The Shoulder and Pectoral Girdle Flashcards
3 joints of the shoulder complex
- Sternoclavicular
- Acromioclavicular
- Glenohumeral
Proximal and distal articulations of the humerus
- P = glenoid fossa of scapula
- D = head of radius and trochlear notch of ulna
Proximal landmarks of the humerus
- Head
- Anatomical neck
- Greater tubercle
- Lesser tubercle
- Intertubercular sulcus
- Lips
- Surgical neck
Function of anatomical neck
Separates head from tubercles
Function of greater tubercle
Attachment for:
- Supraspinatus
- Infraspinatus
- Teres minor
Function of lesser tubercle
Attachment for subscapularis
Function of intertubercular sulcus
- Separates 2 tubercles
- Tendon of long head of biceps brachii runs through it
Function of lips
Attachment for:
- Pectoralis major
- Teres major
- Latissimus
Shaft landmarks of humerus
- Deltoid tuberosity
- Radial groove
Function of deltoid tuberosity
Attachment for deltoid muscle
Function of radial groove
Houses radial nerve
Distal landmarks of humerus
- Medial + lateral supraepicondylar ridges
- Medial + lateral epicondyles
- Trochlea
- Capitulum
- Coronoid, radial + olecranon fossae
What does the trochlea articulate with?
Trochlear notch of ulna (T+U together like alphabet)
What does the capitulum articulate with?
Head of radius (R+C together like remote control)
Function of the coronoid, radial and olecranon fossae
Accommodate forearm bones during flexion and extension at elbow
Are each of the coronoid, radial and olecranon fossae found anteriorly or posteriorly?
- CF = anterior
- RF = anterior
- OF = posterior
Which 2 bones form the pectoral girdle?
- Scapula
- Clavicle
Curvatures of the clavicle
- Medial 2/3 convex anteriorly
- Lateral 1/3 concave anteriorly
3 regions of clavicle
- Sternal end
- Shaft
- Acromial end
What is found at the sternal end of the clavicle and what is its function?
- Large facet
- Articulation with manubrium
Which muscles attach to the shaft of the clavicle?
- Deltoid
- Trapezius
- Subclavius
- Pectoralis major
- Sternocleidomastoid
- Sternohyoid
What is found at the acromial end of the clavicle and what is its function?
- Small facet
- Articulation with acromion of scapula
4 markings found on the inferior surface of the clavicle
- Conoid tubercle
- Trapezoid line
- Subclavian groove
- Impression for costoclavicular ligament
Which ribs does the scapula overly?
2-6/7
What does the spine of the scapula divide the posterior surface into?
- Supraspinous fossa
- Infraspinous fossa
What fossa is found on the anterior surface of the scapula?
Subscapular fossa
Landmarks of the lateral border of the scapula
- Glenoid fossa
- Supraglenoid tubercle
- Infraglenoid tubercle
Which 3 muscles attach to the coracoid process?
- Pectoralis minor
- Coracobrachialis
- Short head of biceps brachii
What type of joint is the sternoclavicular joint?
Saddle synovial joint
Articulating surfaces of the sternoclavicular joint
- Sternal end of clavicle
- Manubrium
- Part of 1st costal cartilage
What does the articular disc in the sternoclavicular joint do?
- Separate joint into 2 compartments
- Allows clavicle and manubrium to slides over each other more freely, allowing rotation and movement in third axis
What is the sternoclavicular joint strengthened by?
- The several shoulder muscles
- Joint capsule
- Ligaments
What do the joint capsules of the sternoclavicular and acromioclavicular joints consist of?
- Fibrous outer layer
- Inner synovial membrane producing synovial fluid
Ligaments of the sternoclavicular joint
- Sternoclavicular ligaments (anterior + posterior)
- Interclavicular ligament
- Costoclavicular ligament
What do the anterior and posterior sternoclavicular ligaments do?
Strengthen joint capsule anteriorly and posteriorly
What does the interclavicular ligament run between?
Sternal ends of each clavicle
What does the interclavicular ligament do?
Reinforce joint capsule superiorly
What type of joint is the acromioclavicular joint?
Plane synovial joint
What is the acromioclavicular joint between?
- Acromial end of clavicle
- Acromion of scapula
2 atypical features of the acromioclavicular joint
- Articular surfaces lined with fibrocartilage
- Joint cavity partially divided by articular disc
What is the acromioclavicular joint strengthened by?
- Joint capsule
- Trapezius muscle
- Acromioclavicular ligament
- Coracoclavicular ligament
What does the trapezius muscle do to strengthen the acromioclavicular joint?
Reinforces posterior aspect of joint capsule
What does the acromioclavicular ligament run between?
