Clinical means the science and practice of or for the treatment of patients. That is to say it encompasses not only doctors but also nurses, physiotherapists, occupational therapists and any other healthcare worker who comes into direct contact with the patient.

When discussing negligence the traditional umbrella was medical negligence. However that would suggest that the negligence is always on the part of doctors. Since some incidents which give rise to claims for negligence do not relate to doctors, but to other healthcare professionals, the generic and inclusive term clinical negligence is now preferred.

Forensic relates to the work of the courts. Thus forensic science is science applied to the work of the courts; forensic medicine is medicine applied to the work of the courts; and forensic psychiatry is psychiatry as relating to the work of the courts. In practice forensic medicine and clinical forensic medicine are used more restrictively to relate mainly to the activity of the criminal courts. Doctors who practise clinical forensic medicine examine living patients who are subject to injuries or are suspected of having committed offences which have come to the attention of the legal system and where medical evidence is relevant to the case. They are to be distinguished from forensic pathologists who examine the body after death (post mortem) or dead tissue.

Distinction between different types of doctors
Traditionally there were two species of healthcare practitioner: physicians and surgeons.

In broad terms physicians treated patients with medicine (physic) and seldom touched their patients. The adjective medical is still used (in its more restrictive sense) to denote this difference, a practice of physicians, rather than surgeons. Physicians were intellectuals and wrote Latin. They left the more menial tasks involving touching (such as the pulling of teeth, the draining of abscesses, the letting of blood, etc) to the surgeons, who had little theoretical learning and wrote no Latin.

In medieval times the physicians were licensed by the apothecaries' company; the barber-surgeons had their own company. To this day, there is a tradition (largely confined to England and Wales) for surgeons who have acquired Fellowship of the Royal College of Surgeons of England (the successor to the barber-surgeons company in educating surgeons) to reject the title doctor and revert to Mr. This causes considerable confusion overseas. Further confusion is generated by the American habit of calling all doctors `physicians', a term which in the UK is used only for that group of doctors specialising in medicine rather than surgery.

Doctors may be divided conveniently into eight broad areas of practice, six of which deal directly with patients. These six are:

• medicine;
• surgery;
• paediatrics;
• obstetrics and gynaecology;
• psychiatry;
• anaesthetics.

The two further groups are:

• pathology;
• diagnostic imaging.

These two groups are often described as `service specialties', in that they are called in by the five clinical specialties to perform special investigations on their patients.

There is considerable overlap between the eight groups and some doctors (see below) could conveniently be categorised in more than one broad specialty. Within the six broad specialties there is an almost endless further specialisation and sub-specialisation which defies description.

A general practitioner is a doctor who provides primary healthcare in the community, trained in all six of the clinical specialties. He refers, as necessary, to secondary healthcare providers within the hospital service. Not all hospitals have all specialties represented and there may be a need for tertiary referral within the hospital system.

Accident and emergency
The accident and emergency department of the district general hospital serves as an interface between primary and secondary care. It combines medicine and surgery. Specialists in accident and emergency come from a variety of backgrounds, some with a surgical and some with a medical postgraduate background.

Medicine
The major areas of specialisation within medicine are as follows.

General medicine
Many physicians within the hospital service provide expertise across a broad area which would include some aspects at least of gastroenterology, chest medicine, cardiology, endocrinology and nephrology. A general physician usually has a special interest in at least one of these areas.

Geriatrics
The medicine of the elderly is general medicine applied to the care of patients over a certain age. Age definitions will vary but usually are around 70. Some degree of sub-specialisation also occurs within the care of the elderly. In particular there is cross-over between geriatrics and psychiatry in the sub-specialty of psycho-geriatrics, the management of mental illness in old age.

Cardiology
This is the study of the heart and its diseases. Sometimes the description is extended to cardiovascular to include some aspects of the blood vessels (vascular system). There is a close working relationship with cardiac surgeons and cardiovascular surgeons (qv).

Neurology
This is the study of the brain, the nervous system and its diseases. There is a separate sub-specialty of clinical neurophysiology, concerned mostly with testing and measurement. Neurologists work in close association with neurosurgeons (qv).

