Extrinsic Muscles Of The Shoulder Flashcards
What are the extrinsic muscle? (Why classes as this?)
Those that originate from the trunk and attach to the shoulder bones
What are the superficial extrinsic shoulder muscles?
Trapezius and latissimus dorsi
What are the deep extrinsic shoulder muscles? (3)
Levator scapulae
Rhomboid minor
Rhomboid major
(***All beneath the trapezoid)
What are the attachments of the trapezoid?
Originates from the skull, nuchal ligament and spinous processes of C7-T12
Attached to the clavicle, acromion and scapula spine
What nerve innervates the trapezoid?
Accessory nerve (plus proprioceptor fibres form C3 and C4 spinal nerves)
What is the action of the upper fibres of the trapezoid?
Elevates the scapula and rotates it during abduction of the arm
What is the action of the middle fibres of the trapezoid muscle?
Retract the scapula
What is the action of the lower fibres of the trapezoid?
Depression of the scapula
How can you test the accessory nerve?
By assessing the trapezoid function
- ask patient to shrug shoulders
There may also be muscle wasting of trapezoid-asymmetrical neckline
What are the attachments of the latissimus dorsi?
Arises from the spinous processes of T6-T12, iliac crest, thoracolumbar fascia and inferior 3 ribs
Fibres converge to tendon which attached to inter-tubercular sulcus of the humerus (bicipital grove)
What nerve innervates latissimus dorsi?
Thoracodorsal nerve
What is the action of latissimus dorsi?
Extends, adducts and medically rotates the upper limb
What is the attachment of the levator scapulae?
Originates from the transverse processes of the C1-C4 vertebrae and attaches to the medial border of the scapula
What nerve innervates levator scapulae?
Dorsal scapular nerve and cervical nerve (C3-C5)
What is the action of the levator scapulae?
Elevates (and rotates) the scapula