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MUSCLES – LATS & TERES MAJOR

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TERES MAJOR

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• Origin: The dorsal surface of the inferior angle of the scapula
• Insertion: The medial lip of the intertubercular groove of the humerus^[1].
• Function: Adducts and Internally Rotates the arm^[5]
• Function: Extends the arm from a flexed position

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LATISSIMUS DORSI

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• Origin: Spinous processes of vertebrae T7–L5, thoracolumbar fascia, iliac crest, inferior 3 or 4 ribs and inferior angle of scapula
• Insertion: Floor of intertubercular groove of the humerus
• Primary Actions of the Latissimus Dorsi – source: Physiopedia .

1. Adduction of the arm at shoulder
   Agonists: Pectoralis Major, Teres Major, Triceps Brachii (long head)
   Antagonists: Deltoid (middle) Supraspinatus
2. Extension of the arm at the shoulder
   Agonists: Deltoid (posterior) Triceps brachii (long head), Pectoralis Major (sternal head)
   Antagonists: Deltoid (anterior) Biceps brachii, Coracobrachialis, Pectoralis Major (clavicular head)
3. Internal rotation of the arm at the shoulder
   Agonists: Subscapularis, Deltoid (anterior), Pectoralis Major, Teres Major
   Antagonists: Infraspinatus, Teres minor, Deltoid (posterior)

• Secondary Actions of the Latissimus Dorsi

1. Assists with depression of the scapula
   Agonists: Serratus Anterior (lower fibers), Trapezius (lower fibers), Pectoralis minor
   Antagonists: Levator Scapulae, Trapezius (upper fibers)
2. Assist with protraction of the scapula
3. Assists with deep inspiration and forced expiration ^[5]
4. Assists with extension of the trunk
   Agonists: Longissimus thoracis, Iliocostalis lumborum, Iliocostalis thoracis
   Antagonists: Rectus abdominis
5. Assists with flexion of the trunk
   Agonist: Rectus abdominis
   Antagonists: Longissimus thoracis, Iliocostalis lumborum, Iliocostalis thoracis
6. Assists with lateral flexion of the trunk
   Agonist: Quadratus lumborum, Rectus abdominis
   Antagonists: Longissimus thoracis, Iliocostalis lumborum, Iliocostalis thoracis
7. Assists with anterior and lateral pelvic tilt
   Agonist: Rectus abdominis
   Antagonists: Semitendinosus, Semimembranosus, Biceps femoris

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VIDEOS

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1. 18 Muscles of the Spine – Start at 10:50 – Abelson DC
2. Latissimus Dorsi – Muscle in Motion
3. Teres Major – Muscle in Motion
4. Superficial Back Muscles . Noted Anatomist
   (1) Traps (2) Rhomboids (3) Levator Scapulae (4) Latissimus Dorsi
5. Glenohumeral Joint . Noted Anatomist
   (1) Pectoralis Major (2) Teres Major (3) Latissimus Dorsi
6. Extrinsic (Superficial) Muscles of the Back . – Anatomy Zone
7. Large Shoulder Muscles . Webster
   – Traps 6:15 | LATS 9:15 | Rhomboids 17:30 | Levator Scapulae 18:30 | Teres Major 20:20

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