Chest medicine (respiratory medicine)
Chest physicians deal with the lungs and their diseases and work in close association with cardiothoracic surgeons (qv) who operate on the lungs.

Endocrinology
This is the study of hormones, the organs from which they originate and the diseases associated with them. Curiously many endocrinologists do not deal with one of the commonest endocrine disorders (diabetes mellitus). All general physicians have some expertise in the management of diabetes. There are a few specialist diabetologists. Further sub-specialisation within endocrinology leads to specialists in single hormone disorders (eg thyroid specialists) and specialists in reproductive endocrinology, the hormones associated with conception and childbirth in both sexes.

Rheumatology (physical medicine)
Sometimes called orthopaedic physicians, rheumatologists deal with the non-surgical treatment of bone, joint, muscle and the systems involved in locomotion. They work closely with physiotherapists (one of the professions allied to medicine) who are not medically qualified but have their own system of professional training. Rheumatologists also work closely with orthopaedic surgeons (qv). Both may be involved in sports medicine and the consequences and injuries relating to physical training.

Gastroenterology
The specialty includes most of the digestive system and historically, like other branches of medicine, was strictly non-surgical. Nowadays gastroenterologists are frequently expert endoscopists. This means that they introduce fibre-optic lighting systems into both ends of the gastro-intestinal tract to examine it and occasionally to obtain samples from it. Upper gastrointestinal endoscopy is usually called gastroscopy, whereas lower gastrointestinal endoscopy is called colonoscopy.

Intensive care
The responsibility for intensive care and critical care is often shared between a specialist physician and an anaesthetist (qv).

Nephrology
Nephrology (or renal medicine) covers kidney function and its disorders. Because hypertension (high blood pressure) is often associated with kidney disease nephrologists tend also to be experts in that field as well. They work closely with and refer to urologists (urological surgeons, qv).

Genito-urinary medicine
GUM physicians used to be called venereologists and deal with all aspects of sexually transmitted disease. They also deal with other conditions which may simulate sexually transmitted disease, overlapping (in the female) with the medical aspects of gynaecology (qv) and (in the male) with the management of lower urinary tract abnormalities, otherwise the province of the urologist (qv).

Dermatology
The study of diseases of the skin.

Haematology
Haematology is the study of the blood and its disorders and may equally conveniently be classified under medicine or pathology (qv).

Oncology and radiotherapy
Oncology is the study and treatment of tumours (cancer). Medical oncologists are physicians who specialise in the treatment of cancer with drugs. Radiotherapists are doctors who specialise in treatment with ionising radiations of all types (including x-rays and radioactive isotopes). Whilst they mainly treat cancer (and are often trained in medical oncology as well) they are not exclusively concerned with the treatment of cancer.

Occupational health medicine
Health and disease in the context of occupation and employment.

Public health medicine
Public health physicians cover a broad territory including epidemiology (patterns of disease within society), the protection of the public from disease, the provision of healthcare, advice on the purchasing of healthcare and the prioritisation of health needs, as well as medical education.

Pharmacology and therapeutics
Pharmacology is the study of the action of drugs on the body and a pharmacist is a person qualified to prepare and dispense drugs. He is not medically qualified but has a separate training. Therapeutics is that branch of medicine concerned with drugs and other non-surgical remedies.

Surgery
Fifty years ago almost all surgeons were `general surgeons' and did everything except ophthalmology (qv), oto-rhino-laryngology (qv) and oral surgery.

Now general surgeons usually are primarily abdominal surgeons, some of whom may occasionally operate in the chest; most still deal with the female breast, most will tackle varicose veins and some have expertise in urology. Most general surgery is abdominal and there are two further sub-specialisations within the surgery of the gut. Gastric or upper gastro-intestinal surgeons deal with the upper bowel whereas colo-rectal surgeons (proctologists) deal with the lower bowel. Breast (mammary) surgery is a rapidly developing sub-specialty.

Urology
The urological surgeon deals with the surgery of the kidney and the drainage system including the ureter, bladder, prostate and urethra. Most urologists are fully trained general surgeons; they frequently operate on the bowel.

