BD Chaurasia's Handbook of General Anatomy (4th Edition) PDF

B D Chaurasia'S Late Dr B D Chaurasia 1937-1985  B D Chaurasia'S Fourth Edition Late Dr B D Chaurasia MBBS, MS, PhD, FAMS Department of Anatomy G.R. Medical College Gwal...

B D Chaurasia'S Late Dr B D Chaurasia 1937-1985  B D Chaurasia'S Fourth Edition Late Dr B D Chaurasia MBBS, MS, PhD, FAMS Department of Anatomy G.R. Medical College Gwalior, India Edited by Dr. Krishna Garg MBBS, MS, PhD, FIMSA, FIAMS, FAMS & Chikitsa Ratan Ex. Prof. & Head, Deptt. of Anatomy, Lady Hardinge Medical College, New Delhi CBS CBS PUBLISHERS & DISTRIBUTORS PVT. LTD. NEW DELHI B E N G A L U R U PUNE KOCHI CHENNAI WWW.CBSPD.COM  BD Chaurasia's Handbook of GENERAL ANATOMY Fourth Edition ISBN: 978-81-239-1654-5 Copyright © Author and Publisher Fourth Edition: 2009 Reprint: 2010, 2011,2012, 2013 First Edition: 1978 Second Edition: 1983 Third Edition: 1996 All rights reserved. No part of this book may be reproduced or transmitted in dny form or by any means, electronic or mechanical, including photocopying, recording, or any information storage a n d retrieval system without permission, in writing, from the author a n d the publisher. Published by Satish Kumar Jain for CBS Publishers & Distributors Pvt Ltd 4819/XI Prahlad Street, 24 Ansari Road, Daryaganj, New Delhi 110002, India. Ph: 23289259, 23266861, 23266867 Website: www.cbspd.com Fax: 011 -23243014 e-mail: [email protected]: [email protected]. Corporate Office: 204 FIE, Industrial Area, Patparganj, Delhi 110092 Ph: 4934 4934 Fax: 4934 4935 e-mail: [email protected]; [email protected] Branches Bengaluru: Seema House 2975, 17th Cross, K.R. 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Now, simple coloured diagrams extensively illustrate each chapter. Once initial interest to read text supplemented by diagrams is developed, learning general anatomy is hardly problematic. Clinical anatomy has been illustrated with coloured diagrams. Students have always been encouraging me in improving both text and diagrams. The help of Ms. Priya, MBBS student of Lady Hardinge Medical College during 1990-91, is being acknowledged for improving the "Anatomical word meanings and historical names." Mr. Ajit Kumar, first year student of Banarasidas Chandiwala Institute of Physiotherapy (BCIP) 2004-05, gave constructive suggestions for its betterment. Ms. Stuti Malhotra, first year student of BCIP (2007-08), provided me with a number of tables in various chapters. I feel highly obliged to them. The editor is obliged to Mr. Y.N. Arjuna, Publishing Director, CBS for timely and much needed guidance. Page layout and four colour diagrams work have been diligently done by Ms. Nishi Verma and Mr. Chand Singh Naagar of M/s. Limited Colors. Mr. Vinod Jain, Production Director, and Mr. Satish Jain, Chairman, CBS Publishers and Distributors, have been helping me from time to time. Comments from the students are welcome. Krishna Garg Editor  dedicated to my teacher Shri Uma Shankar Nagayach  Preface to the First Edition This handbook of general anatomy has been written to meet the requirements of students who are newly admitted to medical colleges. It thoroughly introduces the greater part of medical terminology, as well as the various structures which constitute the human body. On account of the late admissions and the shorter time now available for teaching anatomy, the coverage of general anatomy seems to suffer maximum. Since it lays down the foundation of the entire subject of medicine, it was felt necessary to produce a short, simple and comprehensive handbook on this neglected, though important, aspect of the subject. It has been written in a simple language, with the text classified in small parts to make it easier for the students to follow and remember. It is hoped that this will prove quite useful to the medical students. Gwalior B D CHAURASIA November 1978  Contents Preface to the Fourth Edition v Preface to the First Edition vii 1. Introduction 1 2. Skeleton 29 3. Joints 57 4. Muscles 83 5. Cardiovascular System 101 6. Lymphatic System 123 7. Nervous System 137 8. Skin and Fasciae 171 9. Connective Tissue, Ligaments and Raphe 195 10. Principles of Radiography 205 Anatomical Word Meanings and Historical Names 213 References and Suggestions for Additional Reading 243 Index 253 Human anatomy is the science which deals with the structure of the human body. The term, 'anatomy', is derived from a Greek word, "anatome", meaning cutting up. The term 'dissection' is a Latin equivalent of the Greek anatome. However, the two words, anatomy and dissection, are not synonymous. Dissection is a mere technique, whereas anatomy is a wide field of study. Anatomy forms firm foundation of the whole art of medicine and introduces the student to the greater part of medical terminology. "Anatomy is to physiology as geography is to history, i.e. it describes the theatre in which the action takes place." SUBDIVISIONS OF ANATOMY Initially, anatomy was studied mainly by dissection. But the scope of modern anatomy has become very wide because it is now studied by all possible techniques which can enlarge the boundaries of the anatomical knowledge. The main subdivisions of anatomy are: 1. Cadaveric anatomy is studied on dead embalmed (preserved) bodies usually with the naked eye (macroscopic