Hand Anatomy Flashcards
What are the two components of the collateral ligaments in the PIP joint?
The collateral ligaments consist of the proper collateral ligament and the accessory collateral ligament.
The proper ligament - lateral stability
The accessory ligament connects to the volar plate - stability during flexion.
What is the primary function of the collateral ligaments in the PIP joint?
The collateral ligaments primarily prevent lateral deviation (radial and ulnar) of the PIP joint. They do not primarily restrain dorsal or volar deviation.
Where does the proper collateral ligament insert in the PIP joint?
The proper collateral ligament inserts on the lateral aspect of the base of the middle phalanx, not on the volar plate.
Describe the structure of the proper collateral ligament in the PIP joint.
The proper collateral ligament has dorsal and volar components.
The dorsal component tightens during flexion, and the volar component tightens during extension, providing stability throughout the joint’s range of motion.
What role does the volar plate play when the collateral ligaments are incompetent?
The volar plate acts as a secondary stabilizer against lateral deviation when the collateral ligaments are damaged or non-functional, in addition to its primary role of preventing hyperextension.
In a clinical scenario, a patient presents with chronic PIP joint instability following a lateral dislocation. Which structure is most likely compromised?
The proper collateral ligament is most likely compromised, as it is the primary stabilizer against lateral deviation. Damage to this ligament can lead to chronic instability if not properly managed.
During PIP joint flexion, which component of the proper collateral ligament is under tension?
The dorsal component of the proper collateral ligament is under tension during flexion, helping to maintain lateral stability in this position.
What is the origin of the accessory collateral ligament in the PIP joint?
The accessory collateral ligament originates from the proper collateral ligament and extends to insert on the volar plate, contributing to joint stability during flexion.
In surgical repair of a PIP joint, why is it important to preserve the volar plate?
Preserving the volar plate is crucial because it prevents hyperextension and can provide secondary lateral stability if the collateral ligaments are compromised. Damage to the volar plate may lead to joint instability or stiffness.
How does the volar plate contribute to PIP joint stability in cases of collateral ligament injury?
In cases of collateral ligament injury, the volar plate provides secondary lateral stability due to its connection to the middle phalanx and flexor sheath, helping to resist lateral forces.
What is the primary restraint to hyperextension in the PIP joint?
The volar plate
During a PIP joint dislocation, which structure is most commonly injured?
**The volar plate **is most commonly injured in PIP joint dislocations, particularly in dorsal dislocations, due to its role in preventing hyperextension.
In a patient with rheumatoid arthritis, which PIP joint structure is often affected, leading to boutonniere deformity?
The central slip of the extensor tendon is often affected, leading to attenuation or rupture, which results in the characteristic boutonniere deformity involving PIP joint flexion and DIP joint hyperextension.
What is the role of the dorsal capsule in PIP joint stability?
The dorsal capsule, along with the central slip, helps limit hyperflexion/palmar dislocation of the PIP joint, providing stability in the sagittal plane.
What is the origin of the lumbrical muscles in the hand?
The lumbrical muscles originate from the radial side of the flexor digitorum profundus (FDP) tendons. The first and second are unipennate (radial FDP), while the third and fourth are bipennate (adjacent FDPs). This origin drives MCP flexion and IP extension, critical for tendon repair accuracy.
Derived from Green’s Operative Hand Surgery, 7th Ed.
What is the primary function of the dorsal interossei muscles in the hand?
The dorsal interossei abduct the fingers away from the hand’s midline. This function is key for diagnosing ulnar nerve injuries, where loss of abduction signals claw hand.
Confirmed by biomechanical studies and clinical anatomy.
What causes the lumbrical-plus finger phenomenon?
A lumbrical-plus finger results from a flexor digitorum profundus (FDP) tendon disruption distal to the lumbrical origin, causing paradoxical IP extension during attempted flexion as the lumbrical tightens. Surgical release from the FDP origin may be needed.
Noted by Parkes, 1971; FESSH Flexor Tendon Guidelines, 2020.
What deformity results from injury to the triangular ligament in the finger?
Injury to the triangular ligament allows volar subluxation of the lateral bands, leading to boutonnière deformity (PIP flexion, DIP extension), not swan-neck deformity.
Supported by MRI studies and ASSH Textbook, 2021 guidelines.
Where is the oblique retinacular ligament (ORL) positioned relative to the PIP and DIP joints?
The oblique retinacular ligament lies volar to the PIP joint and dorsal to the DIP joint. It tightens during PIP extension to synchronize DIP extension, aiding finger coordination.
Based on Landsmeer’s studies, 1949, and surgical texts.
Why must surgeons distinguish between the triangular and transverse retinacular ligaments?
The triangular ligament prevents volar subluxation (causing boutonnière deformity), while the transverse retinacular ligament prevents dorsal subluxation (causing swan-neck deformity).
Supported by MRI and clinical observations.
Why is the lumbrical origin from the FDP tendons significant in flexor tendon surgery?
Preserving the FDP-lumbrical connection during surgery maintains intrinsic muscle function. Misidentifying this origin can disrupt tendon repairs, impairing hand function.
Highlighted in Green’s Operative Hand Surgery.
Where are Cleland’s ligaments located relative to the digital neurovascular bundles?
Dorsal. Cleland’s ligaments are dorsal to the digital neurovascular bundles, providing skin stability and protecting these structures during movement and surgery.
What is the correct origin of Grayson’s ligaments?
Flexor tendon sheath. Grayson’s ligaments originate from the flexor tendon sheath, not the phalanges, and insert into the skin, which is critical for accurate surgical identification.
Why is the radial digital nerve of the thumb at particular risk during trigger thumb release?
Proximity to A1 pulley. The nerve’s close location to the A1 pulley, especially in percutaneous procedures, increases injury risk, with a noted 5.7% complication rate.
Describe the positioning of the flexor digitorum superficialis (FDS) and profundus (FDP) as they enter the flexor sheath.
FDS is volar to FDP. At the entry point, FDS is superficial (volar) to FDP, which lies deeper (dorsal), essential for correct tendon repair.
Which bifurcates first in the palm: the common digital nerve or the common digital artery?
Common digital nerve. The nerve bifurcates proximal to the artery, with the artery splitting 0.5 to 1.0 cm distally, per anatomical studies.
A surgeon is planning a trigger thumb release. What anatomical consideration is crucial to avoid nerve injury?
Radial digital nerve proximity. The nerve’s closeness to the A1 pulley, particularly in percutaneous methods, must be considered to prevent damage.
How are Cleland’s and Grayson’s ligaments classified based on their location relative to neurovascular bundles?
Cleland’s: dorsal,
Grayson’s: volar.
