Lecture 8: Shoulder and Elbow joint Flashcards
What are the bones that make up the shoulder joint and what are the important features of these that permit wide range of movement at this joint
The head of the humerus is covered in hyaline articular cartilage and is much larger than the glenoid fossa with which it articulates so glenoid fossa doesn’t hold it strongly in place, increasing mobility.
What is an articular capsule
Articular capsule is made of fibrous capsule layer on the outside and synovial membrane lines the inner surfaces of the articular space except for where the bones are articulating which is made of hyaline cartilage .
Compare the supraglenoid and infraglenoid tubercle.
Supraglenoid is intracapsular and is where the tendon of long head of biceps attaches whereas infraglenoid is extracapsular, closer to the armpit.
What are the extracapsular ligaments vs intracapsular ligaments
Extracapsular : coracoacromial ligament
Capsular (part of capsule): coracohumeral ligament , transverse humeral ligament and glenohumeral ligaments
Describe the shape and function of coracoacromial ligament
Prevents superior dislocation of the glenohumeral joint by forming an arch from the acromion to the coracoid
Describe the shape and function of coracohumeral ligament
Reinforces the capsules superiorly, helping to passively suspend the bone but lax in abduction. going from just under the coracoid to the humerus.
Describe the shape and function of the transverse humeral ligament
Holds the tendon of long head of biceps brachii in position when it comes out of the capsule as it just goes from greater to lesser tubercle
Describe the shape and function of glenohumeral ligaments
This is the site of popular dislocation because 3 ligaments made from thickenings of the interior of the capsule that go from inferior and anterior aspects of scapula to the humerus
Where is the sacciform synovial membrane on the shoulder joint
Just under the transverse humeral ligament because it lubricates the tendon of long head of biceps
What is a bursa
A fluid filled pouch which lubricates whatever is on top to minimise friction of tendons as they pass through to their insertions or across bones
Where is the subscapular bursa and what does it protect
Subscapular bursa just underneath the coracoid process in continuity of the synovial joint shoulder joint. It protects the subscapularis from the ridge of the glenoid fossa during contraction
Where is the subacromial bursa and subdeltoid bursa and what does it protect
Subacromial bursa is found underneath the coracoacromial ligament and it separates the arch from the infraspinatus and supraspinatus tendons as they pass under to their insertion onto the humerus.
The Subdeltoid bursa is a lateral continuation of this bursa found underneath the deltoid muscle
What is the “rotator cuff” and what 4 muscles are part of this
The rotator cuff is the muscles that stabilise the joint and attach to the head of the humerus by blending with the capsule of the joint. 4 muscles are Subscapularis, Supraspinatus, Infraspinatus and Teres minor
What is the innervation, origin and insertion of subscapularis
N: upper and lower subscapularis nerve (from posterior cord)
O: Subscapula fossa (surface facing body wall).
I: Lesser tubercle
What is the innervation, origin and insertion of Supraspinatus
N: suprascapular nerve
O: supraspinous fossa of scapula (posterior face)
I: Superior facet of greater tubercle
What is the innervation, origin and insertion of Infraspinatus
N: suprascapular nerve
O: Infraspinous fossa of scapula (post face)
I: middle facet of greater tubercle
What is the innervation, origin and insertion of Teres Minor
N: Axillary nerve
O: Lateral border of the scapula (post face)
I: inferior facet of greater tubercle
Compare the movement of the 4 rotator cuff muscles
Subscapularis internally rotates the arm,
Supraspinatus abducts the arm
Infraspinatus and Teres Minor externally rotates the arm.
What are the 3 joints of the elbow and what movements does this joint undergo
Elbow joint is 3 joints in one capsule, giving 135’ of flexion and extension with the humero-ulnar/humero-radius joint and the superior radio-ulnar doing pronation and supination (humero-radial joint allowing this)
How to tell the ulnar and the radius apart: which is medial and lateral from an anterior view
Ulnar has a larger proximal head compared to the radius but Radius is more lateral when palms up. Radius is on the thumb side
What are the parts of bones articulating at the humero-ulnar joint
The trochlea (medial half of the main bump) fits in the trochlea notch of the olecranon. When fully flexed, the coronoid process just under the olecranon fits into the coronoid fossa just above the trochlea
What are the parts of bones articulating at the humero-radial joint
The capitulum (lateral half of the main bump) fits into the superior surface of the radius. During flexion the radial fossa above the capitulum is filled with the head of the radius (sides of the donut not the frosting)
What are the parts of bones articulating at the superior radio-ulnar joint
The head of the radius (side of donut) fits into the radial notch on the ulnar allowing the radius to rotate.
Describe the 3 important ligaments of the elbow joint
- Medial/ulnar collateral ligament which prevents abduction of the ulna has its top part attached to the medial epicondyle of the humerus with the base around the upper, medial aspect of the ulnar.
- Radial collateral ligament which prevents adduction of the radius goes from the lateral epicondyle to on the annular ligament
- Annular ligament which attaches to the edges of the radial notch of the ulna and surrounds the head of the radius allowing it spin during pronation/supination.
Describe the path of the radial and ulnar nerve at the articular capsule of the elbow joint
Radial nerve goes on anteriorly the whole way, ulnar nerve starts anteriorly, goes behind the medial epicondyle and then back in front
