Anatomy study note · Upper limb

Trapezius

A large flat triangular muscle covering the back of the neck and upper thorax. It moves and steadies the scapula.

Key points

• Occiput + ligamentum nuchae + C7–T12 spines → lateral clavicle, acromion, scapular spine.
• Accessory nerve (CN XI) motor; C3, 4 sensory.
• Upper: shrug. Middle: retract. Lower: depress. Upper + lower: upward rotation.
• Palsy → dropped shoulder.
• Striated muscle: myotomes + local mesenchyme.
• Nerve supply indicates origin.
• Large motor units (thousands of cells).
• Skeletal muscle: multinucleated, peripheral nuclei, striated.

The full note in the atlas also covers

Origin · Insertion · Action · Nerve supply · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 3, PDF pp. 302, 327
• Inderbir Singh’s Human Embryology, ch. 7, PDF pp. 92, 108–109
• BRS Cell Biology & Histology, 7th ed., ch. 8, PDF pp. 135–144, 143

More from the upper limb

• Triceps brachii
• Ulna
• Ulnar artery
• Ulnar nerve
• Veins of the hand
• Wrist joint
• Abductor pollicis longus
• Acromioclavicular joint
• Adductor pollicis
• Anconeus
• Axillary artery
• Axillary lymph nodes

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