Distribution of nerve endings in the human proximal interphalangeal joint and surrounding structures

Distribution of nerve endings in human thumb interphalangeal joint

This study aims to quantitatively analyze the distribution of encapsulated nerve endings in the human thumb interphalangeal (IP) joint capsule. There are three types of nerve endings. Type-I nerve endings (Ruffini-like ending) sense pressure changes, Type II (Pacini-like ending) nerve endings contribute to the kinesthetic sense, and Type III (Golgi-like ending) nerve ending provides proprioceptive information. We dissected five right thumbs IP joints from freshly frozen cadavers (5 men). The mean age of the cadavers at the time of death was 63.4 years (55-73). Sections were stained with the hematoxylin-eosin and antiprotein gene product 9.5 (PGP9.5) to identify encapsulated nerve endings. Transverse sections were cut and divided into volar, dorsal, and then into two equal parts, proximal and distal. The density of encapsulated nerve endings compared to volar versus dorsal and proximal versus distal regions was examined. This study showed that type 1 nerve endings were more common in the distal parts of the IP joint (p < 0.05). Also, type 3 nerve endings were observed in the thumb IP joint. There was no difference between regions in type II and type III nerve endings. The current study demonstrates that the distribution of encapsulated nerve endings in the IP joint is different from the PIP and DIP joints. Moreover, further studies are required to understand the thumb's physiology.

Innervation of digital joints: an anatomical overview

INTRODUCTION

The innervation of the digital joints as well as the anatomical relationships of the articular branches is present in this anatomical work to determine the technical feasibility of a selective and efficient denervation of the digital joints.

MATERIALS AND METHODS

A study of 40 distal interphalangeal (DIP), 40 proximal interphalangeal (PIP), 50 metacarpophalangeal (MCP), 10 interphalangeal (IP) of the thumb, and 10 trapezo-metacarpophalangeal (TMC) joints was performed on ten hands. Under magnification and a proper surgical approach, we collected the course, the source origin, the number of articular nerve branches, and their caliber.

RESULTS

In total, 118 nerve branches arising from the proper palmar digital nerves were found on 10 DIP of each dissected long finger (n = 40). A total of 226 nerve branches were found on 10 PIPs of each long finger (n = 40), of which 204 branches (90.3%) had a palmar origin. Dorsal innervation was found for the ring and little finger, originating from the dorso-ulnar digital nerve. 212 branches were found on 10 MCP of long fingers (n = 40), including 87 branches of palmar origin (41.1%), 107 branches of dorsal origin (50.4%), and 18 branches of the motor branch of the ulnar nerve (8.5%). 42 articular branches directed to the TMC joint (n = 10) were found. 13 branches (31%) originated from the anterior sensory branch of the radial nerve, 13 branches (31%) originated from the lateral cutaneous nerve of the forearm, 5 branches (12%) originated from the palmar cutaneous branch of the median nerve, and 11 (26%) branches originated from the thenar branch of the median nerve. The involvement of the sensory anterior branch of the radial nerve was always present for the innervation of each TMC.

DISCUSSION AND CONCLUSION

Our research shows that finger joints receive their primary innervation from small branches of the digital nerves with the exception of the MCP joint and the TMC joint. To obtain an efficient and a selective digital denervation for articular pain relief, it is necessary to plan the best surgical approach and it is crucial to recognize the articular nervous branch localization and source.

Innervation of the Proximal Interphalangeal Joint: An Anatomical Study

PURPOSE

To describe the innervation of the proximal interphalangeal (PIP) joint of the fingers as well as the anatomical relations of the articular branches.

METHODS

In this anatomical study, 52 fresh-frozen index, long, ring, and little fingers of 6 male and 4 female cadavers were dissected after injection of a colored latex composite. The anatomical dissections were performed under ×3.5 and ×6.0 magnifications. The numbers of articular nerve branches that penetrated the PIP joint on both sides of the fingers were quantified and patterns of innervation were established. We also measured the origin of the branches regarding the PIP articular line, the angle of emergence, and the diameter of the nerves.

RESULTS

The PIP joint was innervated by one articular branch of the proper palmar digital nerve at each side of the finger (pattern 1). Less frequently, an additional distal branch from the same proper palmar digital nerve was found (pattern 2). Dorsal articular branches were identified innervating only the little finger.

