Foramen

“ It presents the form of a cup perforated by a small foramen, through which a ligament passes from the tip of the odontoid process to the occipital condyle, and the part of the cup which lies above the foramen is formed by a transverse ligament. This transverse ligament corresponds to those which pass from side to side of the bodies of other vertebræ and are attached to the superior angles of their anterior aspects—those angles which are derived from the arches. [2] Now, in mammalia, not only is the function of the tranverse ligament of the atlas the same as in birds ”

“ Each lesser wing is prolonged back into a tongue-like process, the anterior chnoid process, just internal to which is the optic foramen (fig. 5, 11) , and the two foramina are joined by the optic groove for the optic commissure. Behind this groove is a transverse elevation, the olivary eminence (22) , which marks the junction of the pre- and basi- sphenoid parts of the body of the sphenoid bone.
The middle cranial fossa is like an hour-glass placed transversely, as there is a central constricted, and two lateral expanded, parts. ”

“ The seventh nerve (facial) is almost entirely motor; it passes through the periotic anterior to VIII., and emerges by the stylo-mastoid foramen (s.m.f.) behind the bulla, to run outside the great jaw muscle across the cheek immediately under the skin (Figure 1) .
Section 129. The ninth (glossopharyngeal) nerve is chiefly sensory; it is the special nerve of taste, and is distributed to the tongue. The tenth nerve (vagus) arises by a number of roots, and passes out of the skull, together with IX and XI, by the foramen lacerum -posterium- [posterius] (f.l.p.) ”

“ The anterior region, as is the laminal surface, is covered with foraminæ; in this case more minute. In the recent state it is covered by the sensitive sole. The posterior region, lying immediately behind the semilunar crest, shows on each side of a median process a large foramen, the Plantar Foramen. From this foramen runs the Plantar Groove, a channel, bounded above by the superior edge, and below by the semilunar crest of the bone, which conducts the plantar arteries into the Semilunar Sinus, a well-marked cavity in the interior of the bone. ”

“ Rami musculares.—Muscular branches are given off near the supracondyloid foramen to the biceps (4) , epitrochlearis (6) , and brachialis muscles. A nutrient artery leaves [297] the brachial proximad of the supracondyloid foramen, either separately or in common with the muscular branches, and passes into the nutrient foramen at the junction of the middle and distal thirds of the shaft of the humerus, supplying the bone. ”

“ Even when, as is sometimes the case, this branch of the human occipital artery passes right through the mastoid foramen, and actually reaches the dura mater, yet a comparison of the diameter of the artery as it enters, with that of the artery as it makes its exit through the foramen, will show a very striking difference in size; the artery, as it makes its appearance at the inner side of the mastoid foramen, not having half the diameter that it possessed on its entrance into the foramen, and, even in these cases, it sends a very considerable off-shoot to the diplöe. ”

“ All of these particulars having been recognized by the senses, it is manifest that the blood passes through the lungs, not through the septum [in its course from the right to the left side of the heart] , and only through them when they are moved in the act of respiration, not when they are collapsed and quiescent; whence we see the probable reason wherefore nature has instituted the foramen ovale in the fœtus, instead of sending the blood by the way of the pulmonary artery into the left auricle and ventricle, which foramen she closes when the new-born creature begins to breathe freely. ”

“ When the parietals are articulated there is left between the tentoria a large foramen by means of which the two fossæ communicate. The foramen is bounded laterally and dorsally by the free margins of the tentoria, while the ventral end of each tentorium articulates with the alisphenoid, and its dorsal end with the opposite tentorium.
The medial border is straight and is united by suture to the opposite bone. ”

“ Each lateral mass bears at its cranial end on its medial surface a concave, pear-shaped facet, cranial (or superior) articular facet, (Fig. 12, e) for articulation with the condyles of the skull. These facets look craniomediad. Dorsad of each is a foramen, the atlantal foramen (Fig. 10, i; Fig. 12, g) , which pierces the dorsal arch at its junction with the lateral mass. Caudal to the facet, on the medial face of each lateral mass, within the vertebral canal, is a tubercle. ”

