Articulations
Synarthrosis, or immoveable
Amphiarthrosis, or mixed
Diarthrosis, or moveable
Kinds of movement
Articulations of the trunk
The vertebral column
The atlas with the axis
The atlas with the occiptal bone
The axis with the occiptal bone
Tempoko-maxillart articulation
The ribs with the vertebras
The cartilages of the ribs with the sternum
Ligaments of the sternum
The pelvis with the spine
The pelvis
Articulations of the upper extremity
Sterno-clavicular articulation
Scapulo-clavicular articulation
Proper ligaments of the scapula
Shoulder joint
Elbow joint
Radio-ulnar articulations
Whist joint
Articulations of the carpus
Capro metacapral articulations
Metacarpo-phalangeal articulations
Articulations of the phalanges
Articulations of the lower extremity
Hip joint
The knee joint
Articulations between the tibia and fibula
Ankle joint
Articulations of the tarsus
Tarso-metatarsal articulations
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The different segments of the vertebral column are connected together by ligaments, which admit of the same arrangement as the vertebrae themselves. They may be divided into five sets. I. Those connecting the bodies of the vertebrae. 2. Those connecting the lamina. 3. Those connecting the articular processes. 4. The ligaments connecting the spinous processes. 5. Those of the transverse processes.
The articulation of the bodies of the vertebrae with each other, form a series of amphiarthrodial joints; whilst those between the articular processes form a series of arthrodial joints. 1. THE LIGAMENTS OF THE BODIES ARE Anterior Common Ligament, Posterior Common Ligament, Intervertebral Substance. The Anterior Common Ligament (fig. 107) is a broad and strong band of ligamen-tous fibres, which extends along the front surface of the bodies of the vertebrae, from the axis to the sacrum. It is broader below than above, and thicker in the dorsal than in the cervical or lumbar regions. It is attached, above, to the body of the axis by a pointed process, which is connected with the tendon of origin of the Longus colli muscle; and, as it descends, is somewhat broader opposite the center of the body of each vertebra, than opposite the intervertebral substance. It consists of dense longitudinal fibres, which are intimately adherent to the intervertebral substance and prominent margins of the vertebrae; but less closely with the centre of the bodies. In this situation the fibres are exceedingly thick, and serve to fill up the concavities on their front surface, and to make the anterior surface of the spine more even. This ligament is composed of several layers of fibres, which vary in their length, but are closely interlaced with each other. The most super- ficial or longest fibres extend between four or five vertebrae. A second subjacent set extend between two or three vertebrae; whilst a third set, the shortest and deepest, extend from one vertebra to the next. At the sides of the bodies, this ligament consists of a few short fibres, which pass from one vertebra to the next, separated from the median portion by large oval apertures, for the passage of vessels. The Posterior Common Ligament is situated within the spinal canal, and extends along the posterior surface of the bodies of the vertebrae, from the body of the axis above, where it is continuous with the occipito-axoid ligament, to the sacrum below. It is broader at the upper than at the lower part of the spine, and thicker in the dorsal than in the cervical or lumbar regions. In the situation of the intervertebral substance and contiguous margins of the vertebras, where the ligament is more intimately adherent, it is broad, and presents a series of dentations with intervening concave margins; but it is narrow and thick over the centre of the bodies, from which it is separated by the vena basis vertebrae. This ligament is composed of smooth, shining, longitudinal fibres, denser and more compact than the anterior ligament, and composed of a superficial layer occupying the interval between three or four vertebrae, and of a deeper layer, which extends between one vertebra and the next adjacent to it. It is separated from the dura mater of the spinal cord by some loose filamentous tissue, very liable to serous infiltration. The Intervertebral Substance (fig. 99) is a lenticular disc of fibro-cartilage, interposed between the adjacent surfaces of the bodies of the vertebras, from the axis to the base of the sacrum. These discs vary in shape, size, and thickness, in 
different parts of the spine. In shape they accurately correspond with the surfaces of the bodies between which they are placed, being oval in the cervical and lumbar regions, circular in the dorsal. Their size is greatest in the lumbar region. In thickness they vary not only in the different regions of the spine, but in different parts of the same region: thus, they are uniformly thick in the lumbar region; thickest in front in the cervical and lumbar regions which are convex forwards, and behind, to a slight extent, in the dorsal region. They thus contribute, in a great measure, to the curvatures of the spine in the neck and loins; whilst the concavity of the dorsal region is chiefly due to the shape of the bodies of the vertebra. The intervertebral discs form about one-fourth of the spinal column, exclusive of the first two vertebrae; they are not equally distributed, however, between the various bones; the dorsal portion of the spine having, in proportion to its length, a much smaller quantity than in the cervical and lumbar regions, which necessarily gives to the latter parts greater pliancy and freedom of movement. The intervertebral discs are adherent, by their surfaces, to the adjacent parts of the bodies of the vertebrae; and by their circumference are closely connected in front to the anterior, and behind to the posterior common ligament; whilst in the dorsal region they are connected laterally to the heads of those ribs which articulate with two vertebrae, by means of the inter-articular ligament; they consequently form part of the articular cavities in which the heads of these bones are received.