or gross anatomy). This can be done by one of the two approaches: (a) In 'regional anatomy' the body is studied in parts, like the upper limb, lower limb, thorax, abdomen, head and neck, and brain; (b) in'systemic anatomy'' the body is studied in systems, like the skeletal system (osteology) (Fig. 1.1), muscular system (myology), articulatory system (arthrology or syndesmology), vascular system (angiology), nervous system (neurology), and respiratory, digestive, urogenital and endocrine systems (splanchnology). The locomotor system inr»1n/^oc A c t a n l n m ; oftV»t-r\lr\rrw o n r l m\/AlAm? 2 I Handbook of General Anatomy Skull Rib Humerus Vertebral column Radius Ulna Hand Femur Tibia Fibula.Foot Fig. 1.1: Skeletal system 2. Living Anatomy is studied by inspection, palpation (Fig. 1.2), percussion, auscultation, endoscopy (bronchoscopy, gastroscopy), radiography, electromyography, etc.  Fig. 1.2: Contracted muscles for palpation 3. Embryology (developmental anatomy) is the study of the prenatal developmental changes in an individual. The developmental history is called 'ontogeny'. The evolutionary history on the other hand, is called 'phylogeny'. 4. Histology (microscopic anatomy) is the study of structures with the aid of a microscope. 5. Surface anatomy (topographic anatomy) is the study of deeper parts of the body in relation to the skin surface. It is helpful in clinical practice and surgical operations (Fig. 1.3). F i g. 1. 3 : Palpating the dorsalis pedis artery 6. Radiographic and imaging anatomy is the study of the bones and deeper organs by plain and contrast radiography by ultra- sound and computerised tomographic (CT) scans (Fig. 1.4). 4 I Handbook of General Anatomy Clavicle Lung Heart Fig. 1.4: X-ray of chest (plain radiograph) 7. Comparative anatomy is the study of anatomy of the other animals to explain the changes in form, structure and function (morphology) of different parts of the human body. 8. Physical anthropology deals with the external features and measurements of different races and groups of people, and with the study of the prehistoric remains. Fig. 1.5: Physical anthropology 9. Applied anatomy (clinical anatomy) deals with application of the anatomical knowledge to the medical and surgical practice (Fig. 1.6). 10. Experimental anatomy is the study of the factors which influence and determine the form, structure and function of different parts of the body. 11. Genetics deals with the study of information present in the chromosomes.  Introduction I 5 Axillary - Radial Ulnar- Fig. 1.6: The relation of nerves to the humerus and likelihood of their injury in case of fracture HISTORY OF ANATOMY 1. Greek Period (B.C.) Hippocrates of Cos (circa 400 B.C.), the 'Father of Medicine', is regarded as one of the founders of anatomy. Parts of Hippocratic collection are the earliest anatomical descriptions. Herophilus of Chalcedon (circa 300 B.C.) is called the "father of anatomy". He was a Greek physician, and was one of the first to dissect the human body. He distinguished cerebrum from cerebellum, nerves from tendons, arteries from veins, and the motor from sensory nerves. He described and named the parts of eye, meninges, torcular Herophili, fourth ventricle with calamus scriptorius, hyoid bone, duodenum, prostate gland, etc. We owe to him the first description of the lacteals. Herophilus was a very successful teacher, and wrote a book on anatomy, A special treatise of the eyes, and a popular handbook for midwives. 6 I Handbook of General Anatomy 2. Roman Period (A.D.) Galen of Pergamum, Asia Minor (circa 130-200 A.D.), the "prince of physicians", practised medicine at Rome. He was the foremost' practitioner of his days and the first experimental physiologist. He wrote voluminously and theorized and dogmatized on many medical subjects like anatomy, physiology, pathology, symptomatology and treatment. He demonstrated and wrote on anatomy De anatomicis- administrationibus. His teachings were followed and considered as the infallible authority on the subject for nearly 15 centuries. 3. Fourteenth Century Mundinus or Mondino d'Luzzi (1276-1326), the 'restorer of anatomy', was an Italian anatomist and professor of anatomy at Bologna. He wrote a book Anathomia which was the standard anatomical text for over a century. He taught anatomy by dissection for which his text was used as a guide. He was the most renowned anatomist before Vesalius. 4. Fifteenth Century Leonardo da Vinci of Italy (1452-1519), the originator of cross-sectional anatomy, was one of the greatest geniuses the world has known. He was a master of arts and contributed substantially in mathematics, science and engineering. He was the first to describe the moderator band of the right ventricle. The most admirable of his works are the drawings of the things he observed with perfection and fidelity. His 60 notebooks containing 500 diagrams were published in 1898. 