132 - Joints of Upper Limb 2. Elbow & Radioulnar Joints Flashcards
Type of joint that elbow joint it
Hinge joint.
Type of joint that radio-ulner joint is
Pivot joint
Part of humerus that radius articulates with
Capitulum
Part of humerus that ulna articulates with
Trochlea
Part of elbow joint that prevents hyperextension
Olecranon, from ulna
Fossa on humerus that ulna fits into during flexion
Coronoid fossa that coronoid (on ulna) fits into.
What limit lateral movement of elbow joint?
Medial and lateral collateral ligaments
What join the medial epicondyle on the elbow?
Superficial flexors of the forearm.
Medial collateral ligament
What join the lateral epicondyle on the elbow?
Superficial extensors of the forearm.
Lateral collateral ligament
Location of insertion of biceps
Antero-medial part of proximal radius
Elbow complex
1
2
• Elbow joint
• Proximal radioulnar joint
- both joints share one synovial cavity
Location of elbow complex capsule
Goes above fossae on humerus.
Attaches anteriorly above radial articulation.
Things that reinforce elbow joint 1 2 3 4 5
Ligaments: -collateral -medial/ ulnar (MCL) -lateral/ radial (LCL) -annular* -attachment between LCL & annular ligament permits pronation/ supination
*Things that reinforce elbow joint
ELBOWCOMPLEX
Ligaments that allow pronation and supernation of forearm
Lateral collateral ligament and annular ligament
How do the lateral collateral ligament and annular ligament allow pronation and supernation of forearm?
Lateral collateral ligament attaches to annular ligament (which is on the ulna)
Non-communicating bursa in elbow
Olecranon bursa
Stability of elbow joint
Very stable
Angles of joints in the elbow
Medial epicondyle, olecranon process, lateral epicondyle are all in alignment.
At flexion these form an isosceles triangle
Valgus displacement of forearm
At extension, forearm is angled at about 15 degrees to arm.
This disappears in flexion.
What happens if there is an increase in valgus angle of forearm?
Puts additional tension on structures on medial aspect of elbow.
EG: Ulnar nerve
Name for interior of elbow
Cubital fossa
Where does brachial artery split?
At head of radius, in cubital fossa (into radial and ulnar arteries)
What fill fossae in elbow when not occupied by bone?
Fat pads
Effect of annular ligament on elbow capsule in flexion
Makes capsule bend laterally with flexion
Types of epiphyses in elbow
Traction epiphyses
Radio-ulnar joints
1
2
Two synovial picot joints.
1) Superior RU Joint - Within elbow complex
2) Inferior RU joint - With triangular fibrocartilaginous complex (disc)
Ligament around which radio-ulnar joint rotates
Annular ligament on ulnar
Reason for direction of fibres in interosseous membrane in radioulnar joint
1
2
1) Provide sites of attachment for deep flexor and extensor muscles in forearm.
2) Transmit force from radius to ulnar
What separates ulnar bone from articulating with the wrist?
Triangular interosseous disc
Quadrate ligament
Vestigial ligament in the radio-ulnar interosseous membrane
Relationship between fractured radius and ulnar bones
If one is fractured, the other normally fractures
Effect of age on triangular interosseous ligament in wrist
Disc increasingly perforated with age (7% in 3rd decade, 50+% in 6th decade)
Pronator muscles
1
2
1) Pronator teres (power pronation)
2) Pronator quadratus (more fine movement)
Supinator muscles
Biceps brachii
‘Student’s elbow’
Olecranon bursitis (in elbow)
Pulled elbow
Annular ligament is weaker in children.
Pulling on a fully-extended elbow can pull the radial head out of annular ligament
Most common direction of elbow dislocation
Posterior
Volkmann’s ischaemia
When a supracondylar fracture occurs (on humerus), brachial artery can be endangered.
Stretch, spasm of brachial artery can lead to ischaemia of forearm musculature.
Structure at risk when there is a fracture of the medial epicondyle
Ulnar nerve
On which bone is the annular ligament located?
Radius
