Posterior longitudinal ligament
The posterior longitudinal ligament is situated within the vertebral canal, extends along the posterior surfaces of the bodies of the vertebrae, from the body of the axis, where it is continuous with the tectorial membrane of atlanto-axial joint, to the sacrum. It is broader above than below, thicker in the thoracic than in the cervical and lumbar regions; the ligament is more narrow at the vertebral bodies and wider at the intervertebral disc space, more pronounced than the anterior longitudinal ligament. This is significant in understanding certain pathological conditions of the spine such as the typical location for a spinal disc herniation. In the situation of the intervertebral fibrocartilages and contiguous margins of the vertebrae, where the ligament is more intimately adherent, it is broad, in the thoracic and lumbar regions presents a series of dentations with intervening concave margins; this ligament is composed of smooth, longitudinal fibers and more compact than those of the anterior ligament, consists of superficial layers occupying the interval between three or four vertebræ, deeper layers which extend between adjacent vertebrae.
It functions to prevent hyperflexion of the vertebral column. Anterior longitudinal ligament Intervertebral disc This article incorporates text in the public domain from page 288 of the 20th edition of Gray's Anatomy Atlas image: back_bone25 at the University of Michigan Health System - "Vertebral Column, Anterior & Posterior Views" lesson7 at The Anatomy Lesson by Wesley Norman - "Lateral Pharyngeal Region"
A synovial joint known as diarthrosis, joins bones with a fibrous joint capsule, continuous with the periosteum of the joined bones, constitutes the outer boundary of a synovial cavity, surrounds the bones' articulating surfaces. The synovial cavity/joint is filled with synovial fluid; the joint capsule is made up of an outer layer, the articular capsule, which keeps the bones together structurally, an inner layer, the synovial membrane, which seals in the synovial fluid. They are the most movable type of joint in the body of a mammal; as with most other joints, synovial joints achieve movement at the point of contact of the articulating bones. Synovial joints contain the following structures: Synovial cavity: all diarthroses have the characteristic space between the bones, filled with synovial fluid Joint capsule: the fibrous capsule, continuous with the periosteum of articulating bones, surrounds the diarthrosis and unites the articulating bones. Articular cartilage: the bones of a synovial joint are covered by this layer of hyaline cartilage that lines the epiphyses of joint end of bone with a smooth, slippery surface that does not bind them together.
Many, but not all, synovial joints contain additional structures: Articular discs or menisci - the fibrocartilage pads between opposing surfaces in a joint Articular fat pads - adipose tissue pads that protect the articular cartilage, as seen in the infrapatellar fat pad in the knee Tendons - cords of dense regular connective tissue composed of parallel bundles of collagen fibers Accessory ligaments - the fibers of some fibrous membranes are arranged in parallel bundles of dense regular connective tissue that are adapted for resisting strains to prevent extreme movements that may damage the articulation Bursae - saclike structures that are situated strategically to alleviate friction in some joints that are filled with fluid, similar to synovial fluidThe bone surrounding the joint on the proximal side is sometimes called the plafond in the talocrural joint. A damage to this occurs in a Gosselin fracture; the blood supply of a synovial joint is derived from the arteries sharing in the anastomosis around the joint.
There are six types of synovial joints. Some are immobile, but are more stable. Others at the expense of greater risk of injury. In ascending order of mobility, they are: The movements possible with synovial joints are: abduction: movement away from the mid-line of the body adduction: movement toward the mid-line of the body extension: straightening limbs at a joint flexion: bending the limbs at a joint rotation: a circular movement around a fixed point The joint space equals the distance between the involved bones of the joint. A joint space narrowing is a sign of either inflammatory degeneration; the normal joint space is at least 2 mm in the hip, at least 3 mm in the knee, 4–5 mm in the shoulder joint. For the temporomandibular joint, a joint space of between 1.5 and 4 mm is regarded as normal. Joint space narrowing is therefore a component of several radiographic classifications of osteoarthritis
The obturator membrane is a thin fibrous sheet, which completely closes the obturator foramen. Its fibers are arranged in interlacing bundles transverse in direction; the membrane is attached to the sharp margin of the obturator foramen except at its lower lateral angle, where it is fixed to the pelvic surface of the inferior ramus of the ischium, i. e. within the margin. Both obturator muscles are connected with this membrane; this article incorporates text in the public domain from page 476 of the 20th edition of Gray's Anatomy Anatomy figure: 17:03-11 at Human Anatomy Online, SUNY Downstate Medical Center lljoints at The Anatomy Lesson by Wesley Norman
Anterior longitudinal ligament
The anterior longitudinal ligament is a ligament that runs down the anterior surface of the spine. It traverses all of intervertebral discs; the ligament is thick and more narrow over the vertebral bodies and thinner but wider over the intervertebral discs, much less pronounced than that seen in the posterior longitudinal ligament. The ligament has three layers: superficial and deep; the superficial layer traverses 3 – 4 vertebrae, the intermediate layer covers 2 – 3 and the deep layer is only between individual vertebrae. Posterior longitudinal ligament intervertebral disc Atlas image: back_bone25 at the University of Michigan Health System - "Vertebral Column, Anterior & Posterior Views" lesson7 at The Anatomy Lesson by Wesley Norman Diagram at spineuniverse.com