5. Sixteenth Century Vesalius (1514-1564), the 'reformer of anatomy', was German in origin, Belgian (Brussels) by birth, and found an Italian (Padua) university favourable for his work. He was professor of anatomy at Padua. He is regarded as the founder of modern anatomy because he taught that anatomy could be learnt only through dissections. He opposed and corrected the erroneous concepts of Galen and fought against his authority, thus reviving anatomy after a deadlock of about 15 centuries. His great anatomical treatise De Febricia Humani Corporis, written  Introduction I 7 in seven volumes, revolutionized the teaching of anatomy and remained as authoritative text for two centuries. Vesalius studied first at Louvain and then at Paris under Gunther and Sylvius. Eustachius was the rival of Vesalius. The followers of Vesalius included Servetus, Columbus, Fallopius, Varolio, Vidius, etc.; all of them lived during 16th century. 6. Seventeenth Century William Harvey (1578-1657) was an English physician who discovered the circulation of blood, and published it as Anatomical Exercise on the Motion of the Heart and Blood in Animals. He also published a book on embryology. The other events of this century included: (a) the first recorded human dissection in 1638 in Massachusetts; (b) foundation of microscopic anatomy by Malpighi; and (c) introduction of alcohol as a preservative. 7. Eighteenth Century William Hunter (1718-1783) was a London anatomist and obstetrician. He introduced the present day embalming with the help of Harvey's discovery, and founded with his younger brother (John Hunter) the famous Hunterian museum. 8. Nineteenth Century Dissection by medical students was made compulsory in Edinburgh (1826) and Maryland (1833). Burke and Hare scandal of 16 murders took place in Edinburgh in 1828. Warburton Anatomy Act (1932) was passed in England under which the unclaimed bodies were made available for dissection. The ' A c t ' was passed in America (Massachusetts) in 1831. Formalin was used as a fixative in 1890s. X-rays were discovered by Roentgen in 1895. Various endoscopes were devised between 1819 and 1899. The anatomical societies were founded in Germany (1886), Britain (1887) and America (1888). The noted anatomists of this century include Ashley Cooper (1768-1841; British surgeon), Cuvier (1769-1832; French naturalist), Meckel (1724-1774; German anatomist), and Henry Gray (1827-1861; the author of Gray's Anatomy). 8 I Handbook of General Anatomy 9. Twentieth Century The electron microscope was invented in 20th century. It was applied in clinical practice, which made startling changes in the study of normal and diseased conditions. Various modifications of electron microscope, transmission EM and SEM, etc. were devised. These helped in better understanding of the body tissues. Besides plain X-rays, in this century, ultrasonography and echocardiography were discovered. This was the non-invasive safe-procedure. Also computer-axial tomography or CT scan, a non-invasive procedure and magnetic resonance imaging were devised. These were extremely useful, sensitive means of understanding the dynamics of body structure in health and disease. Tissue culture was developed which was new and exciting field of research. New advances in cases of infertility were discovered, which gave hopes to some infertile couples. GIFT: Gamete Intrafallopian Transfer got started 10. Twenty First Century Foetal medicine is emerging as a newer subject. Even treatment 'in-utero' is being practised in some cases. Human genome is being prepared. New research in drugs for many diseases, especially AIDS, is being done very enthusiastically. There is also a strong possibility of gene therapy. Indian Anatomists Dr. Inderjit Dewan worked chiefly on osteology and anthropology. Dr. D.S. Choudhry did notable work on carotid body. Dr. H. Chaterjee and Dr. H. Verma researched on embryology. Dr. S.S. Dayal did good work in cancer biology. Dr. Shamer Singh and his team did pioneering work on teratology. Dr. Chaturvedi and Dr. C.D. Gupta's prominent work was on corrosion cast.  Introduction I 9 Dr. L.V. Chako, Dr. H.N. Keswani, Dr. Veena Bijlani, Dr. Gopinath, Dr. Shashi Wadhwa of All India Institute of Medical Sciences, New Delhi, researched on neuroanatomy. Dr. Keswani and his team established museum of history of medicine. Dr. A.K. Susheela of AIIMS, New Delhi, has done profound work on fluorosis. Dr. M.C. Vaidya was well known for his work on leprosy and HLA. Dr. I.B. Singh of Rohtak did enlightening studies on histology. He has been author of several books in anatomy. Dr. A.K. Dutta of West Bengal has authored many books on anatomy. Amongst the medical educationists are Dr. Sita Achaya, Dr. Ved Prakash, Dr. Basu, Dr. M. Kaul, Dr. Chandrama Anand, Dr. Indira Bahl, Dr. Rewa Choudhry, Dr. Smita Kakar, Dr. Anita Tuli, Dr. Shashi Raheja, Dr. Ram Prakash, Dr. Veena Bharihoke, Dr. Madhur Gupta, Dr. J.M. Kaul, Dr. Shipra Paul, Dr. Dharamnarayan, Dr. A.C. Das, Dr. A. Halim, Dr. D.R. Singh and many others. Dr. Swarna Bhardwaj, an educationist, was appointed as Executive Director of "DNB office" and has brought the institution to forefront. Dr. Harish Agarwal, an anatomist, worked in jurisprudence for a number of years. Dr. Cooper of Chennai, Dr. M. Thomas and Dr. Kiran Kucheria did commendable work on genetics. Dr. Mehdi Hasan and Dr. Nafis Ahmad Faruqi did pioneering research in neuroanatomy. ANATOMICAL NOMENCLATURE Galen (2nd century) wrote his book in Greek and Vesalius (16th century) did it in Latin. Most of the anatomical terms, therefore, are either in Greek or Latin. By 19th century about 30,000 anatomical terms were in use in the books and journals. In 1895, the German Anatomical Society held a meeting in Basle, and approved a list of about 5000 terms known as Basle Nomina Anatomica (BNA). The following six rules were laid down to be followed strictly: (1) Each part shall have only one name; (2) each term shall be in Latin; (3) each term shall be as short and simple as possible; (4) the terms shall be merely memory signs; (5) the related terms shall be similar, e.g. femoral artery, femoral vein, and femoral nerve; and (6) the adjectives shall be arranged as opposites, e.g. major and minor, superior and inferior. 