1.
Organ system
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A biological system is a complex network of biologically relevant entities. On the micro to the scale, examples of biological systems are cells, organelles, macromolecular complexes. A biological system is not to be confused with a living system, for further information see e. g. definition of life or synthetic biology. These specific systems are studied in Human anatomy. Human systems are present in many other animals. Circulatory system, pumping and channeling blood to and from the body and lungs with heart, integumentary system, skin, hair, fat, and nails. Skeletal system, structural support and protection with bones, cartilage, ligaments, urinary system, kidneys, ureters, bladder and urethra involved in fluid balance, electrolyte balance and excretion of urine. Respiratory system, the used for breathing, the pharynx, larynx, bronchi, lungs. The lymphatic system includes functions including immune responses and development of antibodies, muscular system, allows for manipulation of the environment, provides locomotion, maintains posture, and produces heat. Includes skeletal muscles, smooth muscles and cardiac muscle, nervous system, collecting, transferring and processing information with brain, spinal cord and peripheral nervous system. The notion of system relies upon the concept of vital or organic function and this idea was already present in Antiquity, but the application of the term system is more reccent. Inspired in the work of Adam Smith, Milne-Edwards wrote that the body of all living beings, whether animal or plant, where the organs, comparable to workers, work incessantly to produce the phenomena that constitute the life of the individual. In more differentiated organisms, the labor could be apportioned between different instruments or systems. Synthesis and Analysis of a Biological System, by Hiroyuki Kurata,1999
2.
Human musculoskeletal system
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The human musculoskeletal system is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body and it is made up of the bones of the skeleton, muscles, cartilage, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together. The musculoskeletal systems primary functions include supporting the body, allowing motion, the skeletal portion of the system serves as the main storage system for calcium and phosphorus and contains critical components of the hematopoietic system. This system describes how bones are connected to other bones and muscle fibers via connective tissue such as tendons, the bones provide stability to the body. Muscles keep bones in place and also play a role in the movement of bones, to allow motion, different bones are connected by joints. Cartilage prevents the bone ends from rubbing directly onto each other, muscles contract to move the bone attached at the joint. There are, however, diseases and disorders that may affect the function. These diseases can be difficult to due to the close relation of the musculoskeletal system to other internal systems. The musculoskeletal system refers to the system having its muscles attached to a skeletal system and is necessary for humans to move to a more favorable position. Complex issues and injuries involving the musculoskeletal system are handled by a physiatrist or an orthopaedic surgeon. The skeletal system serves many important functions, it provides the shape and form for the body, support and protection, allows bodily movement, produces blood for the body, the number of bones in the human skeletal system is a controversial topic. Humans are born with over 300 bones, however, many bones fuse together between birth and maturity, as a result, an average adult skeleton consists of 206 bones. The number of bones varies according to the used to derive the count. While some consider certain structures to be a bone with multiple parts. There are five classifications of bones. These are long bones, short bones, flat bones, irregular bones, the human skeleton is composed of both fused and individual bones supported by ligaments, tendons, muscles and cartilage. It is a structure with two distinct divisions, the axial skeleton, which includes the vertebral column, and the appendicular skeleton. The skeletal system serves as a framework for tissues and organs to attach themselves to and this system acts as a protective structure for vital organs
3.
Artery
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Arteries are blood vessels that carry blood away from the heart. While most arteries carry oxygenated blood, there are two exceptions to this, the pulmonary and the umbilical arteries, the effective arterial blood volume is that extracellular fluid which fills the arterial system. The anatomy of arteries can be separated into gross anatomy, at the level, and microscopic anatomy. The outermost layer is known as the tunica externa, also known as tunica adventitia, inside this layer is the tunica media, or media, which is made up of smooth muscle cells and elastic tissue. The innermost layer, which is in contact with the flow of blood, is the tunica intima. This layer is made up of endothelial cells. The hollow internal cavity in which the flows is called the lumen. Arterial formation begins when endothelial cells begin to express specific genes. Arteries form part of the circulatory system and they carry blood that is oxygenated after it has been pumped from the heart. Arteries also aid the heart in pumping blood, arteries carry oxygenated blood away from the heart to the tissues, except for pulmonary arteries, which carry blood to the lungs for oxygenation. Veins and pulmonary veins carry deoxygenated blood. )The pulmonary artery carries blood from the heart to the lungs and it is unique because the blood in it is not oxygenated, as it has not yet passed through the lungs. The other unique artery is the artery, which carries deoxygenated blood from a fetus to its mother. Arteries have a blood pressure than other parts of the circulatory system. The pressure in arteries varies during the cardiac cycle and it is highest when the heart contracts and lowest when heart relaxes. The variation in pressure produces a pulse, which can be felt in different areas of the body, arterioles have the greatest collective influence on both local blood flow and on overall blood pressure. They are the primary adjustable nozzles in the system, across which the greatest pressure drop occurs. The larger arteries are generally elastic and the smaller ones tend to be muscular, systemic arteries deliver blood to the arterioles, and then to the capillaries, where nutrients and gases are exchanged. After travelling from the aorta, blood travels through peripheral arteries into smaller arteries called arterioles, arterioles help in regulating blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries
4.