The obturator canal is a passageway formed in the obturator foramen by part of the obturator membrane. It connects the pelvis to the thigh; the obturator artery, obturator vein, obturator nerve all travel through the canal. An obturator hernia is a type of hernia involving an intrusion into the obturator canal. Obturator fascia This article incorporates text in the public domain from the 20th edition of Gray's Anatomy
Apical ligament of dens
The ligament of apex dentis is a ligament that spans between the second cervical vertebra in the neck and the skull. It lies as a fibrous cord in the triangular interval between the alar ligaments, which extends from the tip of the odontoid process on the axis to the anterior margin of the foramen magnum, being intimately blended with the deep portion of the anterior atlantooccipital membrane and superior crus of the transverse ligament of the atlas, it is regarded as a rudimentary intervertebral fibrocartilage, in it traces of the notochord may persist. This article incorporates text in the public domain from page 296 of the 20th edition of Gray's Anatomy "Anatomy diagram: 25420.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01
The pelvis is either the lower part of the trunk of the human body between the abdomen and the thighs or the skeleton embedded in it. The pelvic region of the trunk includes the bony pelvis, the pelvic cavity, the pelvic floor, below the pelvic cavity, the perineum, below the pelvic floor; the pelvic skeleton is formed in the area of the back, by the sacrum and the coccyx and anteriorly and to the left and right sides, by a pair of hip bones. The two hip bones connect the spine with the lower limbs, they are attached to the sacrum posteriorly, connected to each other anteriorly, joined with the two femurs at the hip joints. The gap enclosed by the bony pelvis, called the pelvic cavity, is the section of the body underneath the abdomen and consists of the reproductive organs and the rectum, while the pelvic floor at the base of the cavity assists in supporting the organs of the abdomen. In mammals, the bony pelvis has a gap in the middle larger in females than in males, their young pass through this gap.
The pelvic region of the trunk is the lower part of the trunk, between the thighs. It includes several structures: the bony pelvis, the pelvic cavity, the pelvic floor, the perineum; the bony pelvis is the part of the skeleton embedded in the pelvic region of the trunk. It is subdivided into the pelvic spine; the pelvic girdle is composed of the appendicular hip bones oriented in a ring, connects the pelvic region of the spine to the lower limbs. The pelvic spine consists of the coccyx; the pelvic cavity defined as a small part of the space enclosed by the bony pelvis, delimited by the pelvic brim above and the pelvic floor below. Each hip bone consists of 3 sections, ilium and pubis. During childhood, these sections are separate bones, joined by the triradiate cartilage. During puberty, they fuse together to form a single bone; the pelvic cavity is a body cavity, bounded by the bones of the pelvis and which contains reproductive organs and the rectum. A distinction is made between the lesser or true pelvis inferior to the terminal line, the greater or false pelvis above it.
The pelvic inlet or superior pelvic aperture, which leads into the lesser pelvis, is bordered by the promontory, the arcuate line of ilium, the iliopubic eminence, the pecten of the pubis, the upper part of the pubic symphysis. The pelvic outlet or inferior pelvic aperture is the region between the subpubic angle or pubic arch, the ischial tuberosities and the coccyx. Ligaments: obturator membrane, inguinal ligament Alternatively, the pelvis is divided into three planes: the inlet and outlet; the pelvic floor has two inherently conflicting functions: One is to close the pelvic and abdominal cavities and bear the load of the visceral organs. To achieve both these tasks, the pelvic floor is composed of several overlapping sheets of muscles and connective tissues; the pelvic diaphragm is composed of the coccygeus muscle. These arise between the symphysis and the ischial spine and converge on the coccyx and the anococcygeal ligament which spans between the tip of the coccyx and the anal hiatus; this leaves a slit for the urogenital openings.
Because of the width of the genital aperture, wider in females, a second closing mechanism is required. The urogenital diaphragm consists of the deep transverse perineal which arises from the inferior ischial and pubic rami and extends to the urogential hiatus; the urogenital diaphragm is reinforced posteriorly by the superficial transverse perineal. The external anal and urethral sphincters close the urethra; the former is surrounded by the bulbospongiosus which narrows the vaginal introitus in females and surrounds the corpus spongiosum in males. Ischiocavernosus clitoridis. Modern humans are to a large extent characterized by large brains; because the pelvis is vital to both locomotion and childbirth, natural selection has been confronted by two conflicting demands: a wide birth canal and locomotion efficiency, a conflict referred to as the "obstetrical dilemma". The female pelvis, or gynecoid pelvis, has evolved to its maximum width for childbirth—a wider pelvis would make women unable to walk.
In contrast, human male pelvises are not constrained by the need to give birth and therefore are more optimized for bipedal locomotion. The principal differences between male and female true and false pelvis include: The female pelvis is larger and broader than the male pelvis, taller and more compact; the female inlet is oval in shape, while the male sacral promontory projects further. The sides of the male pelvis converge from the inlet to the outlet, whereas the sides of the female pelvis are wider apart; the angle between