The intervertebral substance is composed, at its circumference, of laminae of fibrous tissue and fibro-cartilage; and at its centre of a soft, elastic, pulpy matter. The laminae are arranged concentrically one within the other, with their edges turned towards the corresponding surfaces of the vertebrae, and consist of alternate plates of fibrous tissue and fibro-cartilage. These plates are not quite vertical in their direction, those near the circumference being curved outwards and closely approximated; whilst those nearest the centre curve in the opposite direction, and are somewhat more widely separated. The fibres of which each plate is composed, are directed, for the most part, obliquely from above downwards; the fibres of an adjacent plate have an exactly opposite arrangement, varying in their direction in every layer; whilst in some few they are horizontal. This laminar arrangement belongs to about the outer half of each disc, the central part being occupied by a soft, pulpy, highly elastic substance, of a yellowish colour, which rises up considerably above the surrounding level, when the disc is divided horizontally. This substance presents no concentric arrangement, and consists of white fibrous tissue, having interspersed cells of variable shape and size. The pulpy matter is separated from immediate contact with the vertebras, by the interposition of thin plates of cartilage. 2. LIGAMENTS CONNECTING THE LAMINAE. Ligamenta Subflava. The Ligamenta Subflava are interposed between the lamina of the vertebrae, from the axis to the sacrum. They are most distinct when seen from the inner surface of the spine; when viewed from the outer surface, they appear short, being overlapped by the laminae. Each ligament consists of two lateral portions, which commence on each side at the root of either articular process, and pass backwards to the point where the laminae converge to form the spinous process, where their margins are thickest, and separated by a slight interval, filled up with areolar tissue. These ligaments consist of yellow elastic tissue, the fibres of which, almost perpendicular in direction, are attached to the anterior surface of the margin of the lamina above, and to the posterior surface, as well as to the margin of the lamina below. In the cervical region, they are thin in texture, but very broad and long; they become thicker in the dorsal region; and in the lumbar acquire very considerable thickness. Their highly elastic property serves to preserve the upright posture, and to counteract the efforts of the Flexor muscles of the spine. These ligaments do not exist between the occiput and atlas, or between the atlas and axis. 3. LIGAMENTS CONNECTING THE ARTICULAR PROCESSES. Capsular. Synovia! Membranes. The Capsular Ligaments are thin and loose bags of ligamentous fibre attached to the contiguous margins of the articulating processes of each vertebra, through the greater part of their circumference, and completed internally by the liga-menta subflava. They are longer and more loose in the cervical than in the dorsal or lumbar regions. The capsular ligaments are lined on their inner surface by a delicate synovial membrane. 4. LIGAMENTS CONNECTING THE SPINOUS PROCESSES. Inter-spinous. Supra-spinous. The Inter-spinous Ligaments, thin and membranous, are interposed between the spinous processes in the dorsal and lumbar regions. Each ligament extends from the root to near the summit of each spinous process, and connects together their adjacent margins. They are narrow and elongated in the dorsal region, broader, quadrilateral in form, and thicker in the lumbar region. The Supra-spinous Ligament is a strong fibrous cord, which connects together the apices of the spinous processes from the seventh cervical to the spine of the sacrum. It is thicker and broader in the lumbar than in the dorsal region, and intimately blended, in both situations, with the neighbouring aponeuroses. The most superficial fibres of this ligament connect three or four vertebras; those deeper seated pass between two or three vertebrae; whilst the deepest connect the contiguous extremities of neighbouring vertebras. 5. LIGAMENTS CONNECTING THE TRANSVERSE PROCESSES. Inter-transverse. The Inter-transverse Ligaments consist of a few thin scattered fibres, interposed between the transverse processes. They are generally wanting in the cervical region; in the dorsal, they are rounded cords; in the lumbar region, thin and membranous. The two upper vertebrae, the Atlas and Axis, are connected together by ligaments distinct from those by which the rest are united. |