The collarbone. The 2 clavicles, 1 on each side, form joints with the top of the sternum (breastbone) and the scapula (shoulderblade). The clavicles support the arms and transmit forces from the arms to the central skeleton.
Shoulder-blade or scapula. A ?at bone, about as large as the ?at hand and ?ngers, placed on the upper and back part of the With the arm hanging by the side, the scapula extends from the second to the seventh rib, but, as the arm is raised and lowered, it slides freely over the back of the chest. On the rear surface of the bone is a strong process, the spine of the scapula. This arches upwards and forwards into the acromion process. The latter forms the bony prominence on the top of the shoulder, where it unites in a joint with the outer end of the clavicle.... shoulder
Hodgkin’s disease The incidence is around four new cases per 100,000 population annually, with slightly more men than women contracting it. The ?rst incidence peak is in age group 20–35 and the second in age group 50–
70. The cause of Hodgkin’s is not known, although it is more common in patients from small families and well-educated backgrounds. The disease is three times more likely to occur in people who have had glandular fever (see MONONUCLEOSIS) but no link with the EPSTEIN BARR VIRUS has been established (see Burkitt’s lymphoma, below)
The disease is characterised histologically by the presence of large malignant lymphoid cells (Reed-Sternberg cells) in the lymph glands.
Clinically the lymph glands are enlarged, rubbery but painless; usually those in the neck or just above the CLAVICLE are affected. Spread is to adjacent lymph glands and in young people a mass of enlarged glands may develop in the MEDIASTINUM. The SPLEEN is affected in about one-third of patients with the disorder. Treatment is either with RADIOTHERAPY, CHEMOTHERAPY or both, depending on when the disease is diagnosed and the nature of the abnormal lymph cells. Cure rates are good, especially if the lymphoma is diagnosed early.
Non-Hodgkin’s lymphoma (NHL) This varies in its malignancy depending on the nature and activity of the abnormal lymph cells. The disease is hard to classify histologically, so various classi?cation systems have been evolved. High- and low-grade categories are recognised according to the rate of proliferation of abnormal lymph cells. No single causative factor has been identi?ed, although viral and bacterial infections have been linked to NHL, and genetic and immunological factors may be implicated. The incidence is higher than that of Hodgkin’s disease, at 12 new cases per 100,000 population a year, and the median age of diagnosis is 65–70 years. Suppression of the immune system that ocurs in people with HIV infection has been linked with a marked rise in the incidence of non-Hodgkin’s lymphoma and Hodgkin’s disease.
Most patients have painless swelling of one or more groups of lymph nodes in the neck or groin, and the liver and spleen may enlarge. As other organs can also be affected, patients may present with a wide range of symptoms, including fever, itching and weight loss. If NHL occurs in a single group of lymph nodes, radiotherapy is the treatment of choice; more extensive in?ltration of glands will require chemotherapy – and sometimes both types of treatment will be necessary. If these treatments fail, BONE MARROW TRANSPLANT may be carried out. Prognosis is good for low-grade NHL (75 per cent of patients survive ?ve years or more); in more severe types the survival rate is 40–50 per cent for two years.
Another variety of lymphoma is found in children in Africa, sometimes called after Burkitt, the Irish surgeon who ?rst identi?ed it. Burkitt’s lymphoma is a rapidly growing malignant tumour occurring in varying sites, and the Epstein Barr virus has a role in its origin and growth. A non-African variety of Burkitt’s lymphoma is now also recognised. CYTOTOXIC drug therapy is e?ective.... lymphoma
Structure of bone Bone is composed partly of ?brous tissue, partly of bone matrix comprising phosphate and carbonate of lime, intimately mixed together. The bones of a child are about two-thirds ?brous tissue, whilst those of the aged contain one-third; the toughness of the former and the brittleness of the latter are therefore evident.
The shafts of the limb bones are composed of dense bone, the bone being a hard tube surrounded by a membrane (the periosteum) and enclosing a fatty substance (the BONE MARROW); and of cancellous bone, which forms the short bones and the ends of long bones, in which a ?ne lace-work of bone ?lls up the whole interior, enclosing marrow in its meshes. The marrow of the smaller bones is of great importance. It is red in colour, and in it red blood corpuscles are formed. Even the densest bone is tunnelled by ?ne canals (Haversian canals) in which run small blood vessels, nerves and lymphatics, for the maintenance and repair of the bone. Around these Haversian canals the bone is arranged in circular plates called lamellae, the lamellae being separated from one another by clefts, known as lacunae, in which single bone-cells are contained. Even the lamellae are pierced by ?ne tubes known as canaliculi lodging processes of these cells. Each lamella is composed of very ?ne interlacing ?bres.
GROWTH OF BONES Bones grow in thickness from the ?brous tissue and lime salts laid down by cells in their substance. The long bones grow in length from a plate of cartilage (epiphyseal cartilage) which runs across the bone about 1·5 cm or more from its ends, and which on one surface is also constantly forming bone until the bone ceases to lengthen at about the age of 16 or 18. Epiphyseal injury in children may lead to diminished growth of the limb.
