Axis Health Dictionary

Axis: From 3 Different Sources


The 2nd cervical vertebra in the human spine. The axis is attached by a pivot joint to the atlas, the topmost vertebra, which in turn is attached to the base of the skull. The pivot joint allows the head to turn to either side.
Health Source: BMA Medical Dictionary
Author: The British Medical Association
The name applied to the second cervical vertebra. (See SPINAL COLUMN.)
Health Source: Medical Dictionary
Author: Health Dictionary
n. 1. a real or imaginary line through the centre of the body or one of its parts or a line about which the body or a part rotates. 2. the second *cervical vertebra, which articulates with the atlas vertebra above and allows rotational movement of the head.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Cervical Vertebrae

The seven bones of the top end of the backbone that form the neck. The ?rst cervical vertebra is the atlas and this articulates with the base of the skull. The axis is the second vertebra, which contains a shaft of bone that allows the atlas to rotate on it, thus permitting the head to turn. (See SPINAL COLUMN.)... cervical vertebrae

Transverse

An anatomical description of a line, plane or structure at right-angles to the long axis of an organ or the body.... transverse

Centrifuge

A machine that separates the different components of a body fluid for analysis.

When a fluid such as blood is spun at high speed around a central axis, groups of particles of varying density, for example red and white blood cells, are separated by centrifugal force.... centrifuge

Astigmatism

An error of refraction in the EYE due to the cornea (the clear membrane in front of the eye) being unequally curved in di?erent directions, so that rays of light in di?erent meridians cannot be brought to a focus together on the retina. The curvature, instead of being globular, is egg-shaped, longer in one axis than the other. The condition causes objects to seem distorted and out of place, a ball for instance looking like an egg, a circle like an ellipse. The condition is remedied by suitable spectacles of which one surface forms part of a cylinder. A hard contact lens may be ?tted to achieve an evenly curved surface. Astigmatism may be caused by any disease that affects the shape of the cornea – for example, a meibomian cyst (a swollen sebaceous gland in the eyelid) may press on the cornea and distort it.... astigmatism

Chronic Fatigue Syndrome (cfs)

See also MYALGIC ENCEPHALOMYELITIS (ME). A condition characterised by severe, disabling mental and physical fatigue brought on by mental or physical activity and associated with a range of symptoms including muscle pain, headaches, poor sleep, disturbed moods and impaired concentration. The prevalence of the condition is between 0.2 and 2.6 per cent of the population (depending on how investigators de?ne CFS/ME). Despite the stereotype of ‘yuppie ?u’, epidemiological research has shown that the condition occurs in all socioeconomic and ethnic groups. It is commoner in women and can also occur in children.

In the 19th century CFS was called neurasthenia. In the UK, myalgic encephalomyelitis (ME) is often used, a term originally introduced to describe a speci?c outbreak such as the one at the Royal Free Hospital, London in 1955. The term is inaccurate as there is no evidence of in?ammation of the brain and spinal cord (the meaning of encephalomyelitis). Doctors prefer the term CFS, but many patients see this as derogatory, perceiving it to imply that they are merely ‘tired all the time’ rather than having a disabling illness.

The cause (or causes) are unknown, so the condition is classi?ed alongside other ‘medically unexplained syndromes’ such as IRRITABLE BOWEL SYNDROME (IBS) and multiple chemical sensitivity – all of which overlap with CFS. In many patients the illness seems to start immediately after a documented infection, such as that caused by EPSTEIN BARR VIRUS, or after viral MENINGITIS, Q FEVER and TOXOPLASMOSIS. These infections seem to be a trigger rather than a cause: mild immune activation is found in patients, but it is not known if this is cause or e?ect. The body’s endocrine system is disturbed, particularly the hypothalamopituitary-adrenal axis, and levels of cortisol are often a little lower than normal – the opposite of what is found in severe depression. Psychiatric disorder, usually depression and/or anxiety, is associated with CFS, with rates too high to be explained solely as a reaction to the disability experienced.

Because we do not know the cause, the underlying problem cannot be dealt with e?ectively and treatments are directed at the factors leading to symptoms persisting. For example, a slow increase in physical activity can help many, as can COGNITIVE BEHAVIOUR THERAPY. Too much rest can be harmful, as muscles are rapidly weakened, but aggressive attempts at coercing patients into exercising can be counter-productive as their symptoms may worsen. Outcome is in?uenced by the presence of any pre-existing psychiatric disorder and the sufferer’s beliefs about its causes and treatment. Research continues.... chronic fatigue syndrome (cfs)

Eye, Disorders Of

Arcus senilis The white ring or crescent which tends to form at the edge of the cornea with age. It is uncommon in the young, when it may be associated with high levels of blood lipids (see LIPID).

Astigmatism (See ASTIGMATISM.)

Blepharitis A chronic in?ammation of the lid margins. SEBORRHOEA and staphylococcal infection are likely contributors. The eyes are typically intermittently red, sore and gritty over months or years. Treatment is di?cult and may fail. Measures to reduce debris on the lid margins, intermittent courses of topical antibiotics, steroids or systemic antibiotics may help the sufferer.

Blepharospasm Involuntary closure of the eye. This may accompany irritation but may also occur without an apparent cause. It may be severe enough to interfere with vision. Treatment involves removing the source of irritation, if present. Severe and persistent cases may respond to injection of Botulinum toxin into the orbicularis muscle.

Cataract A term used to describe any opacity in the lens of the eye, from the smallest spot to total opaqueness. The prevalence of cataracts is age-related: 65 per cent of individuals in their sixth decade have some degree of lens opacity, while all those over 80 are affected. Cataracts are the most important cause of blindness worldwide. Symptoms will depend on whether one or both eyes are affected, as well as the position and density of the cataract(s). If only one eye is developing a cataract, it may be some time before the person notices it, though reading may be affected. Some people with cataracts become shortsighted, which in older people may paradoxically ‘improve’ their ability to read. Bright light may worsen vision in those with cataracts.