CONCLUSIONS

The findings suggest that PIP joints of the fingers have a consistent articular nerve anatomy predominantly provided at the palmar aspect of the joint. These findings provide an anatomical basis for procedures to denervate the PIP joint.

CLINICAL RELEVANCE

An accurate understanding of peripheral nerve anatomy of the PIP joint is essential to improve outcomes in denervation techniques.

Anatomy and Biomechanics of the Finger Proximal Interphalangeal Joint

A complete understanding of the normal anatomy and biomechanics of the proximal interphalangeal joint is critical when treating pathology of the joint as well as in the design of new reconstructive treatments. The osseous anatomy dictates the principles of motion at the proximal interphalangeal joint. Subsequently, the joint is stabilized throughout its motion by the surrounding proximal collateral ligament, accessory collateral ligament, and volar plate. The goal of this article is to review the normal anatomy and biomechanics of the proximal interphalangeal joint and its associated structures, most importantly the proper collateral ligament, accessory collateral ligament, and volar plate.

The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment

Ligament injuries are among the most common musculoskeletal injuries seen in clinical practice and ligaments are the most frequently injured structures in a joint. Ligaments play an important role in balancing joint mobility and joint stability. Disruption of joint ligaments severely impairs joint function. Over the past 10 years, a new appreciation of a neuroanatomy and neurophysiology of joint ligaments and its biofeedback loops to surrounding muscles and tendons has emerged to explain the relationship between primary and secondary restraints that allow normal joint motion yet prevent pathological motion. This review focuses on this recent information with a view to new clinical approaches to these common problems.

The role of tactile afference in shaping motor behaviour and implications for prosthetic innovation

The present review focusses on how tactile somatosensory afference is encoded and processed, and how this information is interpreted and acted upon in terms of motor control. We relate the fundamental workings of the sensorimotor system to the rehabilitation of amputees using modern prosthetic interventions. Our sense of touch is central to our everyday lives, from allowing us to manipulate objects accurately to giving us a sense of self-embodiment. There are a variety of specialised cutaneous mechanoreceptive afferents, which differ in terms of type and density according to the skin site. In humans, there is a dense innervation of our hands, which is reflected in their vast over-representation in somatosensory and motor cortical areas. We review the accumulated evidence from animal and human studies about the precise interplay between the somatosensory and motor systems, which is highly integrated in many brain areas and often not separable. The glabrous hand skin provides exquisite, discriminative detail about touch, which is useful for refining movements. When these signals are disrupted, such as through injury or amputation, the consequences are considerable. The development of sensory feedback in prosthetics offers a promising avenue for the full integration of a missing body part. Real-time touch feedback from motor intentions aids in grip control and the ability to distinguish different surfaces, even introducing the possibility of pleasure in artificial touch. Thus, our knowledge from fundamental research into sensorimotor interactions should be used to develop more realistic and integrative prostheses.

Comparative analysis of inter- and intraligamentous distribution of sensory nerve endings in ankle ligaments: a cadaver study

BACKGROUND

The aim of this study was to analyze the inter-, intraligamentous, and side-related patterns of sensory nerve endings in ankle ligaments.

METHODS

A total of 140 ligaments from 10 cadaver feet were harvested. Lateral: calcaneofibular, anterior-, posterior talofibular; sinus tarsi: lateral- (IERL), intermediate-, medial-roots inferior extensor retinaculum, talocalcaneal oblique and canalis tarsi (CTL); medial: tibionavicular (TNL), tibiocalcaneal (TCL), superficial tibiotalar, anterior/posterior tibiotalar portions; syndesmosis: anterior tibiofibular. Following immunohistochemical staining, the innervation and vascularity was analyzed between ligaments of each anatomical complex, left/right feet, and within the 5 levels of each ligament.

RESULTS

Significantly more free nerve endings were seen in all ligaments as compared to Ruffini, Pacini, Golgi-like, and unclassifiable corpuscles (P ≤ .005). The IERL had significantly more free nerve endings and blood vessels than the CTL (P ≤ .001). No significant differences were seen in the side-related distribution, except for Ruffini endings in right TCL (P = .016) and unclassifiable corpuscles in left TNL (P = .008). The intraligamentous analysis in general revealed no significant differences in mechanoreceptor distribution.

