845 published articles
The inferior margin of the vomer has been found in the intermaxillary suture, participating with the palatine bones in the formation of the hard palate. The vomer may be separated from the perpendicular plate of the ethmoid by a strip of cartilage from the nasal septum. The vomer may be fenestrated.
Eggemann and Inke (1963) cited by Lang (1983) reported that the greatest depth of the Sella Turcica was 8 mm with a range of 4 to 12 mm. The average depth was 6.85 mmin Europids; 7.03 mm in Mongolids, and 6.93 mm in Nigrids. The average length of the sella is 10.5 mm and a range of 5 - 16 mm and an average width of 14.0 mm and a range of 10 - 16 mm. The Sellar spine was first described by Lang (1977). The bony spine was 4.35 mm long and protruded from the dorsal side of the pituitary fossa into the fossa itself .
The number of ribs may be increased by addition at either the cervical or lumbar end of the series. It is extremely rare to find an additional rib or pair of ribs in both the cervical and lumbar regions at the same time. Eight true ribs have been observed. The first rib may be shorter than usual, slender and connected with the second costal cartilage. The number of ribs may also be decreased. The first rib is occasionally absent. It may be absent on one (or both sides) and shortened or hypoplastic on the other side.
Studies (see references) have shown that the stapes exhibits show marked variations. The head diffcrs in the prominence of its margins, shape of the articular facet and degree of inclination in relation to crural arches. No correlation can be made between the length of the stapcs and its weight. There may be a better relationship between breadth and weight of the ossicle. In the majority of cases, the posterior crus was found to be thicker, larger, and more curved than the anterior crus.
The first lumbar, instead of the twelfth thoracic vertebra, may present the transitional form of articular process. A lumbar rib may be present, united with the ventral surface of the transverse process or the tip of a short transverse process. The accessory rib may be elongated but is usually rudimentary. Lumbar ribs are less important clinically than cervical ribs and are usually mere rudiments An extra levator costae muscle is associated with a lumbar rib. In 559 skeletons of the Washington University collection, 8.8% had lumbar ribs (Lanier, 1944).
The number of vertebrae in the sacrum may be increased by fusion of the first coccygeal, by (less often) addition of the last (fifth) lumbar, or by addition of both the last lumbar and first coccygeal vertebrae. The number may be reduced to four by the "lumbarization" of the first sacral vertebra. In one study of 631 bodies, the sacrum was composed of five vertebrae in 77%, six in 21.7%, four in 1%, and seven in 0.2%.
References: Takata, G. (1922) On the value of bones as diagnostic material of fetal age. Folia Rnat. Japon. l(l):63-68.
According to Lang (1991) Blumenbach called sutural bones "gusset bones" because they are often situated like "patches" stitched into place between actual sutural lines. It is incorrect to call these wormian bones (for the description by Ole Worm (1588-1654), the anatomist), having been described about 100 years earlier by Paracelsus (Lang, 1991). Nearly 40% of skulls have sutural bones in the vicinity of the lambdoidsuture. Frequencies as high as 90% have been reported. Berry found sutural bones in 19th century Londoners in the vicinity of the lambda in 28.7% of men and 17.1% of women.
In a study of 433 knee joints, the menisci were found to be "C"-shaped in 422, discoid in nine, and circular in two. The medial meniscus may not be "C"-shaped but rather a ring completed by a ligament. In 140 knees, a menicofemoral ligament was present in 99 (71%). In 50 cases (36%) the ligament was the anterior meniscofemoral and in the remaining 49 cases (35%) it was the posterior meniscofemoral ligament. In 17 cases (12%) the anterior ligament was bilateral, in 12 cases (8%) the posterior was bilateral, and in two cadavers both ligaments were found in both knees.