The extent of visual impairment depends on the nature of the cataracts, and the ?rst symptoms noticed by patients include di?culty in recognising faces and in reading, while problems watching television or driving, especially at night, are pointers to the condition. Cataracts are common but are not the only cause of deteriorating vision. Patients with cataracts should be able to point to the position of a light and their pupillary reactions should be normal. If a bright light is shone on the eye, the lens may appear brown or, in advanced cataracts, white (see diagram).

While increasing age is the commonest cause of cataract in the UK, patients with DIABETES MELLITUS, UVEITIS and a history of injury to the eye can also develop the disorder. Prolonged STEROID treatment can result in cataracts. Children may develop cataracts, and in them the condition is much more serious as vision may be irreversibly impaired because development of the brain’s ability to interpret visual signals is hindered. This may happen even if the cataracts are removed, so early referral for treatment is essential. One of the physical signs which doctors look for when they suspect cataract in adults as well as in children is the ‘red re?ex’. This is observable when an ophthalmoscopic examination of the eye is made (see OPHTHALMOSCOPE). Identi?cation of this red re?ex (a re?ection of light from the red surface of the retina –see EYE) is a key diagnostic sign in children, especially young ones.

There is no e?ective medical treatment for established cataracts. Surgery is necessary and the decision when to operate depends mainly on how the cataract(s) affect(s) the patient’s vision. Nowadays, surgery can be done at any time with limited risk. Most patients with a vision of 6/18 – 6/10 is the minimum standard for driving – or worse in both eyes should

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bene?t from surgery, though elderly people may tolerate visual acuity of 6/18 or worse, so surgery must be tailored to the individual’s needs. Younger people with a cataract will have more demanding visual requirements and so may opt for an ‘earlier’ operation. Most cataract surgery in Britain is now done under local anaesthetic and uses the ‘phaco-emulsi?cation’ method. A small hole is made in the anterior capsule of the lens after which the hard lens nucleus is liqui?ed ultrasonically. A replacement lens is inserted into the empty lens bag (see diagram). Patients usually return to their normal activities within a few days of the operation. A recent development under test in the USA for children requiring cataract operations is an intra-ocular ?exible implant whose magnifying power can be altered as a child develops, thus precluding the need for a series of corrective operations as happens now.

Chalazion A ?rm lump in the eyelid relating to a blocked meibomian gland, felt deep within the lid. Treatment is not always necessary; a proportion spontaneously resolve. There can be associated infection when the lid becomes red and painful requiring antibiotic treatment. If troublesome, the chalazion can be incised under local anaesthetic.

Conjunctivitis In?ammation of the conjunctiva (see EYE) which may affect one or both eyes. Typically the eye is red, itchy, sticky and gritty but is not usually painful. Redness is not always present. Conjunctivitis can occasionally be painful, particularly if there is an associated keratitis (see below) – for example, adenovirus infection, herpetic infection.

The cause can be infective (bacteria, viruses or CHLAMYDIA), chemical (e.g. acids, alkalis) or allergic (e.g. in hay fever). Conjunctivitis may also be caused by contact lenses, and preservatives or even the drugs in eye drops may cause conjunctival in?ammation. Conjunctivitis may addtionally occur in association with other illnesses – for example, upper-respiratory-tract infection, Stevens-Johnson syndrome (see ERYTHEMA – erythema multiforme) or REITER’S SYNDROME. The treatment depends on the cause. In many patients acute conjunctivitis is self-limiting.

Dacryocystitis In?ammation of the lacrimal sac. This may present acutely as a red, painful swelling between the nose and the lower lid. An abscess may form which points through the skin and which may need to be drained by incision. Systemic antibiotics may be necessary. Chronic dacryocystitis may occur with recurrent discharge from the openings of the tear ducts and recurrent swelling of the lacrimal sac. Obstruction of the tear duct is accompanied by watering of the eye. If the symptoms are troublesome, the patient’s tear passageways need to be surgically reconstructed.

Ectropion The lid margin is everted – usually the lower lid. Ectropion is most commonly associated with ageing, when the tissues of the lid become lax. It can also be caused by shortening of the skin of the lids such as happens with scarring or mechanical factors – for example, a tumour pulling the skin of the lower lid downwards. Ectropion tends to cause watering and an unsightly appearance. The treatment is surgical.

Entropion The lid margin is inverted – usually the lower lid. Entropion is most commonly associated with ageing, when the tissues of the lid become lax. It can also be caused by shortening of the inner surfaces of the lids due to scarring – for example, TRACHOMA or chemical burns. The inwardly directed lashes cause irritation and can abrade the cornea. The treatment is surgical.

Episcleritis In?ammation of the EPISCLERA. There is usually no apparent cause. The in?ammation may be di?use or localised and may affect one or both eyes. It sometimes recurs. The affected area is usually red and moderately painful. Episcleritis is generally not thought to be as painful as scleritis and does not lead to the same complications. Treatment is generally directed at improving the patient’s symptoms. The in?ammation may respond to NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) or topical CORTICOSTEROIDS.

Errors of refraction (Ametropia.) These will occur when the focusing power of the lens and cornea does not match the length of the eye, so that rays of light parallel to the visual axis are not focused at the fovea centralis (see EYE). There are three types of refractive error: HYPERMETROPIA or long-sightedness. The refractive power of the eye is too weak, or the eye is too short so that rays of light are brought to a focus at a point behind the retina. Longsighted people can see well in the distance but generally require glasses with convex lenses for reading. Uncorrected long sight can lead to headaches and intermittent blurring of vision following prolonged close work (i.e. eye strain). As a result of ageing, the eye becomes gradually long-sighted, resulting in many people needing reading glasses in later life: this normal process is known as presbyopia. A particular form of long-sightedness occurs after cataract extraction (see above). MYOPIA(Short sight or near sight.) Rays of light are brought to a focus in front of the retina because the refractive power of the eye is too great or the eye is too short. Short-sighted people can see close to but need spectacles with concave lenses in order to see in the distance. ASTIGMATISMThe refractive power of the eye is not the same in each meridian. Some rays of light may be focused in front of the retina while others are focused on or behind the retina. Astigmatism can accompany hypermetropia or myopia. It may be corrected by cylindrical lenses: these consist of a slice from the side of a cylinder (i.e. curved in one meridian and ?at in the meridian at right-angles to it).