10 I Handbook of General Anatomy BNA was revised in 1933 by a committee of the Anatomical Society of Great Britain and Ireland in a meeting held at Birmingham. The revised BNA was named as Birmingham Revision (BR). An independent revision of the BNA was also done by German anatomists in 1935, and was known as Jena Nomina Anatomica (JNA or INA). However, the BR and IN A found only local and restricted acceptance. In 1950, it was agreed at an International Congress of Anatomists held at Oxford that a further attempt should be made to establish a generally acceptable international nomenclature. In the Sixth International Congress of Anatomists held at Paris (1955), a somewhat conservative revision of BNA with many terms from BR and INA was approved. Minor revisions and corrections were made at the International Congresses held in New York (1960), and Wiesbaden, Germany (1965), and the 3rd edition of Nomina Anatomica (Ed. G.A.G. Mitchell, 1968) was published by the Excerpta Medica Foundation. The drafts on Nomina Histologica and Nomina Embryologica prepared by the subcommittee of the International Anatomical Nomenclature Committee (IANC) were approved in a plenary session of the Eleventh International Congress of Anatomists held in Leningrad in 1970. After a critical revision, the 4th edition of Nomina Anatomica (Ed. Roger Warwick, 1977) containing Nomina Histologica and Nomina Embryologica was published by the same publisher. LANGUAGE OF ANATOMY Various positions, planes, terms in relation to various regions and movements are described. Positions Anatomical position: When a person is standing straight with eyes looking forwards, both arms by the side of body, palms facing forwards, both feet together, the position is anatomical position (Fig. 1.7). Supine position: When a person is lying on her/his back, arms by the side, palms facing upwards and feet put together, the position is supine position (Fig. 1.8). Prone position: Person lying on his/her face, chest and abdomen is said to be in prone position (Fig. 1.9).  Introduction I 11 Fig. 1.7: Anatomical position Fig. 1.8: Supine position Fig. 1.9: Prone position 12 I Handbook of General Anatomy Lithotomy position: Person lying on her back with legs up and feet supported in straps. This position is mostly used during delivery of the baby (Fig. 1.10). Fig. 1.10: Lithotomy position Planes A plane passing through the centre of the body dividing it into two equal right and left halves, is the median or midsagittal plane (Fig. 1.11). Plane parallel to median or midsagittal plane is the sagittal plane. Transverse plane Coronal plane Median plane Fig. 1.11: Planes of the body  Introduction I 13 A plane at right angles to sagittal or median plane which divides the body into anterior and posterior halves is called a coronal plane (Fig. 1.12). A plane at right angles to both sagittal and coronal planes which divides the body into upper and lower parts is called a transverse plane (Fig. 1.12). Transverse plane -Median plane Coronal plane Fig. 1.12: Planes of the body in a child Terms Used in Relation to Trunk Ventral or Anterior is the front of trunk. Dorsal or Posterior is the back of trunk (Fig. 1.13). Medial is a plane close to the median plane (Fig. 1.13). Lateral is plane away from the median plane. Proximal/Cranial/Superior is close to the head end of trunk (Fig. 1.14). Distal/Caudal/Inferior is close to the lower end of the trunk. Superficial is close to skin/towards surface of body (Fig. 1.15). Deep away from skin/away from surface of body. Ipsilateral on the same side of the body as another structure (Fig. 1.13). Contralateral on opposite side of body from another structure. Invagination is projection inside. Evagination is projection outside (Fig. 1.16). Handbook of General Anatomy Superior- Dorsal or posterior -Root Ventral or anterior -Proximal Medial - Medial -Distal Lateral - Lateral border Ipsilateral Dorsal/extensor aspect Contralateral Inferior - - Medial border Fig. 1.13: Language of anatomy Lateral border Proximal/superior or Upper end ^ -Anterior surface Flexor aspect - Medial border - Palmar surface Distal / inferior end of hand -Anterior surface Dorsum of foot Fig. 1.14: Language of anatomy  Introduction I 15 Superficial" Deep Fig. 1.15: Language of anatomy Invagination Evagination Fig. 1.16: Language of anatomy Terms Used in Relation to Upper Limb Ventral or Anterior is the front aspect (Fig. 1.13). Dorsal or Posterior is the back aspect. Medial border lies along the little finger, medial border of forearm and arm. Lateral border follows the thumb, lateral border of forearm and arm (Fig. 1.14). Proximal is close to root of limb, while distal is away from the root. Palmar aspect is the front of the palm (Fig. 1.14). Dorsal aspect of hand is on the back of palm. Flexor aspect is front of upper limb. Extensor aspect is back of upper limb. Terms Used in Relation to Lower Limb Posterior aspect is the back of lower limb. Anterior aspect is front of lower limb. Medial border lies along the big toe or hallux, medial border of leg and thigh (Fig. 1.13). 