CONCLUSIONS

The IERL at the entrance of the sinus tarsi contained more free nerve endings and blood vessels, as compared to the deeper situated CTL. Despite different biomechanical functions in the medial and lateral ligaments, the interligamentous distribution of sensory nerve endings was equal.

CLINICAL RELEVANCE

The intrinsic innervation patterns of the ankle ligaments provides an understanding of their innate healing capacities following injury as well as the proprioception properties in postoperative rehabilitation.

Biomechanical differences of the proximal interphalangeal joint volar plate during active and passive motion: a dynamic ultrasonographic study

PURPOSE

To define the biomechanical differences of the volar plate (VP) of the proximal interphalangeal joint during active and passive motion, which may provide clues to understanding the functional importance of the volar elevation of the VP.

METHODS

We imaged the volar aspect of the proximal interphalangeal joint in 10 healthy middle fingers using ultrasonography. Cine videos recorded the movements of the VP during joint motion from full extension to more than 60° of flexion both actively and passively. We plotted 5 points on the volar surface of the VP and traced them for motion analysis. We statistically analyzed the volar distances and volar angulation of the VP in full extension, 30°, 45°, and 60° of flexion to determine the differences between active and passive flexion.

RESULTS

In active flexion, the VP showed significantly higher volar distances in 45° and 60° and changed its configuration from the original flattened figure to an inverted U shape, with a significant higher angulation at 45° compared with passive flexion. Conversely, in passive flexion, we did not observe the volar elevation of the VP and the flattened configuration was maintained throughout the motion arc.

CONCLUSIONS

From an anatomical viewpoint, volar elevation of the VP seen in active flexion could provide dynamic stresses on the adjacent ligaments and contribute to the stability and smooth gliding of the joint.

Nerve fiber staining investigations in traumatic and degenerative disc lesions of the wrist

PURPOSE

Traumatic and degenerative disc lesions cause ulnar-sided wrist pain. To date, anatomical investigations of cadaver triangular fibrocartilage discs examining the innervation of the triangular fibrocartilage complex have found no evidence of nerve fibers in the healthy disc. In this study, we immunohistologically investigated biopsies from patients with either central traumatic or degenerative disc lesions, to determine the existence of nerve fibers. We hypothesized that an ingrowth of nerve fibers causes ulnar-sided wrist pain associated with traumatic and degenerative disc lesions.

METHODS

We included 32 patients with a traumatic Palmer 1A lesion and 17 patients with a degenerative Palmer 2C lesion in the study. We obtained a biopsy of each patient and stained the specimen with protein gene product 9.5 for nerve fiber detection.

RESULTS

There were no nerve fibers in either traumatic or degenerative disc lesions. In addition, the marginal areas of the biopsies showed no evidence of nerve fibers.

CONCLUSIONS

Traumatic and degenerative disc lesions show no ingrowth of nerve fibers.

Distribution of nerve endings in human distal interphalangeal joint and surrounding structures

PURPOSE

To examine the distribution of encapsulated nerve endings called mechanoreceptors in the human distal interphalangeal (DIP) joint and surrounding structures.

METHODS

We processed 12 right index finger DIP joints and surrounding structures from fresh cadavers for immunohistochemistry of the anti-protein gene product 9.5 (PGP9.5) and silver staining to detect encapsulated nerve endings. Serial transverse sections were cut throughout the whole specimen and divided into 3 regions along the longitudinal axis: distal, middle, and proximal. Each of the transverse sections was partitioned into dorsal capsule (DC), radial capsule (RC), ulnar capsule (UC), volar plate (VP), and radial and ulnar assemblage nuclei (RAN and UAN); the RAN and UAN are located on both the radial and ulnar side of the VP. The C3 pulley contained the proximal region of the RAN and UAN, whereas the A5 pulley contained the middle and distal. The accessory collateral ligament contained all the regions of the RAN and UAN. We analyzed and compared the density of encapsulated nerve endings among the 18 different regions.

RESULTS

According to the modified Freeman and Wyke classification, we identified type I (eg, Ruffini-like endings) and type II (eg, Pacini-like endings) nerve endings. The density of type II nerve endings in the proximal region of the RAN and UAN was considerably higher than that in the proximal region of the VP, RC, UC and DC, and that in the proximal region of the VP, RC, UC, and DC, respectively.

CONCLUSIONS

Our examination of the distribution of type I and type II nerve endings provides new information on the sensory systems of the DIP joints and surrounding structures.