The shoulder and arms (B) Flashcards
Which muscles make up the intrinsic shoulder muscle compartment?
Rotator cuff muscles (supraspinatus, infraspinatus, teres minor and subscapularis)
Teres major
Deltoid
Describe the attachments of deltoid.
Proximal – lateral 1/3 of the clavicle (deltoid tubercle of clavicle), acromion process and crest of the spine of the scapula (deltoid tubercle of spine of scapula)
Distal – deltoid tuberosity of the humerus
Which nerve supplies the deltoid and what movement is it responsible for?
Axillary nerve
It is responsible for abduction of the arm
Describe the attachment of the rotator cuff muscles and state the nerves that innervate them. Supraspinatus Infraspinatus Teres minor Subscapularis
Supraspinatus-
Supraspinatus fossa to greater tubercle of the humerus (look on 3D anatomy)
Innervated by suprascapular nerve
Infraspinatus - infraspinatus fossa to greater tubercle of humerus
Innervated by suprascapular nerve
Teres minor - lateral border of the scapula to the greater tubercle
Innervated by the axillary nerve
Subscapularis - Subscapular fossa to the lesser tubercle
Innervated by the subscapular nerve
NOTE; THE FIRST 3 MUSCLES HAVE A ROLE IN EXTERNAL ROTATION, HENCE THEY ATTACH TO THE GREATER TUBERCLE (imagine the rotation when it contracts). Subscapularis is involved in internal rotation and hence attaches to the lesser tubercle of the humeruss
Which rotator cuff muscle is important for abducting the arm?
Supraspinatus is important in the first 15 degree of abduction of the arm, then the deltoid takes over.
Describe the attachments of teres major.
Inferior angle of the scapula to the medial lip of the intertubercular sulcus
Medial lip is different to lesser tuberosity of the humerus. Medial Lip refers to the medial ‘edge’ of the groove from top to bottom of the sulcus. Lesser tuberosity is only a small circular bit at the top of the humerus (search up a pic)
Which nerve innervates teres major?
Lower subscapular nerve
Which muscles make up the anterior compartment of the arm and which nerve innervates them?
Biceps brachii
Brachialis
Coracobrachialis
Innervated by: musculocutaneous nerve
Describe the attachments of biceps brachii.
Long head – supraglenoid tubercle
Short head – coracoid process
Distal attachment – radial tuberosity
long head of biceps - supraglenoid tubercle
long head of triceps - infraglenoid tubercle
Describe the attachments of coracobrachialis.
Proximal: coracoid process
Distal: anteromedial surface of the shaft of the humerus
Describe the attachments of brachialis.
Proximal: shaft of the humerus
Distal: coronoid process of ulna
Which muscles make up the posterior compartment of the arm?
Triceps Anconeus (ancon=elbow)
What are the attachments of the triceps?
Long head – infraglenoid tubercle
Medial and lateral head – proximal part of the shaft of the humerus
Distal attachment: olecranon process of the ulna
What are the attachments of anconeus?
Proximal: lateral epicondyle of the humerus
Distal: shaft of the ulna
Which nerve innervates the posterior compartment of the arm?
Radial nerve