Keratitis In?ammation of the cornea in response to a variety of insults – viral, bacterial, chemical, radiation, or mechanical trauma. Keratitis may be super?cial or involve the deeper layers, the latter being generally more serious. The eye is usually red, painful and photophobic. Treatment is directed at the cause.

Nystagmus Involuntary rhythmic oscillation of one or both eyes. There are several causes including nervous disorders, vestibular disorders, eye disorders and certain drugs including alcohol.

Ophthalmia In?ammation of the eye, especially the conjunctiva (see conjunctivitis, above). Ophthalmia neonatorum is a type of conjunctivitis that occurs in newborn babies. They catch the disease when passing through an infected birth canal during their mother’s labour (see PREGNANCY AND LABOUR). CHLAMYDIA and GONORRHOEA are the two most common infections. Treatment is e?ective with antibiotics: untreated, the infection may cause permanent eye damage.

Pinguecula A benign degenerative change in the connective tissue at the nasal or temporal limbus (see EYE). This is visible as a small, ?attened, yellow-white lump adjacent to the cornea.

Pterygium Overgrowth of the conjunctival tissues at the limbus on to the cornea (see EYE). This usually occurs on the nasal side and is associated with exposure to sunlight. The pterygium is surgically removed for cosmetic reasons or if it is thought to be advancing towards the visual axis.

Ptosis Drooping of the upper lid. May occur because of a defect in the muscles which raise the lid (levator complex), sometimes the result of ageing or trauma. Other causes include HORNER’S SYNDROME, third cranial nerve PALSY, MYASTHENIA GRAVIS, and DYSTROPHIA MYOTONICA. The cause needs to be determined and treated if possible. The treatment for a severely drooping lid is surgical, but other measures can be used to prop up the lid with varying success.

Retina, disorders of The retina can be damaged by disease that affects the retina alone, or by diseases affecting the whole body.

Retinopathy is a term used to denote an abnormality of the retina without specifying a cause. Some retinal disorders are discussed below. DIABETIC RETINOPATHY Retinal disease occurring in patients with DIABETES MELLITUS. It is the commonest cause of blind registration in Great Britain of people between the ages of 20 and 65. Diabetic retinopathy can be divided into several types. The two main causes of blindness are those that follow: ?rst, development of new blood vessels from the retina, with resultant complications and, second, those following ‘water logging’ (oedema) of the macula. Treatment is by maintaining rigid control of blood-sugar levels combined with laser treatment for certain forms of the disease – in particular to get rid of new blood vessels. HYPERTENSIVE RETINOPATHY Retinal disease secondary to the development of high blood pressure. Treatment involves control of the blood pressure (see HYPERTENSION). SICKLE CELL RETINOPATHY People with sickle cell disease (see under ANAEYIA) can develop a number of retinal problems including new blood vessels from the retina. RETINOPATHY OF PREMATURITY (ROP) Previously called retrolental ?broplasia (RLF), this is a disorder affecting low-birth-weight premature babies exposed to oxygen. Essentially, new blood vessels develop which cause extensive traction on the retina with resultant retinal detachment and poor vision. RETINAL ARTERY OCCLUSION; RETINAL VEIN OCCLUSION These result in damage to those areas of retina supplied by the affected blood vessel: the blood vessels become blocked. If the peripheral retina is damaged the patient may be completely symptom-free, although areas of blindness may be detected on examination of ?eld of vision. If the macula is involved, visual loss may be sudden, profound and permanent. There is no e?ective treatment once visual loss has occurred. SENILE MACULAR DEGENERATION (‘Senile’ indicates age of onset and has no bearing on mental state.) This is the leading cause of blindness in the elderly in the western world. The average age of onset is 65 years. Patients initially notice a disturbance of their vision which gradually progresses over months or years. They lose the ability to recognise ?ne detail; for example, they cannot read ?ne print, sew, or recognise people’s faces. They always retain the ability to recognise large objects such as doors and chairs, and are therefore able to get around and about reasonably well. There is no e?ective treatment in the majority of cases. RETINITIS PIGMENTOSAA group of rare, inherited diseases characterised by the development of night blindness and tunnel vision. Symptoms start in childhood and are progressive. Many patients retain good visual acuity, although their peripheral vision is limited. One of the characteristic ?ndings on examination is collections of pigment in the retina which have a characteristic shape and are therefore known as ‘bone spicules’. There is no e?ective treatment. RETINAL DETACHMENTusually occurs due to the development of a hole in the retina. Holes can occur as a result of degeneration of the retina, traction on the retina by the vitreous, or injury. Fluid from the vitreous passes through the hole causing a split within the retina; the inner part of the retina becomes detached from the outer part, the latter remaining in contact with the choroid. Detached retina loses its ability to detect light, with consequent impairment of vision. Retinal detachments are more common in the short-sighted, in the elderly or following cataract extraction. Symptoms include spots before the eyes (?oaters), ?ashing lights and a shadow over the eye with progressive loss of vision. Treatment by laser is very e?ective if caught early, at the stage when a hole has developed in the retina but before the retina has become detached. The edges of the hole can be ‘spot welded’ to the underlying choroid. Once a detachment has occurred, laser therapy cannot be used; the retina has to be repositioned. This is usually done by indenting the wall of the eye from the outside to meet the retina, then making the retina stick to the wall of the eye by inducing in?ammation in the wall (by freezing it). The outcome of surgery depends largely on the extent of the detachment and its duration. Complicated forms of detachment can occur due to diabetic eye disease, injury or tumour. Each requires a specialised form of treatment.

