Abstract
BackgroundThe intramuscular nerve distribution and relative spindle abundance of the human hand have not been well defined, although this is important in guiding hand surgery.MethodsForty human hands were dissected and subjected to modified Sihler’s stain and haematoxylin and eosin stain to investigate intramuscular nerve distribution and relative spindle abundance, respectively.ResultsThe flexor pollicis brevis (FPB), adductor pollicis (AP), and abductor digiti minimi (ADM) contain separate nerve compartments. Neural anastomoses were observed in the thenar and hypothenar muscles, including the Y-like, O-like, H-like, and U-like appearance. We found that U-like neural anastomoses may be the characteristic of the opponens muscles. The relative spindle abundance was the greatest in the opponens muscles which may coordinate fine movements.ConclusionExcept for the two opponens muscles, the rest of the thenar and hypothenar muscles could be used as whole muscle or half-muscle donors for muscle transplant. Our nerve map of the hand offers valuable guidance for hand reconstruction.
Highlights
The origins and the precise courses of the nerves outside the thenar and hypothenar muscles have been morphologically documented using gross anatomy and microdissection methods [1,2,3,4], the precise intramuscular nerve distribution patterns of the thenar and hypothenar muscles have not been clearly described
The deep branch divides below the hypothenar fibro-muscular tunnel, traverses across the deep palm, and divides into four terminal branches to abductor digiti minimi (ADM), flexor digiti minimi brevis (FDMB), opponens digiti minimi (ODM) and adductor pollicis (AP)
In 32 of the 40 hands (80%), the deep head of abductor pollicis brevis is innervated by a branch from the ulnar nerve, which enters the muscle from the proximal part.The average length of this branch is 2.2360.6 cm
Summary
The origins and the precise courses of the nerves outside the thenar and hypothenar muscles have been morphologically documented using gross anatomy and microdissection methods [1,2,3,4], the precise intramuscular nerve distribution patterns of the thenar and hypothenar muscles have not been clearly described. Previous studies have found that muscle spindle densities are higher in flexor and deep muscles than that in extensor and superficial muscles [13,14,15]. The relative spindle abundance of the human hand has not been completely defined some intrinsic hand muscles have been examined. The intramuscular nerve distribution and relative spindle abundance of the human hand have not been well defined, this is important in guiding hand surgery
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