[The proximal sesamoid bone of the horse; vascular and neurologic characteristics].
Authors: Cornelissen
Journal: Tijdschrift voor diergeneeskunde
Summary
# Editorial Summary: The Proximal Sesamoid Bone of the Horse; Vascular and Neurologic Characteristics Sesamoiditis remains a significant cause of chronic lameness in horses, yet its underlying mechanisms have been incompletely understood. Cornelissen's 1998 thesis examined the vascular supply and sensory innervation of the proximal sesamoid bones through anatomical and histological analysis of cadaver material, seeking to clarify why these small bones are prone to degenerative changes and recurrent lameness. The research revealed that proximal sesamoid bones possess remarkably robust arterial reserves, supported by an arterial shift mechanism that provides collateral blood flow—a finding suggesting that vascular compromise alone may not fully explain sesamoiditis pathogenesis. Additionally, the bones receive dedicated sensory innervation via a distinct "sesamoid nerve" branching from the medial and lateral palmar nerves, and contain nociceptive neuropeptides (substance P and calcitonin gene-related peptide) indicating pain-sensing capacity, though the surrounding ligaments demonstrated even greater sensitivity. For practitioners, these findings have direct clinical utility: the identification of a specific sesamoid nerve enables more targeted diagnostic analgesia to differentiate sesamoid-origin pain from adjacent soft tissue injury, whilst the vascular anatomy may inform understanding of why sesamoiditis responds variably to rest and treatment regimens.
Read the full abstract on PubMed
Practical Takeaways
- •A specific sesamoid nerve anaesthetic technique can be used clinically to differentiate pastern lameness and localize pain to sesamoid structures
- •Understanding sesamoid bone innervation and vascular anatomy provides insight into why sesamoiditis causes chronic lameness and informs treatment approaches
- •The high pain sensitivity of periarticular ligaments suggests that ligamentous structures around the sesamoids may be primary pain generators in some cases of apparent sesamoiditis
Key Findings
- •Proximal sesamoid bones possess an enormous arterial reserve due to arterial shift formation, providing redundant blood supply
- •Sesamoid bones have dedicated sensory innervation via branches of the medial and lateral palmar nerves (sesamoid nerve)
- •Sesamoid bones contain nociceptive neuropeptides (substance P and calcitonin gene-related peptide) indicating pain sensitivity
- •Adjacent ligaments demonstrate greater pain sensitivity than the sesamoid bones themselves