Shoulder Flashcards
Glenohumeral joint
Humeral head + glenoid fossa.
Movements:
- Add/Abduction
- Flex/Extension
- Med/Lateral rotation
- Cirumduction.
Very unstable joint
- Due to large humeral head on shallow glenoid fossa.
Acromioclavicular joint
Acromion articulates with clavicle in a planar joint
Stabilised by acromioclavicular ligament
Common dislocated in collision sports (ice hockey, rugby, judo, American football)
Ligaments of the shoulder
Overall
- Stabilise and support the shoulder region.
- Acromioclavicular
- Coracoacromial Forms coracoacromial arch to support head of humerus + prevent superior dislocation.
- Coracoclavicular Major stabilizing ligament, has two parts sitting right angle to each other.
- Glenohumeral Superior, middle inferior.
Features that stabilise the glenohumeral joint
Coracoacromial arch
- Prevents superior dislocation
Deepening of the glenoid fossa by the labrum.
Rotator cuff muscle tendons
Long heads of the biceps and triceps
Glenohumeral ligaments
- Supports the anterior joint
Muscles that rotate the scapula in adduction
Rhomboids
Levator scapulae
Muscles that rotate the scapula in abduction
Upper and lower deltoid fibres
Serratus anterior
Most common shoulder dislocation
Anterior dislocation
- Humeral head descends inferior and is pulled anterior to joint.
Occurs to no rotator cuff tendon supporting it inferiorly.
Deltoid
- Origin
- Insertion
- Innervation
- Action
Origin
- Lateral clavicle
- Acromion
- Spine of scapula
Insertion
- Deltoid tuberosity of humerus
Innervation
- Axillary nerve (Posterior cord, C5-6)
Action
- All fibres= abduction from 10-15 degrees
- Posterior fibres= Extension at shoulder and lateral rotation
- Anterior fibres= medial rotation, flexion at shoulder
Muscles involved in adducting the arm [4]
Rotation of scapula
- Levator scapulae
- Rhomboids
Latissimus dorsi
Pectoris major
Muscles involved in abducting the arm [4]
Rotation of scapula
- Upper and lower fibres of trapezius
- Serratus anterior
Deltoid- past 15 degrees
Supraspinatus
Biceps
- Origin [2]
- Insertion
- Innervation
- Action
Origin
- Long head= supraglenoid tubercle of scapula
Passes through joint capsule, under transverse humeral ligament- continues along biciptal groove
- Short head= Coracoid process
Insertion
- Radial tuberosity
Innervation
- Musculocutaneous nerve (C5-7, lateral cord)
Action
- Flexion of arm at shoulder
- Flexion of forearm at elbow
Muscles that flex arm at the shoulder [4]
Biceps
Coracobrachialis
Anterior deltoid fibres
Pectoralis major
Coracobrachialis
- Origin
- Insertion
- Innervation
- Action
Origin
- Coracoid process
Insertion
- Humeral shaft (anteromedial surface)
Innervation
- Musculocutaneous nerve
Action
- Flexion of arm shoulder
Muscles that extend the arm (at the shoulder)
Triceps
Posterior deltoid fibres
Latissimus dorsi
Triceps
- Origin [3]
- Insertion
- Innervation
- Action
Origins
- Long head= Infraglenoid tubercle of scapula
- Medial head= Below radial groove
- Lateral head= Above radial groove
Insertion
-Olecranon of ulna.
Innervation
- Radial and axillary nerve
Action
- Long head= extension of arm at shoulder
- Medial and lateral head= extension of forearm at elbow
Supraspinatus
- Origin
- Insertion
- Innervation
- Action
Rotator cuff muscle
- Most commonly torn due to limitted space under coracoacromial arch.
- Initiates abduction
- Stabilises glenohumeral joint superiorly
Origin
- Supraspinous fossa
Tendon passes under subacromial bursa, under coracoacromial arch.
Attachment
- Greater tubercle of humerus, above infraspinatus
Innervation
- Suprascapular nerve (C5-6)
Infraspinatus
- Origin
- Insertion
- Innervation
- Action
Rotator cuff muscle
- Lateral rotation of arm at shoulder
- Stabilises shoulder joint posteriorly.
Origin
- Infraspinous fossa of scapula
Attachment
- Greater tubercle of humerus, below supraspinatus, above teres minor.
Innervation
- Suprascapular nerve (C5-6)
Teres minor
- Origin
- Insertion
- Innervation
- Action
Rotator cuff muscle
- Lateral rotation
- Stabilises shoulder joint posteriorly.
Origin
- Infraspinous fossa of scapula
Attachment
- Greater tubercle of humerus, below Infraspinatus.
Innervation
- Axillary nerve (C5-6)
Subscapularis
- Origin
- Insertion
- Innervation
- Action
Rotator cuff muscle
- Stabilises shoulder anteriorly
- Medial rotation at shoulder.
Origin
- Subscapular fossa of scapula
Attachment
- Lesser tubercle of humerus
Innervation
- Upper and lower Subscapular nerve (C5-6)
Teres major
- Origin
- Insertion
- Innervation
- Action
Origin
- Posterior aspect of Inferior angle of scapula
Attachment
- Medial lip of bicipital groove (of humerus)
Innervation
- Lower Subscapular nerve (C5-6)
Action
- Medial rotation
- Stabilises humerus during abduction in eccentric contraction
Scapular anastomosis
Branches of the subclavian and axillary arteries
- Provides continuous blood supply to shoulder muscles during movement.
SCA
- Dorsal scapular
- Thyrocervical–> Suprascapular
Axillary
- Subscapular
Suprascapular nerve
(C5-6)
-Superior trunk
Supplies supraspinatus and infraspinatus
Axillary nerve
(C5-6, posterior cord)
- Deltoid
- Teres minor
Badge area of arm (sensation)
Radial nerve
- Motor
(C5-T1, posterior cord)
- Triceps brachii
Posterior cord branches innervations [3]
Supplies
- Subscapularis
- Teres major-
(Upper and lower subscapular nerves)
- Latissimus dorsi.
(Thoracodorsal nerve)
Quadrangular space
Space in axillary
Borders
- Humerus, laterally
- Tricep long head, medially
- Teres minor, superiorly (over tricep)
- Teres major, inferiorly (under triceps)
Structures that traverses the space
- Axillary nerve
- Posterior circumflex humeral artery
Clinical significance–>Fracture to surgical neck of humerus
- Damage of axillary nerve= weakness/ paralysis of detloid/ teres minor, loss of sensation in badge area of arm.
- Laceration of post. cirumflex humeral artery.