Scleritis In?ammation of the sclera (see EYE). This can be localised or di?use, can affect the anterior or the posterior sclera, and can affect one or both eyes. The affected eye is usually red and painful. Scleritis can lead to thinning and even perforation of the sclera, sometimes with little sign of in?ammation. Posterior scleritis in particular may cause impaired vision and require emergency treatment. There is often no apparent cause, but there are some associated conditions – for example, RHEUMATOID ARTHRITIS, GOUT, and an autoimmune disease affecting the nasal passages and lungs called Wegener’s granulomatosis. Treatment depends on severity but may involve NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS), topical CORTICOSTEROIDS or systemic immunosuppressive drugs.

Stye Infection of a lash follicle. This presents as a painful small red lump at the lid margin. It often resolves spontaneously but may require antibiotic treatment if it persists or recurs.

Sub-conjunctival haemorrhage Haemorrhage between the conjunctiva and the underlying episclera. It is painless. There is usually no apparent cause and it resolves spontaneously.

Trichiasis Inward misdirection of the lashes. Trichiasis occurs due to in?ammation of or trauma to the lid margin. Treatment involves removal of the patient’s lashes. Regrowth may be prevented by electrolysis, by CRYOTHERAPY to the lid margin, or by surgery.

For the subject of arti?cial eyes, see under PROSTHESIS; also GLAUCOMA, SQUINT and UVEITIS.... eye, disorders of

Joints

A joint is the articulation point between di?erent parts of the skeleton, whether bone or cartilage. Joints are divided into those which are ?xed or relatively ?xed (?brous and cartilaginous joints), and those which allow free movement (synovial joints). In the former, exempli?ed by the sutures between the bones of the skull, a layer of cartilage or ?brous tissue lies between the bones, binding them ?rmly together. Amphiarthrodial joints, exempli?ed by the joints between the vertebral bodies (see SPINAL COLUMN), have a thick disc of ?brocartilage between the bones. Although the individual joint is capable of very little movement, a series of these gives to the spinal column, as a whole, a ?exible character.

All movable joints involve four structures: the bones whose junction forms the joint; a layer of cartilage covering the ends of these, making them smooth; a ?brous sheath, the capsule, thickened at various points into bands or ligaments, which hold the bones together; and, ?nally, the synovial membrane, which lines the capsule and produces a synovial ?uid, lubricating the movements of the joint. In addition, the bones are kept in position at the joints by the various muscles passing over them and by atmospheric pressure. Where the ends of the bones do not quite correspond, a subsidiary disc of ?bro-cartilage may help to adapt the ends of the bones more perfectly to each other. Larger cavities may be ?lled by movable pads of fat under the synovial membrane, giving additional protection to the joint.

Varieties After this main division of joints into those which are ?xed and those movable, the movable joints may be further subdivided. In gliding joints, such as the wrist and ankle, the bones have ?at surfaces capable of only a limited amount of movement. In hinge joints, such as the elbow and knee, movement takes place around one axis. Ball-and-socket joints, exempli?ed by the shoulder and hip, allow free movement in any direction. Subsidiary varieties are named according to the shape of the bones which enter the joint.... joints

Retroversion

An abnormal position of the UTERUS, occurring in about 20 per cent of women, in which its long axis is pivoted backwards in relation to the CERVIX UTERI and VAGINA instead of forwards.... retroversion

Scatter Diagram

A graph in which each dot represents paired values for two continuous variables, with the X axis representing one variable and the Y axis representing the other; used to display the relationship between two variables; also called a scattergram.... scatter diagram

Genetic Code

The message set out sequentially along the human CHROMOSOMES. The human gene map is being constructed through the work of the international, collaborative HUMAN GENOME project; so far, only part of the code has been translated and this is the part that occurs in the GENES. Genes are responsible for the PROTEIN synthesis of the cell (see CELLS): they instruct the cell how to make a particular polypeptide chain for a particular protein.

Genes carry, in coded form, the detailed speci?cations for the thousands of kinds of protein molecules required by the cell for its existence, for its enzymes, for its repair work and for its reproduction. These proteins are synthesised from the 20 natural AMINO ACIDS, which are uniform throughout nature and which exist in the cell cytoplasm as part of the metabolic pool. The protein molecule consists of amino acids joined end to end to form long polypeptide chains. An average chain contains 100–300 amino acids. The sequence of bases in the nucleic acid chain of the gene corresponds in some fundamental way to the sequence of amino acids in the protein molecule, and hence it determines the structure of the particular protein. This is the genetic code. Deoxyribonucleic acid (see DNA) is the bearer of this genetic information.

DNA has a long backbone made up of repeating groups of phosphate and sugar deoxyribose. To this backbone, four bases are attached as side groups at regular intervals. These four bases are the four letters used to spell out the genetic message: they are adenine, thymine, guanine and cystosine. The molecule of the DNA is made up of two chains coiled round a common axis to form what is called a double helix. The two chains are held together by hydrogen bonds between pairs of bases. Since adenine only pairs with thymine, and guanine only with cystosine, the sequences of bases in one chain ?xes the sequence in the other. Several hundred bases would be contained in the length of DNA of a typical gene. If the message of the DNA-based sequences is a continuous succession of thymine, the RIBOSOME will link together a series of the amino acid, phenylalanine. If the base sequence is a succession of cytosine, the ribosome will link up a series of prolines. Thus, each amino acid has its own particular code of bases. In fact, each amino acid is coded by a word consisting of three adjacent bases. In addition to carrying genetic information, DNA is able to synthesise or replicate itself and so pass its information on to daughter cells.