- Acromion
- Lateral clavicle
Parts of the coracoclavicular ligament
- Conoid ligament
- Trapezoid ligament
What do each of the parts of the coracoclavicular ligament run between?
- Conoid
> Coracoid process of scapula
> Conoid tubercle of clavicle - Trapezoid
> Coracoid process of scapula
> Trapezoid line of clavicle
What type of joint is the glenohumeral joint?
Ball and socket synovial joint
What is the glenohumeral joint between?
- Head of humerus
- Glenoid fossa of scapula
What is the glenoid labrum and what does it do?
- Fibrocartilage rim on glenoid fossa
- Deepens socket to increase stability
What structures stabilise the glenohumeral joint?
- Glenoid labrum
- Ligaments
- Rotator cuff muscles
- Biceps tendon
Ligaments of the glenohumeral joint
- Glenohumeral ligaments (superior, middle, inferior)
- Coracohumeral ligament
- Coracoacromial ligament
- Transverse humeral ligament
What do the superior, middle and inferior glenohumeral ligaments form?
Joint capsule
Function of superior, middle and inferior glenohumeral ligaments
Stabilise anterior aspect of joint
What does the coracohumeral ligament run between?
- Coracoid process
- Greater tubercle of humerus
What does the coracohumeral ligament do?
Supports superior part of joint capsule
What does the coracoacromial ligament run between?
- Coracoid process
- Acromion
What does the coracoacromial ligament do?
- Forms coracoacromial arch
- Prevents superior displacement of humeral head
What does the transverse humeral ligament run between?
2 tubercles of humerus
What does the transverse humeral ligament do?
Holds tendon of long head of biceps in intertubercular groove
How many bursae in the shoulder joint?
5
Which 3 bursae of the shoulder are usually contiguous?
- Subacromial bursa
- Subcoracoid bursa
- Subscapular bursa
What is the subacromial bursa found deep and superficial to?
- Deep to deltoid and acromion
- Superficial to supraspinatus tendon and joint capsule
What does the subacromial bursa do?
- Reduces friction beneath deltoid
- Promotes free motion of rotator cuff tendons
What is the subcoracoid bursa found deep to?
Coracoid process
What is the subscapular bursa found between?
- Subscapularis tendon
- Scapula
What does the subscapular bursa do?
Reduces wear and tear on subscapularis tendon during movement at shoulder joint
Movements attainable at the shoulder joint
- Extension
- Flexion
- Abduction
- Adduction
- Medial rotation
- Lateral rotation
Muscles involved in extension of the shoulder joint
- Posterior deltoid
- Latissimus dorsi
- Teres major
Muscles involved in flexion of the shoulder joint
- Pectoralis major
- Anterior deltoid
- Coracobrachialis
- Biceps brachii (weakly)
Muscles involved in abduction of the shoulder joint
- Supraspinatus (0-15°)
- Middle deltoid (15-90°)
- Trapezius (>90°)
- Serratus anterior (>90°)
Muscles involved in adduction of the shoulder joint
- Pectoralis major
- Latissimus dorsi
- Teres major
Muscles involved in medial rotation of the shoulder joint
- Subscapularis
- Pectoralis major
- Latissimus dorsi
- Teres major
- Anterior deltoid
Muscles involved in lateral rotation of the shoulder joint
- Infraspinatus
- Teres minor
4 rotator cuff muscles
- Subscapularis
- Supraspinatus
- Infraspinatus
- Teres minor
Origin and insertion of subscapularis
- O = subscapular fossa of scapula
- I = lesser tubercle of humerus
Origin and insertion of supraspinatus
- O = supraspinous fossa of scapula
- I = greater tubercle of humerus
Origin and insertion of infraspinatus
- O = infraspinous fossa of scapula
- I = greater tubercle of humerus
Origin and insertion of teres minor
- O = lateral border of scapula
- I = greater tubercle of humerus
Innervation of subscapularis
Upper and lower subscapular nerves (C5-6)
Innervation of supraspinatus
Suprascapular nerve (C5-6)
Innervation of infraspinatus
Suprascapular nerve (C5-6)
Innervation of teres minor
Axillary nerve (C5-6)
What usually causes anterior dislocation of the shoulder joint
Excessive extension and lateral rotation
Which nerve runs in close proximity to the shoulder joint and can be damaged during dislocation?
Axillary nerve
What does injury to the axillary nerve in a dislocation cause?
- Paralysis of deltoid
- Loss of sensation over regimental badge area
What usually prevents winging of the scapula in a healthy person?
Serratus anterior attaching to the anterior face of the scapula and pulling it against the ribcage
What causes winging of the scapula?
Damage to the long thoracic nerve