Myology of the Shoulder girdle Flashcards
Upper trapezius
- Origin: Occipital bone: superior nuchal line and external
protuberence, nuchal lig., spinous process C7. - Insertion: Lateral third of clavicle.
- Action: Elevation of the scapula; Ipsi inclination (unilateral)
extension of the head (bilateral). - Innervation: Accessory nerve (cervical plexus).
Intermediate trapezius
- Origin: Spinous process T1-T4.
- Insertion: Acromion.
- Action: Retraction of the scapula.
- Innervation: Accessory nerve (cervical plexus).
Lower trapezius
- Origin: Spinous process T5-T12.
- Insertion: Spine of scapula.
- Action: Scapula: Retraction, depression, upward rot.
- Innervation: Accessory nerve (cervical plexus).
Rhomboids major and minor
- Origin Major: Spinous process T2-T5.
Origin Minor: Spinous process C7-T1. - Insertion: Medial margin of the scapula.
- Action: Scapula- Retraction, elevation, downward rotation.
- Innervation: Dorsal scapular nerve (cervical plexus).
Levatore scapulae
- Origin: Transverse process C1-C4.
- Insertion: Superior angle of the scapula.
- Action: Proximal insertion fixed: elevation, downward
rotation of the scapula. Distal insertion fixed : extension and
ipsilateral. Inclination of cervical spine. - Innervation: Dorsal scapular nerve (cervical plexus).
Serratus anterior
- Origin: 1st-9th rib.
- Insertion: Medial margin of the scapula.
- Action: Protraction and upward rotation of scapula.
- Innervation: Long thoracic nerve.
Subclavius
- Origin: 1st rib.
- Insertion: Lateral third of inferior face of clavicle.
- Action: Depression of scapula, coaptation of
sternoclavicular joint. - Innervation: Subclavius nerve.
Pectoralis minor
- Origin: 3th-5th ribs.
- Insertion: Coracoid process.
- Action: Distal insertion fixed : scapula depression,
protraction, and downward rotation. Proximal insertion fixed:
elevation of ribs à accessory inspiration. - Innervation: Medial pectoral nerve.
Supraspinatus
- Origin: Supraspinous fossa.
- Insertion: Major tubercle of the humerus.
- Action: Shoulder: Abduction, synergic action with external
rotator muscles. - Innervation: Suprascapular nerve.
Infraspinatus
- Origin: Infraspinous fossa.
- Insertion: Major tubercle of the humerus.
- Action: Shoulder: external rotation.
- Innervation: Suprascapular nerve.
Teres minor
- Origin: 2/3 sup of lateral margin of the scapula.
- Insertion: Major tubercle of the humerus.
- Action: Shoulder: External rot., Adduction.
- Innervation: Axillary nerve.
Subscapularis
- Origin: Subscapular fossa.
- Insertion: Minor tubercle of the humerus.
- Action: Shoulder Internal rotation.
- Innervation: Subscapular nerve.
Muscles of the rotator cuff
Avoid separation of the humeral head from the glenoid cavity).
Subscapularis - only one superior to scapula, not inserting in greater tubercle.
Supraspinatus - Superior, passes under acromion.
Infraspinatus - Primary external rotator
Teres minor - Primary external rotator (synergist with infrasp.)
Teres major
- Origin: Inferior angle of the scapula.
- Insertion: Medial side of the bicipital groove.
- Action: Adduction, extension, internal rotation of the
shoulder. - Innervation: Subscapular nerve.
Deltoid anterior (clavicular) fibers
- Origin: Lateral third of clavicle.
- Insertion: Deltoid tuberosity.
- Action: Shoulder: flexion, abduction, internal rotation,
horizontal ADD. - Innervation: Axillary nerve.
Deltoid middle (acromial) fibers
- Origin: Acromion.
- Insertion: Deltoid tuberosity.
- Action: Shoulder: Abduction.
- Innervation: Axillary nerve.
Deltoid posterior (spinal) fibers
- Origin: Spine of the scapula.
- Insertion: Deltoid tuberosity.
- Action: Shoulder: extension, external rot., horizontal
abduction. - Innervation: Axillary nerve.
Latissimus dorsi
- Origin: Spinous process T7-S5 (via thoracolumbar fascia),
iliac crest, 9-12th ribs, inferior angle of the scapula. - Insertion: Medial side of bicipital groove.
- Action: Shoulder extension, adduction, internal rot.
- Innervation: Thoracodorsal nerve.
Coracobrachialis
- Origin: Coracoid process.
- Insertion: Middle third of medial margin of the humerus.
- Action: Shoulder: flexion, adduction.
- Innervation: Musculocutaneus nerve.
Pectoralis major
- Origin: Clavicular fibers: Medial half of the clavicle
Sternocostal fibers: Sternum, 2nd-6th costal cartilages. - Insertion: Lateral margin of the bicipital groove.
- Action: Shoulder adduction, horiz. adduction, internal rot.
(entire muscle); flexion (clavicular fibers). - Innervation: Medial and lateral pectoral nerve.
Muscles of the glenohumeral joint
Supraspinatus Infraspinatus Teres minor Subscapularis Teres major Deltoid Latissimus dorsi Coracobrachialis Pectoralis major Bicep brachii Tricep brachii
Muscles of the shoulder girdle
Trapezius Rhomboids Levatore scapulae Serratus anterior Subclavius Pectoralis minor
Main shoulder adductors?
Teres major
Latissimus dorsi
synergists
Most important shoulder muscle regarding movement?
Deltoid
Does everything except adduction.