Anatomical variations of the abducent nerve in humans

Anatomical variation of the nervus abducens in human encephali were found and described. They consisted of (1) an unusual trifurcation of the abducent nerve, limited to the extradural portion of the neural trunk (1.4% of the cases) and (2) the duplicity (11.1%) of the neural trunk, starting before reaching the orbit and ending before reaching the m. rectus lateralis. The possibility of correlating these variations with clinical aspects and forensic interpretations is mentioned.     

Anatomical variations of the arterial pattern in the right hemiliver

The arterial supply to the right hemiliver was studied in 80 liver casts. The arteries were divided into 10 groups according to their origin and branching pattern. The right hemiliver was supplied by one artery in 96% of cases and by two arteries in 4%. When there was only one artery it originated from the proper hepatic artery in 73/77 cases and from the superior mesenteric artery in 4/77 cases. The replacing right hepatic artery which originated from the superior mesenteric vessel supplied the whole right hemiliver in 5% of cases. The incomplete replacing right hepatic artery which supplied only a part of the right hemiliver was found in 4% of cases. The anterior section (segments 5 and 8) was supplied by one artery in 61%, by two arteries in 30% and by three arteries in 9% of cases. The posterior section (segments 6 and 7) was supplied by one artery in 66%, by two arteries in 31% and by three arteries in 3% of cases. Segments 5 and 7 were predominantly supplied by one artery, whereas segments 6 and 8 by two arteries.     

Anatomical variations of the arterial pattern in the left hemiliver

The arterial supply to the left hemiliver was studied in 70 liver casts. The arteries were divided into 15 groups according to their origin and branching pattern. The left hemiliver was supplied by one artery in 53% of cases, by two arteries in 40% and by three arteries in 7%. The left hepatic artery, which originated from the proper hepatic artery, supplied all three left segments in 39% of specimens. The replacing left hepatic artery, which originated from the left gastric artery, supplied the whole left hemiliver in 3% of cases. The incomplete, replacing left hepatic artery supplied segments 2, 3 and a part of segment 4 in 6% of cases, and only segments 2 and 3 in 11%. There was one segmental artery for segment 2 in 86%, and two in 14%. Segment 3 was supplied by one artery in 87%, and by two in 13%. Segment 4 was supplied by one artery in 39% of cases, by two arteries in 43%, by three in 14% and by four arteries in 4%.     

Anatomical variations of the intracavernous branches of the internal carotid artery with reference to the relationship of the internal carotid artery and sixth cranial nerve. A microsurgical study

Thirty cavernous sinuses were dissected and examined using microsurgical methods under a magnification of X10 and X16. The anatomical variations of the intracavernous branches of the internal carotid artery (ICA) and the anatomical relationship of the sixth nerve with the ICA are described and discussed in relation to the findings from other microsurgical works.     

Benign missense variations in the cystic fibrosis gene.

The common mutation causing cystic fibrosis is a deletion of phenylalanine 508 (delta F508), which occurs in a putative nucleotide-binding fold of the gene product. We report two additional mutations, substitution of cysteine for phenylalanine 508 (F508C) and substitution of valine for isoleucine 506 (I506V). Three compound heterozygous persons, two delta F508/F508C and one delta F508/I506V, had normal clinical and epithelial physiological studies indicating that the F508C and I506V mutations are benign. This opportunity to study the in vivo function of these mutations suggests that amino acid substitutions are more benign than changes in the length of this portion of the putative nucleotide-binding fold. These mutations must be taken into account when performing molecular diagnosis and carrier detection for cystic fibrosis.     

Avoiding facial nerve injuries in rhytidectomy. Anatomical variations and pitfalls

Injury to the facial nerve in rhytidectomy has been occurring in less than one percent of the cases, and a spontaneous return of function in more than 80 percent of these injuries has resulted within 6 months. With the introduction of the newer and more aggressive techniques of platysmal and subplatysmal flaps and SMAS dissections, the risk of injury to facial nerve branches is obviously increased. Though there has not yet been an increase in the facial nerve injuries reported, these techniques are still relatively recent additions to the face-lift operation-and usually they have been done by more experienced surgeons, taking more time and working under direct vision with a more careful dissection. More care is needed to prevent injuries. We discuss here the detailed anatomy of the muscular branches of the facial nerve, how to prevent injuries to them during rhytidectomy, and how to manage injuries when they do occur.     

Anatomical variability of the left gastric artery and vein in newborn infants]

Structural variants of the left gastric artery (LGA) and left gastric vein (LGV) in newborns have been studied on 93 preparations of the stomach with ++extra-organic arteries and on 90 preparations of the stomach with ++extra-organic veins. There is certain correlation between the length of the trunk and character of branching of the LGA. A branch of the LGA, running to the posterior surface of the cardial part in the upper part of the gastric body, which is not described in the literature, has been found. Rather often in newborn children from the iliac trunk instead of the LGA, a left gastro-hepatic trunk has got off. The number of tributaries from the posterior surface of the gastric body to the LGV is found to be significantly greater than the number of tributaries from the anterior surface of the gastric body to this vein.     

Experimentally induced variations in vitelline artery development and circulatory pattern in the early chick embryo

White Leghorn eggs were incubated to desired prevasular stages. Each embryo, upon its intact yolk and surrounded by albumen, was rolled from the shell into a sterile 50 ml beaker. In an uppermost position, the blastoderm was lightly stained with neutral red. Three types of localized cuts were made as indicated below, and the beaker-embryo unit placed in a sterile humidified chamber for further incubation. Results: (1) Unilateral cuts adjacent to the body and parallel with its axis blocked or suppressed formation of the vitelline artery on the cut side, even though healing occurred; (2) A specific site was found in the area pellucida opposite the sinus rhomboidalis which, when lightly cut perpendicular to the body axis, resulted in blockage or shifting of the final junction between aorta and vitelline artery as far cephalad as the thirteenth somite level. Formation of a dual final junction with the aorta also occurred. (3)Transverse cuts through the body axis and into the area pellucida bilaterally, frequently resulted in bilateral blockage or bilateral shifting. In still other cases, growth of a functional loop around the cut to connect the aortae in anterior and posterior segments with the vitelline artery were observed. Other unique circulatory patterns are described. Apparently, slight interference with the capillary plexus which precedes the vitelline artery causes anomalous development. Circulation is considered a major factor in arterial differentiation. Cutting probably alters the plexus and relation of its components to the onset of blood flow.