Nerve
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A nerve is an enclosed, cable-like bundle of axons in the peripheral nervous system. A nerve provides a pathway for the electrochemical nerve impulses that are transmitted along each of the axons to peripheral organs. In the central system, the analogous structures are known as tracts. Each nerve is a structure containing bundles of axons. Within a nerve, each axon is surrounded by a layer of tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of tissue called the perineurium. Finally, the nerve is wrapped in a layer of connective tissue called the epineurium. Efferent nerves conduct signals from the nervous system along motor neurons to their target muscles. Mixed nerves contain both afferent and efferent axons, and thus conduct both incoming sensory information and outgoing muscle commands in the same bundle and they are given letter-number designations according to the vertebra through which they connect to the spinal column. Cranial nerves innervate parts of the head, and connect directly to the brain and they are typically assigned Roman numerals from 1 to 12, although cranial nerve zero is sometimes included. In addition, cranial nerves have descriptive names, each nerve is covered externally by a dense sheath of connective tissue, the epineurium. Underlying this is a layer of cells, the perineurium. Perineurial septae extend into the nerve and subdivide it into several bundles of fibres, surrounding each such fibre is the endoneurium. This forms a tube from the surface of the spinal cord to the level where the axon synapses with its muscle fibres. The endoneurium consists of a sleeve of material called the glycocalyx. Nerves are bundled along with vessels, since the neurons of a nerve have fairly high energy requirements. Within the endoneurium, the nerve fibres are surrounded by a low protein liquid called endoneurial fluid. This acts in a way to the cerebrospinal fluid in the central nervous system
5.
Lymph
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Lymph is the fluid that circulates throughout the lymphatic system. The lymph is formed when the fluid is collected through lymph capillaries. Since the lymph is derived from the fluid, its composition continually changes as the blood. It is generally similar to blood plasma except that it doesnt contain red blood cells, lymph returns proteins and excess interstitial fluid to the bloodstream. Lymph may pick up bacteria and bring them to lymph nodes, metastatic cancer cells can also be transported via lymph. Lymph also transports fats from the system to the blood via chylomicrons. The word lymph is derived from the name of the ancient Roman deity of fresh water, lymph has a composition comparable to that of blood plasma, but it may differ slightly. In particular, the lymph that leaves a lymph node is richer in lymphocytes, likewise, the lymph formed in the human digestive system called chyle is rich in triglycerides, and looks milky white because of its lipid content. As the blood and the surrounding cells continually add and remove substances from the interstitial fluid, thus, lymph when formed is a watery clear liquid with the same composition as the interstitial fluid. However, as it flows through the nodes it comes in contact with blood. Tubular vessels transport lymph back to the blood, ultimately replacing the volume lost during the formation of the interstitial fluid and these channels are the lymphatic channels, or simply lymphatics. Unlike the cardiovascular system, the system is not closed and has no central pump. Lymph transport, therefore, is slow and sporadic, despite low pressure, lymph movement occurs due to peristalsis, valves, and compression during contraction of adjacent skeletal muscle and arterial pulsation. Lymph that enters the lymph vessels from the interstitial spaces usually does not flow backwards along the vessels because of the presence of valves. If excessive hydrostatic pressure develops within the vessels, though, some fluid can leak back into the interstitial spaces. Flow of the lymph in the duct in an average resting person usually approximates 100ml per hour. Accompanied by another ~25ml per hour in other vessels, total lymph flow in the body is about 4 to 5 liters per day. Which can be elevated several folds in case of exercising, thus it can be estimated that without lymphatic flow, an average resting person would die within 24 hours
6.
