Lecture 6: Elbow Flashcards
What are the articulating surfaces on the anterior aspect of the distal humerus?
Trochlea and capitulum
the trochlea forms part of the ______________ articulation
humeroulnar
What portion of the trochlea projects more distally, the medial or lateral?
medial
the capitulum is part of the ___________ articulation
humeroradial
What does the capitulotrochlear groove separate?
The capitulum and the trochlear
The olecranon fossa articulates with the _____ and is on the _________ side of the distal humerus
ulna
posterior
What is the radial fossa meant to do?
receive the head of the radius during elbow flexion
What articulates with the trochlear groove of the humerus?
the trochlear notch and trochlear ridge of ulna
Which process is more distal, the olecranon or coronoid?
Coronoid
During flexion, the ulna ________ process slides to the ________ fossa. In extension the ________ slides to the __________ fossa.
coronoid
coronoid
olecranon
olecranon
When is the trochlea fully congruent?
When loaded
The head of the radius has a _______ fovea that articulates with a _______ capitulum in flexion and extension
concave
convex
In humeroradial extension, there is no _______ made between the radial head and the capitulum
contact
The “elbow” joint is made up of what three joints?
Humeroradial
Humeroulnar
superior radioulnar
The elbow is enclosed in a large, loose capsule that is relatively weak in what direction?
anterior/posterior
The capsule of the elbow joint us more stable medially and laterally. Why?
It blends with the annular ligament, MCL and LCL
The medial collateral ligament is on what side of the elbow, radial or ulnar?
Ulnar
What does the MCL do? 4 main jobs
Resists valgus stress at the elbow such as throwing or golfing
Limits extension at the end of the elbow extension
guides jt through flexion ROM
provides resistance to longitudinal distraction of the elbow
The MCL is divided into 3 bundles– what are they?
Anterior, posterior, and oblique
What does the anterior bundle of the MCL do?
Primarily restrain of valgus stress at 20-120 degrees
What does the posterior bundle of the MCL do?
restrain of valgus stress in elbow extension by keeping jt surfaces in approximation
What does the oblique bundle of the MCL do?
may be effective in resisting valgus stress and more in joint approximation
Injury to the MCL occurs most frequently during what activity?
the backswing portion of pitching, with the shoulder in ER and the elbow flexed
What muscles cover the MCL?
FDS, PT, FCU
What does the Annular Ligament do?
Encircles the radial head
What ligament is fan shaped from the lateral epicondyle to the annular ligament and olecranon that reinforces the humeroradial joint and provides primary resistance to varus stress and to joint distraction?
LCL
What ligament runs from the lateral epicondyle to the ulna and assists LCL in resisting varus stress and adds humeral ulnar stability; close to suprinator, extensor, and anconeus
LUCL
What muscle is the primary flexor of the forearm?
Brachialis
The wrist and hand extensors originate on the ________ side of the arm on the _______ epicondyle
posterior
lateral
The wrist and hand flexors originate on the ________ side of the arm on the _______ epicondyle
anterior
medial
The carrying angle is typically ____ - ____ degrees and typically decreases with what movement?
8-15
pronation
The major flexors of the elbow are:
biceps brachii
Brachialis
Brachioradialis
The major extensors of the elbow are:
triceps
anconeus
When us the humerolunar joint in a close-packed position?
In full extension
How much flexion does the elbow have both AROM and PROM?
AROM: 135-145
PROM: 150-160
How does the forearm and shoulder position affect the brachialis muscle action?
It doesn’t! It is a one joint muscle from the humerus to the ulna.
In what position do you test the brachialis muscle?
Pronation resisting supination
What muscle helps with supination of the forearm but is affected by the position of the forearm and shoulder?
Biceps bracii
What elbow flexor is considered a “stability” muscle due to its distal attachment far from the joint?
brachioradialis
What are the two jobs of the anconeus?
Elbow extension
stabilizing during pronation/supination
Is the triceps affected by forearm position?
No
When is the moment arm of the triceps the best?
at 90 degrees
What head of the triceps can become actively insufficient based on shoulder position?
Long head
What head of the triceps is active in unresisted extension?
Medial head
What muscle controls the elbow in the closed kinematic chain?
Triceps
Name two closed chain activities of the elbow:
Pull ups: brachialis (eccentric lowering and concentric pulling up)
Push ups (concentric pushing up and eccentric lowering)
What are the articulating surfaces of the superior/proximal radioulnar joint?
ulnar radial notch
annular ligament
capitulum
radial head
What are the articulating surfaces of the inferior/distal radioulnar joint?
ulnar notch of the radius
articular disc (part of TFCC)
ulnar head
Both the proximal and distal ends of the TFCC are shaped how?
Concavely
What does the TFCC do?
Provides stability
Why is the TFCC considered to be a pain producer?
Highly vascular peripherally
The proximal and distal radioulnar joints are linked mechanically, this means that they move ________.
Together
What ligaments are at the proximal radioulnar joint?
annular
quadrate
oblique cord
What is the purpose of the quadrate ligament?
anchors the ulna to the radial neck
Limits the spin of the radius in pronation and supination
What does the oblique cord do?
Holds the radius and ulna together
What radioulnar ligament is at the distal joint?
Interosseous membrane
What is the function fo the interosseous membrane?
keeps radius and ulna aligned AND transfers forces from radius to the ulna
Why is the central band of the interosseous membrane high in tensile strength?
It is composed of high collagen and it is thick and strong
Where are the dorsal and palmar radioulnar ligaments taut, respectively?
pronation and supination
