Week 8 - Scapulohumeral muscles Flashcards
How many scapulohumeral muscles are there?
Six
Name the six scapulohumeral muscles
Deltoid Teres major Supraspinatus Infraspinatus Subscapularis Teres minor
What are scapulohumeral muscles?
Relatively short muscles that pass from the scapula to the humerus and act on the glenohumeral joint
What is the deltoid muscle?
A thick, powerful, coarse-textured muscle covering the shoulder and forming its surrounded contour
What happens when all three parts of the deltoid contract simultaneously?
The arm is abducted
What do the anterior and posterior parts of the deltoids do?
Steady the arm as it is abducted
What assists the deltoid to initiate movement during the first 15 degrees of abduction?
The supraspinatus
When the arm is fully adducted, what must abduction be intitiated by?
The supraspinatus, or leaning to the side, allowing gravity to initiate the movement
When does the deltoid become fully effective as and abductor?
After the first 15 degrees of initial abduction
What are the anterior and posterior parts of the deltoid used for?
To swing the limbs during walking
What part of the deltoid assists the pectoralis major in flexing the arm?
The anterior part
What part od the deltoid assists the latissimus dorsi in extending the arm?
The posterior part
What holds the head of the humerus in the glenoid cavity during movements of the upper limb?
The deltoid
What is the teres major?
A thick, rounded muscle passing laterally from the inferolateral third of the scapula
What does the inferior border of the teres major form?
The inferior border of the lateral part of the posterior wall of the axilla
What does the teres major do to the arm?
Adducts and medially rotates it
It can also help extend it from the flexed position and is an important stabalizer of the humeral head in the glenoid cavity - that is, it steadies the head in its socket
What are the for muscles that are called rotator cuff muscles?
Supraspinatus
Infraspinatus
Teres minor
subscapular
What is the only muscle of the rotator cuff that is a rotator of the humerus
The supraspinatus
What does the supraspinatus do besides being part of the rotator cuff?
Initiates and assists the deltoid in the first 15 degrees of abduction of the arm
Where does the supraspinatus occupy?
The supra spinous fossa of the scapula
What separates the supraspinatus from the lateral quarter of the fossa
A bursa
Where does the infraspinatus occupy?
The medial three quarters of the infraspinous fossa
What partly covers the infraspinatus?
The deltoid and trapezius
What does the infraspinatus do in addition to helping to stabalize the glenohumeral joint?
It is a powerful lateral rotator of the humerus
What is the teres minor?
A narrow , elongate muscle that is completely hidden by the deltoid and is often not clearly delineated from the infraspinatus
What does the teres minor do?
Works with the infraspinatus to rotate the arm laterally and assists in adduction
What nerve supplies the teres minor?
The axillary nerve
What nerve supplies the spinatus ?
The suprascapular nerve
What is the subscapularis?
A thick, triangular muscle that lies on the costal surface of the scapula and forms part of the posterior wall of the axilla
What aspect of the scapulohumeral joint does the subscapularis cross on its way to the humerus?
The anterior aspect
What is the primary medial rotator of the arm and also adducts it?
The subscapularis