All DNA is part of the chromosome and so remains con?ned to the nucleus of the cell (except in the mitochondrial DNA). Proteins are synthesised by the ribosomes which are in the cytoplasm. DNA achieves control over pro-tein production in the cytoplasm by directing the synthesis of ribonucleic acid (see RNA). Most of the DNA in a cell is inactive, otherwise the cell would synthesise simultaneously every protein that the individual was capable of forming. When part of the DNA structure becomes ‘active’, it acts as a template for the ribonucleic acid, which itself acts as a template for protein synthesis when it becomes attached to the ribosome.

Ribonucleic acid exists in three forms. First ‘messenger RNA’ carries the necessary ‘message’ for the synthesis of a speci?c protein, from the nucleus to the ribosome. Second, ‘transfer RNA’ collects the individual amino acids which exist in the cytoplasm as part of the metabolic pool and carries them to the ribosome. Third, there is RNA in the ribosome itself. RNA has a similar structure to DNA but the sugar is ribose instead of deoxyribose and uracil replaces the base thymine. Before the ribosome can produce the proteins, the amino acids must be lined up in the correct order on the messenger RNA template. This alignment is carried out by transfer RNA, of which there is a speci?c form for each individual amino acid. Transfer RNA can not only recognise its speci?c amino acid, but also identify the position it is required to occupy on the messenger RNA template. This is because each transfer RNA has its own sequence of bases and recognises its site on the messenger RNA by pairing bases with it. The ribosome then travels along the chain of messenger RNA and links the amino acids, which have thus been arranged in the requisite order, by peptide bonds and protein is released.

Proteins are important for two main reasons. First, all the enzymes of living cells are made of protein. One gene is responsible for one enzyme. Genes thus control all the biochemical processes of the body and are responsible for the inborn di?erence between human beings. Second, proteins also ful?l a structural role in the cell, so that genes controlling the synthesis of structural proteins are responsible for morphological di?erences between human beings.... genetic code

Abduction

Movement of a limb away from the central line of the body, or of a digit away from the axis of a limb. Muscles that carry out this movement are called abductors. (See also adduction.)... abduction

Adduction

Movement of a limb towards the central line of the body, or of a digit towards the axis of a limb. Muscles that carry out this movement are often called adductors. (See also abduction.)... adduction

Atlas

The topmost cervical vertebra in the human spine. The atlas is attached to and supports the skull. A pivot joint attaching the atlas to the second cervical vertebra, the axis, allows the atlas to rotate and therefore the head to turn from side to side.... atlas

Ad

prefix denoting towards or near. Examples: adaxial (towards the main axis); adoral (towards or near the mouth).... ad

Axial

adj. at right angles to the long *axis of the body, i.e. denoting a horizontal plane through a standing patient at 90° to the *coronal and *sagittal planes. This is the usual plane for the primary images obtained at *computerized tomography. See also multiplanar reconstruction.... axial

Clinodactyly

n. congenital deflection of one or more digits from the central axis of the hand or foot. Clinodactyly may affect both hands (or feet) but most commonly affects the fifth finger (which curves towards the fourth). It has an incidence of 9% and may be found in isolation, in association with other congenital malformations, or it may occur as part of a syndrome (e.g. Down’s syndrome). No treatment is necessary.... clinodactyly

Liver

The liver is the largest gland in the body, serving numerous functions, chie?y involving various aspects of METABOLISM.

Form The liver is divided into four lobes, the greatest part being the right lobe, with a small left lobe, while the quadrate and caudate lobes are two small divisions on the back and undersurface. Around the middle of the undersurface, towards the back, a transverse ?ssure (the porta hepatis) is placed, by which the hepatic artery and portal vein carry blood into the liver, and the right and left hepatic ducts emerge, carrying o? the BILE formed in the liver to the GALL-BLADDER attached under the right lobe, where it is stored.

Position Occupying the right-hand upper part of the abdominal cavity, the liver is separated from the right lung by the DIAPHRAGM and the pleural membrane (see PLEURA). It rests on various abdominal organs, chie?y the right of the two KIDNEYS, the suprarenal gland (see ADRENAL GLANDS), the large INTESTINE, the DUODENUM and the STOMACH.

Vessels The blood supply di?ers from that of the rest of the body, in that the blood collected from the stomach and bowels into the PORTAL VEIN does not pass directly to the heart, but is ?rst distributed to the liver, where it breaks up into capillary vessels. As a result, some harmful substances are ?ltered from the bloodstream and destroyed, while various constituents of the food are stored in the liver for use in the body’s metabolic processes. The liver also receives the large hepatic artery from the coeliac axis. After circulating through capillaries, the blood from both sources is collected into the hepatic veins, which pass directly from the back surface of the liver into the inferior vena cava.

Minute structure The liver is enveloped in a capsule of ?brous tissue – Glisson’s capsule – from which strands run along the vessels and penetrate deep into the organ, binding it together. Subdivisions of the hepatic artery, portal vein, and bile duct lie alongside each other, ?nally forming the interlobular vessels,

which lie between the lobules of which the whole gland is built up. Each is about the size of a pin’s head and forms a complete secreting unit; the liver is built up of hundreds of thousands of such lobules. These contain small vessels, capillaries, or sinusoids, lined with stellate KUPFFER CELLS, which run into the centre of the lobule, where they empty into a small central vein. These lobular veins ultimately empty into the hepatic veins. Between these capillaries lie rows of large liver cells in which metabolic activity occurs. Fine bile capillaries collect the bile from the cells and discharge it into the bile ducts lying along the margins of the lobules. Liver cells are among the largest in the body, each containing one or two large round nuclei. The cells frequently contain droplets of fat or granules of GLYCOGEN – that is, animal starch.

