Podcast
Questions and Answers
Which of the following bones does NOT make up the elbow joint?
Which of the following bones does NOT make up the elbow joint?
- Tibia (correct)
- Ulna
- Humerus
- Radius
What is the primary function of the anterior band of the ulnar collateral ligament?
What is the primary function of the anterior band of the ulnar collateral ligament?
- Increase tension with Internal Rotation
- Limit Valgus and Extension (correct)
- Provide articular stability
- Resist Varus forces
Which ligament of the elbow becomes taut during extreme elbow flexion?
Which ligament of the elbow becomes taut during extreme elbow flexion?
- Radial Collateral Ligament
- Transverse Fibers of Ulnar Collateral Ligament
- Lateral (Ulnar) Collateral Ligament (correct)
- Ulnar Collateral Ligament (Posterior Fibers)
Which joint is NOT considered as part of the elbow joint?
Which joint is NOT considered as part of the elbow joint?
What force does the radial collateral ligament primarily resist?
What force does the radial collateral ligament primarily resist?
Which characteristic best describes the transverse fibers of the ulnar collateral ligament?
Which characteristic best describes the transverse fibers of the ulnar collateral ligament?
What is the primary role of the ulnar collateral ligament's posterior band?
What is the primary role of the ulnar collateral ligament's posterior band?
Which of the following best describes the humero-ulnar joint?
Which of the following best describes the humero-ulnar joint?
Which muscular tissue is primarily responsible for resisting a distal pull of the radius?
Which muscular tissue is primarily responsible for resisting a distal pull of the radius?
What role do the transverse fibers of the medial collateral ligament play?
What role do the transverse fibers of the medial collateral ligament play?
Which ligament is classified as a nonmuscular tissue that resists distal pull of the radius?
Which ligament is classified as a nonmuscular tissue that resists distal pull of the radius?
During elbow flexion, how do the fibrous connections behave in the medial collateral ligament?
During elbow flexion, how do the fibrous connections behave in the medial collateral ligament?
What occurs at the humeroradial joint during elbow flexion?
What occurs at the humeroradial joint during elbow flexion?
How do the fibers of the medial collateral ligament respond during forearm supination?
How do the fibers of the medial collateral ligament respond during forearm supination?
Which nonmuscular tissue contributes to joint stabilization by surrounding the joints?
Which nonmuscular tissue contributes to joint stabilization by surrounding the joints?
What happens to the anterior fibers of the medial collateral ligament as the elbow flexes?
What happens to the anterior fibers of the medial collateral ligament as the elbow flexes?
What ligament and structure allow for the internal rotation of the Humerus and Ulna proximally?
What ligament and structure allow for the internal rotation of the Humerus and Ulna proximally?
Which structure forms the roof of the cubital fossa?
Which structure forms the roof of the cubital fossa?
Which muscle is innervated by the Median nerve around the elbow?
Which muscle is innervated by the Median nerve around the elbow?
What is the medial boundary of the cubital fossa?
What is the medial boundary of the cubital fossa?
What is the function of knowing the boundaries of the cubital fossa for a physical therapist?
What is the function of knowing the boundaries of the cubital fossa for a physical therapist?
Which muscles receive motor input from the Anterior Interosseous nerve, a branch of the Median nerve?
Which muscles receive motor input from the Anterior Interosseous nerve, a branch of the Median nerve?
What is the position of the head of the Ulna in relation to the fixed ulnar notch of the radius distally?
What is the position of the head of the Ulna in relation to the fixed ulnar notch of the radius distally?
Which of the following is the lateral boundary of the cubital fossa?
Which of the following is the lateral boundary of the cubital fossa?
What role does the anterior deltoid play during a pushing motion that combines elbow extension and shoulder flexion?
What role does the anterior deltoid play during a pushing motion that combines elbow extension and shoulder flexion?
Which muscle acts as the most direct antagonist to the brachialis muscle?
Which muscle acts as the most direct antagonist to the brachialis muscle?
What does the passive 'drifting' of the forearm towards supination during an extension stretch indicate?
What does the passive 'drifting' of the forearm towards supination during an extension stretch indicate?
Which position of the upper extremity maximally elongates the biceps brachii muscle?
Which position of the upper extremity maximally elongates the biceps brachii muscle?
What biomechanical benefit does the central band of the interosseous membrane provide during pronation and supination?
What biomechanical benefit does the central band of the interosseous membrane provide during pronation and supination?
When applying an extension torque to the elbow, which muscle is most likely to resist the stretch if tight?
When applying an extension torque to the elbow, which muscle is most likely to resist the stretch if tight?
What is the function of the anterior deltoid when opposing shoulder extensor torque?
What is the function of the anterior deltoid when opposing shoulder extensor torque?
Which joint motion is primarily influenced by the rotation at the proximal radioulnar joint?
Which joint motion is primarily influenced by the rotation at the proximal radioulnar joint?
What is the primary role of force transmission between the radius and ulna during weight-bearing activities?
What is the primary role of force transmission between the radius and ulna during weight-bearing activities?
How does the isometric behavior of associated tissues aid in forearm motion?
How does the isometric behavior of associated tissues aid in forearm motion?
Which muscle primarily resists the movement toward supination due to contraction or tightness?
