The Shoulder Girdle (Muscles)

Posterior muscles of the shoulder girdle - Three (3).

1.Trapezius 2.Rhomboids 3.Levator scapulae

anterior and posterior muscles of the scapula

Anterior: Serratus Anterior Pectoralis Minor Subclavius Posterior: Trapezius Rhomboids Levator Scapulae

Cervical Plexus, which muscles are innervated

C1-C5

Rhomboid muscles - major & minor Innervation?

Dorsal Scapular Nerve C5

Levator Scapulae Action

Elevates scapula and tilts its glenoid cavity inferiorly by rotating scapula.

Serratus Anterior innervation?

Innervation: Long thoracic nerve arising from the ventral rami of C5, C6, C7.

Pectoralis minor innervation

Innervation: medial pectoral nerve C8 and T1

Rhomboids (Major and Minor) Insertion?

Insertion Medial border of scapula below spine to the "inferior angle" of the scapula.

trapezius insertion

Insertion together they insert into Superior to medial border of the scapula, outer clavicle, acromion process

Levator Scapulae location

Located superior to the rhomboid minor.

Nerves, cervical and brachial plesus

Muscles of shoulder girdle are innervated by nerves of cervical and brachial plexus. Roots of cervical plexus are formed by spinal nerves C1-C4. Roots of brachial plexus are formed by the spinal nerves C5 to T1.

trapezius origin

Origin Base of skull (occipital protuberance) to the spine of T12. Upper: Base of skull, occipital protuberance Middle: Spinous process of C7 and T1-T3 Lower: Spinous process of T4 to T12

Rhomboids (Major and Minor) Origin?

Origin: Rhomboid Minor : Nuchal Ligament and spinous processes of C7 Rhomboid Major: Spinous processes of T2 -T5 vertebrae.

Serratus Anterior muscle origin and insertion?

Origin: upper 9 ribs Insertion: costal aspect of medial border of scapula.

Levator Scapulae Origin

Posterior tubercles of transverse processes of C1 -C4 vertebrae.

Rhomboid muscles - major & minor Action?

Rhomboid major & minor muscles work together Retraction: draw scapula toward spinal column Downward rotation: from upward rotated position they draw scapula in downward rotation Elevation: slight upward movement accompanying Retraction Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall

Levator Scapulae Insertion

Superior part of medial border of scapula, above scapula spine

Trapezius: Actions

The trapezius is multi-articular. -This means it affects movements at both attachments. The scapula and the spinal column Upper fibers: elevation of scapula, extension of head Middle fibers: elevation, upward rotation, & retraction Lower fibers: depression, retraction, & upward rotation

Serratus anterior action

also stabilizes scapula

Pectoralis minor action

controls movements of the shoulder girdle Stabilizes the scapula by drawing it inferiorly and anteriorly against thoracic wall

Levator Scapulae Innervation

dorsal scapular nerve C5 and branches of C3 and C4.

Scapular Rotators

levator: elevates and rotates inferiorly Rhomboids: retract

brachial plexus, which muscles are innervated

network of interlacing nerves found in the upper arm area k C5-T1 -Levator scapulae (C5) -Rhomboids (C5) -pectoralis minor (C8 and T1) -Serratus Anterior (C5 to C7)

Pectoralis Minor origin and insertion and inervation?

origin: anterior surfaces of ribs 3 to 5 near their costal cartilages. Insertion: medial border and superior surface of coracoid process of scapula

Subcalvius origin and insertion

origin: first rib insertion: inferior groove of middle clavicle

subclavian action

stabilization and protection of the sternoclavicular joint. depression of clavicle

subclavian innervation

subclavian nerve c5 and c6

Muscles overview

•6 muscles primarily involved in shoulder girdle movements •All originate on axial skeleton & insert on scapula, ribs, and/or clavicle. •Do not attach to humerus and & do not cause shoulder joint actions. •Essential in providing dynamic stability of the scapula so it can serve as a relative base of support for shoulder joint activities such as throwing, batting and blocking

Rhomboids (major and minor) overview

•Functions as a single muscle • Rhomboid in shape • Located under trapezius Uniarticular - little effect on spine

trapezius innervation

•Spinal root of accessory nerve: 11th Cranial. This is the "Motor" nerve. •Cervical nerves C3 and C4

Stability: Shoulder Girdle Muscles

•Stabilize scapula so the shoulder joint muscles will have a stable base from which to exert force for moving the humerus •Contract to maintain scapula in a relatively static position during shoulder joint actions -To ensure pure upward rotation, ie. in the frontal plane we must have no unwanted movements in any other planes. -Need for "neutralization" of unwanted movements. •Shoulder joint and shoulder girdle work together in carrying out upper extremity activities -Contract to move shoulder girdle and to enhance movement of upper extremity when shoulder goes through extreme ROM •Shoulder girdle movement is not dependent upon the shoulder joint and its muscles