16 I Handbook of General Anatomy Lateral border lies along the little toe, lateral border of leg and thigh. Flexor aspect is back of lower limb. Extensor aspect is front of lower limb (Fig. 1.13). Proximal is close to the root of limb, while distal is away from it. Terms of Relation Commonly Used in Embryology a n d Comparative Anatomy, but sometimes in Gross Anatomy (a) Ventral - Towards the belly (like anterior). (b) Dorsal - Towards the back (like posterior). (c) Cranial or Rostral - Towards the head (like superior). (d) Caudal - Towards the tail. TERMS RELATED TO BODY MOVEMENTS Movements in general at synovial joints are divided into four main categories. 1. Gliding movement: Relatively flat surfaces move back-and- forth and from side-to-side with respect to one another. The angle between articulating bones does not change significantly. 2. Angular movements: Angle between articulating bones decreases or increases. In flexion there is decrease in angle between articulating bones and in extension there is increase in angle between articulating bones. Lateral flexion is movement of trunk sideways to the right or left at the waist. Adduction is movement of bone toward midline whereas abduction is movement of bone away from midline. 3. Rotation: A bone revolves around its own longitudinal axis. In medial rotation anterior surface of a bone of limb is turned towards the midline. In lateral rotation anterior surface of bone of limb is turned away from midline. 4. Special movements: These occur only at certain joints, e.g. pronation, supination at radioulnar joints, protraction and retraction at temporo-mandibular joint. In Upper limb Flexion: When two flexor surfaces are brought close to each other, e.g. in elbow joint when front of arm and forearm are opposed to each other [Fig. 1.17 (i-v)].  Introduction I 17 Extension: When extensor or dorsal surfaces are brought in as much approximation as possible, e.g. straighten the arm and forearm at the elbow joint. Abduction: When limb is taken away from the body. Adduction: When limb is brought close to the body. Circumduction: It is movement of distal end of a part of the body in a circle. A combination of extension, abduction, flexion and adduction in a sequence is called circumduction as in bowling. Medial rotation: When the arm rotates medially bringing the flexed forearm across the chest. Lateral rotation: When arm rotates laterally taking the flexed forearm away from the body. Supination: When the palm is facing forwards or upwards, as in putting food in the mouth (Fig. 1.17). Pronation: When the palm faces backwards or downwards, as in picking food with fingers from the plate. Adduction of digits/fingers: When all the fingers get together. Abduction: When all fingers separate. The axis of movement of fingers is the line passing through the centre of the middle finger. Opposition of thumb: When tip of thumb touches the tips of any of the fingers. Circumduction of thumb: Movement of extension, abduction, flexion and adduction in sequence. In Lower Limb Flexion of thigh: When front of thigh comes in contact with front of abdomen. Extension of thigh: When person stands erect. Abduction: When thigh is taken away from the median plane. Adduction: When thigh is brought close to median plane. Medial rotation: When thigh is turned medially. Lateral rotation: When thigh is turned laterally (Fig. 1.18). Flexion of knee: When back of thigh and back of leg come in opposition. 18 I Handbook of General Anatomy (i) Circumduction: Moving in circular away from midline Adduction: Moving toward midline Bending, decreasing the joint angle (iii) Extension: (v) Pronation: Straightening, increasing Turning downward the joint angle Supination: Turning upward Fig. 1.17: Terms related to movements of upper limb Extension of knee: When thigh and leg are in straight line as in standing. Dorsiflexion of foot: When dorsum of foot is brought close to front of leg and sole faces forwards (Fig. 1.18). Plantarflexion of foot: When sole of foot or plantar aspect of foot faces backwards. Inversion of foot: When medial border of foot is raised from the ground (Fig. 1.18). Eversion of foot: When lateral border of foot is raised from the ground. In the Neck Flexion: When face comes closer to chest. Extension: When face is brought away from the chest.  Introduction I 19 (i) Medial rotation: Lateral rotation: Turning toward midline Turning away from midline (ii) Eversion: Inversion: Turning outward Turning inward (iii) Dorsiflexion Plantarflexion Fig. 1.18: Terms related to movements of lower limb Lateral flexion: When ear is brought close to shoulder. »Rotation: When neck rotates so that chin goes to opposite side. Opening the mouth: When lower jaw is lowered to open the mouth. Closure of the mouth: When lower jaw is opposed to the upper jaw, closing the mouth. Protraction: When lower jaw slides forwards in its socket in the temporal bone of skull. Retraction: When lower jaw slides backwards in its socket in the temporal bone of skull (Fig. 1.19). 