
Example Exercise/Movement: Russian Twist.
10. Transverse Abdominus:
Origin:Cartilages of the lower ribs, iliac crest and lumbodorsal fascia
Insertion: Linea alba and pubis
Action: Compresses the abdomen
Example Exercise/Movement: Crunches
The different muscles mentioned above are just some of the many upper body muscles.
Note:Before starting/changing an exercise, dietary and supplementation program consult a qualified doctor/health care professional.
References:
1. ISSA CFT Text
Certain specific fibers organised into bands or bundles that may contract and produce bodily movement are called muscle tissue. Upon contraction, muscles pull both ends towards the middle or belly of the muscle. The points at which a muscle attaches are known as the origin and insertion of the muscle. A muscle may have one or more origin and/or insertion point. Origin is the proximal attachment, the least moveable or closest to the midline or centre of the body. While, insertion is the distal attachment, the most moveable or farthest from the midline or centre of the body.
So, lets get started with the upper body muscles first and in a separate post we will look into the muscles of the lower body.
1. Trapezius (upper and middle):
Origin:
Upper: Base of skull, occipital protuberance and posterior ligaments of neck.
Middle: Spinous process of 7C and T1-T3.
Lower: Spinous process of T4-T12.
Insertion:
Upper: Posterior aspect of the lateral clavicle.
Middle: Medial border of the acromion process and upper boarder of acromion.
Lower: Base of Scapular Spine.
Actions:
Upper: Scapula elevation and extension of the head at neck.
Middle: Elevation, upward rotation and adduction of scapula.
Lower: Depression adduction, upward rotation of the scapula
Example Exercise/Movement:
Upper: Barbell Shrug, Dumbbell Shrug.
Middle: Bent-over Barbell or Dumbbell Row.
Lower: Bent-over Barbell or Dumbbell Row, Face Pull.
2. Deltoid (Anterior, Middle and Posterior):
Origin:
Anterior: Anterior Lateral third of Clavicle.
Middle: Lateral Aspects of acromion.
Posterior: Inferior edge of spine scapula.
Insertion:
Anterior: Deltoid tuberocity on lateral humerus.
Middle: Deltoid tuberocity on lateral humerus.
Posterior: Deltoid tuberocity on lateral humerus.
Action:
Anterior: Abduction, flexion, horizontal adduction and internal rotation of glenohumeral joint.
Middle: Abduction of the glenohumeral joint.
Posterior: Abduction, extension, horizontal abduction and external rotation of glenohumeral joint.
Example Exercise/Movement:
Anterior: Barbell Over Head Press.
Middle: Dumbbell lateral raise.
Posterior: Face Pull, Rear Delt Fly.
3. Latissimus Dorsi:
Origin: Posterior crest of illium, back of sacrum and spinious process of lumbar and lower T6-T12.
Insertion : Medial side of intertubercular groove of humerus.
Action:Adduction, extension and internal rotation of glenohumeral joint, transverse extension.
Example Exercise/Movement: Pull up, Seated machine row, Pull in.
4. Pectoralis Major:
Origin:
Clavicular: Medial half of anterior surface of clavicle.
Sternal: Anterior surfaces of costal cartilage of first 6 ribs and adjacent portion of sternum.
Insertion:
Clavicular: Flat tendon 2 or 3 inches wide to the outer lip of intertubercular.
Sternal: Groove of humerus.
Action:
Clavicular: Internal rotation, horizontal adduction, flexion abduction and adduction (when the arm is 90 degree of abduction of the glenohumeral joint).
Sternal: Internal rotation, horizontal adduction, extension, and adduction of the glenohumeral joint.
Example Exercise/Movement: Dumbbell incline bench chest press, pec-deck.
5. Biceps Brachii:
Origin:
Long Head: Supraglenoid tubercle above the superior lip of glenoid fossa.
Short Head: Coracoid process of scapula and upper lip of glenoid fossa.
Insertion:
Long Head and Short Head: Tuberosity of radius and bicipital aponeurosis.
Action:
Long Head and Short Head: Flexion of elbow, supination of forearm.
Example Exercise/Movement: Cable biceps curl, dumbbell hammer curl.
6. Brachioradialis:
Origin:Distal 2/3 of lateral condyloid ridge of humerus.
Insertion:Lateral surface, distal end of the radius at styloid process.
Action:Flexion of elbow, pronation from supinated to neutral position, supination from pronation to neutral position.
Example Exercise/Movement: Dumbbell hammer curl.
7. Triceps Brachii:
Origin:
Long Head: Infraglenoid tubercle below inferior lip of glenoid fossa of scapula.
Medial Head: Distal 2/3 of posterior surface of humerus.
Lateral Head: Upper half of posterior surface of humerus.
Insertion:Long, Medial and Lateral Head: Olecranon process of the ulna.
Action:
Long Head: Adduction of the shoulder joint, extension of the elbow.
Long Medial and Lateral Head: Extension of the elbow.
Example Exercise/Movement: Triceps cable extension with rope, French Press.
8. Rectus Abdominus:
Origin: Superior surface of pubis around syphysis
Insertion:Inferior surfaces of costal cartilages (ribs 5 – 7) and xiphoid process of sternum.
Action:Depresses ribs, flexes vertebral column.
Example Exercise/Movement: Hanging leg raise.
9. External and Internal Oblique:
Origin:
External: External and inferior borders of ribs 5 – 12.
Internal: Lumbodorsal fascia and iliac crest
Insertion:
External: Linea alba and iliac crest.
Internal: Inferior surface of ribs 9-12, costal cartilage 8-10, linea alba and pubis.
Action:
External and Internal: Compresses abdomen; depresses ribs; flexes, bends to side, or rotates spine.
Example Exercise/Movement: Russian Twist.
10. Transverse Abdominus:
Origin:Cartilages of the lower ribs, iliac crest and lumbodorsal fascia
Insertion: Linea alba and pubis
Action: Compresses the abdomen
Example Exercise/Movement: Crunches
The different muscles mentioned above are just some of the many upper body muscles.
Note:Before starting/changing an exercise, dietary and supplementation program consult a qualified doctor/health care professional.
References:
1. ISSA CFT Text
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