Shoulder muscles Flashcards
What are the extrinsic muscles of the shoulder?
Muscles that originate from the torso and attach to the clavicle, scapula or humerus:
Trapezius, Latissimus dorsi- superficial
Levator scpulae, rhomboid major, rhomboid minor-deep
What are the intrinsic muscles of the shoulder?
Muscles that originate from the scapula/clavicle and attach to the humerus:
Deltoid , teres major
Rotator cuff: supraspinatus, infraspinatus, subscapularis, teres minor
What is the trapezius
What innervates it?
Broad, flat triangluar muscle of the back
Acessory nerve, C3, C4 spinal nerves
Where does the trapezius attach?
What are its functions
Originates from skull, nuchal ligament and spinous process of C7-T12
Upper fibres elevate and rotate scapula. Allow for arm abduction
Middle fibres retract scapula
lower fibres pull scapula inferiorly
How would you test if their was damage to the accessory nerves?
Ask patient to shrug shoulders, commonly damaged in surgery
What is the latissimus dorsi?
What innervates it?
Large muscle of the lowerback, extends around the lateral, posterior region of the trunk
Thoracodorsal nerve
What are the attachments of lattisimus dorsi?
What are its actions?
Has a broad origin, arises from the spinous process of T7-T12, iliac crest, thoracolumbar fascia and inferior three ribs. The fibres converge into a tendon that attaches to the intertubercular sulcus of the humerus
Extends, addicts and medically rotates the upper limb
What is the rhomboid major muscle?
What innervates it?
Larger of the to muscles connecting the vertebrae to the scapula. Sits inferiorly to rhomboid major
Dorsal scapular nerve
What are the attachments of rhomboid major?
What are its actions?
Originates from the spinous process of T2-T5 vertebrae. Attatches to the medial broder of the scapula between the scapula spine and the inferior angle
Retracts and rotates the scapula
What is rhomboid minor?
What innervates it?
Smaller of the two muscles connecting the vertebrae to the scapula
Dorsal scapula nerve
What are the attachments of rhimboid minor?
What are its actions
Originates from the spinosu processes of C7-T1. Attatches to the medial vorder of the scapula at the spine.
Retracts and rotates the scapula
What is levator scapulae?
What innervates it?
Small strap like muscle. It begins at the neck and attatched to the scapula
Dorsal scapular nerve
What are the attachments of levator scapuale
What are its actions?
Originates from the transverse processes of C1-C4 vertebrae and attaches to the medial border of the scapula
Elevates the scapula
What is the deltoid muscle?
What innervates it?
Shaped like the greek letter delta, it is a triangular shaped muscle that sits over the shoulder
Axillary nerve
What are the attachments of the deltoid muscle?
What are its actions?
Originates from the lateral third of the clavicle, the acromion and the spine of the scapula. Attaches to the deltoid tuberosity of the humerus
Anterior fibres- flexion and medial rotation
Posterior fibres- extesnion and lateral rotation
Middle fibres- Major abductors of the arm
What is the teres major muscle?
What innervates it?
Small muscle that forms inferior border of the quadroangluar space
The lower subscapular nerve
What are the attachments of teres major?
What is its function?
Originates from the posterior surface of the inferior angle of the scapula, attaches to the medial lip of the intertubercular groove of the humerus
Adducts the shoulder and medially rotates the arm
What is the supraspinatus?
What innervates it?
One of the four rotator cuff muscles designed to stabilise the glenohumeral joint
Suprascapular nerve
What are the attachments of the supraspinatus?
What is its function?
Originates from supraspinosu fossa of scapula and attaches to greatertubercel of the humerus
Abduction of the arm 0-15 degrees, assists deltoid for 15-90.
What is the infraspinatus?
What innervates it?
One of the four rotator cuff muscles designed to stabilise the glenohumeral joint
Subscapular nerve
What are the attachemtns of infraspinatus
What is it s fucntion
originates from infraspinatous fossa, attatches near greater tubercle of the humerus
Laterally rotates the arm
What is the subscapularis
What innervates it?
One of the four rotator cuff muscles designed to stabilise the glenohumeral joint
Upper and lower subscapular nerves
What are the attachment of the subscapularis?
what is its fucntion
Originates from the subscapular fossa on the costal surface of the scapula, attaches to lesser tubercle of humerus
Medially rotates the arm
What is teres minor?
What innervates it
One of the four rotator cuff muscles designed to stabilise the glenohumeral joint
Axillary nerve
What are the attachments of teres minor
what is its function?
Originates from posterior surface of scapula, attaches to greater tubercle of humerus
Laterally rotates arm
What is rotator cuff tendontis
What is it caused by
Inflammation of the rotator cuff tendons
Caused by rubbing of the coraco-acromial arch. This is due to overuse of the shoulder joint