Superficial inguinal lymph nodes
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The superficial inguinal lymph nodes are the inguinal lymph nodes that form a chain immediately below the inguinal ligament. They lie deep to Campers fascia which overlies the femoral vessels at medial aspect of the thigh and they are found in the triangle bounded by the inguinal ligament superiorly, the border of the sartorius muscle laterally, and the adductor longus muscle medially. There are approximately 10 superficial lymph nodes, inguinal lymph nodes may normally be up to 2 cm in size. The superficial nodes drain to the inguinal lymph nodes
7.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
8.
Anatomical terminology
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Anatomical terminology is a form of scientific terminology used by anatomists, zoologists, and health professionals such as doctors. Anatomical terminology uses many terms, suffixes, and prefixes deriving from Ancient Greek. These terms can be confusing to those unfamiliar with them, but can be more precise reducing ambiguity, also, since these anatomical terms are not used in everyday conversation, their meanings are less likely to change, and less likely to be misinterpreted. By using precise anatomical terminology such ambiguity is eliminated, an international standard for anatomical terminology, Terminologia Anatomica has been created. Anatomical terminology has quite regular morphology, the prefixes and suffixes are used to add meanings to different roots. The root of a term refers to an organ, tissue. For example, in the disorder hypertension, the prefix hyper- means high or over, the roots, prefixes and suffixes are often derived from Greek or Latin, and often quite dissimilar from their English-language variants. Latin names of such as musculus biceps brachii can be split up and refer to, musculus for muscle, biceps for two-headed. The first word tells us what we are speaking about, the second describes it, when describing the position of anatomical structures, structures may be described according to the anatomical landmark they are near. These landmarks may include structures, such as the umbilicus or sternum, or anatomical lines, the cephalon or cephalic region refers to the head. This area is differentiated into the cranium, facies, frons, oculus, auris, bucca, nausus, oris. The neck area is called the cervicis or cervical region, examples of structures named according to this include the frontalis muscle, submental lymph nodes, buccal membrane and orbicularis oculi muscle. Sometimes, unique terminology is used to reduce confusion in different parts of the body, for example, different terms are used when it comes to the skull in compliance with its embryonic origin and its tilted position compared to in other animals. Here, Rostral refers to proximity to the front of the nose, similarly, in the arms, different terminology is often used in the arms, in part to reduce ambiguity as what is the front, back, inner and outer surfaces. For this reason, the terms below are used, Radial referring to the radius bone, ulnar referring to the ulna bone, medially positioned when in the standard anatomical position. Other terms are used to describe the movement and actions of the hands and feet. International morphological terminology is used by the colleges of medicine and dentistry and it facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields of research, teaching and medical care. The international morphological terminology refers to morphological sciences as a biological sciences branch, in this field, the form and structure are examined as well as the changes or developments in the organism
9.
Anus
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The anus is an opening at the opposite end of an animals digestive tract from the mouth. Amphibians, reptiles, and birds use the same orifice for excreting liquid and solid wastes, for copulation, monotreme mammals also have a cloaca, which is thought to be a feature inherited from the earliest amniotes via the therapsids. Marsupials have a single orifice for excreting both solids and liquids and, in females, a vagina for reproduction. The development of the anus was an important stage in the evolution of multicellular animals and it appears to have happened at least twice, following different paths in protostomes and deuterostomes. In animals at least as complex as an earthworm, the forms a dent on one side, the blastopore, which deepens to become the archenteron. In deuterostomes, the original dent becomes the anus while the gut tunnels through to make another opening. The protostomes were so named because it was thought that in their embryos the dent formed the mouth first and the anus was formed later at the opening made by the other end of the gut. More recent research, however, shows that in protostomes the edges of the dent close up in the middle, leaving openings at the ends become the mouth. Anal canal Imperforate anus, a birth defect, media related to Anus at Wikimedia Commons
10.
