ABSTRACT
The tendon of flexor pollicis longus angulates at the trapezio-metacarpal joint level. The degree of angulation varies with extent of radial/ulnar deviation (Rack and Ross [1984] J. Physiol. 351:99-110). We report a fibrous pulley at this level that helps stabilize the tendon and facilitates its action. The morphology of the pulley is described. We believe that it has an important role to play in the unique function of the tendon facilitating the movement of the thumb perpendicular to the plane of the thumbnail.
Subject(s)
Metacarpal Bones/anatomy & histology , Metacarpophalangeal Joint/anatomy & histology , Tendons/anatomy & histology , Trapezium Bone/anatomy & histology , Biomechanical Phenomena , Dissection , Hand Joints/anatomy & histology , Hand Joints/physiology , Humans , Tendons/physiology , Thumb/anatomy & histology , Thumb/physiologyABSTRACT
OBJECTIVE: "Blind" shoulder injections are often inaccurate and infiltrate untargeted structures. We tested a hypothesis that optimizing certain anatomical and positional factors would improve accuracy and reduce dispersal. METHODS: We evaluated one subacromial and one glenohumeral injection technique on cadavers. RESULTS: Mean accuracy was 91% for subacromial-targeted and 74 and 91% (worst- and best-case scenarios) for joint-targeted injections. Mean dispersal was 19% for subacromial-targeted and 16% for joint-targeted injections. All results bettered those reported previously. CONCLUSION: These "optimized" techniques might improve accuracy and limit dispersal of blind shoulder injections in clinical situations, benefiting efficacy and safety. However, evaluation is required in a clinical setting.
