Extensor Ligaments Lumbrical tendon passes volar to transverse metacarpal ligament Interossei tendon passes dorsal to transverse metacarpal ligament Retinacular Ligaments Function retain and position common extensor mechanism during PIP and DIP flexion similar to sagittal band function Anatomic Components oblique band (oblique retinacular ligament of Landsmeer) function login to view 2 more bullets anatomy login to view 2 more bullets biomechanics login to view 2 more bullets pathology login to view 8 more bullets transverse band function login to view 2 more bullets anatomy login to view 2 more bullets pathology login to view 2 more bullets Digital Cutaneous Ligaments Function tether skin to deeper layers of fascia and bone to prevent excessive mobility of skin and improve grip stabilize the digital neurovascular bundle with finger flexion and extension Anatomic Components Cleland's ligaments (remember "C" for ceiling) dorsal to digital nerves not involved in Dupuytren's disease Grayson's ligament (remember "G" for ground) volar to digital nerves Expansion Hood Function works to extend PIP and DIP joint Anatomic Components central slip functions to extend PIP inserts into base of middle phalanx lateral band functions to extend DIP inserts into distal phalanx login to view 1 more bullet MCP Joint Collateral Ligaments Function stabilize MCP joint during motion MCP joint "cam" nature leads to inconstant arc of motion because of joint asymmetry login to view 1 more bullet collaterals looser in extension, tighten during increasing flexion login to view 1 more bullet Anatomic Components radial collateral ligaments (RCL) are more horizontal than ulnar collateral ligaments (UCL) RCL and UCL have 2 parts each: proper and accessory ligaments accessory ligament login to view 8 more bullets proper ligament login to view 8 more bullets Deep Transverse Metacarpal Ligament Function prevents metacarpal heads from splaying apart (abduction) allows some dorsal-volar translation Anatomic components connects 2nd to 5th metacarpal heads together at volar plate of the MP joint Natatory Ligament (Superficial Transverse Metacarpal Ligament) Function resists abduction Anatomic components most superficial MP joint ligament origin: from distal to the MP joint insertion: proximal phalanx of all 5 fingers (runs in the web space) Sagittal Bands Function keep extensor mechanism tracking in the midline during flexion of MP joint Anatomy origin: palmar plate insertion: extensor mechanism (curves around radial and ulnar side of MP joint) Triangular ligament Function counteracts pull of oblique retinacular ligament, preventing lateral subluxation of the common extensor mechanism Anatomy triangular in shape located on dorsal side of extensor mechanism, distal to PIP joint Pathology contracture leads to swan neck deformity Volar Plate Function prevent hyperextension Anatomy thickening of joint capsule volar to the MP joint in the thumb, sesamoid bones are located here origin: metacarpal head insertion: periarticular surface of proximal phalanx , via checkrein ligaments Biomechanics loose in flexion folds into metacarpal neck during flexion tight in extension