Pubic symphysis
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The pubic symphysis or symphysis pubis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones. It is located anterior to the bladder and superior to it. In males, the ligament of the penis attaches to the pubic symphysis. In females, the symphysis is intimately close to the clitoris. In normal adults it can be moved roughly 2 mm and with 1 degree rotation and this increases for women at the time of childbirth. The pubic symphysis is an amphiarthrodial joint. The name comes from the Greek word symphysis, meaning growing together, the width of the pubic symphysis at the front is 3–5 mm greater than its width at the back. The ends of both bones are covered by a thin layer of hyaline cartilage attached to the fibrocartilage. The fibrocartilaginous disk is reinforced by a series of ligaments and these ligaments cling to the fibrocartilaginous disk to the point that fibers intermix with it. Two such ligaments are the superior pubic ligament and the inferior pubic ligament, which provide the most stability, the anterior and posterior ligaments are weaker. The strong and thicker superior ligament is reinforced by the tendons of the rectus muscle, the abdominal external oblique muscle, the gracilis muscle. The superior pubic ligament connects together the two pubic bones superiorly, extending laterally as far as the pubic tubercles, fibrocartilage is composed of small, chained bundles of thick, clearly defined, type I collagen fibers. This fibrous connective tissue bundles have cartilage cells between them, these cells to a certain extent resemble tendon cells, the collagenous fibers are usually placed in an orderly arrangement parallel to tension on the tissue. It has a low content of glycosaminoglycans, glycosaminoglycans are long, unbranched polysaccharides consisting of repeating disaccharide units. Fibrocartilage does not have a surrounding perichondrium, perichondrium surrounds the cartilage of developing bone, it has a layer of dense, irregular connective tissue and functions in the growth and repair of cartilage. Hyaline cartilage is the white, shiny gristle at the end of long bones and this cartilage has poor healing potential, and efforts to induce it to repair itself frequently end up with a similar, but poorer fibrocartilage. In the newborn, the pubis is 9–10 mm in width, with thick cartilaginous end-plates. By mid-adolescence the adult size is achieved, during adulthood the end-plates decrease in width to a thinner layer
11.
Erogenous zone
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Erogenous zones are located all over the human body, but the sensitivity of each varies, and depends on concentrations of nerve endings that can provide pleasurable sensations when stimulated. The touching of another persons erogenous zone is regarded as an act of physical intimacy, some people may resent stimulation in this manner while others may find it pleasing, and this may also depend on the relationship between the persons involved. Erogenous zones may be classified by the type of response that they generate. Many people are gently aroused when their eyelids, eyebrows, temples, shoulders, hands, arms, gently touching or stroking of these zones stimulates a partner during foreplay and increases the arousal level. Also, the massage or stroke of the abdominal area along with kissing or simply touching the navel can be a type of stimulation. Erogenous zones are either nonspecific or specific, in these zones, the skin is similar to normal-haired skin and has the normal high density of nerves and hair follicles. These areas include the sides and back of the neck, the inner arms, an exaggerated tickle and anticipatory response are responsible for the heightened sensual response. The neuroanatomy and neurophysiology of erogenous zones is partly unknown and these zones are apparently mucocutaneous skin. The rete ridges of the epithelium are well-formed and more of the nerves are close to the surface of the skin than in normal-haired skin. These zones seem to have a density of innervation, an efficiency of wound healing. Moreover, a connection with the system seems also necessary. The prostate gland may be stimulated from inside the rectum, such as by anal sex, men who report the sensation of prostate and seminal vesicles stimulation often give descriptions similar to females accounts of G-spot stimulation. The foreskin, which carries the ridged band and lower frenular delta, has mucocutaneous end-organs extending from the margin to the point where hairy skin starts. The thin dermis and minimal subcutaneous tissue results in closely set nerve networks, the mucocutaneous end-organs are formed after birth, with few in newborn infants and many well-organized endings in adults. Cold and Taylor state in 1999 that the foreskin is primary erogenous tissue, alanis and Lucidi in 2004 describe this as speculative and unproven. Parts of the vulva, especially the clitoris, are erogenous zones, the lips and tongue are sensitive and can be stimulated by kissing and licking. Biting at the lip can also provide stimulus, many people find a gentle scalp massage, or any stimulation of the hair follicles, to be anywhere from relaxing to extremely stimulating. The neck, clavicle area and the back of the neck are very sensitive in males and females, which can be stimulated by licking, kissing or light caressing
12.
Greek language
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Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
13.
