Anatomical Study On The Entrapment Of The Ulnar Nerve At The Wrist And The Structure Of Guyon's Canal

Objective: To investigate the microsurgical anatomy of the ulnar nerve cannal at the wrist and to confirm the course,distribution and the relationship with the structure of the nerve and blood vessel of the ulnar nerve cannal and analyse the important structure quantitatively.To approach the protection and location mark of the nerve and blood vessel of the ulnar nerve cannal and provide an anatomic basis for clinic surgery.Methods: Microsurgical Anatomic study was done on both sides of 20 antiseptic adult cadavers with 5-times operation microscope,the feature of the nerve and blood vessel of which and the relationships with ulnar nerve canal at the wrist structures were observed.Results:1.The longth of the ulnar nerve canal is (18.86±3.09)mm;The external diameter from left to right is (6.76±1.82)mm;The external diameter from anterior to posterior is (7.13±2.37)mm.2.The external diameter from left to right of ulnar nerve in the ulnar canal at the wrist is (3.60±0.7)mm;The external diameter from anterior to posterior of ulnar nerve in the ulnar canal at the wrist is (2.7±0.5)mm.3.The deep branches of ulnar nerve are derived from the superior,lateral,inferior of the pisiform bone.4.The external diameter of ulnar artery in the ulnar canal is (2.17±0.20)mm.5. There were three types of crossing relationships between the ulnar artery and the ulnar nerve: (1)nutrient vessels of muscle of hypothenar originated from ulnar artery crossed over profundus nervi ulnaris;(2)the deep branch of the ulnarartery crossed over the superficial branch of the ulnar nerve;(3)the deep branch of the ulnar artery over the superficial and deep branch of the ulnar nerve.Conclusions: 1.Through the microdissection of wrist cubital nerve cerebromedullary tube ,we can have an intimate knowledge of the interrelationship of its inter-structure and relative position between it and its adjacent structure, prevent injurying endotube structure,be helpful to dealing the operation of anterior region of wrist and identifying its structure, be helpful to preoperative design and application of operation.2.Wrist cubital nerve cerebromedullary tube have 4 parieses: The copular part is consist of ligament capivolare,ligament carpi volare,ulnaris , cubitalis anterior.The basal part is consist of ligament carpi transversum and ligament pisohamatum。But,it separate into proximum extreme and distally extreme .The medial wall is consist of radialis of lenticular bone of hand and cubitalis anterior superior part.The lateral wall proximal end is consist of ligament carpi volare and ligament carpi transversum fusion.The distal end is consist of hamular process of unciform bone.3.The reason of block and press of wrist cubital nerve possibly is surgical trauma ,vocational factor,paraplasm of cubital nerve tube wall,abnormality of UN ,congenital deformity of cubital nerve.4.The block and press position of wrist profundus nervi ulnaris is muscle of hypothenar and digitus minimus opponens musculotendinous cuff.Borderline keen antithenar arcus tendineus may directly compress the profundus nervi ulnaris.musculus opponens digiti minim spatium intermusculare is consist of low mobility muscle aliens punctum and bone tissue,when increase the inerpression, it will cause the compression to profundus nervi ulnaris.5.In the inside of UN cerebromedullary tube,the branches of ulnar artery step over the ramus superficialis nervi ulnaris and deep branch。The three kinds of crossing relationship of cubital nerve and arteria ulnaris can cause the compression to cubital nerve and clinic symptom.