Topic Overview

Muscles Connecting Upper Limb with Vertebral Column

These are the extrinsic muscles of the back (superficial group).

1. Trapezius

• Origin → External occipital protuberance, ligamentum nuchae, spinous processes of C7–T12.

• Insertion → Lateral ⅓ of clavicle, acromion, spine of scapula.

• Nerve supply → Spinal accessory nerve (motor), C3–C4 ventral rami (sensory proprioception).

• Actions →

  • Upper fibers → elevate scapula.

  • Middle fibers → retract scapula.

  • Lower fibers → depress scapula.

  • Upper + lower → rotate scapula upward (abduction >90°).

• Clinical → Spinal accessory nerve injury → shoulder droop, difficulty elevating shoulder.

2. Latissimus Dorsi

• Origin → Spinous processes of T7–L5, thoracolumbar fascia, iliac crest, lower 3–4 ribs.

• Insertion → Floor of intertubercular sulcus of humerus.

• Nerve supply → Thoracodorsal nerve (C6–C8).

• Actions → Extends, adducts, medially rotates arm; climbing and swimming muscle.

• Clinical → Used in tendon/muscle grafts (e.g., breast reconstruction).

3. Levator Scapulae

• Origin → Transverse processes of C1–C4.

• Insertion → Superior angle and medial border of scapula.

• Nerve supply → Dorsal scapular nerve (C5), C3–C4 ventral rami.

• Actions → Elevates scapula, tilts glenoid cavity downward.

• Clinical → Spasm causes stiff neck.

4. Rhomboid Major

• Origin → Spinous processes of T2–T5.

• Insertion → Medial border of scapula (below spine).

• Nerve supply → Dorsal scapular nerve (C5).

• Action → Retracts and stabilizes scapula.

5. Rhomboid Minor

• Origin → Ligamentum nuchae, spinous processes of C7–T1.

• Insertion → Medial border of scapula at level of spine.

• Nerve supply → Dorsal scapular nerve (C5).

• Action → Retracts scapula, assists in rotation.

Dissection of These Muscles

Step 1: Expose Superficial Muscles

• After skin and fascia removal → identify trapezius in upper back and latissimus dorsi in lower back.

• Clear attachments and outline their borders.

Step 2: Reflection of Trapezius

• Incise trapezius near midline and reflect laterally.

• Identify accessory nerve and transverse cervical vessels beneath.

Step 3: Reflection of Latissimus Dorsi

• Incise near vertebral attachment and reflect laterally toward humerus.

• Identify thoracodorsal nerve and vessels entering muscle.

Step 4: Expose Deeper Muscles

• Levator scapulae and rhomboids lie deep to trapezius.

• Reflect trapezius → identify levator scapulae superiorly, rhomboids attaching to scapula medially.

• Dorsal scapular nerve and artery lie along medial border of scapula.

Step 5: Clinical Demonstrations

• Show shoulder elevation test for trapezius.

• Demonstrate pull-up motion for latissimus dorsi.

• Palpate medial border of scapula for rhomboid contraction during retraction.