Surface anatomy
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Surface anatomy is the study of the external features of the body. It deals with anatomical features that can be studied by sight, as such, it is a branch of gross anatomy, along with endoscopic and radiological anatomy. Surface anatomy is a descriptive science, in addition, the science of surface anatomy includes the theories and systems of body proportions and related artistic canons. The study of anatomy is the basis for depicting the human body in classical art. Some pseudo-sciences such as physiognomy, phrenology and palmistry rely on surface anatomy, some sources include the fourth left interspace. Human female breasts are located on the chest wall, most frequently between the second and sixth rib, on the trunk of the body in the thoracic area, the shoulder in general is the acromial, while the curve of the shoulder is the deltoid. The back as an area is the dorsum or dorsal area. The shoulderblades are the area and the breastbone is the sternal region. The abdominal area is the region between the chest and the pelvis, the breast is called the mamma or mammary, the armpit as the axilla and axillary, and the navel as the umbilicus and umbilical. The pelvis is the torso, between the abdomen and the thighs. The groin, where the thigh joins the trunk, are the inguen, the buttocks are the gluteus or gluteal region and the pubic area is the pubis. Anatomists divide the limb into the thigh and the leg. The thigh is the femur and the femoral region, the kneecap is the patella and patellar while the back of the knee is the popliteus and popliteal area. The leg is the crus and crural area, the aspect of the leg is the peroneal area. The ankle is the tarsus and tarsal, and the heel is the calcaneus or calcaneal, the foot is the pes and pedal region, and the sole of the foot the planta and plantar. As with the fingers, the toes are also called the digits, phalanges, the big toe is referred to as the hallux. Following are lists of surface features in humans and other animals. Sorted roughly from head to tail, cranial to caudal, homologues share a bullet point and are separated by commas
14.
Human anus
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The human anus is the external opening of the rectum. Two sphincters control the exit of feces from the body during an act of defecation, the inner sphincter is involuntary and the outer is voluntary. It is located behind the perineum which is located behind the vagina in females, with anal sex, the anus can play a role in sexuality. Attitudes towards anal sex vary and it is illegal in some countries, the anus is often considered a taboo part of the body, and it is known by a large number of usually vulgar slang terms. The anus is also the site of infections and other conditions. The traditional polite synonym for anus was fundament, though this euphemism is rarely heard now that medical terms are widely acceptable, the anus is the final component of the gastrointestinal tract, and directly continues from the rectum. The anus passes through the pelvic floor, the anus is surrounded by muscles. The top and bottom of the anus are surrounded by the internal and external anal sphincters, the anus is surrounded in its length by folds called anal valves, which converge at a line known as the pectinate line. This represents the point of transition between the hindgut and the ectoderm in the embryo, below this point, the mucosa of the internal anus becomes skin. The pectinate line is also the division between the internal and external anus, the anus receives blood from the inferior rectal artery and innervation from the inferior rectal nerves, which branch from the pudendal nerve. The pseudostratified columnar epithelium of the gastrointestinal tract transitions to stratified squamous epithelium at the pectinate line, the stratified squamous epithelium gradually accumulates sebaceous and apocrine glands. During puberty, as testosterone triggers androgenic hair growth on the body, although initially sparse, it fills out by the end of puberty, if not earlier. However, in some genetic populations androgenic hair is less common, intra-rectal pressure builds as the rectum fills with feces, pushing the feces against the walls of the anal canal. Contractions of abdominal and pelvic floor muscles can create pressure which further increases intra-rectal pressure. The internal anal sphincter responds to the pressure by relaxing, thus allowing the feces to enter the canal, the rectum shortens as feces are pushed into the anal canal and peristaltic waves push the feces out of the rectum. Relaxation of the internal and external anal sphincters allows the feces to exit from the anus, finally, in psychology, the Freudian term anal fixation is used. The anus has a high concentration of nerve endings and can be an erogenous zone. The pudendal nerve that branches to supply the external anal sphincter also branches to the nerve of clitoris
15.
Ischial tuberosity
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The ischial tuberosity, also known informally as the sit bones, or as a pair the sitting bones is a large swelling posteriorly on the superior ramus of the ischium. It marks the boundary of the pelvic outlet. When sitting, the weight is placed upon the ischial tuberosity. The gluteus maximus provides cover in the posture, but leaves it free in the seated position. The tuberosity is divided into two portions, a lower, rough, somewhat triangular part, and an upper, smooth, sensitivity for pressure difference on the ischial tuberosity. Color Atlas of Human Anatomy, Vol.1, Locomotor System
16.
