Rotator Cuff Muscles Flashcards
Shape and DoF: Subscapularis
large multipennate muscle
fibres run superolaterally to form a broad thick tendon
Attachments: Subscapularis
O: medial 2/3rd subscapular fossa
I: lesser tubercle of humerus & the capsule
Action and Function: Subscapularis
Strong medial rotator
Assists Adduction
Holds humeral head in glenoid fossa
Undoing bra/scratching back
Nerve supply: Subscapularis
upper and lower subscapular nerves
C5,6,7
Shape and DoF: Supraspinatus
thin and slender
passes laterally over the top of the shoulder joint
Attachments: Supraspinatus
O: medial 2/3rds supraspinous fossa
I: deep surface blends with JC, then inserts to UPPER facet of GREATER tubercle
Nerve supply: Supraspinatus
Suprascapular nerve (C5, 6)
Function and Action: Supraspinatus
Initiation of abduction
Braces humeral head in glenoid fossa
Used in side reaching
Shape and DoF: Teres Minor
thin muscle
runs superolaterally forming a narrow tendon
Attachments of Teres Minor
O: upper 2/3rd of lateral border of scapula
I: inferior facet on greater tubercle of humerus
Nerve supply: Teres Minor
Axillary Nerve
C5, 6
Action and function of teres minor
Reinforces lower JC
Lateral rotation - in anatomical position
In abduction - Lateral rotation and adduction
Used in brushing hair
Shape and DoF of infraspinatus
thick, triangular muscle
runs superolaterally converging into narrow tendon
Attachments of infraspinatus
O: medial 2/3rds infraspinous fossa
I: middle fact on greater tubercle of humerus and posterior JC
Nerve supply of infraspinatus
suprascapular nerve
C5, 6
action and function of infraspinatus
lateral rotation
brushing hair
Overall function of the rotator cuff
musculotendinous cuff - act as ligaments to stabilise the joint
hold the humeral head in the glenoid fossa to reduce shearing and sliding forces
act as lateral rotators to ensure that the greater tubercle clears the coracoacromial arch to allow full ROM