REPAIR OF BONE is e?ected by cells of microscopic size, some called osteoblasts, elaborating the materials brought by the blood and laying down strands of ?brous tissue, between which bone earth is later deposited; while other cells, known as osteoclasts, dissolve and break up dead or damaged bone. When a fracture has occurred, and the broken ends have been brought into contact, these are surrounded by a mass of blood at ?rst; this is partly absorbed and partly organised by these cells, ?rst into ?brous tissue and later into bone. The mass surrounding the fractured ends is called the callus, and for some months it forms a distinct thickening which is gradually smoothed away, leaving the bone as before the fracture. If the ends have not been brought accurately into contact, a permanent thickening results.
VARIETIES OF BONES Apart from the structural varieties, bones fall into four classes: (a) long bones like those of the limbs; (b) short bones composed of cancellous tissue, like those of the wrist and the ankle; (c) ?at bones like those of the skull; (d) irregular bones like those of the face or the vertebrae of the spinal column (backbone).
The skeleton consists of more than 200 bones. It is divided into an axial part, comprising the skull, the vertebral column, the ribs with their cartilages, and the breastbone; and an appendicular portion comprising the four limbs. The hyoid bone in the neck, together with the cartilages protecting the larynx and windpipe, may be described as the visceral skeleton.
AXIAL SKELETON The skull consists of the cranium, which has eight bones, viz. occipital, two parietal, two temporal, one frontal, ethmoid, and sphenoid; and of the face, which has 14 bones, viz. two maxillae or upper jaw-bones, one mandible or lower jaw-bone, two malar or cheek bones, two nasal, two lacrimal, two turbinal, two palate bones, and one vomer bone. (For further details, see SKULL.) The vertebral column consists of seven vertebrae in the cervical or neck region, 12 dorsal vertebrae, ?ve vertebrae in the lumbar or loin region, the sacrum or sacral bone (a mass formed of ?ve vertebrae fused together and forming the back part of the pelvis, which is closed at the sides by the haunch-bones), and ?nally the coccyx (four small vertebrae representing the tail of lower animals). The vertebral column has four curves: the ?rst forwards in the neck, the second backwards in the dorsal region, the third forwards in the loins, and the lowest, involving the sacrum and coccyx, backwards. These are associated with the erect attitude, develop after a child learns to walk, and have the e?ect of diminishing jars and shocks before these reach internal organs. This is aided still further by discs of cartilage placed between each pair of vertebrae. Each vertebra has a solid part, the body in front, and behind this a ring of bone, the series of rings one above another forming a bony canal up which runs the spinal cord to pass through an opening in the skull at the upper end of the canal and there join the brain. (For further details, see SPINAL COLUMN.) The ribs – 12 in number, on each side – are attached behind to the 12 dorsal vertebrae, while in front they end a few inches away from the breastbone, but are continued forwards by cartilages. Of these the upper seven reach the breastbone, these ribs being called true ribs; the next three are joined each to the cartilage above it, while the last two have their ends free and are called ?oating ribs. The breastbone, or sternum, is shaped something like a short sword, about 15 cm (6 inches) long, and rather over 2·5 cm (1 inch) wide.
APPENDICULAR SKELETON The upper limb consists of the shoulder region and three segments – the upper arm, the forearm, and the wrist with the hand, separated from each other by joints. In the shoulder lie the clavicle or collar-bone (which is immediately beneath the skin, and forms a prominent object on the front of the neck), and the scapula or shoulder-blade behind the chest. In the upper arm is a single bone, the humerus. In the forearm are two bones, the radius and ulna; the radius, in the movements of alternately turning the hand palm up and back up (called supination and pronation respectively), rotating around the ulna, which remains ?xed. In the carpus or wrist are eight small bones: the scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate and hamate. In the hand proper are ?ve bones called metacarpals, upon which are set the four ?ngers, each containing the three bones known as phalanges, and the thumb with two phalanges.
The lower limb consists similarly of the region of the hip-bone and three segments – the thigh, the leg and the foot. The hip-bone is a large ?at bone made up of three – the ilium, the ischium and the pubis – fused together, and forms the side of the pelvis or basin which encloses some of the abdominal organs. The thigh contains the femur, and the leg contains two bones – the tibia and ?bula. In the tarsus are seven bones: the talus (which forms part of the ankle joint); the calcaneus or heel-bone; the navicular; the lateral, intermediate and medial cuneiforms; and the cuboid. These bones are so shaped as to form a distinct arch in the foot both from before back and from side to side. Finally, as in the hand, there are ?ve metatarsals and 14 phalanges, of which the great toe has two, the other toes three each.