Functions The liver is, in e?ect, a large chemical factory and the heat this produces contributes to the general warming of the body. The liver secretes bile, the chief constituents of which are the bile salts (sodium glycocholate and taurocholate), the bile pigments (BILIRUBIN and biliverdin), CHOLESTEROL, and LECITHIN. These bile salts are collected and formed in the liver and are eventually converted into the bile acids. The bile pigments are the iron-free and globin-free remnant of HAEMOGLOBIN, formed in the Kup?er cells of the liver. (They can also be formed in the spleen, lymph glands, bone marrow and connective tissues.) Bile therefore serves several purposes: it excretes pigment, the breakdown products of old red blood cells; the bile salts increase fat absorption and activate pancreatic lipase, thus aiding the digestion of fat; and bile is also necessary for the absorption of vitamins D and E.

The other important functions of the liver are as follows:

In the EMBRYO it forms red blood cells, while the adult liver stores vitamin B12, necessary for the proper functioning of the bone marrow in the manufacture of red cells.

It manufactures FIBRINOGEN, ALBUMINS and GLOBULIN from the blood.

It stores IRON and copper, necessary for the manufacture of red cells.

It produces HEPARIN, and – with the aid of vitamin K – PROTHROMBIN.

Its Kup?er cells form an important part of the RETICULO-ENDOTHELIAL SYSTEM, which breaks down red cells and probably manufactures ANTIBODIES.

Noxious products made in the intestine and absorbed into the blood are detoxicated in the liver.

It stores carbohydrate in the form of glycogen, maintaining a two-way process: glucose

glycogen.

CAROTENE, a plant pigment, is converted to vitamin A, and B vitamins are stored.

It splits up AMINO ACIDS and manufactures UREA and uric acids.

It plays an essential role in the storage and metabolism of FAT.... liver

Coeliac

adj. of or relating to the abdominal region. The coeliac axis (or trunk) is a branch of the abdominal *aorta supplying the stomach, spleen, liver, and gall bladder.... coeliac

Coma

n. 1. a state of unrousable unconsciousness. See also Glasgow Coma Scale. 2. (in optics) an *aberration, inherent in certain optical designs or due to imperfection in the lens or cornea, that results in off-axis point sources (e.g. stars) appearing to have a tail, like the coma of a comet. —comatic adj.... coma

Lie

n. 1. the long axis of the fetus in relation to that of the mother. It may be longitudinal, transverse, or oblique. 2. (in ethics) an untruthful statement that is intended to deceive. See also truth-telling.... lie

Maddox Rod

a series of transparent cylinders that change a point source of light into a linear streak perpendicular to the axis of the rods, used in the assessment of binocular visual functions. [E. E. Maddox (1860–1933), British ophthalmologist]... maddox rod

Neural Plate

the strip of ectoderm lying along the central axis of the early embryo that forms the *neural tube and subsequently the central nervous system.... neural plate

Odontoid Process

a toothlike process from the upper surface of the axis vertebra. See cervical vertebrae.... odontoid process

Phoria

combining form denoting (in ophthalmology) an abnormal deviation of the eyes or turning of the visual axis. Example: heterophoria (tendency to squint).... phoria

Spinal Column

Also known as the spine, this forms an important part of the skeleton, acting both as the rigid pillar which supports the upper parts of the body and as a protection to the SPINAL CORD and nerves arising from it. The spinal column is built up of a number of bones placed one upon another, which, in consequence of having a slight degree of turning-movement, are known as the vertebrae. The possession of a spinal cord supported by a vertebral column distinguishes the higher animals from the lower types, and is why they are called vertebrates. Of the vertebrates, humans alone stand absolutely erect, and this erect carriage of the body gives to the skull and vertebral column certain distinctive characters.

The human backbone is about 70 cm (28

inches) in length, and varies little in full-grown people; di?erences in height depend mainly upon the length of the lower limbs. The number of vertebrae is 33 in children, although in adult life ?ve of these fuse together to form the sacrum, and the lowest four unite in the coccyx, so that the number of separate bones is reduced to 26. Of these there are seven in the neck, known as cervical vertebrae; 12 with ribs attached, in the region of the thorax known as thoracic or dorsal vertebrae; ?ve in the loins, called lumbar vertebrae; ?ve fused to form the sacrum; and four joined in the coccyx. These numbers are expressed in a formula thus: C7, D12, L5, S5, Coc4=33.

Although the vertebrae in each of these regions have distinguishing features, all the vertebrae are constructed on the same general plan. Each has a thick, rounded, bony part in front, known as the body, and these bodies form the main thickness of the column. Behind the body of each is a ring of bone, the neural ring, these rings placed one above another forming the bony canal which lodges the spinal cord. From each side of the ring a short process of bone known as the transverse process stands out, and from the back of the ring a larger process, the spinous process, projects. These processes give attachment to the strong ligaments and muscles which unite, support, and bend the column. The spines can be seen or felt beneath the skin of the back lying in the centre of a groove between the muscular masses of the two sides, and they give to the column its name of the spinal column. One of these spines, that of the seventh cervical vertebra, is especially large and forms a distinct bony prominence, where the neck joins the back. Between the bodies of the vertebrae lies a series of thick discs of ?brocartilage known as intervertebral discs. Each disc consists of an outer portion, known as the annulus ?brosus, and an inner core, known as the nucleus pulposus. These 23 discs provide the upper part of the spine with pliability and resilience.

The ?rst and second cervical vertebrae are specially modi?ed. The ?rst vertebra, known as the atlas, is devoid of a body, but has a specially large and strong ring with two hollows upon which the skull rests, thus allowing forward and backward movements (nodding). The second vertebra, known as the axis, has a pivot on its body which ?ts into the ?rst vertebra and thus allows free rotation of the head from side to side. The spinal column has four natural curves (see diagram) which help to cushion the shocks of walking and running.