Orthopaedics
The surgery of bones, joints and locomotion, working closely with rheumatologists (qv). Trauma is often combined with orthopaedics; a trauma surgeon deals with the consequences of physical injury not only to bones but also to soft tissue. Trauma surgery is to be distinguished from elective orthopaedics, which may be sub-divided into broad areas or individual organs, eg foot, hand and back surgery. Fracture management is a sub-specialty within trauma surgery. Orthopaedic surgeons may be involved, with rheumatologists, in sports medicine and the consequences of physical training injuries. Spinal surgery is sometimes undertaken by orthopaedic surgeons and sometimes by neurosurgeons.

Neurosurgery
The surgery of the brain and the nervous system (including spinal surgery), working closely with their specialist physicians, the neurologists.

Plastic and reconstructive surgery
The terms are synonymous and include the sub-specialties of burns surgery (including an element of critical care) and cosmetic surgery. Some plastic and cosmetic surgeons specialise in particular parts of the body.

Cardiac and thoracic
Cardiac surgeons operate on the heart. Thoracic surgeons traditionally operate on the lungs. Now most do both (cardio-thoracic surgeons).

Vascular
Vascular surgeons do not usually operate on the heart (there are some cardiovascular surgeons) but specialise in the surgery of the blood vessels. The term theoretically can be extended to include the surgery of varicose veins.

Ophthalmology
The surgery of the eye and the orbit.

ENT (oto-rhino-laryngology)
The surgery of the ear, nose and throat often further divided into sub-specialties dealing with only one part of the traditional specialty (otology, rhinology and laryngology). Other ENT surgeons would describe themselves more expansively as head and neck surgeons.

Minimal access surgery
Traditionally surgery was done by making an incision large enough to see directly into a body cavity and to operate within it. Increasingly surgery is now done by the passage of a fibre-optic telescope into a body cavity through a tiny incision, operating without major access (eg laparoscopy - looking into the belly). Similar flexible telescopes can be inserted into the body orifices to explore the gastrointestinal tract (endoscopy) either from the upper (gastroscopy) or lower (colonoscopy) end, or the lung (bronchoscopy). Minimal access surgery occurs in almost every surgical specialty and has created a further sub-division of each surgical specialty; much orthopaedic surgery is now done by passing telescopes into joints (arthroscopy).

Paediatrics
The care of children is principally divided between the following:

Neonatology
The care of children in the first few weeks of life.

General paediatrics
The care of older children. Paediatrician is the term normally applied to the physician who cares for children. There is a different specialty of paediatric surgery, surgeons who operate exclusively on children. Within paediatric surgery there are the same sub-specialties as occur in surgery generally, eg paediatric urology, paediatric orthopaedics, etc.

Child health and child development both come within the general specialty of paediatrics. Child psychiatry and adolescent psychiatry are sub-divisions of that subject (qv). Paediatric neurology is of special forensic interest because of the expertise required to examine handicap, such as cerebral palsy.

Obstetrics and gynaecology
Traditionally all members of this specialty practised both obstetrics (the care of pregnant women) and gynaecology (the female genital tract and its diseases), at least in the UK. Now there is an increasing tendency to sub-specialisation so that some practise only obstetrics. Within obstetrics there are sub-specialties, eg:

Pre-natal diagnosis
This includes ultrasound and invasive procedures to sample the liquor amni (the fluid around the baby), the placenta or the fetus for biochemical or genetic testing.

Fetal medicine
This is the study of the fetus while still in the womb. As a specialty it overlaps with pre-natal diagnosis (see above) and peri-natal medicine (below).

Peri-natal medicine
This is essentially the medicine of labour ward care. It specifically concentrates on the time around birth (peri-natal).

Gynaecology
Gynaecology is further sub-divided into:

Reproductive medicine
Reproductive medicine is concerned with the study of infertility and its correction.

Family planning
This is concerned with the provision of contraception and abortion, dealing with the termination of pregnancy. Specialists in this field often describe themselves as practitioners in women's healthcare.

