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# Middle trapezius

The middle trapezius runs across the upper back from the spine to the shoulder blade; it pulls the shoulder blades back together.

Official name: Trapezius, middle (transverse) part

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## What it is

The middle part of the trapezius, between the spine and the shoulder blade.

## What it does

Pulls the shoulder blades back together.

## Key points

- Its fibres run horizontally from the upper thoracic spines to the acromion and spine of the scapula: with the rhomboid major and rhomboid minor it is the main retractor of the scapula
- [Trapezius](https://durgical.com/en/anatomy/trapezius-muscle/) palsy ([accessory nerve](https://durgical.com/en/anatomy/accessory-nerve/)) gives lateral winging: the scapula slides down and away from the spine, worse on raising the arm to the side; [serratus anterior](https://durgical.com/en/anatomy/serratus-anterior/) palsy gives medial winging, worse on pushing forward
- It inserts on the upper lip of the spine of the scapula, facing the origin of the [rear deltoid](https://durgical.com/en/anatomy/deltoid-posterior-part/) on the lower lip

## Key facts

**Origin**
Spinous processes C7–T3

**Insertion**
Acromion and spine of the scapula

**Action**
Retracts the scapula

**Nerve**
Accessory nerve (CN XI)

**Blood supply**
Transverse cervical artery

## Relations

**Superficial**
[Skin](https://durgical.com/en/anatomy/skin/) and fascia of the upper back between the shoulder blades

**Deep**
[Rhomboid minor](https://durgical.com/en/anatomy/rhomboid-minor/) and [rhomboid major](https://durgical.com/en/anatomy/rhomboid-major/) medially, with the [dorsal scapular nerve](https://durgical.com/en/anatomy/dorsal-scapular-nerve/) and artery deep to them; [supraspinatus](https://durgical.com/en/anatomy/supraspinatus/) near its insertion

**Medial**
Spinous processes C7–T3 and the [supraspinous ligament](https://durgical.com/en/anatomy/supraspinous-ligament/); with the other side it forms a tendinous diamond around C7

**Lateral**
Acromion and [spine](https://durgical.com/en/anatomy/region/spine/) of the [scapula](https://durgical.com/en/anatomy/scapula/)

## How to find it

Lying prone with the arm abducted to 90° and turned out (thumb up), lifting the arm toward the ceiling squeezes the shoulder blades together and the horizontal band between the spine and the scapula tightens under the fingers.

## Examination

- Manual muscle test (prone, arm at 90° abduction, examiner pressing the arm toward the floor): weakness with the scapula drifting away from the spine points to CN XI injury or marked deconditioning
- Winging pattern: winging that grows with resisted abduction and eases on forward flexion points to the trapezius (accessory nerve); winging on a wall push-up points to the serratus anterior ([long thoracic nerve](https://durgical.com/en/anatomy/long-thoracic-nerve/))

## On imaging

On axial CT or MRI of the upper [chest](https://durgical.com/en/anatomy/region/chest/) it is the most superficial muscle between the spine and the scapula, over the [rhomboids](https://durgical.com/en/anatomy/rhomboid-major-muscle/). Accessory nerve palsy shows as atrophy and fatty change. Scapular winging is a clinical sign; imaging is used mainly to compare sides and to rule out a mass. Ultrasound measures its thickness at the bedside.

## Clinical notes

- After accessory nerve injury the scapula sits lower and further from the spine at rest, and the shoulder may ache from traction on the [brachial plexus](https://durgical.com/en/anatomy/roots-of-brachial-plexus/)
- Weak middle and lower fibres with a protracted, forward-tipped scapula is a common picture in scapular dyskinesis and in overhead athletes with shoulder pain

## Related conditions

- [Winged scapula](https://durgical.com/en/conditions/winged-scapula/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which muscles are the main retractors of the scapula?

The middle trapezius, with the rhomboid major and rhomboid minor.

## How does trapezius winging differ from serratus anterior winging?

Trapezius (accessory nerve): lateral winging, the scapula slides down and away, worse on abduction. Serratus anterior: medial winging, worse on pushing forward.

## Where does the middle trapezius insert?

On the acromion and the upper lip of the spine of the scapula, facing the origin of the rear deltoid on the lower lip.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
pars transversa musculi trapezii TA2 2228

**Official Spanish (DeCS)**
Porción transversa del músculo trapecio

**English (TA2)**
Trapezius, middle (transverse) part

## Related

- [Clavicle](https://durgical.com/en/anatomy/clavicle/)
- [Scapula](https://durgical.com/en/anatomy/scapula/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Back, Trapezius](https://www.ncbi.nlm.nih.gov/books/NBK518994/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/trapezius-middle-part/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/trapezius-middle-part/