Brachial Plexus Flashcards
Is elbow extension essential or supplementary for most activities of daily living after brachial plexus injury?
Essential. Active elbow extension enables critical functional movements necessary for self-care, occupational tasks, and independence; compensatory mechanisms without elbow extension are energy-inefficient and suboptimal.
Injury to which anatomical structure of the brachial plexus directly results in elbow extension palsy?
Injury to the posterior cord, as it gives rise to the radial nerve that innervates the triceps brachii muscle, the primary elbow extensor.
Which spinal nerve root is most critically associated with elbow extension function?
C7 nerve root; it provides primary innervation to the triceps brachii muscle, making its integrity crucial for maintaining elbow extension strength.
Why is active elbow extension biomechanically advantageous for manual wheelchair propulsion?
Active elbow extension allows efficient force generation throughout the push phase, improving propulsion speed and endurance while decreasing upper limb fatigue and compensatory movements.
Which muscle transfer is currently preferred over pectoralis major for restoring elbow extension in brachial plexus injuries?
Biceps-to-triceps transfer is preferred due to consistently superior functional outcomes, including at least grade 4 strength and significant improvements in daily tasks requiring active elbow extension.
What nerve transfer technique has demonstrated high success rates (M4 strength) for restoring elbow extension after brachial plexus injury?
Ulnar nerve fascicle transfer to the triceps branch; studies report high success rates with nine out of ten patients achieving M4 strength.
Which alternative nerve transfer technique has shown reliable outcomes for restoring elbow extension function following brachial plexus injury?
Intercostal nerve transfers to native triceps or free-functioning muscle transfers, with studies reporting 17 out of 21 reconstructions achieving ≥M4 strength.
What specific complication risk is significantly reduced by using a medial rather than lateral approach in biceps-to-triceps tendon transfers?
Radial nerve injury; medial routing avoids the anatomical region where the radial nerve is vulnerable during lateral routing.
Which functional outcomes are typically achievable with a medial approach biceps-to-triceps tendon transfer?
Grade 4 or higher elbow extension strength with minimal lag (<8 degrees), while preserving supination and flexion strength due to optimal tensioning and anatomical routing.
In a patient with brachial plexus injury, preservation of which spinal nerve root is most critical for maintaining triceps function?
C7; it predominantly innervates the triceps via the posterior cord and radial nerve, making its preservation crucial for maintaining elbow extension.
Compared to muscle transfers, what advantage do nerve-based reconstruction techniques offer for restoring elbow extension after brachial plexus injury?
Nerve-based reconstructions provide more natural motor control patterns and typically lower donor site morbidity while achieving comparable strength outcomes (≥M4).
In rehabilitation after brachial plexus injury, why are purposeful activities involving elbow extension emphasized over non-specific exercises?
Purposeful activities lead to better functional outcomes by enhancing motor learning, patient engagement, and effective carryover into daily functional tasks compared to non-specific exercises.
Why is maintaining supination strength clinically important following biceps-to-triceps tendon transfer surgery?
Supination strength preservation is essential for fine motor tasks and self-care activities; medial routing techniques specifically help maintain this function despite using biceps as a donor muscle.
In patients lacking active triceps function due to posterior cord injury, which tendon transfer provides optimal alignment and minimal donor-site morbidity for restoration of active elbow extension?
Posterior deltoid muscle transfer is commonly selected due to its aligned line of pull with the triceps tendon insertion site, resulting in minimal loss of donor-site function.
After biceps-to-triceps tendon transfer surgery via medial routing technique, what specific postoperative clinical findings indicate successful surgical outcome regarding tension adjustment?
Correct tension adjustment results in neutral thumb position at rest (elbow at 45° flexion), key pinch position at 20° wrist extension, and thumb tenodesis into extension with wrist flexion—indicating optimal tension balance achieved intraoperatively.