“ On its inner side opening ventro-anteriorly is the fenestra ovalis, opening ventro-posteriorly the internal auditory meatus (Fig. 23, VIII) , while dorsally there is a wide opening [74] which forms a communication through the roof of the brain case with the tympanic cavity of the other side. On its posterior wall is the prominent foramen through which the facial nerve passes on its way to its final exit from the skull through the exoccipital; this foramen is bounded by the quadrate, squamosal, and exoccipital. ”

“ Weight, 3.6 grams; basilar length, 43.5; zygomatic breadth less than distance between condylar foramen and M1 and more or less than (in the single specimen, equal to) that between anterior palatine foramen and anterior margin of tympanic bulla; least width of palate more or less than (about equal to) outside length of P4; tympanic bulla as far posterior to foramen ovale as width of 4 or 5 upper incisors; height of tympanic bulla less than distance from its anterior margin to foramen ovale.
The skull of the female is 48 per cent lighter than that of the male. ”

“ The nerve is sensitive to pressure, the most tender points being its emergence from the greater sciatic foramen, the hollow between the trochanter and the ischial tuberosity, and where the common peroneal nerve winds round the neck of the fibula. ”

“ Six per cent. exhibit an anomaly which is extremely rare among normal individuals—the olecranon foramen, a perforation in the head of the humerus where it articulates with the ulna. This is normal in the ape and dog and is frequently found in the bones of prehistoric man and in some of the existing inferior races of mankind. ”

“ To reach the foramen rotundum (second division) —a rather more difficult procedure—it is necessary to find the posterior border of the orbital process of the malar bone, prolonging this line downwards to the lower border of the zygoma and inserting the needle 1⁄2 cm. posterior to this point. The needle is pushed horizontally inwards and the point directed slightly upwards, the foramen being reached in the pterygo-maxillary fossa at a depth of about 3 cm. from the zygoma. ”

“ Its occlusion may be effected by means of a sterilized wooden match or bone peg, by a small piece of bone derived from those osseous fragments which have been removed during the operation, or with [147] the aid of a piece of catgut; in each case the occluding medium should be well driven into the foramen. ”

“ The dorsal plane surface of the centrum is marked by a median longitudinal ridge on either side of which is an opening (nutrient foramen) for a blood-vessel. The ends are nearly plane, the caudal being slightly concave; they are harder and smoother than the other surfaces. They may be easily separated in a young specimen as thin plates of bone known as epiphyses.
Fig. 2.—Fourth Thoracic Vertebra, Cranial End.
Fig. 3.—Fourth Thoracic Vertebra, Side View.
a, vertebral foramen; b, centrum; c, caudal, and d, cranial, costal demifacets; e, radix or pedicle; f, lamina; g, transverse process ”

“ The Foramen Ovale and Septum of the Auricles.—In markedly deformed hearts the entire septum may be in greater or less degree wanting, as seen in cases of the bilocular or trilocular organ. This defect is comparatively rare, and the foetus has but a short extra-uterine life. In other cases the septum is complete, but the foramen may be unusually large, and remain unclosed wholly or in part ”

“ General thinning of intervertebral substance through a condition of disturbed metabolism itself produced through the agency of some one serious subluxation, may narrow all the foramina and increase impingement of nerves at any point where a slight subluxation previously existed. An irritated nerve may become swollen and the nerve impinged at the foramen. ”

“ When, in the human subject, a process of bone passes up from the arch of the atlas, to meet the superior articular surface and convert the groove for the nerve and vertebral artery into a foramen, the process in question is a true oblique process. ”

“ Between the slender process of the malleus and the region of the inferior dental foramen, the cartilage later on disappears and its fibrous sheath forms the long internal lateral or sphenomandibular ligament (see fig. 33, L.I.L) . ”

