Elbow and joints of forearm Flashcards
What type of joint is the elbow?
-Hinge-type synovial joint
At full extension of the forearm, what is the angle of the humerus with the ulna?
-170 degrees
What is the carrying angle?
-The angle between the forearm and the trunk at rest
What muscles are responsible for flexion at the elbow?
- Biceps Brachii
- Brachialis
- Brachioradialis
- Palmaris Longus (weak)
What muscles are responsible for extension of the elbow?
-Triceps Brachii
-What does the fibrous capsule cover at the elbow?
- The elbow joint
- The proximal radioulnar joint
Why is the capsule of the elbow weak anteriorly and posteriorly?
-To allow movement
What are the collateral ligaments?
-Ligaments on the medial and lateral sides of the capsule (ulnar and radial, respectively) which provide strength
What is beneath the fibrous capsule?
-Synovial membrane (secreting lubricating fluid)
Describe the ulnar collateral ligament
-Has 3 bands
anterior -> strongest, cord-like band
posterior -> fan-like band
oblique-> deepens the socket for trochlea and provides additional stength
Describe the radial collateral ligament
- Fan-like
- Blends with the annular ligament
- Prevents dislocation
What are the two most clinically relevant bursae?
- Subcutaneous olecranon bursa
- Subtendinous olecranon bursa
Where does the radial nerve pass the elbow?
-Anterior to lateral epicondyle
Where does the ulnar nerve pass the elbow?
-Posterior to medial epicondyle
Describe the blood supply to the elbow
-Arterial anastamoses surround the elbow formed by collateral arteries and recurrent branched of the ulnar, radial and interosseous arteries
What are the three joints in the forearm?
- Proximal radioulnar
- Interosseous membrane
- Distal radioulnar
What do the joints of the forearm allow?
-Pronation and supination
What type of joint is the proximal radioulnar joint?
-Pivot joint
What articulations are involved in the proximal radioulnar joint?
- Radial head
- Radial notch of ulna
What is the anatomical location of the annular ligament, including its insertions?
-A ligament which arises from the ulna, wraps around the head of the radius and attaches posteriorly to the radial notch of the ulna to form a ligamentous collar
What is pulled elbow?
-A common sublaxation of radial head from annular ligament
Why is pulled elbow common in children?
-Annular ligamentt hasnt yet adapted funnel-like arrangement and isnt taut
What type of joint is the interosseous membrane?
-Fibrous joint
In which direction do the fibres of the membrane run? Why is this important?
- Inferio-medially
- Allows distribution of force from radius to ulna as the radius recieves force first as it lays more distal
What articulations are involved in the proximal radioulnar joint?
-Head of ulna with ulnar notch of radius
What is the function of the articular disk of the distal radioulnar joint?
- To maintain structure and joint integrity during pronation and supination
- Separates cavity of distal radioulnar joint from wrist cavity
What are the articulations at the elbow?
- Olecronon fossa with olecranon
- Trochlea with trochlear notch
- Coronoid process with coronoid fossa
- Radial head with capitulum
- Radial head with radial fossa
What is the sacciform recess?
-A superior extension of the synovial capsule which allows twisting of the capsule during movement
What muscles are responsible for supination?
- Biceps brachii
- Supinator
What musclees are responsible for pronation?
- Pronator quadratus
- Pronator teres
What articulations occur at the wrist?
-Distal radius and articular disk with scaphoid, lunate and triquitrum
Name the ligaments of the wrist
- Radial collateral ligament
- Ulnar collateral ligament
- Palmar radiocarpal ligaments -> ensures hand follows raduis in supination
- Dorsal radiocarpal ligaments-> ensures had follows radius during pronation
What are the movements of the wrist?
- Flexion/Extension
- ABduction (Radial deviation)
- ADduction (ulnar deviation)
What is a colles fracture?
-Fracture which occurs in distal radius causing posterior displacement of the distal fragment (dinnerfork deformity)
What is a possible complication of fracture of scaphoid? Why?
-Avascular necrosis as blood supply comes distally
Where would you clinically examine for tenderness if a scaphoid fracture was suspected?
-Over the anatomical snuff box