20 I Handbook of General Anatomy detraction Protraction Fig. 1.19: Retraction and protraction at temporo-mandibular joints In the Trunk Backward bending is called extension. Forward bending is flexion (Fig. 1.20). Sideward movement is lateral flexion. Sideward rotation is lateral rotation. Fig. 1.20: Movements of the trunk: (a) extension, (b) flexion, (c) lateral flexion Terms Used for Describing Muscles (a) Origin: The end of a muscle which is relatively fixed during its contraction (Fig. 1.21). (b) Insertion: The end of a muscle which moves during its contraction.  Introduction I 21 - Origin of short head from coracoid process Origin of long head from supraglenoid tubercle Muscle belly /Biceps brachii tendon inserted into Bicipital aponeurosis radial tuberosity F i g. 1.21: Terms used for describing m u s c l e s The two terms, origin and insertion, are sometimes interchangeable, when the origin moves and the insertion is fixed. (c) Belly: The fleshy and contractile part of a muscle. (d) Tendon: The fibrous noncontractile and cord-like part of a muscle. (e) Aponeurosis: The flattened tendon. (f) Raphe: A fibrous band made up of interdigitating fibres of the tendons or aponeuroses. Unlike a ligament, it is stretchable. Ligaments are fibrous, inelastic bands which connect two segments of a joint. Terms Used for D e s c r i b i n g Vessels (a) Arteries carry oxygenated blood away from the heart, with the exception of the pulmonary and umbilical arteries which carry deoxygenated blood. Arteries resemble trees because they have branches (arterioles) (Fig. 1.22). 22 I Handbook of General Anatomy Artery Valve in the vein Fig. 1.22: Artery, capillaries arid vein (b) Veins carry deoxygenated blood towards the heart, with the exception of the pulmonary and umbilical veins which carry oxygenated blood. Veins resemble rivers because they have tributaries (venules). Veins have valves to allow unidirectional flow of blood. (c) Capillaries are networks of microscopic vessels connecting arterioles to venules. (d) Anastomosis is a precapillary or postcapillary communication between the neighbouring vessels (Fig. 1.23). Terms Used for Describing Bone Features (a) Elevations 1. Linear elevation may be a line, lip, ridge, or crest. 2. Sharp elevation may be a spine, styloid process, cornu (horn), or hamulus (Fig. 1.24). 3. Rounded or irregular elevation may be a tubercle, tuberosity, epicondyle, malleolus, or trochanter. A ramus is a broad arm or process projecting from the main part or body of the bone (Figs 1.25-1.27). (b) Depressions may be a pit, impression, fovea, fossa, groove (sulcus), or notch (incisura). (c) Openings may be a foramen, canal, hiatus, or aqueduct.  Introduction ! 23 From profunda- - Brachial artery brachii artery Anterior and Superior ulnar collateral artery posterior descending branches Supratrochlear (inferior ulnar collateral artery) - Anterior ulnar recurrent Radial recurrent artery - - Posterior ulnar recurrent Interosseous recurrent- from posterior interosseous - Common interosesseous Radial artery - Ulnar artery Anterior interosseous Fig. 1.23: Anastomoses around elbow joint Styloid process Foramen Mastoid process magnum Fig. 1.24: Norma basalis 24 I Handbook of General Anatomy Frontal bone Coronal suture Optic canal Superior orbital fissure Nasal bone Zygomatic bone Infraorbital foramen Anterior nasal spine Intermaxillary suture Ramus Angle of mandbile Mandible Mental foramen Fig. 1.25: Norma frontalis Coracoid process Acromion ' Superior angle Head Greater tubercle Lesser tubercle — Medial border Anterior border Inferior angle Deltoid tuberosity Lateral border Humerus Lateral supracondylar ridge Medial supracondylar ridge Lateral epicondyle Medial epicondyle Capitulum Trochlea Fig. 1.26: Right scapula and humerus (anterior view)  Introduction ! 25 Head Greater- trochanter Interochanteric line ^ Neck- Interochanteric crest -Gluteal Lesser trochanter tuberosity Spiral line Anterior surface Linea aspera with two l i p s - Lateral supracondylar line Medial supracondylar l i n e \ J \ Medial condyle ^ N y 0k / Adductor tubercle// "Popliteal surface Lateral- Medial— " Lateral condyle epicondyle epicondyle Articular surface for patella Intercondylar fossa (b) Fig. 1.27 Femur—anterior surface (a) and posterior surface (b) (d) Cavities: A large cavity within a bone is called sinus, cell or antrum. (e) Smooth a r t i c u l a r areas may be a facet, condyle, head, capitulum, or trochlea. Terms Used in Clinical Anatomy 1. The suffix, '-itis', means inflammation, e.g. appendicitis, tonsillitis, arthritis, neuritis, dermatitis, etc. 2. The suffix, '-ectomy', means removal from the body, e.g. appendicectomy, tonsillectomy, gastrectomy, nephrectomy, etc. 3. The suffix, '-otomy', means to open and then close a hollow organ, e.g. laparotomy, hysterotomy, cystotomy, cystolithotomy, etc. 26 I Handbook of General Anatomy 4. The suffix, '-ostomy', means to open hollow organ and leave it open, e.g. cystostomy, colostomy, tracheostomy, etc. 5. The suffix, '-oma\ means a tumour, e.g. lipoma, osteoma, neurofibroma, haemangioma, carcinoma, etc. 6. Puberty: The age at which the secondary sexual characters develop, being 12-15 years in girls and 13-16 years in boys. 7. Symptoms are subjective complaints of the patient about his disease. 