Shoulder & Upper Arm and Skeletal Muscle Flashcards
What is the Shoulder Girdle and what is its function?
It consists of the clavicle and the scapula and it connects the arm to the axial skeleton.
Name 3 joints that are part of the shoulder girdle and one that is not.
Sternoclavicular joint
Acromioclavicular joint
Scapulothoracic joint
Glenohumoral joint
Name the features of the proximal humerus.
The head, then the anatomical neck before the lesser tubercle (medial), intertubercular groove (for tendon for long head of biceps) and greater tubercle, then surgical neck before shaft.
The glenohumeral joint is the most commonly dislocated joint. It has a wide range of movements in multiple planes, because it is which type of joint?
Synovial joint - ball and socket type.
What is the glenoid labrum?
A fibrocartilage extension of the glenoid fossa, which deepens it.
What surrounds the glenohumeral joint?
A loose articular capsule as well as superior, middle and inferior glenohumeral ligaments.
Name the 3 extra capsular ligaments?
Coracohumeral ligament
Coracoacromonial (which creates arch, giving stability and stops superior-posterior dislocation)
Coracoclavicular ligament
Name the 4 rotator cuff muscle’s, what they’re innervated by and where they attach.
Supraspinatus (suprascapular N.), Infraspinatus (suprascapular N.) and Teres Minor (axillary N.), all attach at the greater tuberosity of the humerus. The Subscapularis (upper and lower subscapular N.) inserts on the lesser tubercle of the humerus.
What’s the overall function of the rotator cuff and which movements do the individual muscles perform?
Overall it is an important stabiliser of the shoulder joint.
The supraspinatus initiates abduction at the shoulder. The infraspinatus and teres minor externally rotate the shoulder. The subscapularis internally rotates at the shoulder.
The space between the acromion and the head of the humerus is only 1-1.5cm in size, but holds which 4 things?
Subacromonial Bursa - fluid filled sac reduces friction
Rotator cuff tendons
Capsule
Long head of biceps
Which muscles contribute towards the abduction of the arm? Name their nerves if possible.
0-15 degrees - Supraspinatus (suprascapular N.)
15-90 - Deltoid (axillary N.)
>90 - due to scapulothoracic joint through scapular rotation - upper trapezius and serratus anterior
Which muscles (and so nerves) are responsible for adduction of the arm?
Pectoralis major (medial and lateral pectoral N.), Latissimus Dorsi (thoracodoral N.) and Teres Major (thoracodorsal N.).
Which muscles (and so nerves) are responsible for flexion of the arm?
Anterior fibres of the Deltoid muscle (axillary N.)
Pectoralis Major (medial and lateral pectoral N.)
Coracobrachialis (musculoskeletal N.)
Biceps Brachii (musculoskeletal N.)
Which muscles (and so nerves) are responsible for extension of the arm?
Posterior fibres of the Deltoid muscle (axillary N.) Latissimus Dorsi (thoracodorsal N.) Teres Major (thoracodorsal N.)
Which muscles (and so nerves) are responsible for internal rotation of the arm?
Subscapularis (upper and lower subscapular N.) Teres Major (thoracodorsal N.) Pectoralis Major (medial and lateral pectoral N.) Latissimus Dorsi (thoracodorsal N.)
Which muscles (and so nerves) are responsible for external rotation of the arm?
Infraspinatus (suprascapular N.) Teres minor (axillary N.)
What is the effect of the imbalance of strength in muscles which internally and externally rotate the arm?
An electric shock or seizure may cause internal rotation and so posterior dislocation at the glenohumeral joint.
When there’s an arm injury, why should you always examine the neurovascular status of the limb - what in particular may be damaged?
The axillary artery becomes the brachial artery which has branches of the anterior and posterior circumflex arteries which wrap around the humerus and may become damaged if there’s a fracture.
A fracture or dislocation may also damage the brachial plexus with the trunks and divisions running behind the clavicle. The posterior cord provides the axillary and radial nerves which may become damaged.
Name 6 static stabilisers of the glenohumeral joint.
Articular anatomy Glenoid labrum Capsule Glenohumeral ligaments Extracapsular ligaments Negative intraarticular pressure
Name 3 components which are dynamic stabilisers of the glenohumeral joint.
Rotator cuff muscles
Biceps brachii
Muscles crossing over the shoulder
Which type of shoulder dislocation is less common and often missed on x-rays?
What may cause it?
Posterior dislocation. May be caused by an electric shock or seizure - the shoulder is fixed in internal rotation.
Acromioclavicular joint dislocations may require surgery, which ligament tears?
The coracoclavicular ligament.
What happens in the degenerative condition of Calcific Tendinitis?
Calcium hydroxyapatite deposits cause a subacrominal impingement if they’re large. If it bursts, then there’s acute tendinitis (rapidly progressive very severe pain which resolves after 1-2 weeks).
What may cause the appearance of the ‘Popeye muscle’? It is a cosmetic issue.
Long head of the biceps rupture.