Besides these named bones there are others sometimes found in sinews, called sesamoid bones, while the numbers of the regular bones may be increased by extra ribs or diminished by the fusion together of two or more bones.... bone
Reasons for operation The cause of laryngeal obstruction should be treated but, if obstruction is acute and endangering the patient’s life, urgent intervention is necessary. In most cases the insertion of an endotracheal tube either through the nose or mouth and down the pharynx through the larynx to bypass the obstruction is e?ective (see ENDOTRACHEAL INTUBATION). If not, tracheostomy is performed. The majority of tracheostomies performed nowadays are for patients in intensive-therapy-unit situations. These patients require airway intervention for prolonged periods to facilitate arti?cial ventilation which is performed by means of a mechanical ventilator. The presence of a tube passing through the larynx for a prolonged period of time is associated with long-term damage to the larynx, and therefore any patients requiring prolonged intubation usually undergo a tracheostomy to prevent further damage. Endotracheal intubation is also the preferred method of airway-intervention for acute in?ammatory disorders of the upper airway (as opposed to tracheostomy); tracheostomy in these cases is performed only in the emergency situation if facilities for endotracheal intubation are not available or if they are unsuccessful. Tracheostomy may also be performed for large tumours which obstruct the larynx until some form of treatment is instituted. Similarly it may be needed in conditions whereby the nerve supply to the larynx has been jeopardised, impairing its protective function of the upper airway and its respiratory function.
Tracheostomy tubes When the trachea has been opened – by an incision through the skin between the Adam’s apple and the clavicles; another through the THYROID GLAND followed by a small vertical incision in the trachea
– a metal or plastic tube is inserted to maintain the opening. There is always an outer tube which is ?xed in position by tapes passing round the neck, and an inner tube which slides freely out of and into the other, so that it may be removed at any time for cleansing, and is readily coughed-out should it happen to become blocked by mucus.
After-treatment When the operation has been performed for some permanent obstruction, the tube must be worn permanently; and the double metal tube is in such cases replaced after a short time by a soft plastic single one. When the operation has relieved some obstruction caused, say, by diphtheria, the tube is left out now and then for a few hours, and ?nally, at the end of a week or so, is removed altogether, after which the wound quickly heals up.... tracheostomy
cavities; it may be red or yellow. Red bone marrow is present in all bones at birth and is the factory for most of the blood cells. During the teens, red bone marrow is gradually replaced in some bones by less active yellow marrow. In adults, red marrow is confined chiefly to the spine, sternum, (breastbone), ribs, pelvis (hip-bones), scapulae (shoulderblades), clavicles (collarbones), and bones of the skull.
Stem cells within the red marrow are stimulated to form blood cells by the hormone erythropoietin.
Yellow marrow is composed mainly of connective tissue and fat.
If the body needs to increase its rate of blood formation, some of the yellow marrow will be replaced by red.
Sometimes marrow fails to produce sufficient numbers of normal blood cells, as occurs in aplastic anaemia (see anaemia, aplastic) or when marrow has been displaced by tumour cells.
In other cases, marrow may overproduce certain blood cells, as occurs in polycythaemia and leukaemia.... bone imaging
Common sites of fracture include the hand, wrist (see Colles’ fracture), ankle joint, clavicle, and the neck of the femur (see femur, fracture of). There is usually swelling and tenderness at the fracture site. The pain is often severe and is usually made worse by movement.
X-rays can confirm a fracture. Because bone begins to heal soon after it has broken, the first aim of treatment is to ensure that the bone ends are aligned. Displaced bone ends are manoeuvred
back into position, under general anaesthetic, by manipulation either through the skin or through an incision. The bone is then immobilized. In some cases the ends of the bone may be fixed with metal pins or plates.
Most fractures heal without any problems. Healing is sometimes delayed because the blood supply to the affected bone is inadequate (as a result of damaged blood vessels) or because the bone ends are not close enough together. If the fracture fails to unite, internal fixation or a bone graft may be needed. Osteomyelitis is a possible complication of open fractures. (See also Monteggia’s fracture; pelvis; Pott’s fracture; rib, fracture of; skull, fracture of.)... fracture
The neck contains many important structures: the spinal cord (which carries nerve impulses to and from the brain); the trachea (windpipe); the larynx (voice box); the oesophagus; the thyroid and parathyroid glands; lymph nodes; and several major blood vessels. The upper 7 vertebrae of the spine are in the neck; a complex system of muscles is connected to these vertebrae, the clavicles (collarbones), the upper ribs, and lower jaw.
Neck disorders include torticollis (wry neck) in which the head is twisted to one side. Fractures and dislocations of vertebrae in the neck and whiplash injury can injure the spinal cord causing paralysis or even death (see spinal injury). Any condition causing swelling in the neck may interfere with breathing or swallowing.
Degeneration of the joints between the neck vertebrae may occur due to cervical osteoarthritis, causing similar symptoms to those of disc prolapse. In ankylosing spondylitis, fusion of the vertebrae may result in permanent neck rigidity. Cervical rib is a rare congenital defect in which there is a small extra rib in the neck.Neck pain of unknown origin is very common.
As long as neurological symptoms (such as loss of sensation or muscle power) are absent, the condition is unlikely to be serious and usually disappears within a few weeks.... neck
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