8. Signs (physical signs) are objective findings of the doctor on the patient. 9. Diagnosis: Identification of a disease, or determination of the nature of a disease. 10. Prognosis: Forecasting the probable course and ultimate outcome of a disease. 11. Pyrexia: Fever. 12. Lesion: Injury, or a circumscribed pathologic change in the tissues. 13. Inflammation is the local reaction of the tissues to an injury or an abnormal stimulation caused by a physical, chemical, or biologic agent. It is characterized by: (a) Swelling; (b) pain; (c) redness; (d) warmth of heat; and (e) loss of function. 14. Oedema: Swelling due to accumulation of fluid in the extracellular space. 15. Thrombosis: Intravascular coagulation (solidification) of blood. 16. Embolism: Occlusion of a vessel by a detached and circulating thrombus (embolus). 17. Haemorrhage: Bleeding which may be external or internal. 18. Ulcer: A localized breach (gap, erosion) in the surface continuity of the skin or mucous membrane. 19. Sinus: A blind track (open at one end) lined by epithelium. 20. Fistula: A track open at both the ends and lined by epithelium. 21. Necrosis: Local death of a tissue or organ due to irreversible damage to the nucleus. 22. Degeneration: A retrogressive change causing deterioration in the structural and functional qualities. It is a reversible process, but may end in necrosis.  Introduction ! 27 23. Gangrene: A form of necrosis (death) combined with putrefaction. 24. Infarction: Death (necrosis) of a tissue due to sudden obstruction of its artery of supply (often an end-artery). 25. Atrophy: Diminution in the size of cells, tissue, organ, or a part due to loss of its nutrition. 26. Dystrophy: Diminution in the size due to defective nutrition. 27. Hypertrophy: Increase in the size without any increase in the number of cells. 28. Hyperplasia: Increase in the size due to increase in the number of cells. 29. Hypoplasia: Incomplete development. 30. Aplasia: Failure of development. 31. Syndrome: A group of diverse symptoms and signs constituting together the picture of a disease. 32. Paralysis: Loss of motor power (movement) of a part of body due to denervation or primary disease of the muscles. 33. Hemiplegia: Paralysis of one-half of the body. 34. Paraplegia: Paralysis of both the lower limbs. 35. Monoplegia: Paralysis of any one limb. 36. Quadriplegia: Paralysis of all the four limbs. 37. Anaesthesia: Loss of the touch sensibility. 38. Analgesia: Loss of the pain sensibility. 39. Thermanaesthesia: Loss of the temperature sensibility. 40. Hyperaesthesia: Abnormally increased sensibility. 41. Paraesthesia: Perverted feeling of sensations. 42. Coma: Deep unconsciousness. 43. Tumour (neoplasm): A circumscribed, noninflammatory, abnormal growth arising from the body tissues. 44. Benign: Mild illness or growth which does not endanger life. 45. Malignant: Severe form of illness or growth, which is resistant to treatment and ends in death. 46. Carcinoma: Malignant growth arising from the epithelium (ectoderm or endoderm). 47. Sarcoma: Malignant growth arising from connective tissue (mesoderm). 28 I Handbook of General Anatomy 48. Cancer: A general term used to indicate any malignant neoplasm which shows invasiveness and results in death of the patient. 49. Metastasis: Spread of a local disease (like the cancer cells) to distant parts of the body. 50. Convalescence: The recovery period between the end of a disease and restoration to complete health. 51. Therapy: Medical treatment. ARRANGEMENT OF STRUCTURES IN THE BODY FROM WITHIN OUTWARDS 1. Bones form the supporting framework of the body. 2. Muscles are attached to bones. 3. Blood vessels, nerves and lymphatics form neurovascular bundles which course in between the muscles, along the fascial planes. 4. The thoracic and abdominal cavities contain several internal organs called viscera. 5. The whole body has three general coverings, namely (a) skin; (b) superficial fascia; and (c) deep fascia.  2 Skeleton Skeleton includes bones and cartilages. It forms the main supporting framework of the body, and is primarily designed for a more effective production of movements by the attached muscles. BONES Synonyms 1. Os (L), 2. Osteon (G). Compare with the terms, osteology, ossification, osteomyelitis, osteomalacia, osteoma, osteotomy, etc. Definition Bone is one-third connective tissue. It is impregnated with calcium salts which constitute two-thirds part. The inorganic calcium salts (mainly calcium phosphate, partly calcium carbonate, and traces of other salts) make it hard and rigid, which can afford resistance to compressive forces of weight-bearing and impact forces of jumping. The organic connective tissue (collagen fibres) makes it tough and resilient (flexible), which can afford resistance to tensile forces. In strength, bone is comparable to iron and steel. Despite its hardness and high calcium content the bone is very much a living tissue. It is highly vascular, with a constant turn-over of its calcium content. It shows a characteristic pattern of growth. It is subjected to disease and heals after a fracture. It has greater regenerative power than any other tissue of the body, except blood. It can mould itself according to changes in stress and strain it bears. It shows disuse atrophy and overuse hypertrophy. 