3. Anatomy of the Shoulder Joint Flashcards
Glenohumeral joint
Humeral head and glenoid fossa
Highly mobile ball and socket joint
Very unstable joint due to large humeral head on shallow glenoid fossa
Acromioclavicular joint
Junction between acromion and clavicle
Stabilised by acromioclavicular ligament
Commonly dislocated in sports injuries
Ligaments of the shoulder region
Stabilize/support the shoulder region
- Very strong
- Acromioclavicular
- Coracoclavicular- Major stabilizing ligament, 2 parts sitting at right angles to each other
- Coracoacromial- Forms arch to support for head of humerus & prevents superior dislocation
- Glenohumeral- superior, middle and inferior parts
Muscles that rotate the scapula during abduction
Upper and lower fibres of trapezius
Serratus anterior
Muscles that rotate the scapula during adduction
Rhomboids
Levator scapulae
Most common shoulder dislocation
95% anterior dislocation
-Humeral head descends inferiorly and ends up anterior
Factors increasing stability
- Coracoacromial arch- prevents superior dislocation
- Glenohumeral ligaments- superior of joint
- Deepening of glenoid fossa by glenoid labrum
- Long heads of biceps (above) and triceps (below)
- Tendons of rotator cuff muscles
Muscles involved in abduction
Rotation of scapula
- Upper and lower fibres of trapezius
- Serratus anterior
Deltoid
Supraspinatus
Muscles involved in adduction
Rotation of scapula
- Lev scap
- Rhomboids
Lat dorsi
Pec Major
Insertion point of supraspinatus, infraspinatus and teres minor
Greater tubercle
Supraspinatus
- origin
- function
- innervation
supraspinous fossa
-initiate abduction
first 15 degrees
-Suprascapular nerve
Infraspinatus
- origin
- function
- infraspinous fossa
- Lateral rotation of the arm at the glenohumeral joint
- Suprascapular nerve
Teres minor
- origin
- function
- lateral border of the scapula
- lateral rotation of the at the glenohumeral joint
Subcapsularis
- origin
- function
- subscapular fossa
- medial rotation of the arm at the glenohumeral joint
- Upper and lower subscapular nerves
Teres major
- Origin
- Insertion
- Innervation
- Function
Origin: Inferior angle of scapula
Insertion: medial lip of bicipital groove
Innervation: Inferior subscapular nerve
Function: medial rotation, Stabilises the humerus during abduction (eccentric contraction)
Nerve supply to the shoulder
Suprascapular nerve
from posterior cord of brachial plexus
The axillary nerve supplies which muscles
deltoid and teres minor
The radial nerve supplies which muscles
triceps brachii
Origin of the long head of the biceps
supraglenoid tubercle
Origin of the short head of the biceps
corocoid
Suprascapular nerve
from superior trunk of brachial plexus
supplies the supraspinatus and infraspinatus muscles
Latissimus dorsi
-Innervation
Thoracodorsal nerve
Teres major
-Innervation
Lower subscapular nerve
Deltoid Muscle
- Origin
- Insertion
- Innervation
- Function
Origin: spine of scapula, acromion, clavicle
Insertion: Deltoid tuberosity
Innervation: axillary nerve
Function:
posterior fibres- extension+lateral rotation
anterior fibres: flexion+medial rotation
Triceps Muscle
- Origin
- Insertion
- Innervation
- Function
Origin:
long head: infraglenoid tubercle of scapula
medial and lateral head: posterior surface of humerus
insertion: olecranon
Innervation: radial nerve
Function: extension arm
Which ligament prevents superior dislocation of the shoulder?
Coracoacromial ligament
Rotator cuff injuries
Supraspinatus impingement as supraspinatus most commonly injured
most commonly injured due to limited space for tendon under coracoacromial arch
Describe the anastomosis of axillary and subclavian arteries in the scapula
Axillary-subscapular-dorsal scapular-subclavian-thyrocervical trunk-suprascapular trunk
Quadrangular space
-borders
- Teres minor, teres major, humerus, long head of triceps
- damage here most likely to affect axillary nerve