The neural rings of the vertebrae form a canal, which is wide in the neck, smaller and almost round in the dorsal region, and wide again in the lumbar vertebrae. Down the canal runs the spinal cord, and the nerves leaving the cord do so through openings between the vertebrae which are produced by notches on the upper and lower margins of each ring. The intervertebral foramina formed by these notches are so large in comparison with the nerves passing through them that there is no chance of pressure upon the latter, except in very serious injuries which dislocate and fracture the spine.... spinal column

Brain Disorders

Usually associated with some loss of sensation and power in another part of the body. Taste, smell, hearing, sight and movement may be affected. The following are some of the disorders that may affect the brain. Each has a separate entry in this book.

Abscess, Alzheimer’s Disease, anoxia (oxygen starvation), coma, concussion, haemorrhage, Down’s syndrome, epilepsy, tumour, hydrocephalus (water on the brain), meningitis, multiple sclerosis, stroke (rupture of blood vessel), spina bifida, syphilis (general paralysis of the insane), sleepy sickness.

Poor circulation through the brain due to hardening of the arteries: Ginkgo, Ginseng. Ginseng stimulates the hypothalmic/pituitary axis of the brain and favourably influences its relationship with the adrenal glands.

Congestion of the brain – Cowslip (Boerwicke). Irritability of brain and spine – Hops. Oats. Inflammation of the brain (encephalitis) as in viral infection, poliomyelitis, rabies, sleepy sickness, etc: Echinacea, Passion flower, Skullcap and Lobelia. Gelsemium acts as a powerful relaxant in the hands of a practitioner: Tincture BPC (1973): dose 0.3ml.

Brain storm from hysteria, locomotor ataxia, etc – Liquid Extract Lobelia: 5ml teaspoon in water when necessary (Dr Jentzsch, 1915, Ellingwood) Supplement with Zinc, Vitamins C and E.

Blood clot, thrombosis: Yarrow. Neurasthenia: Oats, Basil, Hops.

Brain fag and jet-lag: Chamomile, Skullcap, Oats, Ginseng, Ginkgo.

Tumour may be present years before manifesting: Goldenseal.

Mental state: depression, anxiety, schizophrenia.

Tea. Formula. Skullcap, Gotu Kola and German Chamomile; equal parts. 1 heaped teaspoon to each cup water gently simmered 10 minutes. Strain. 1 cup thrice daily.

Unspecified tensive state. Formula. Tinctures. Hops 1; Passion flower 2; Valerian 2. Dose: 2 teaspoons thrice daily until diagnosis is concluded.

Unspecified torpor. Formula. Tinctures. Ginseng 1; Kola 1; Capsicum quarter. 2 teaspoons in water thrice daily until diagnosis is concluded.

Brain weakness in the elderly: Ginkgo. See: ALZHEIMER’S DISEASE.

Fluid on the brain: see HYDROCEPHALUS.

Abscess of the brain: see ABSCESS.

Brain restoratives. Black Haw, True Unicorn root, Galangal, Oats, Oatstraw, False Unicorn root, Kola, Hops. Vitamin B6. Magnesium.

Cerebral thrombosis. See entry.

Note: Cold water may help victims to survive: rapid loss of body heat protects the brain. (Child Health Department, University of Wales)

Treatment by or in liaison with general medical practitioner or hospital specialist. ... brain disorders

Pole

n. (in anatomy) the extremity of the axis of the body, an organ, or a cell.... pole

Renovascular Hypertension

disease affecting the arterial supply to the kidneys, leading to ischaemia and resultant stimulation of the renin-*angiotensin-aldosterone axis. In the major vessels, the most common cause is atheromatous plaque disease. Other causes are fibromuscular dysplasia and *Takayasu’s disease.... renovascular hypertension

Elbow

The hinge joint formed where the lower end of the humerus meets the upper ends of the radius and ulna. The elbow is stabilized by ligaments at the front, back, and sides. It enables the arm to be bent and straightened, and the forearm to be rotated through almost 180 degrees around its long axis without more than very slight movement of the upper arm.

Disorders of the elbow include arthritis and injuries to the joint and its surrounding muscles, tendons, and ligaments. Repetitive strain on the tendons of the muscles of the forearm, where they attach to the elbow, can result in an inflammation that is known as epicondylitis. There are 2 principle types of epicondylitis: tennis elbow and golfer’s elbow. Alternatively, a sprain of the ligaments may occur. Olecranon bursitis develops over the tip of the elbow in response to local irritation. Strain on the joint can produce an effusion or traumatic synovitis. A fall on to the hand or on to the elbow can cause a fracture or dislocation.elderly, care of the Appropriate care to help minimize physical and mental deterioration in the elderly. For example, failing vision and hearing are often regarded as inevitable in old age, but removal of a cataract or use of a hearing-aid can often improve quality of life. Isolation or inactivity leads to depression in some elderly people. Attending a day-care centre can provide social contact and introduce new interests.

Many elderly people are cared for by family members. Voluntary agencies can often provide domestic help to ease the strain on carers. Sheltered housing allows independence while providing assistance when needed. Elderly people who have dementia or physical disability usually require supervision in a residential care or hospital setting. (See also geriatric medicine.)... elbow

Juxtaglomerular Apparatus

(JGA) a microscopic structure within the kidney that is important in regulating blood pressure, body fluid, and electrolytes. It is situated in each nephron, between the afferent arteriole of the glomerulus and the returning distal convoluted tubule of the same nephron. The JGA consists of specialized cells within the distal tubule (the macula densa), which detect the amount of sodium chloride passing through the tubule and can secrete locally acting vasoconstrictor substances that act on the associated afferent arteriole to induce a reduction in filtration pressure (tubuloglomerular feedback). Modified cells within the afferent arterioles secrete *renin in response to a fall in perfusion pressure or feedback from the macula densa and form a central role in the renin-*angiotensin-aldosterone axis. Mesangial cells support and connect the macula densa and the specialized cells in the afferent arteriole and have sympathetic innervation, facilitating the renin response to sympathetic nervous stimulation.... juxtaglomerular apparatus