Gynaecological oncology
Gynaecological oncology deals with the management of cancer within gynaecology.

Gynaecological urology
This deals with problems of female continence.

Psychiatry
There are two main divisions of psychiatry dealing with:

• mental illness
• mental handicap (now called learning disability).

Most general psychiatrists deal only with mental illness.

Psychiatrists
These are medical practitioners who may use a full range of treatments, drugs and physical methods such as electro-convulsant therapy. Child psychiatry, adolescent psychiatry and psycho-geriatrics are sub-divisions within psychiatry.

Some psychiatrists and psychologists specialise in particular clinical presentations such as puerperal (ie following childbirth) mental illness, post-traumatic stress disorder or eating disorders.

Psychology
Psychology is the scientific study of normal and abnormal behaviour and experience. Academic psychological research examines cognition (perception, memory, thinking, language, decision-making), development, learning, social behaviour, and relationships between brain, body functioning and behaviour.

Psychologists
Psychologists are not medically qualified but have their own professional training. They have a first degree in psychology and have also undertaken further professional training in a specific area of psychology. The most important specialist groups, acting as experts, are:

Clinical psychologists
Primarily concerned with the assessment and treatment of emotional and psychiatric problems in adult mental health (including rehabilitation and psychological therapy), child health, services for people with learning disabilities, care of the elderly, and substance abuse. Clinical psychologists operate in both primary care and general hospital services.

Clinical neuropsychologists
Concerned with changes which occur following damage to, or disease of, the nervous system. Their skills lie in the management of changes in intelligence, thinking, memory, personality and other aspects of behaviour so that neurological conditions may be more accurately detected, diagnosed and treated.

Educational psychologists
They are applied psychologists working within both the school system and the community. They are concerned with children's learning and development. They have skills in a range of psychological and educational assessment techniques and in different methods of helping children and young people who are experiencing difficulties in learning or social adjustment.

Forensic psychologists
They contribute to criminological and legal services in many ways (often referred to generically as forensic psychology). They might be interested in the behaviour of people within the legal system; or they might study offenders, offenders' behaviour and crime detection, the administration of justice (including the giving of evidence) or the management of individuals following sentencing.

Anaesthetics
The anaesthetist specialises in the relief of pain, most commonly in the context of surgery. There are four major sub-divisions. General anaesthetics provide pain relief and support for surgery. Obstetric anaesthesia provides pain relief (usually regional block, epidural or spinal) for labour and for Caesarean section. Pain relief is the treatment of chronic pain, often on an out-patient basis by drug therapy and local injections. Intensive care/intensive therapy/critical care anaesthetists are usually (but not always) responsible for the intensive care/therapy units (ITU).

Pathology
Traditionally pathology is sub-divided into:

• microbiology;
• histopathology;
• haematology; and
• biochemistry,

Microbiology
This deals with infectious disease of all kinds whether caused by fungi (mycology), bacteria (bacteriology) or viruses (virology). Microbiologists are also responsible for the control of infection and for advising public health physicians in aspects of disease prevention.

Histopathology (morbid anatomy)
This is the study of dead tissue either removed surgically (as a biopsy or a surgical excision specimen) or after death in post mortem examinations. The study of exfoliated cells (as in cervical smears) is a sub-division (cytopathology).

Haematology
The study of the blood and its diseases including the bone marrow and bone marrow failures. Originally a laboratory specialty, the haematologist usually now has both laboratory and clinical responsibilities.

Haematologists are also in charge of blood transfusion, sometimes as a sub-specialty.

Biochemistry (chemical pathology)
The study of blood chemistry. Some chemical pathologists have clinical interests in fields where blood chemistry is especially relevant, such as diabetes.

Diagnostic imaging
Traditionally imaging was achieved by x-rays (radiology) but the specialty now includes ultrasound and other forms of sophisticated imaging such as magnetic resonance (MRI). There is a sub-specialty of invasive radiology which involves the passage of instruments within the body under X-ray control. Lines (catheters) can be passed along blood vessels to aid diagnostic imaging, assist in the destruction of tumours and occlude blood vessels (for the arrest of haemorrhage).