Musculoskeletal Anatomy Study Guide: Upper Back, Shoulder Girdle & Rotator Cuff Architecture

Vocabulary flashcards covering origins, insertions, innervations, actions, and key anatomical landmarks for upper back and shoulder muscles.

Trapezius (Upper Fibers)

Bilaterally extends head & neck; unilaterally laterally flexes head/neck to same side, rotates head/neck to opposite side, elevates & upwardly rotates scapula.

Trapezius (Middle Fibers)

Adducts (retracts) & stabilizes scapula.

Trapezius (Lower Fibers)

Depresses & downwardly/upwardly rotates scapula.

Trapezius (Origin)

External occipital protuberance, medial portion of superior nuchal line of occiput, ligamentum nuchae, spinous processes of C7–T12.

Trapezius (Insertion)

Lateral 1/3 of clavicle, acromion process, and spine of scapula.

Trapezius (Innervation)

Spinal portion of Cranial Nerve XI (Accessory) and ventral rami C2, C3, C4.

Trapezius Palpation Action

Elevate (or depress) your shoulder against resistance.

Latissimus Dorsi (Actions)

Extends, adducts, and medially rotates the shoulder at the glenohumeral joint.

Latissimus Dorsi (Origin)

Inferior angle of scapula, spinous processes of last 6 thoracic vertebrae (T7–T12), last 3–4 ribs, thoracolumbar aponeurosis, posterior iliac crest.

Latissimus Dorsi (Insertion)

Intertubercular groove of humerus (bicipital groove).

Latissimus Dorsi (Innervation)

Thoracodorsal nerve (C6, C7, C8).

Thoracolumbar Aponeurosis

Connects Latissimus Dorsi to lumbar spine, sacrum, and iliac crest (aka lumbodorsal fascia).

Spiral Pathway of Latissimus Dorsi

Arises posteriorly and wraps to insert anteriorly on the bicipital groove of the humerus, enabling powerful extension & medial rotation.

"Lat's Little Helper"

Refers to Teres Major due to its functional synergy with Latissimus Dorsi in shoulder extension, adduction, and medial rotation.

Teres Major (Actions)

Extends, adducts, and medially rotates the shoulder at the glenohumeral joint.

Teres Major (Origin)

Inferior angle and lower 1/3 of lateral border of scapula.

Teres Major (Insertion)

Crest of lesser tubercle of humerus (bicipital groove).

Teres Major (Innervation)

Lower subscapular nerve (C5, C6, C7).

Supraspinatus (Actions)

Abducts the shoulder (G/H joint) and stabilizes the head of humerus in glenoid cavity.

Supraspinatus (Origin)

Supraspinous fossa of scapula.

Supraspinatus (Insertion)

Greater tubercle of humerus.

Supraspinatus (Innervation)

Suprascapular nerve (C4, C5, C6).

SITS Muscles

Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.

Supraspinatus (Abduction Function)

Initiates shoulder abduction before Deltoid takes primary mechanical control.

Levator Scapulae Anatomy

Deep cervical attachment running to superior angle of scapula.