Anatomy of the elbow Flashcards
(31 cards)
What type of joint is the elbow joint?
It is a hinge, synovial joint, that moves uniaxially
What are the bones that articulates in the elbow?
1) Humeroulnar articulation
- Between the “trochlea” of the humerus, & the trochlear notch of the “ulna”
2) Humeroradial articulation
- Between the capitulum of the humerus and the upper articular surface of the head of the radius
Describe the structure of the capsule of the elbow joint
- Attached outside of the margins of the articular surfaces
- It is continuous with the synovial membrane and the superior radioulnar joint
1) Upper attachment (attachment to the humerus)
- Anteriorly it is attached to the margins of the coronoid and radial fossa & to the trochlea medially and the capitulum laterally
- Posteriorly, It is attached above the olecranon fossa
2) Lower attachment (attachment with the ulna & radius)
- Anteriorly, it is attached to the margins of the coronoid process & the annular ligament
- Posteriorly, it is attached to the margins of the olecranon fossa and the annular ligament
Describe the synovial membrane of the elbow joint
- Lines the inner surface of the fibrous “joint” capsule
- Lines the coronoid, radial & olecranon fossae
- Continuous with the synovial membrane of the superior radioulnar joint
What is meant by olecranon bursitis?
- It is the rupture/inflammation of the Olecranon bursa (closed sac filled with synovial fluid) found between the olecranon process and the skin
What strengthens the capsule?
1) Ulnar collateral ligament
- Thick triangular ligament which consists of 3 bands (anterior, posterior & oblique) that are connected between the medial epicondyle of the humerus and the medial margin of the olecranon of the ulna
2) Radial collateral ligament
- A band that connects the lateral epicondyle with the annular ligament
FYI: Both ligaments control the joint movement, and prevent adduction and abduction
Describe the different bands of the ulnar collateral ligament
1) Anterior:
- Strong & cord-like
- Medial epicondyle to medial margin of the coronoid process
- Remains taut during flexion and extension
2) Posterior band:
- Weak and fan-like
- Connects the medial epicondyle to the medial margin of the olecranon
- It tightens when flexed beyond 90 degrees
3) Oblique band:
- Connects the anterior (coronoid) & posterior bands (olecranon)
Describe the radial collateral ligament
1) Resists excessive varus (adduction) forces
2) Triangular in shape
3) Attached above to the lateral epicondyle
4) Merges below with the annular ligament
5) Posterior fibers attaches to the supinator crest
Which muscles flexes the elbow?
1) Brachialis (prime mover of the forearm)
2) Biceps brachii
3) brachiocardialis
4) pronator teres
5) common flexor origin
Which muscle extends the elbow joint?
1) Triceps brachii (main extensors)
2) Anconeus
Why is the elbow more stable during extension?
As the olecranon fossa is fully occupied by the olecranon process
The stability of the elbow joint during flexion depends on what?
Lateral “radial collateral ligament” and the medial “ulnar collateral ligament”
What are the different anastomosis around the elbow?
1) Infront of the lateral epicondyle
2) Behind the lateral epicondyle
What is the anastomoses that occurs in-front of the lateral epicondyle?
- The radial collateral artery (anterior descending branch of the profunda artery) anastomoses with the radial recurrent artery in-front of the lateral epicondyle of the elbow joint
What is the anastomoses that occurs behind the lateral epicondyle?
- From the posterior descending branch of the profunda artery the “middle collateral artery” anastomoses with the interosseous recurrent artery “from the posterior interosseous artery”
What is the anastomoses that occurs in front of the medial epicondyle?
Anterior branch of the inferior ulnar collateral artery with the anterior ulnar recurrent artery from the “ulnar artery”
What is the anastomoses that occurs behind the medial epicondyle?
The superior ulnar collateral artery & posterior branch of the inferior ulnar collateral artery with the posterior ulnar recurrent artery (from the ulnar artery
Describe the superior radio-ulnar joint
- Type: Synovial pivot
- Articulation: Head of the radius and the radial notch on the ulna
- Ligaments: Annular & quadrate ligaments
What are the ligaments of the superior radio-ulnar joint?
1) Annular ligament
2) Quadrate ligament
- These ligaments have no attachment to the radius bone, they just keep it in place, so the radius can freely rotate inside it but can’t dislocate
What are the functions/description of the annular ligament?
1) Stabilizes the radial head at the superior radio-ulnar joint
2) U-shaped
3) Forms 4/5 of osseofibrous ring
4) Attached medially to the anterior and posterior margins of the radial notch
5) Laterally winds around the head and neck of the radius
6) Continuous with the capsule from above
Describe the quadrate ligament
Extends medially from the medial surface of the neck of the radius to the lower margin of the radial notch of the ulna
Describe nursemaids elbow
- Radial head dislocates from the annular ligament
- Its a common injury seen most often in children between the ages of 1-3 years
- Usually it involves an incidents where the extended arm was pulled, like when a child falls and the person catching his hand does not let go, or when he is swinging while being held by the hands
- Then the head slips out of the hold in a sudden accidental pull of the forearm of the child
- Most common in children as their epiphysis is noy yet ossified
What are the movements of the superio-radioulnar joint?
1) Pronation
2) Supination
- FYI: In these movements it is the radius that moves and not the ulna
Which muscle is responsible for the pronation movement?
1) Pronator teres
2) Pronator quadrants
