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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…
L’osso zigomatico varia per numero e posizione dei suoi forami e può essere bipartito (os japonicum o os ainoicum) o tripartito, con suture soprannumerarie e ossa accessorie; può inoltre partecipare o meno alla formazione della fessura orbitaria inferiore.
Le due metà laterali dello sterno possono non unirsi, dando origine a uno sterno bifido (cosiddetta fissura sterni); altre variazioni comprendono l’asimmetria delle cartilagini costali, gli ossicini soprasternali, le perforazioni del corpo e la variabilità del processo xifoideo.
L’osso sfenoide presenta numerose variazioni dei propri forami e canali — forame di Vesalio, forame pterigospinoso e pterigoalare, forame spinoso assente o duplicato, ponti ossei carotico-clinoidei — oltre a un’ampia variabilità di forma, dimensione ed estensione del seno sfenoidale.
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.
In the maxilla, the inferior wall of the infraorbital canal may be incomplete, and hence the infraorbital nerve is in contact with the mucosa of the maxillary sinus. In about 5% of skulls, the infraorbital groove is present as a canal. Two or more infraorbital foramina have been reported. The infraorbital foramen may lie anywhere from 3 to 7 mm below the infraorbital margin. Occasionally, a bony spine covers the foramen. The infraorbital canal (groove) may be shifted laterally as far as the suture between the maxilla and zygomatic bones.
The mandible shows extensive variation in size and weight during an individual's lifetime. The chin may protrude or recede; there may be one rather than two mental tubercles. Although the coronoid and condylar processes vary in size and form, they are rarely united by sutures with the ramus (subcoronoid and subcondyloid sutures). The condylar processes may be doubled. In some individuals, the two halves of the jaw fail to co-ossify. The mental foramen may be doubled or tripled.
The lacrimal bone may be divided into two or more parts or fused with neighboring bones. This bone may exhibit so many minute foramina that it takes the appearance of a bony net. It may be fused with or divided by the lamina papyracea. A contribution from the frontal bone has been reported. The pars lacrimalis may be deficient and this may be filled by the frontal process of the maxilla. In some cases the crest is reduced in size or absent. The hamulus may be absent, represented by a fibrous band, or be unusually long.
The hip bone or os coxae is not subject to great variation: however, relatively few pelves are easily classified as male or female. A canal may groove the iliac fossa, transmitting a vein that connects the external pelvic and internal pelvic veins. Conversion of the obturator sulcus (or groove) into a bony foramen has been reported. Defect or nonunion of the pubic and ischial rami is occasionally observed.
La regione interparietale del cranio può restare separata per tutta la vita, dando l’osso interparietale o osso degli Incas. Raramente il parietale è composto da due o più parti separate da suture, e i forami parietali possono essere assenti o assai ampi.
The articular surface of the occipital condyles may possess a transverse ridge of cartilage that corresponds to a groove on the articular surface of the atlas, or notches at the margin may partly divide the condyle in two parts. A shallow fossa is occasionally found on the ventral surface of the basilar portion anterior to the pharyngeal tubercle, which has been interpreted as a vestige of the canal of the notochord. Precondylar tubercles, unilateral or bilateral, just anterior to the anterior margin of the foramen magnum, were found in 10% of 1527 skulls (Broman).
L’osso temporale varia per persistenza di suture fetali, estensione e asimmetria delle cellule mastoidee, forma del processo mastoideo e del canale carotico. Il processo stiloideo varia marcatamente in lunghezza, può essere composto da più ossicini o mancare, e anche gli ossicini dell’udito mostrano variazioni.
I seni frontali possono essere assenti, piccoli o assai ampi, e la sutura metopica può persistere con frequenze variabili dall’1 al 12% dei crani. Sono descritte inoltre l’iperostosi frontale interna, quasi esclusiva delle donne, e la presenza di una spina frontale.
La tibia può mancare e presentare platicnemia, retroversione dell’estremità prossimale, faccette articolari aggiuntive e un canale osseo distale. L’assenza del perone è stata registrata frequentemente e le variazioni principali riguardano forma e dimensioni relative delle superfici del corpo.
Il femore può mancare, in tutto o nel solo corpo, e presentare un terzo trocantere, una fossa ipotrocanterica o un processo sopracondiloideo. La rotula è talvolta bipartita e ne è stata riportata l’assenza congenita.
Le variazioni dell’etmoide comprendono la riduzione della lamina orbitaria, la sua suddivisione da parte di fissure verticali e la formazione di ossicini accessori. È comune un aumento del numero dei cornetti nasali, e il numero dei forami etmoidali si discosta spesso dai due canonici.