“ Slight subluxations may exist, because of the adaptation of surrounding parts and the slight play within the intervertebral foramen, without producing noticeable effect. They always, however, evidence a tendency to disease. ”

“ Fig. 16.—Under surface of the cranium of a Dog. × 1⁄2. apf, Anterior palatine foramen; as, posterior opening of alisphenoid canal; AS, alisphenoid; BO, basioccipital; BS, basisphenoid; cf, condylar foramen; eam, external auditory meatus; Ex.O, exoccipital; flm, foramen lacerum medium; flp, foramen lacerum posterius; fm, foramen magnum; fo, foramen ovale; fr, foramen rotundum; Fr, frontal; gf, glenoid fossa; gp, post-glenoid process; Ma, malar; Mx, maxilla; oc, occipital condyle; op, optic foramen ”

“ After the brain has been removed, the skin is stripped off a limited area of the skull, and the bone at the place of junction of the sagittal and lambdoid sutures above the occipital foramen is filed away, so that only a point, like a bony outgrowth, is left. ”

“ The large spongy ends also give elasticity and lessen jar, and by bringing the tendons to the bone at a greater angle increase their effectiveness. Blood is brought to the long bones not only by the vessels of the periosteum but by the medullary artery, which penetrates the compact tissue by the nutrient foramen and divides into an ascending and a descending branch. ”

“ That portion of the bone lying laterad of a line joining the medial borders of these two pairs of foramina is known as the lateral mass of the sacrum and is composed of the fused transverse processes of the sacral vertebræ. At the caudal margin of the ventral surface there is a notch between the lateral mass and the centrum (g) . When the caudal vertebræ are articulated, this notch helps to form a foramen for the third sacral nerve.
The dorsal surface (Fig. 6) is narrower at its cranial end than is the ventral surface. ”

“ If we examine the structures underlying the skin, we find that in the skull the orbits are entirely shut in by a bony wall, so that the finger cannot be passed into the temporal depression behind, as could be done in the Lemurine skull, and that the lachrymal foramen opens within the cavity for the eye. ”

“ The sculpturing of the internal surface of the cranial cavity bespeaks the high vascularity of the soft parts which it contained, and there are evident indications that the upper and lateral surfaces of the brain had been disposed in a few simple parallel longitudinal convolutions. The two anterior condyloid foramina (m) have the same relative position as the single corresponding foramen in the Glossothere, Orycterope, and Armadillos, and the inner surface of the skull slopes outwards from these foramina to the inner margin of the occipital condyle. ”

“ It consists of two layers, an outer fibrous and an inner cellular layer; the cells, which are called osteoblasts, are continuous with those lining the Haversian canals and the medullary cavity.
The arrangement of the blood vessels determines to some extent the incidence of disease in bone. The nutrient artery, after entering the medullary canal through a special foramen in the cortex, bifurcates, and one main division runs towards each of the extremities, and terminates at the ossifying junction in a series of capillary loops projected against the epiphysial cartilage. ”

“ Such, for instance, is the preservation in the adult of the foramen ovale between the auricles of the heart, or of the open ductus arteriosus by which blood of the pulmonary and body circulation may mingle. In case of the veins also an arrangement of vessels is often found in the adult which is due to the persistence of a truly embryonic condition. ”

“ We are told, and with perfect truth, that in man the occipital foramen--the aperture through which the brain is connected with the spinal cord--is so placed that the head is nearly in equilibrium when he stands upright. ”

“ Eight are cervical, thirteen thoracic, seven lumbar, three sacral, and seven or eight caudal. Those leaving the cervical (Fig. 133, 5-8 and I) and lumbar (Fig. 136) enlargements are larger than the others. The first cervical nerve leaves the vertebral canal through the atlantal [338] foramen, the second leaves between the arches of the atlas and axis, while all the others leave the vertebral canal by way of the intervertebral foramina. Each nerve arises from the cord by a dorsal and a ventral root. The dorsal root is chiefly sensory, the ventral motor in character. ”