Muscle Anatomy of the Upper Trapezius

Origin:

  • External occipital protuberance
  • Medial third of the superior nuchal line
  • Nuchal ligament
  • Spinous process of C7

Insertion:

  • Lateral third of the clavicle
  • Medial aspect of the acromion process of the scapula

Action:

  • Upward rotation of the scapula
  • Elevation of the scapula

Innervation:

  • Motor: Accessory nerve (CN XI)
  • Sensory: Anterior rami of spinal nerves C3-C4 (via cervical plexus)

Blood Supply: Branches from the thyrocervical trunk

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Trapezius Muscle Actions With Agonists and Antagonists

Primary Actions of the Upper Trapezius Muscle

1. Upward rotation of the scapula

Agonists:

  • Serratus anterior (lower part)
  • Trapezius (lower part)

  Antagonists:

  • Levator scapulae
  • Serratus anterior (upper part)
  • Rhomboid major
  • Rhomboid minor
  • Pectoralis minor

2. Elevation of the scapula

  Agonists:

  • Levator Scapulae

  Antagonists:

  • Serratus anterior (lower part)
  • Trapezius (lower part)
  • Pectoralis minor

1. Assists with extension of the cervical spine

Agonists:

  • Sternocleidomastoid
  • Rectus Capitis Posterior Major
  • Rectus Capitis Posterior Minor
  • Obliquus Capitis Superior
  • Splenius Cervicis
  • Splenius Capitis
  • Ilocostalis Cervicis
  • Longissimus Cervicis
  • Longissimus Capitis
  • Spinalis Cervicis
  • Spinalis Capitis
  • Semispinalis Cervicis
  • Semispinalis Capitis

Antagonists: 

  • Longus Colli
  • Longus Capitis
  • Anterior Scalene
  • Sternocleidomastoid

2. Assists with lateral flexion of the cervical spine

  Agonists:

  • Longus colli
  • Rectus capitis lateralis
  • Scalenes
  • Sternocleidomastoid
  • Obliquus capitis superior
  • Splenius cervicis
  • Splenius capitis
  • Iliocostalis cervicis
  • Longissimus capitis

Antagonists: Same muscles on the contralateral side

  • Longus colli
  • Rectus capitis lateralis
  • Scalenes
  • Sternocleidomastoid
  • Obliquus capitis superior
  • Splenius cervicis
  • Splenius capitis
  • Iliocostalis cervicis
  • Longissimus capitis

3. Assists with contralateral rotation of the head and cervical spine when acting unilaterally

Agonists:

  • Semispinalis capitis
  • Semispinalis cervicis
  • Multifidus
  • Sternocleidomastoid

Antagonists: Same muscles on the contralateral side

  • Semispinalis capitis
  • Semispinalis cervicis
  • Multifidus
  • Sternocleidomastoid

Information about the cause and effect of gluteus maximus pain:

Gluteus Maximus Muscle: Low Back, Hip, Tailbone, Buttock Pain

Recommended Beginner Anatomy Books
The Anatomy Coloring Book is one of the best study and reference books for beginning anatomy students. The diagrams are clearly labeled and allow you to see the relationship and placement of the various structures of the body.

The Trail Guide To The Body is another excellent book to help you learn the musculature of the human body. Though the book is geared toward massage therapists and physical therapist assistants, the book with its illustrations and text helps anyone gain a thorough understanding of the human musculoskeletal system and movement. I highly recommend this book for anyone studying anatomy.

Recommended by TWD:
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Muscle Anatomy of the Middle Trapezius

Origin: 

  • Spinous processes of T1 to T5

Insertion:

  • Medial edge of the superior surface of the acromion process of the scapula
  • The superior edge of the scapular spine

Actions: Retraction of the scapula

Innervation: 

  • Spinal accessory nerve (cranial nerve XI)
  • The ventral rami of spinal nerves C2, C3, C4

Blood Supply: Branches from the thyrocervical trunk

Primary Actions of the Middle Trapezius

1.  Retraction of the scapula

  Agonists:

  • Rhomboid major
  • Rhomboid minor

  Antagonists: 

  • Serratus anterior
  • Pectoralis minor
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Muscle Anatomy of the Lower Trapezius

Origin: Spinous processes of T6 to T12
Insertion: Tubercles at the apex of the scapular spine
Actions: Upward rotation of the scapula
Innervation: 

  • Spinal accessory nerve (cranial nerve XI)
  • The ventral rami of spinal nerves C2, C3, C4

Blood Supply: Branches from the thyrocervical trunk.

Primary Actions of the Lower Trapezius

1. Upward rotation of the scapula

Agonists:

  • Trapezius (upper part)
  • Serratus anterior (lower part)

Antagonists: 

  • Levator scapulae
  • Serratus anterior (upper part)
  • Rhomboid major
  • Rhomboid minor
  • Pectoralis minor

2. Depression of the scapula

  Agonists:

  • Serratus anterior (lower part)
  • Pectoralis minor

  Antagonists:

  • Trapezius (upper part)
  • Levator scapulae

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