Nerve connections in the Upper Extremity Flashcards
(17 cards)
What are the sources of innervation to the brachialis muscle?
The brachialis muscle is dually innervated by the musculocutaneous nerve (primary, C5-C6) and radial nerve (secondary). This allows its musculocutaneous branch to be used in nerve transfers while preserving elbow flexion.
What is the Berrettini anastomosis and how prevalent is it?
The Berrettini anastomosis usually connects the common digital nerve of the median nerve (supplying the radial side of the ring finger and ulnar side of the middle finger) with the common digital nerve of the ulnar nerve (supplying the ulnar side of the ring finger and little finger).
Present in 60-90% of hands.
Most Common!
What is the clinical significance of the Berrettini anastomosis during hand surgery?
Inadvertent injury to the Berrettini anastomosis during palmar procedures can cause unexpected sensory deficits or neuromas. Surgeons must be aware of this common variation (60-90%) to prevent iatrogenic injuries.
Describe the anatomical course and direction of the Martin Gruber anastomosis.
The Martin Gruber anastomosis runs from the median nerve to the ulnar nerve in the forearm, typically in the proximal third. It carries motor fibers from C8-T1.
Mnemonic: “Martin Goes Median to Ulnar.”
What is the prevalence of the Martin Gruber anastomosis and its clinical significance?
Present in 15-32% of people, the Martin Gruber anastomosis can confound electrodiagnostic findings by preserving ulnar muscle function in proximal ulnar nerve injuries.
What is the Marinacci anastomosis and how does it differ from the Martin Gruber anastomosis?
The Marinacci anastomosis carries motor fibers from the ulnar nerve to the median nerve in the forearm, present in 4-6% of people.
Mnemonic: “Marinacci Moves Ulnar to Median.”
What is the Riche-Cannieu anastomosis and where is it located?
The Riche-Cannieu anastomosis is a motor connection between the median and ulnar nerves in the thenar region, allowing anomalous innervation of thenar muscles.
Mnemonic: “Riche-Cannieu Connects Motors in the Thenar.”
What is the prevalence of the Riche-Cannieu anastomosis and its clinical significance?
Present in 50-77% of people, the Riche-Cannieu anastomosis can preserve thenar function despite median nerve transection at the wrist.
Memory Aid: “Riche-Cannieu Rescues Thenar Function.”
Why is the Riche-Cannieu anastomosis not considered a sensory communication?
The Riche-Cannieu anastomosis is primarily motor, connecting the recurrent motor branch of the median nerve and the deep motor branch of the ulnar nerve.
A patient has a complete median nerve transection at the wrist but shows preserved thenar muscle function. What anatomical variation best explains this finding?
The Riche-Cannieu anastomosis (present in 50-77%) explains preserved thenar function via motor communication from the ulnar nerve.
Mnemonic: “Riche-Cannieu: Thenar Savior.”
How would you describe the clinical implications of the dual innervation of the brachialis muscle in brachial plexus reconstruction?
Dual innervation allows using the musculocutaneous branch for transfers while preserving elbow flexion via the radial nerve.
Memory Aid: “Brachialis: Dual Nerves, Donor Potential.”
What is the typical direction of neural impulse flow in the Martin Gruber anastomosis?
Neural impulses flow from the median nerve to the ulnar nerve in the forearm.
Compare and contrast the Martin Gruber and Marinacci anastomoses regarding their direction and prevalence.
Martin Gruber: Median to Ulnar 15-32%
Marinacci: Ulnar to Median 4-6%
Mnemonic: “Martin Gruber: More common, Median to Ulnar; Marinacci: Rare, Reverse.”
Which nerve anastomosis in the upper extremity has the highest prevalence?
The Berrettini anastomosis is the most prevalent (60-90%).
During surgical exploration for a penetrating trauma to the palm, you observe a communicating branch between the common digital branches of the median and ulnar nerves. What is this structure?
This is the Berrettini anastomosis, connecting median and ulnar nerves in the palm (60-90% prevalence).
What is the typical location of the Marinacci anastomosis and how does this affect management of forearm nerve injuries?
The Marinacci anastomosis (forearm, 4-6%) can explain unexpected muscle preservation in forearm nerve injuries.
A patient with a complete median nerve transection at the wrist has preserved opposition of the thumb. What is the most likely anatomical explanation?
The Riche-Cannieu anastomosis preserves thumb opposition via ulnar nerve motor fibers.
Mnemonic: “Riche-Cannieu: Retains Opposition.”
