Elbow Flashcards
What are the joints at the elbow and forearm?
- Humeroulnar
- Humeroradial
- Proximal radioulnar
- Distal radioulnar
Is the humeroulnar or humeroradial joint more stable?
Humeroulner; due to processes and grooves reinforced with capsule and ligaments
Humeroradial joint provides about ___% of resistance to a valgus-producing force to the elbow.
50%
What are the normal ranges of carrying angle?
13 degrees ( + or - 6 degrees)
- females typically have 2 degrees more than makes
- 5 to 25 degrees is functional
Gunstock deformity; forearm is deviated medially 5 degrees
Cubitus varus
What is usually the cause of varus or valgus deviation of the elbow?
Fracture through the growth plate of the distal humerus
Excessive cubital valgus (20-25 degrees) may overstretch and damage _______ nerve on the medial side of the elbow
Ulnar
What would be considered excessive cubitus valugus?
lateral deviation of 30 degrees (according to Jason, book says 20-25 degrees)
What is the ROM at the elbow in the saggital plane?
Elbow Flexion = 145°
Elbow Extension = 0° to 5° beyond neutral
How many degrees do you need to have functional elbow motion?
100 degree functional arc from 30 - 130 degrees
[Convex/Concave] trochlea of humerus. [Convex/Concave] trochlear notch of ulna
Convex; concave
What can potentially limit passive elbow extension?
- Anterior skin
- Flexor muscles
- Anterior capsule
- Anterior fibers of the medial collateral ligament
- Broad tendon of the brachialis muscle
- Olecranon process of ulna becomes wedged into the olecranon fossa of the humerus
What can potentially limit passive elbow flexion?
- Posterior capsule
- Extensor muscles
- Ulnar nerve
- Posterior fibers of the medial collateral ligament
At the humeroradial joint: [Concave/convex] fovea of radial head. [Concave/convex] capitulum of humerus. What happens during active flexion?
Concave; convex; muscle pulls fovea against the capitulum (minimal boney contact during full extension)
The Radial head is held against the proximal ulna by a ring consisting of 75 % ______ and 25% _______.
Annular ligament; radial notch of the ulna
What are the functions of the interosseous membrane between the radius and ulna?
- Binds the radius to the ulna
- Stable attachment for some extrinsic muscles of the hand
- Provide a mechanism for transmitting force proximally through the upper extremity
What force pulls the interosseous membrane taut?
compression force, greater during active pronation
Distal radioulnar joint: [Convex/ concave] head of ulna into the [convex/concave] ulnar notch of radius. Head of ulna also fits into the proximal surface of the _____
Convex; concave; articular disc
Occupies most of the ulnocarpal space between the head of the ulna and the ulnar side of the wrist; Primary stabilizer of the distal radio-ulnar joint; functions similar to meniscus (periphery heals we’ll)
Articular disc AKA triangular fibrocartilage couples (TFCC)
[Pronation/Supination]
- Places palm down
- Thumb same side as medial epicondyle of elbow
[Pronation/ Supination]
- Places palm up
- Thumb same side as lateral epicondyle of elbow.
What does the axis of rotation connect?
Pronation; supination; radioulnar joint
- Radius, wrist, and hand rotate together around a fixed ulna and humerus