Gantzer muscles; a study on 50 cadaveric upper limbs

Background : Gantzer muscle is the name given to the additional head of Flexor Digitorum Profudus (FDP) or Flexor Pollicis Longus (FPL). It connects the superficial flexors and deep flexors of forearm. It sometimes may be related to Anterior Interosseous Nerve (AIN) and Ulnar artery causing Compressive Neuropathy or Vascular symptoms. Aim: To assess incidence of Gantzer muscle in South Indian population, its morphology and clinical significance. Materials and methods: The study was carried out on 50 upper limbs dissected by first year M.B.B.S students. Results : Nine upper limbs showed the presence of Gantzer muscle, three belonged to the right and six belonged to the left. Observations : Additional heads were associated as follows: From FDP-2 and from FPL-7. Innervation was either from Median nerve, Anterior Interosseous nerve or Ulnar nerve. Superficially median nerve was related, deep relations were Ulnar artery and Anterior Interosseous nerve. In one case, Median nerve and artery were related superficially. Conclusion: Gantzer muscle is important clinically as a cause of vascular or nerve compression.

Magnetic Resonance Imaging Assessment of Mechanical Interactions Between Human Lower Leg Muscles in Vivo

Evidence on epimuscular myofascial force transmission (EMFT) was shown for undissected muscle in situ. We hypothesize that global length changes of gastrocnemius muscle-tendon complex in vivo will cause sizable and heterogeneous local strains within all muscles of the human lower leg. Our goal is to test this hypothesis. A method was developed and validated using high-resolution 3D magnetic resonance image sets and Demons nonrigid registration algorithm for performing large deformation analyses. Calculation of strain tensors per voxel in human muscles in vivo allowed quantifying local heterogeneous tissue deformations and volume changes. After hip and knee movement (Δ knee angle ≈ 25 deg) but without any ankle movement, local lengthening within m. gastrocnemius was shown to occur simultaneously with local shortening (maximally by +34.2% and −32.6%, respectively) at different locations. Moreover, similar local strains occur also within other muscles, despite being kept at constant muscle-tendon complex length. This is shown for synergistic m. soleus and deep flexors, as well as for antagonistic anterior crural and peroneal muscle groups: minimum peak lengthening and shortening equaled 23.3% and 25.54%, respectively despite global isometric conditions. These findings confirm our hypothesis and show that in vivo, muscles are in principle not independent mechanically.

Volkmann’s contracture of the forearm due to an insect bite: a case report and review of the literature

Compartment syndrome affecting the upper limb is reported rarely in the literature and is usually limited to single case reports. Upper limb compartment syndrome secondary to envenomation is rare, especially in the UK. Worldwide, it has been reported resulting from snake and insect bites, mostly from snakes from the Viperidae family, and from insects such as bees and wasps. Reports from the UK are limited to one case of an adder bite. We present a case of a previously fit and well adult who developed an ischaemic contracture of the forearm after an insect bite. Surgical exploration revealed segmental necrosis and contracture of the superficial and deep flexors of the fingers, requiring fasciotomy and tendon-lengthening procedures. This is the first report of a compartment syndrome, or a late ischaemic contracture from an insect bite in the UK. Owing to the rarity of compartment syndrome of the upper limb secondary to envenomation, a delay in diagnosis and treatment can lead to irreversible changes in the muscular compartments of the forearm.

The localization of the motoneurons supplying the hindlimb muscles of the mouse

The method of retrograde axonal transport of horseradish peroxidase (HRP) has been used to localize the motoneurons that innervate the mouse hindlimb musculature. Motoneurons were labelled following either intramuscular injection of an HRP solution or application of HRP to the cut end of a muscle nerve. When intramuscular injection was used the nerves to adjacent muscles were cut and deflected from the injection site to prevent motoneurons projecting to these muscles being labelled with HRP. For some muscles this procedure was inadequate since the nerves to adjacent muscles were too short to enable adequate deflexion. The motoneurons projecting to these muscles were labelled by the method of cut nerve exposure. The motoneurons that project to a single muscle or a group of muscles were organized as longitudinal columns. The positions of such motonuclei within the lateral motor column were similar in different animals for any given muscle or muscle group. Motoneurons innervating the anterior and medial femoral muscles were located in spinal segments L1 and L2. Motoneurons innervating the remaining hindlimb muscles were found in segments L3-L5. Topographic relationships between muscle motonuclei were in general found to be similar to those described for the cat. The principal differences to be noted between the two species were that the adductors motonucleus did not overlap with the hamstrings motonucleus in the mouse. Also the motonuclei supplying the deep flexors of the crural musculature and intrinsic musculature of the foot were located more ventrally relative to the posterior crural motonucleus in the mouse as compared to the cat. Consideration of muscle homologies between vertebrate classes enabled comparisons of the localization of motonuclei between the mouse and the other species studied. It was found that topographical relations between motonuclei were similar in all the species so far studied. There was no absolute correlation between the rostrocaudal position of a motonucleus and the position in the hindlimb of the muscle that it innervated. In general, motonuclei innervating muscles derived from the dorsal muscle mass were located lateral to motonuclei innervating muscles derived from the ventral muscle mass. Furthermore, within each muscle mass there is a relationship between rostrocaudal position of a motonucleus and the anteroposterior position of the muscle it supplies. Thus there is a relation between position of a motonucleus within the spinal cord and the derivation from the embryonic muscle mass of the muscle that it supplies.

Identification of excitatory and inhibitory neuromuscular synapses in the crayfish thoracic deep flexor musculature

Excitatory and inhibitory neuromuscular synapses in the thoracic deep flexors of the crayfish were examined using electron microscopy. Excitatory nerve terminals were found to have larger synaptic vesicles and a greater synaptic cleft distance than did inhibitory terminals. These results were confirmed by fixation enhancement of differences in synaptic vesicle morphology and the experimental depletion of vesicles in the excitatory nerve terminals.

THE CAUDAL MUSCULATURE OF HOPLOPAGRUS GUNTHERI GILL (PERCIFORMES: LUTJANIDAE)

The caudal musculature of Hoplopagrus comprises dorsal and ventral superficial flexors reinforced by a deltoid flexor tendon, dorsal and ventral deep flexors a hypochordal longitudinal muscle, a dorsal adductor, and interradials. These provide for flexion, extension, abduction, adduction, rotation, and probably circumduction of fin rays. The muscles are innervated by a spinal nerve plexus. The fin rays articulate with the caudal vertebral skeleton by a well-developed joint capsule with a synovial space. Dissection of a series embracing Palaeoniscoidei–Holostei–Teleostei suggests how there has been an evolution of specialized effectors to actuate a caudal fin of increasingly complex function. A table of synonyms of muscles of the caudal fin is included.