In a study of 184 cartilages, 38% had a foramen in the lamina. In 90% of these, blood vessels were transmitted and in 50% nerve fibers as well. The nerve may be a branch of the superior laryngeal (vagus nerve) which may anastomose with the internal laryngeal (also a branch of the vagus nerve). A sesamoid cartilage has been reported in the superior (false) vocal fold. Thyroid Cartilage
Table 1 Paired Foramina Foramen Average Size (mm) Largest Size (mm) Smallst Size (mm) Anterior Ethmoid 2.27 x 1.14 8 x 3 0.64 x 0.64 Carotid Canal 7.13 x 5.29 12 x 5 5.5 x 4 Foramen Ovale 7.11 x 3.60 8 x 7 5 x 2 Foramen Rotundum 3.26 x 2.66 4.5 x 3.5 2 x 2 Foramen Spinosum 2.39 x 1.96 4 x 3 1 x 1 Greater Palatine 4.01 x 2.16 8 x 3 1.67 x 1.67 Hiatus for the Greater Petrosal 0.77 x 0.68 3 x 2 0.3 x 0.3 Hiatus for the Lesser Petrosal 0.37 x 0.37 0.83 x 0.83 0.3 x 0.3 Hypoglossal (Exocranial) 4.66 x 3.21 7.5 x 5 2 x 0.92 Infraorbital Foramen 3.42 x 2.40 6 x 4 1.67 x 1.67 Innominate 2.13 x 1.1 4 x…
The foramina of the zygomatic bone that transmit branches of the zygomatic nerve are often subject to variation in number and position. A bipartite zygomatic (os japonicum or os ainoicum) has frequently been observed. The incidence in Japanese is 7%, hence the name, and in other ethnic groups 2.5-6.5%. A zygomatic bone may also be tripartite, possessing extra sutures and accessory bones.
The two lateral halves of the sternum may fail to unite and thereby form a cleft sternum (so-called fissura sterni). In other cases, the union of the two halves occurs in the manubrial region but fails distally. The cranial and caudal parts may be fused but the intermediate part remains separate. The failure to fuse can be very slight or very extensive and is sometimes accompanied by ectopia cordis. A more common variation in the sternum is asymmetry of the costal cartilages, which may articulate in an alternating pattern.
The superior part of the dorsum sellae may be a separate bone or it may be joined to the petrous portion of the temporal bone. According to Bruneton, et al. the floor of the sellae may be concave (58% of patients), flat (32-35%), or convex (9.5%). A bridge of bone joining the anterior and posterior clinoid processes is reported to occur in 5% of individuals studied. In another study of 157 skulls, the frequency was 0.64%. Vesalius was the first to describe and illustrate the foramen that bears his name (foramen vesalii).
The scapular notch is frequently bridged by bone rather than a ligament (5% of cases studied), converting it into a foramen which is normal in some animals. Accessory notches may be present; one frequently is found on the inferior angle. The acromion may fail to unite. In about 5% of individuals (more commonly males), the separate part (os acromion) is on the right side. Fascicles of the subclavius muscle may be inserted onto the coracoid process by passing through the clavipectoral fascia. The tendon of m.
Congenital absence (partial or complete) of the radius with normal hand development or with absence of the thumb has been reported. A sesamoid bone may develop in the bicipital tendon over the radial tuberosity. The congenital bilateral absence of the radius in identical twins has been recorded. Congenital absence (partial or complete) of the ulna has also been reported. The ulna may only be represented by an olecranon-like vestige. A sesamoid bone is occasionally contained within the tendon of the triceps muscle proximal to the olecranon.
The spheno-palatine notch of the palatine bone is frequently replaced by a foramen. This spheno-palatine foramen may be doubled. The size of the orbital process is quite variable. The horizontal plate of the palatine bone may contain a portion of the maxillary sinus. The lesser palatine canal is frequently absent. It may also be located between the palatine and maxillary bones. A longitudinal ridge of the bony palate, torus palatinus, may be present in the region of the median palatine suture and extends laterally from it.
Nasal bones may be reduced in size with a concavity of the lateral margins. This is frequently accompanied by expansion of the frontal process of the maxillae. Nasal bones are rarely absent, but are frequently assymmetric. A process of the forntal bone may extend between the nasal bones and the frontal process of the maxilla. There may be only one nasal bone (unpaired) or there may be several. Internasal bones have been found at the edge of the nasal bones at the upper corner of the pyriform aperature, lying on the anterior tip of the perpendicular plate of the ethmoid.
