Shoulder Girdle Muscles

The shoulder girdle consists primarily of the scapula bone and the clavicle bone or collar bone which move together as a unit. The shoulder girdle muscle are those which attach to and move these two bones.

Trapezius muscle explained

  • Part 1: Upper fibres of the cervical vertebrae. This is the weakest part of the muscle and only provides minor elevation of the clavicle.
  • Part 2: The area commonly known as upper trapz. This is a strong elevator, rotator and retractor of the scapula.
  • Part 3: The mid-portion of the Trapzius. These fibres are mainly responsible for scapula retraction.
  • Part 4: The lower fibres of Trapezius. This part of the muscle assists in retraction and rotation.

When all parts of the muscle work together they have the effect of simultaneously elevating and retracting the scapula. The Trapezius is used most commonly to fix the scapula to allow the Deltoid to move the Humerus.

Origin

  • Occipital protuberance (base of skull)
  • Ligaments cervical spine.
  • Spinous processes of C7-T12

Insertion.

  • Posterior outer 1/3 of the clavicle.
  • Acromion process.
  • Spine of the scapula

Actions

  • Scapula elevation.
  • Scapula retraction.
  • Upward rotation of the scapula

Innervation

  • Cranial nerve

Daily uses

  • Shrugging shoulders.
  • Overhead movements

Example strengthening exercises

  • Shrugs
  • Reverse fly using a resistance band

Example stretches

  • Lateral Neck Flexion
  • Forward Neck Flexion
  • Neck Rotation

Related injuries

  • Tight muscles in the upper back and neck
  • Postural kyphosis

Related muscles

  • Rhomboids.
  • Deltoid muscle.

Serratus Anterior

Origin

  • Upper nine ribs at the side of the chest

Insertion

  • Costal aspect (side articulating with the ribs) of the medial border of the scapula

Actions

  • Scapula protraction
  • Rotation of the scapula upwards

Innervation

  • Long thoracic nerve

Daily uses

  • Reaching up to open a high window

Example strengthening exercises

  • Push-ups using a resistance band

Related injuries

  • Winged scapula
  • Postural kyphosis

Rhomboids

Origin

  • Spinous processes of C7-T5.

Insertion

  • Medial border of the scapula, below the level of the spine of the scapula.

Actions

  • Scapula retraction (bringing the shoulder blades together).
  • Rotation of the scapula downwards

Innervation

  • Dorsal scapular nerve.

Daily uses

  • Pulling a drawer open.

Example strengthening exercises

  • Reverse fly with a resistance band.
  • Seated row with a resistance band.

Example stretches

  • Posterior shoulder stretch.

Related injuries

  • Postural kyphosis.

Related muscles

  • TrapeziusSerratus anterior.

Pectoralis Minor

Origin

  • Outer surface of ribs 3-5 Insertion Coracoid process of the scapula

Action

  • Scapula protraction
  • Rotation of the scapula downwards

Innervation

  • Medial pectoral nerve

Daily uses

  • Pushing a door open

Example strengthening exercises

  • Pec fly using a resistance band
  • Chest Press using a resistance band

Example stretches

  • Chest stretch
  • Chest stretch with a partner

Related injuries

  • Pectoral strain

Related muscles

  • Pectoralis major

Levator Scapulae

Origin

  • Transverse processes of C1-4

Insertion

  • Medial border of the scapula above the level of the scapula spine.

Actions

  • Scapula elevation
  • Lateral flexion of the cervical spine (each side independently)
  • Extension of the cervical spine (each side independently)

Which nerves supply this muscle?

  • Cervical nerve
  • Dorsal scapular nerve

Daily uses

  • Shrugging shoulders
  • Carrying a heavy shopping bag

Example strengthening exercises

  • Shrugs

Example stretches

  • Lateral neck flexion stretch
  • Forward neck flexion stretch

Related injuries

  • Tight muscles in the upper back and neck

Related muscles

  • TrapeziusSternocleidomastoid

Sternocleidomastoid

Origin

  • Anterior surface of the upper sternum Inner part of the clavicle.

Insertion

  • Mastoid process (behind the ear).

Actions

  • Contraction on both sides: Flexes the neck.
  • Contraction on one side only: Laterally flexes (side bends) to the same side and rotates to the other side.

Innervation

  • Acessory XI nerve.

Daily uses

  • Looking at the floor.
  • Looking over your shoulder.
  • Holding the phone between your ear and shoulder.

Example stretches

  • Neck rotation stretch.

Related injuries

  • Postural kyphosis.
  • Tight muscles in the upper back and neck.

Related muscles

  • Levator scapulae.