Mesenteric Ischaemia

impairment of the blood flow to the arteries that supply the small and large intestine. The arteries include the *coeliac axis and the superior and inferior mesenteric arteries. Partial or total occlusion of blood flow may occur abruptly or over a protracted period (acute vs. chronic mesenteric ischaemia). Causes of an acute episode include migration of an arterial blood clot or embolus into the mesenteric vessels, an arterial blood clot in patients with atherosclerosis, profound low blood pressure, or states promoting coagulation. Typically a patient presents with severe abdominal pain, nausea and vomiting, diarrhoea, and rectal bleeding. Rapid diagnosis is essential since impaired intestinal blood flow predisposes to the development of gangrene and necrosis of the bowel. Treatment includes aggressive fluid resuscitation, pain relief, antibiotics, surgical resection of nonviable bowel, and radiological or surgical *revascularization of implicated arteries. In chronic mesenteric ischaemia, abdominal pain precipitated by eating is the main symptom, often accompanied by loss of appetite and marked weight loss.... mesenteric ischaemia

Sacrocolpopexy

n. surgical treatment of *vault prolapse, which can be an abdominal or laparoscopic procedure. It involves suspending the prolapsed vaginal vault to the sacral promontory using a synthetic mesh or biological material; however, it is associated with a significant risk of haemorrhage and mesh erosion. Posterior intravaginal slingplasty (or infracoccygeal sacropexy) is a more recent technique in which a neo-uterosacral ligament (which supports the vagina) is formed. This helps to relocate the vaginal apex and restore the normal vaginal axis. The procedure appears to have similar efficacy to those currently in use but with minimal surgical morbidity.... sacrocolpopexy

Sagittal

adj. describing a dorsoventral plane that extends down the long axis of the body, parallel to the median plane, dividing it into right and left parts (see illustration).... sagittal

Salzmann’s Degeneration

a noninflammatory condition of the cornea resulting in yellow-white nodules under the epithelium in the central area. These may cause symptoms if the epithelium over them breaks down or if they are located along the visual axis. [M. Salzmann (1862–1954), German ophthalmologist]... salzmann’s degeneration

Symmetry

n. (in anatomy) correspondence of form on either side of a plane or axis. Human bodies are symmetrical around the *sagittal plane.... symmetry

Trochoid Joint

(pivot joint) a form of *diarthrosis (freely movable joint) in which a bone moves round a central axis, allowing rotational movement. An example is the joint between the atlas and axis vertebrae.... trochoid joint

Section

1. n. (in surgery) the act of cutting (the cut or division made is also called a section). For example, an abdominal section is performed for surgical exploration of the abdomen (see laparotomy). A transverse section is a cut made at right angles to a structure’s long axis. See also Caesarean section. 2. n. (in imaging) a three-dimensional reconstruction of body scans obtained by computerized tomography or magnetic resonance imaging. These are reconstituted as transverse, sagittal, and coronal plane sections. 3. n. (in microscopy) a thin slice of the specimen to be examined under a microscope. 4. vb. (in psychiatry) to issue an order for the compulsory admission of a patient to a psychiatric hospital for assessment and/or treatment of a mental disorder under the appropriate provision or section of the *Mental Health Act 1983 as amended by the Mental Health Act 2007. There are formal procedures, such as review and right to appeal, to ensure this legislation is not abused. A patient who otherwise has *capacity may still consent to or refuse treatment for conditions unrelated to the mental disorder for which he or she is detained.... section

Anise, Star

Illicium verum

FAMILY: Illiciaceae

SYNONYMS: Chinese anise, illicium, Chinese star anise.

GENERAL DESCRIPTION: Evergreen tree up to 12 metres high with a tall, slender white trunk. It bears fruit which consist of five to thirteen seed-bearing follicles attached to a central axis in the shape of a star.

DISTRIBUTION: Native to south east China, also Vietnam, India and Japan. Mainly produced in China.

OTHER SPECIES: Several other related species, e.g. Japanese star anise which is highly poisonous!

HERBAL/FOLK TRADITION: Used in Chinese medicine for over 1300 years for its stimulating effect on the digestive system and for respiratory disorders such as bronchitis and unproductive coughs. In the East generally, it is used as a remedy for colic and rheumatism, and often chewed after meals to sweeten the breath and promote digestion. A common oriental domestic spice.

ACTIONS: Antiseptic, carminative, expectorant, insect repellent, stimulant.

EXTRACTION: Essential oil by steam distillation from the fruits, fresh or partially dried. An oil is also produced from the leaves in small quantities.

CHARACTERISTICS: A pale yellow liquid with a warm, spicy, extremely sweet, liquorice like scent. It blends well with rose, lavender, orange, pine and other spice oils, and has excellent masking properties.

PRINCIPAL CONSTITUENTS: Trans-anethole (80–90 per cent).

SAFETY DATA: Despite the anethole content, it does not appear to be a dermal irritant, unlike aniseed. In large doses it is narcotic and slows down the circulation; it can lead to cerebral disorders. Use in moderation only.

AROMATHERAPY/HOME: USE

Circulation Muscles And Joints: Muscular aches and pains, rheumatism.

Respiratory System: Bronchitis, coughs.

Digestive System: Colic, cramp, flatulence, indigestion.

Immune system: Colds.

OTHER USES: By the pharmaceutical industry in cough mixtures, lozenges, etc. and to mask undesirable odours and flavours in drugs. As a fragrance component in soaps, toothpaste and detergents as well as cosmetics and perfumes. Widely used for flavouring food, especially confectionery, alcoholic and soft drinks.... anise, star




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