Pubic arch
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The pubic arch is part of the pelvis. It is formed by the convergence of the inferior rami of the ischium and pubis on either side, the angle at which they converge is known as the subpubic angle. The pubic arch is one of three notches that separated the eminences of the circumference of the true pelvis. The subpubic angle is the angle in the body as the apex of the pubic arch, formed by the convergence of the inferior rami of the ischium. The subpubic angle is important in anthropology, in determining the sex of someone from skeletal remains. A subpubic angle of 50-82 degrees indicates a male, an angle of 90 degrees indicates a female, women have wider hips - a greater subpubic angle - in order to allow for child birth. Other sources operates with 50-60 degrees for males and 70-90 degrees in females, as seen in the picture, there is a distinctive difference between the pubic arch of a male and a female. This difference is found in the subpubic angle, the area in which the pubic arch is located is the pelvis, the area that is most different between male and female anatomy. The subpubic angle of a man is generally 50-60 degrees while that of a woman is generally 70-90 degrees, a woman’s pubic arch needs to be wider in order to enable childbirth. The pelvic inlet of a female is wider because the child’s head must pass through it. The pubic arch is referred to as the ischiopubic arch. This article incorporates text in the domain from the 20th edition of Grays Anatomy
17.
Inferior pubic ligament
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The pubic symphysis or symphysis pubis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones. It is located anterior to the bladder and superior to it. In males, the ligament of the penis attaches to the pubic symphysis. In females, the symphysis is intimately close to the clitoris. In normal adults it can be moved roughly 2 mm and with 1 degree rotation and this increases for women at the time of childbirth. The pubic symphysis is an amphiarthrodial joint. The name comes from the Greek word symphysis, meaning growing together, the width of the pubic symphysis at the front is 3–5 mm greater than its width at the back. The ends of both bones are covered by a thin layer of hyaline cartilage attached to the fibrocartilage. The fibrocartilaginous disk is reinforced by a series of ligaments and these ligaments cling to the fibrocartilaginous disk to the point that fibers intermix with it. Two such ligaments are the superior pubic ligament and the inferior pubic ligament, which provide the most stability, the anterior and posterior ligaments are weaker. The strong and thicker superior ligament is reinforced by the tendons of the rectus muscle, the abdominal external oblique muscle, the gracilis muscle. The superior pubic ligament connects together the two pubic bones superiorly, extending laterally as far as the pubic tubercles, fibrocartilage is composed of small, chained bundles of thick, clearly defined, type I collagen fibers. This fibrous connective tissue bundles have cartilage cells between them, these cells to a certain extent resemble tendon cells, the collagenous fibers are usually placed in an orderly arrangement parallel to tension on the tissue. It has a low content of glycosaminoglycans, glycosaminoglycans are long, unbranched polysaccharides consisting of repeating disaccharide units. Fibrocartilage does not have a surrounding perichondrium, perichondrium surrounds the cartilage of developing bone, it has a layer of dense, irregular connective tissue and functions in the growth and repair of cartilage. Hyaline cartilage is the white, shiny gristle at the end of long bones and this cartilage has poor healing potential, and efforts to induce it to repair itself frequently end up with a similar, but poorer fibrocartilage. In the newborn, the pubis is 9–10 mm in width, with thick cartilaginous end-plates. By mid-adolescence the adult size is achieved, during adulthood the end-plates decrease in width to a thinner layer
18.