Which muscle primarily resists the movement toward supination due to contraction or tightness?
What role does the interosseous membrane play during forearm rotation?
What role does the interosseous membrane play during forearm rotation?
Which structure can restrict active supination when tight?
Which structure can restrict active supination when tight?
How does the stability provided by maintaining near-constant length of certain tissues affect forearm movement?
How does the stability provided by maintaining near-constant length of certain tissues affect forearm movement?
Which condition might occur in the proximal and distal radioulnar joints that could limit rotational movement?
Which condition might occur in the proximal and distal radioulnar joints that could limit rotational movement?
What is the effect of the latissimus dorsi contracting during a weight-bearing position?
What is the effect of the latissimus dorsi contracting during a weight-bearing position?
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Study Notes
Elbow Joint Anatomy
- The elbow joint is comprised of three bones: humerus, ulna, and radius.
- These bones form three joints: humero-radial, humero-ulnar, and proximal radioulnar.
Elbow Ligaments
- The Ulnar Collateral Ligament (UCL) is a key stabilizer against valgus force (abduction).
- Anterior Band: The strongest and stiffest part, limiting valgus, extension, and flexion.
- Posterior Band: Less defined and weaker than the anterior, resisting valgus force and taut during extreme flexion.
- Transverse Fibers: Limited impact on stability, connecting the anterior and posterior fibers.
- Lateral (Ulnar) Collateral Ligament: Resists varus forces (adduction) and excessive external rotation.
- Radial Collateral Ligament: Offers resistance against varus forces and increases tension with external rotation.
- Annular Ligament: Helps rotate the radial head around the ulna during pronation/supination.
Cubital Fossa
- The cubital fossa is a triangular space on the anterior elbow.
- Superior Boundary: Imaginary line connecting the medial and lateral epicondyles.
- Medial Boundary: Pronator Teres muscle.
- Lateral Boundary: Brachioradialis muscle.
- Floor: Brachialis and Supinator muscles.
- Roof: Brachial and antebrachial fascia, reinforced by bicipital aponeurosis, subcutaneous tissue, and skin.
Cubital Fossa Importance (For PT)
- Knowing the boundaries helps identify injuries or conditions impacting nerves and blood vessels in the area.
Muscles Innervated by Elbow Nerves
-
Median Nerve:
- Pronator Teres,
- Flexor Carpi Radialis,
- Palmaris Longus,
- Flexor Digitorum Superficialis
- Anterior Interosseous Nerve (branch of median)
- Flexor Pollicis Longus
- Flexor Digitorum Profundus (lateral half, for digits 2 & 3)
-
Ulnar Nerve:
- Flexor Carpi Ulnaris,
- Flexor Digitorum Profundus (medial half, for digits 4 & 5),
- Intrinsic hand muscles (not specified)
-
Radial Nerve:
- Brachioradialis,
- Extensor Carpi Radialis Longus,
- Extensor Carpi Radialis Brevis
Radius Distal Pull Resistance
-
Muscular Tissues:
- Biceps Brachii,
- Brachialis,
- Brachioradialis,
- Extensor Carpi Radialis Longus,
- Extensor Carpi Radialis Brevis
-
Non-muscular Tissues:
- Annular Ligament,
- Radial Collateral Ligament,
- Joint Capsules,
- Articular Cartilage,
- Fascia
UCL Fiber Function
- Anterior Fibers: Primary stabilizer during extension and taut in full extension, gradually loosening for smoother flexion.
- Posterior Fibers: Relaxed at full extension, taut during flexion, and aids in stabilizing the elbow against valgus stress during flexion.
- Transverse Fibers: Minor role compared to the other two fibers, contributing to overall UCL integrity.
Humeroradial Joint Arthrokinematics
- Flexion: Concave radial head rolls and glides posteriorly within the convex humerus.
- Supination: Radial head spins around the stationary ulna in the radial notch, occurring at the proximal radioulnar joint.
Deltoid and "Pushing"
- During combined elbow extension and shoulder flexion (pushing motion), the anterior deltoid opposes and exceeds the shoulder extensor torque produced by the triceps.
Brachialis Antagonist
- Triceps Brachii is the most direct antagonist to the brachialis muscle.
Elbow Flexion Contracture & Supination Drift
- Forearm supination drift during elbow extension stretch indicates biceps brachii tightness, as it functions as both an elbow flexor and forearm supinator.
Biceps Brachii Max Elongation
- Shoulder extension + Full elbow extension + Full forearm pronation maximally elongates the biceps brachii.
Interosseous Membrane Benefits
- Plays a near-isometric role during pronation and supination.
- Force Transmission: Efficiently transmits force between radius and ulna during weight-bearing.
- Stability: Stabilizes radius and ulna during rotation, enabling smooth coordinated movement.
- Energy Conservation: Minimizes muscle contraction for stability.
- Joint Protection: Guards against excessive stress or displacement during rotational movements.
Latissimus Dorsi and Supination
- In weight-bearing positions with a fixed hand, latissimus dorsi contraction internally rotates the humerus, which can passively supinate the forearm.
- Limiters: Pronator teres, pronator quadratus, interosseous membrane, radioulnar joint capsules, tight wrist flexor muscles (ex. flexor carpi radialis).
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