Serial sections of human embryos and the brain stem together with cerebellum offetuses, young and adults were studied by Cajal I and Nissl methods for demonstratingthe development and connections of mesencephalic nucleus of the trigeminal nerve. It was found that at C.R. 12.4 mm the mesencephalic root with some scattered cellgroups made its appearance along the sulcus limitus from the entrance of the trigeminalnerve up to the isthmus region. At C.R. 56mm it extended into the midbrain regionand the base of the cerebellum. Later on, the root cells differentiated in a caudo-rostraldirection. They were therefore somewhat larger in its caudal part than those in the ros-tral. With the increase of age the morphology of the mesencephalic root cells alsochanged from the fetal multipolar type to the adult unipolar. The present study confirm the previous observations that the mesencephalic root hadconnections with some cranial nerves and the cerebellum. And in addition, some scat-tered mesencephalic root cells were found in the posterior commissure, in its nucleus andin the interstitial nucleus. Discussion on their functional significance were made.

The length of the muscular branches of the nerves in the upper limb from a fixed point along the nerve and its branches in 40 cadavours was measured.The muscular branches of the median and the radial nerve were measured by Sunderland's method, while for the muscular branches of the musculo-cutaneous nerve,we selected the middle point of the clavicle as a fixed point.The shortest and the longest distances and the numbers of muscular branches to the individual muscles supplied by the nerves were re- corded. The point of origin of the muscular branches of individual muscles in each muscle group followed a definite order,for instance,the shortest of the muscular branches of the median nerve was those to the pronator teres,then next by order were those to the flexor digitorum sublimis,the palmaris longus,the flexor pollicis longus and the pro- nator quadratus.The serial order of branches from the radial nerve was that to the long head of the triceps brachii,the medial head of the same muscle,the brachialis, the extensor carpi radialis longus,and the extensor carpi radialis brevis.Among the muscular branches of the musculo-cutaneous nerve,those to the coracobrachialis came out first,then followed by those to the biceps brachii and the brachialis. The number of the branches to the individual muscles in each muscle group seemed to be proportional to the size of the muscle and to the role played by that muscle in the specific movement.The pronator and supinator muscles,though small in size,received quite a number of branches.It is suggested that the more muscular branches a muscle receives,the greater the importance it has in moving a joint.

Measurement of the length of the muscular branches of the nerves in the lower extremity was made on 40 dissection-room specimens.The muscular branches of sciatic nerve and of its two major divisions were measured according to Sunderland's method. For the femoral nerve,we chose the interspinous line as the fixed point.The results were as follows: A muscle may be innervated by a single or several branches.In most cases,the popliteus was supplied by a single branch,the extensors of the thigh were usually sup- plied by many branches.In each muscle group,the number of the muscular branches to one or two muscles was always larger than that to the others.The largest and most powerful muscle (or muscles) received most nerve supply. The order of origin of the muscular branches to a muscle in each muscle group was usually fixed.The muscle of high origin received earlier branch from the trunk.The muscle of superficial position seemed to enjoy the similar previlege as that of higher origin.Thus in the anterior muscle group of the thigh,the branch to the sartorius came out first,branch to the rectus femoris the next,then followed by that of the vastus inter- medius the vastus lateralis and the vastus medialis;This order corresponds to the se- quence generation of the peripheral nerves after injury.