Topographic anatomy of the ulnar tunnel

Anatomy of the Palmar Region of the Carpus of the Dog

The palmar region of the canine carpus is anatomically complex, and the information found in the literature about its anatomy is inconsistent. The aims of this prospective, descriptive, anatomic study were (1) the clarification and (2) the description of the precise anatomic composition of the palmar region of the canine carpus, with special reference to the canalis carpi. For this study, 92 cadaveric specimens were obtained from 46 dogs that had died for reasons unrelated to this study. Of these, 43 medium-to-large-breed dogs were randomly selected for the dissection of transverse slices of the carpus. Samples of the flexor retinaculum and flexor carpi radialis tendon and surrounding tissues were taken for complementary histology. For additional histology of the palmar structures in their anatomical position, three small breed dogs were randomly selected for obtaining transverse slices. The anatomic characteristics of the components of the palmar region of the canine carpus were qualitatively described, with special attention to the following structures: flexor retinaculum, flexor carpi radialis muscle, arteria and vena mediana, nervus medianus, interflexorius muscle, flexor digitorum profundus muscle, canalis carpi, and arteria and nervus ulnaris. The findings from this study provide reference information about the anatomy of the palmar region of the canine carpus.

Possible points of compression of the ulnar nerve: Tricks and traps that await clinicians from an anatomical point of view

The ulnar nerve can be subject to numerous types of compression. The most common are cubital tunnel and ulnar tunnel syndromes, but there are many others with more uncommon etiologies. The existence of additional communicating branches, median nerve involvement, various types of injuries, and unusual anatomical variations can be a challenge for both diagnosis and treatment. This review presents a comprehensive depiction of ulnar nerve entrapment syndromes with particular reference to their anatomical background, risk factors, and clinical evaluation. Even common disorders can result from atypical morphological changes. It is important to be familiar with them as it is a key ability in daily medical practice.

The ulnar nerve is surrounded by the tendon expansion of the flexor carpi ulnaris muscle at the wrist: an anatomical study of Guyon's canal

The ulnar tunnel (Guyon's canal) is an osseofibrous tunnel for the ulnar nerve and artery. With regard to the proximal palmar wall (palmar carpal ligament) of the ulnar tunnel, detailed anatomical data such as attachment sites, fibrous continuity to surroundings, and variations have not been clearly described. In this study, topology of Guyon's canal was examined, especially to the palmar side of the ulnar nerve, focusing on the continuity of tendinous structures to reveal a more detailed constitution of Guyon's canal. The palmar wall of Guyon's canal was investigated in 113 forearms of 57 cadavers. The dorsal wall of the canal was also investigated in 25 subjects. The ulnar nerve passed lateral to the pisiform and the flexor carpi ulnaris tendon. At the level of the pisiform, except for one, the ulnar nerve passed dorsal to the aponeurosis expanding from the flexor carpi ulnaris tendon and the periosteum of the pisiform, and this aponeurosis laterally merged with the palmar aspect of the flexor retinaculum. Moreover, the ulnar nerve ran palmar to the pisohamate ligament and the flexor retinaculum extended from the same tendon. The present study suggests that the aponeurosis of palmar side to the ulnar nerve connected with the flexor carpi ulnaris tendon, the periosteum of the pisiform, and the palmar surface of the flexor retinaculum. These findings indicate that the ulnar nerve is surrounded by the aponeurotic portion expanding from the flexor carpi ulnaris tendon at the wrist, which is a new insight of Guyon's canal.

Ultrasound of the ulnar-palmar region of the wrist: normal anatomy and anatomic variations

Ultrasound (US) assessment of the wrist is frequently used for the evaluation of carpal tunnel due to high frequency of local compression of the median nerve (MN), but the ulnar-palmar wrist region (UPWR) has received limited attention in the medical literature. The possibilities of US in the assessment of UPWR are therefore likely underestimated by sonologists. This review article is focused on the US assessment of the normal anatomy and anatomic variations of the UPWR. The anatomy of this region of the wrist is complex and less studied than the radial side. In an effort to simplify it and to present it didactically, we have divided this region in three parts on the basis of osseous landmarks. Our review indicates sonography is effective in identifying the UPWR and related disorders, and is thus a valuable tool for ensuring appropriate management of a variety of disorders.

Anatomical insights of the palmaris brevis muscle for clinical procedures of the hand

The purpose of the present study is to provide useful data for anatomists and clinicians by describing the topography of the palmaris brevis muscle, taking particular note of its morphology and distribution pattern of the nerve and artery. Forty-nine hands from Korean adult cadavers were used in this study. Parameters with respect to the size, scale, and location of the muscle were measured using a ultrasonography system, digital caliper, and surgical microscope. Histologic sections were obtained to clarify the positional relationship with surrounding tissues. The branches of the ulnar nerve and artery, which supply the muscle, were observed. The minimum and maximum depths in which the palmaris brevis muscle can be existed, including the thickness of the skin (1.9 mm), were 3.7 and 6.9 mm, respectively. It was inserted into the hypothenar fascia and the dermis. The main trunk of the ulnar nerve and artery were positioned under the lateral side of the muscle. The richest arborization of perforating branches of the ulnar nerve and artery was mostly confined to the distal section of the lateral side of the muscle. Our findings provide theoretical evidence of the palmaris brevis muscle for clinical procedures of the hand, such as botulinum toxin injection. Clinicians should pay attention not to injure the ulnar artery under the lateral side of the muscle. Botulinum toxin should be injected at a depth of between approximately 2 and 7 mm, considering the range of depth of the muscle. Clin. Anat. 30:397-403, 2017. © 2017 Wiley Periodicals, Inc.

Analysis of the position of the branches of the ulnar nerve in Guyon's canal using high-resolution MRI in positions adopted by cyclists

PURPOSE

To study variations in the anatomical relationships of the branches of the ulnar nerve in Guyon's canal relative to the hamulus of hamate (HH) in a grip encountered among cyclists.

MATERIALS AND METHODS

Forty-seven wrist examinations were performed on a 3-T MRI (soft antenna, 16 channels) in propeller sequence in the plane perpendicular to the carpus in 28 healthy volunteers in three cycling positions (neutral, hyperextension and ulnar deviation). The positions and distance between the superficial (SB) and deep (DB) branches of the ulnar nerve with respect to the HH were determined on the section passing through the HH.

RESULTS

The mean distances between the SB (d s) and DP (d p) and HH were 2.4 and 0.6 mm, respectively. The d s in hyperextension and ulnar deviation were 2.2 mm (P = 0.3) and 3 mm (P = 0.07), respectively. The d p in hyperextension and ulnar deviation were 0.3 mm (P = 0.02) and 0.5 mm (P = 0.15), respectively. Hyperextended, 60 % of SB and 40 % of DB were close to the HH, and 26 % of DB came directly in contact with it. In ulnar deviation, 30 % of SB and 29 % of DB approached HH, and 47 % of DB were in contact with it.

CONCLUSION

This study shows that SB and DB positions of the ulnar nerve vary with respect to the HH depending on the position of the wrist, and such differences may promote Guyon's canal syndrome in cyclists.