Sacrotuberous ligament
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The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, and triangular in form, narrower in the middle than at the ends and it runs from the sacrum to the tuberosity of the ischium. It is a remnant of part of Biceps femoris muscle and its oblique fibres descend laterally, converging to form a thick, narrow band that widens again below and is attached to the medial margin of the ischial tuberosity. It then spreads along the ischial ramus as the process, whose concave edge blends with the fascial sheath of the internal pudendal vessels. The lowest fibres of gluteus maximus are attached to the surface of the ligament. The ligament is pierced by the branches of the inferior gluteal artery. The membranous falciform process of the ligament was found to be absent in 13% of cadavers. When present it extends towards the ischioanal fossa travelling along the ischial ramus, the lower border of the ligament was found to be directly continuous with the tendon of origin of the long head of the Biceps femoris in approximately 50% of subjects. Biceps femoris could therefore act to stabilise the sacroiliac joint via the sacrotuberous ligament, the sacrotuberous ligament contains the coccygeal branch of the inferior gluteal artery. If the pudendal nerve becomes entrapped between this ligament and the sacrospinous ligament causing perineal pain, the ligament is surgically severed to relieve the pain. Anatomy figure,13, 03-04 at Human Anatomy Online, SUNY Downstate Medical Center - Deep muscles of the region with gluteus medius and maximus muscles removed. Anatomy figure,17, 02-05 at Human Anatomy Online, SUNY Downstate Medical Center - Posterior view of the bones and ligaments of the hip joint
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Pelvic floor
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The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus muscle, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the levatores ani and coccygei, the pelvic floor separates the pelvic cavity above from the perineal region below. The right and left levator ani lie almost horizontally in the floor of the pelvis, separated by a gap that transmits the urethra, vagina. The levator ani is usually considered in three parts, pubococcygeus, puborectalis, and iliococcygeus, the pubococcygeus, the main part of the levator, runs backward from the body of the pubis toward the coccyx and may be damaged during parturition. Some fibers are inserted into the prostate, urethra, and vagina, the right and left puborectalis unite behind the anorectal junction to form a muscular sling. Some regard them as a part of the sphincter ani externus, the iliococcygeus, the most posterior part of the levator ani, is often poorly developed. The coccygeus, situated behind the levator ani and frequently tendinous as much as muscular, extends from the spine to the lateral margin of the sacrum. The pelvic cavity of the pelvis has the pelvic floor as its inferior border. The perineum has the floor as its superior border. However, other include the fascia as part of the diaphragm. In practice, the two terms are used interchangeably. Posteriorly, the pelvic floor extends into the anal triangle, the pelvic floor has two hiatuses, Anteriorly urogenital hiatus through which urethra and vagina pass through and posteriorly rectal hiatus through which anal canal passes. It is important in providing support for pelvic viscera, e. g. the bladder, intestines, the uterus and it facilitates birth by resisting the descent of the presenting part, causing the fetus to rotate forwards to navigate through the pelvic girdle. It helps maintain optimal intra-abdominal pressure, in women, the levator muscles or their supplying nerves can be damaged in pregnancy or childbirth. There is some evidence that these muscles may also be damaged during a hysterectomy, pelvic surgery using the perineal approach is an established cause of damage to the pelvic floor. In female high-level athletes, perineal trauma is rare and is associated with sports, water-skiing, bicycle racing. Damage to the pelvic floor not only contributes to urinary incontinence, pelvic organ prolapse occurs in women when pelvic organs protrude into or outside of the vagina. The causes of pelvic organ prolapse are not unlike those that contribute to urinary incontinence
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Levator ani
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It is part of the levator ani muscle. Between the termination of the column and the anus, the two pubococcygei muscles come together and form a thick, fibromuscular layer lying on the raphe or formed by the iliococcygei. The greater part of muscle is inserted into the coccyx. This insertion into the column is, however, not accepted by all observers. The pubococcygeus muscle controls urine flow and contracts during orgasm as well as assisting in male ejaculation and it also aids in childbirth as well as core stability. A strong pubococcygeus muscle has also linked to a reduction in urinary incontinence. The Kegel exercises are a series of contractions of all the perineal muscles. Such movement is done in an effort to all the striated muscles in the perineums area. They are often referred to simply as kegels, named after their founder, Kegel exercises have been prescribed to ameliorate erectile dysfunction due to venous leakage and to help men control premature ejaculation and to treat urinary incontinence in both sexes. Bulbospongiosus muscle -60096433 at GPnotebook pelvis at The Anatomy Lesson by Wesley Norman
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External anal sphincter
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The external anal sphincter is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus. It consists of two strata, superficial and deep, the deeper portion forms a complete sphincter to the anal canal. Its fibers surround the canal, closely applied to the anal sphincter. In a considerable proportion of cases the fibers decussate in front of the anus, posteriorly, they are not attached to the coccyx, but are continuous with those of the opposite side behind the anal canal. The upper edge of the muscle is ill-defined, since fibers are given off from it to join the levator ani, the action of this muscle is peculiar. It is, like other muscles, always in a state of tonic contraction and it can be put into a condition of greater contraction under the influence of the will, so as more firmly to occlude the anal aperture, in expiratory efforts unconnected with defecation. Taking its fixed point at the coccyx, it helps to fix the point of the perineum. Anismus is a contraction of the external anal sphincter, when the intent is relaxation. Abnormal function of muscle is also seen in anorectal malformation and after certain surgeries
. PMID 16393642.
