Trapezius Upper (Descending Part)
Back · Trunk
The descending, or upper, part of the trapezius forms the sloping contour between the neck and shoulder. It arises from the medial third of the superior nuchal line, the external occipital protuberance, and the ligamentum nuchae, and its fibres run downward and laterally to insert onto the lateral third of the clavicle. Because these fibres pull upward on the shoulder girdle, they elevate the scapula and, working with the lower fibres, rotate the glenoid cavity superiorly so the arm can be raised overhead; acting on a fixed shoulder they also help extend the neck. Like the rest of the trapezius, its motor supply is the accessory nerve (CN XI), with proprioceptive fibres from the anterior rami of C3-C4.
Origin, Insertion, Action & Nerve
Origin
Medial third of the superior nuchal line, external occipital protuberance, and ligamentum nuchae
Insertion
Lateral third of the clavicle
Action
Elevates the scapula and rotates the glenoid cavity superiorly; extends the neck
Nerve
Motor: accessory nerve (CN XI); proprioception: anterior rami of C3–C4
Attachments explained
The Trapezius Upper (Descending Part) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Medial third of the superior nuchal line, external occipital protuberance, and ligamentum nuchae
Insertion
Lateral third of the clavicle
Action & function
When the Trapezius Upper (Descending Part) contracts, it produces the following movements: Elevates the scapula and rotates the glenoid cavity superiorly; extends the neck.
As part of the Back group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Trapezius Upper (Descending Part) receives its nerve supply from the Motor: accessory nerve (CN XI); proprioception: anterior rami of C3–C4. This nerve carries fibres from spinal segment(s) C3, C4.
Because a muscle can only contract when its nerve is intact, injury to the Motor: accessory nerve or to its spinal roots (C3, C4) can weaken or paralyse the Trapezius Upper (Descending Part), impairing the movements it normally produces (elevates the scapula and rotates the glenoid cavity superiorly). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Trapezius Upper (Descending Part) (the OIANS method)
Study the trapezius as three functional parts and pin the descending part to the top: it runs from the skull and ligamentum nuchae down to the clavicle, so its downward-and-lateral line of pull lifts the shoulder (a shrug) and helps swing the glenoid upward for overhead reach. Deriving elevation from that geometry is more reliable than rote memorising.
Lock in the shared innervation across all three parts: motor supply from the accessory nerve (CN XI) with proprioception from C3-C4. Because this is the classic muscle tested by asking a patient to shrug against resistance, connecting the upper fibres to the shrug and to CN XI gives you a single clinical hook that also confirms the nerve for the middle and lower parts.
Frequently asked questions
Where is the Trapezius Upper (Descending Part) located?
The Trapezius Upper (Descending Part) is a muscle of the Back group, located in the Trunk.
What is the origin of the Trapezius Upper (Descending Part)?
Medial third of the superior nuchal line, external occipital protuberance, and ligamentum nuchae
What is the insertion of the Trapezius Upper (Descending Part)?
Lateral third of the clavicle
What movements does the Trapezius Upper (Descending Part) produce?
Elevates the scapula and rotates the glenoid cavity superiorly; extends the neck
What nerve supplies the Trapezius Upper (Descending Part)?
Motor: accessory nerve (CN XI); proprioception: anterior rami of C3–C4
Is the Trapezius Upper (Descending Part) free to study in OIANS?
The Trapezius Upper (Descending Part) is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Trunk is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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