Muscles in the shoulder region Flashcards
Pectoralis Major
The proximal attachment
- Clavicular Head
- Anterior surface, medial 1/2 clavicle
- Sternocostal Head
- Anterior sternum
- 1-7 costal cartilages
- Sternal end of 6th rib
- Aponeurosis of external oblique
The distal attachment
- Lateral lip of Intertubercular Groove, passing front of bicepital groove
What is the nerve supply?
- Medial and Lateral Pectoral nerves C5-8, T1
What is the action of the muscle?
- Clavicular Head - Flexion
- Sternocostal Head - Extension
- Both heads - adduction and medial rotation
Latissimus Dorsi
What is the proximal attachment?
- Thoracolumbar Fascia
- Spinous Processes T7-12
- Spinous Processes Lumbar/Sacral vertebrae
- Related interspinous ligaments in between
processes
- Iliac crest
- Lower 3-4 ribs
What is the distal attachment?
- Floor of Intertubercular groove on the anterior
humerus
What is the nerve supply?
- Thoracodorsal nerve C6-8
What is the action of the muscle?
- Shoulder extension
- Shoulder medial rotation
- Shoulder adduction
Deltoid
What is the proximal attachment?
- Anterior - anterior border, lateral 1/3 clavicle
- Middle - lateral margin of acromion
- Spine of scapula
- SIMILAR attachments to Trapezius
What is the distal attachment?
- Deltoid tuberosity on mid shaft of humerus
What is the nerve supply?
- Axillary Nerve C5-6
What is the action of the muscle?
- Shoulder lateral rotation - posterior
- Shoulder extension - posterior
- Shoulder medial rotation - anterior
- Shoulder flexion - anterior
- Shoulder abduction
Coracobrachialis - sits behind biceps
What is the proximal attachment?
- Apex of coracoid process
What is the distal attachment?
- Medial aspect, mid-shaft of humerus
What is the nerve supply?
- Musculocutaneous Nerve C5-6
What is the action of the muscle?
- Shoulder adduction
- Weak shoulder flexion
Teres Major
What is the proximal attachment?
- Posterior surface, inferior angle of scapula
What is the distal attachment?
- Medial lip of Intertubercular groove
- Goes under the arm and attracts to anterior
humerus
What is the nerve supply?
- Inferior Subscapular Nerve C5-7
What is the action of the muscle?
- ASSISTS extension from flexed position
- Shoulder medial rotation
- Shoulder adduction
Supraspinatus (Rotator Cuff)
What is the proximal attachment?
- Medial 2/3 supraspinous fossa
What is the distal attachment?
- Superior facet on greater tubercle of humerus
- Passes laterally
What is the nerve supply?
- Suprascapular nerve C5-6
What is the action of the muscle?
- Stabilises Gleno-humeral joint
- Assists in abduction of shoulder
Infraspinatus (Rotator Cuff) - inferior to scapula spine
What is the proximal attachment?
- Medial 2/3 infraspinous fossa
What is the distal attachment?
- Middle facet on greater tubercle of humerus
What is the nerve supply?
- Suprascapular Nerve C5-6
What is the action of the muscle?
- Stabilises GH Joint
- Lateral rotation of shoulder
Teres Minor (Rotator Cuff)
What is the proximal attachment?
- Posterior surface, upper 2/3 lateral scapular
What is the distal attachment?
- Inferior facet on greater tubercle of humerus
What is the nerve supply?
- Axillary nerve C5-6
What is the action of the muscle?
- Stabilises GH Joint
- Lateral rotation of shoulder
Subscapularis (Rotator Cuff)
What is the proximal attachment?
- Medial 2/3 subscapular fossa
- Sits on costal surface of scapular
What is the distal attachment?
- Lesser tubercle of humerus
What is the nerve supply?
- Upper and lower subscapular nerves C5-7
What is the action of the muscle?
- Stabilises GH Joint
- Medial rotation of shoulder
The Rotator Cuff - what is primary function of rotator cuff?
Stabilise the glenohumeral joint during movement of the shoulder (dynamic stability)
All muscles pull humeral head into glenoid fossa
When cuff muscles are working, it stabilises humeral head into glenoid foss
Any movement starts in rotator cuff to stabilise shoulder
Biceps Brachii
What is the proximal attachment?
- Long head - Supraglenoid tubercle and passes through bicipital groove
- Short head - Coracoid process
What is the distal attachment?
- Long head - Tuberosity of radius
- Short head - Bicipital Aponeurosis
What is the nerve supply?
- Musculocutaneous nerve C5-6
What is the action of the muscle?
- Long head involved in shoulder flexion
- Flexion of elbow
- Supination of forearm
Triceps Brachii
What is the proximal attachment?
- Long Head - infraglenoid tubercle
- Lateral Head - upper part, posterior surface of humerus
- Medial Head - lower part, posterior surface of humerus
What is the distal attachment?
- Posterior surface of olecranon of ulna
What is the nerve supply?
- Radial nerve C6-8
What is the action of the muscle?
- Extends elbow - primary action
- The long head adducts and extends shoulder
The Axilla - What are its borders?
- Posterior - Subscapularis
- Anterior - Pec Major
- Medial - Serratus Anterior
The Axilla - what are its contents?
- Axillary Sheath
- Brachial plexus and Axillary artery
- Axillary vein
- Pec minor
