NERVE FIBRES AND NERVES 



821 



genital organs, the serous membranes, and many other structures. Each cor- 

 puscle consists of a number of capsular Connective-tissue lamellae arranged more 

 or less concentrically around a central granular protoplasmic core, pierced by a 

 single axone which usually divides into two or more branches giving off col- 

 laterals of beaded appearance and terminating in rounded knobs. 



Bulboid corpuscles (corpuscula bulboidea; Krause's end bulbs) are minute cylin- 

 drical or oval bodies, consisting of a capsule continuous with the perineurium 

 which encloses a core (inner bulb) of semifluid, finely granular protoplasm. 

 The axone is bulbed peripherally and quite free distally, or, as is frequently 

 observed, divides into a number of branches, to each of which is attached an 

 end bulb. 



Dendritic branchings. 



Rings. 



Spirals.'/ 

 FIG. 592. Middle third of a terminal plaque in the muscle spindle of an adult cat. (After Ruffini.) 



The genital corpuscles (corpuscula nervorum genitalia) and the articular cor- 

 puscles (corpuscula nervorum articularia) very much resemble the bulboid cor- 

 puscles just described. The genital corpuscles form aggregations of from two 

 to six knob-like masses in the penis and clitoris. The articular corpuscles are 

 found in the synovial membranes of the joints. 



Neuromuscular spindles ( muscle spindles of Kiihrie) are found in nearly all the 

 skeletal muscles and are most numerous in the Extrinsic muscles of the tongue, 

 in the small muscles of the hand and foot, and in the Intercostal muscles. Most 

 elaborate investigations upon these spindles have been conducted recently by 

 Ruffini in Italy, Sihler, Huber, and De Witt in America. Neuromuscular 

 spindles are usually found in the fibrous septa of the perimysium, and consist of 

 the flattened nerve fibrils of centripetal axones arranged in one or all of three 

 ways: (1) annular, where the fibrils surround the muscle fibres in rings; (2) 

 spiral, and (3) dendritic or branched (Fig. 592). They are doubtlessly concerned 

 with the so-called muscle sense. 



Neurotendinous Spindles (organs of Golgi\ The nerves conveying sensor im- 

 pulses from the tendons have a special modification of the peripheral fibres, in 

 the form of numerous fibrils with branching end plates or of an annular and 

 spiral arrangement resembling the neuromuscular spindles. They usually occur 

 at the junction of the tendon bundles with the muscle fibres (Fig. 593). 