30 I Handbook of General Anatomy Divisions of the Skeletal System (Fig. 2.1) Regions of the Skeleton Number of Bones Cranial and facial bones: AXIAL SKELETON (mnemonic is A-Z) Skull Cranium 8 A-D - Face 14 Ethmoid 1 Hyoid 1 Frontal 1 Auditory ossicles (3 in each ear): 6 G-H - (Malleus, incus, stapes) Inferior nasal Vertebral column 26 choncha 2 Thorax J-K - Sternum 1 Lacrimal 2 Ribs 24 Maxilla 2 APPENDICULAR SKELETON Mandible 1 Pectoral (shoulder) girdles Nasal 2 Clavicle 2 Occipital 1 Scapula 2 Parietal 2 Upper extremities Palatine 2 Humerus 2 Q-R - Ulna 2 Sphenoid 1 Radius 2 Temporal 2 Carpals 16 U - Metacarpals 10 Vomer 1 Phalanges 28 W-Y - Pelvic (hip) girdle Zygomatic 2 Pelvic, or hip bone 2 Lower extremities Femur 2 Fibula 2 Tibia 2 Patella 2 Tarsals 14 Metatarsals 10 Phalanges 28 Total 206  Skeleton 31 Functions 1. Bones give shape and support to the body, and resist any forms of stress (Fig. 2.1). 2. These provide surface for the attachment of muscles, tendons, ligaments, etc. 3. These serve as levers for muscular actions. 4. The skull, vertebral column and thoracic cage protect brain, spinal cord and thoracic viscera, respectively. 5. Bone marrow manufactures blood cells. 6. Bones store 97% of the body calcium and phosphorus. 7. Bone marrow contains reticuloendothelial cells which are phagocytic in nature and take part in immune responses of the body. 8. The larger paranasal air sinuses affect the timber of the voice. Frontal bone- Parietal bone Orbit- -Skull Maxilla- Atlas Mandible- Clavicle Scapula. Ribs Humerus Iliac crest Radius Ulna Acetabulum Carpal Hip joint bones Metacarpals Femur Phalanges Patella Fibula Fibula Tibia Tibia Tarsals Metatarsals Talus (a) Phalanges (b) Fig. 2.1: Human skeleton: (a) Anterior view, (b) Posterior view 32 I Handbook of General Anatomy CLASSIFICATION OF BONES A. According to Shape 1. Long bones: Each long bone has an elongated shaft (diaphysis) and two expanded ends (epiphyses) which are smooth and articular. The shaft typically has 3 surfaces separated by 3 borders, a central medullary cavity, and a nutrient foramen directed away from the growing end. Examples: (a) typical long bones like humerus, radius, ulna, femur, tibia and fibula; (b) miniature long bones have only one epiphysis like metacarpals, metatarsals and phalanges; and (c) modified long bones have no medullary cavity like clavicle (Fig. 2.2). 2. Short bones: Their shape is usually cuboid, cuneiform, trape- zoid, or scaphoid. Examples: tarsal and carpal bones (Fig. 2.3). 3. Flat bones resemble shallow plates and form boundaries of certain body cavities. Examples: bones in the vault of the skull, ribs, sternum and scapula (Fig. 2.4). 4. Irregular bones: Examples: vertebra, hip bone, and bones in the base of the skull (Fig. 2.5). 5. Pneumatic bones: Certain irregular bones contain large air spaces lined by epithelium Examples: maxilla, sphenoid, ethmoid, etc. They make the skull light in weight, help in resonance of voice, and act as air conditioning chambers for the inspired air (Fig. 2.6). 6. Sesamoid bones: These are bony nodules found embedded in the tendons or joint capsules. They have no periosteum and ossify after birth. They are related to an articular or nonarticular bony surface, and the surfaces of contact are covered with hyaline cartilage and lubricated by a bursa or synovial membrane. Examples: patella, pisiform, fabella, etc. (Fig. 2.7). Functions of the sesamoid bones are: (a) to resist pressure; (b) to minimise friction; (c) to alter the direction of pull of the muscle; and (d) to maintain the local circulation.  Skeleton I 33 Head Greater tubercle Lesser tubercle Anterior border Deltoid tuberosity Lateral supracondylar ridge Medial supracondylar ridge Lateral epicondyle Medial epicondyle Capitulum Trochlea c0) Lunate Capitate 2 Carpal bones Scaphoid and its tubercle Triquetral to CL Trapezium and its crest Pisiform Trapezoid Hamate and its hook First metacarpal Fifth metacarpal 2nd, 3rd and 4th metacarpals Phalanges (b) Trapezius Sternocleidomastoid Medial Lateral end end Capsule of Deltoid sternoclavicular joint Pectoralis major (c) Fig. 2.2: Long bones: (a) Humerus, (b) Metacarpals, (c) Clavicle 34 I Handbook of General Anatomy Carpal bones Lunate Capitate Scaphoid and its tubercle Trapezium and its crest Pisiform Trapezoid Hamate and its hook First metacarpal - metacarpal Fig. 2.3: Small bones: Carpal bones (a) (b) Fig. 2.4: Flat bones: (a) Rib, (b) Scapula  Skeleton I 35 (a) (b) Fig. 2.5: Irregular bones: Vertebrae (a) 1st cervical, (b) 2nd cervical Crista galli Ala Ethmoidal air cells - Nasal slit t — E t h m o i d a l grooves Cribriform plate — Orbital plate — Fig. 2.6: Pneumatic bone: Ethmoid 36 I Handbook of General Anatomy Fig. 2.7: Sesamoid bone: Patella 7. Accessory (supernumerary) bones are not always present. These may occur as ununited epiphyses developed from extra centres of ossification. Examples: sutural bones, os trigonum (lateral tubercle of talus), os vesalianum (tuberosity of 5th metatarsal), etc. In medicolegal practice, accessory bones may be mistaken for fractures. However, these are often bilateral, and have smooth surfaces without any callus. 8. Heterotopic bones: Bones sometimes develop in soft tissues. Horse riders develop bones in adductor muscles (rider's bones). B. Developmental Classification 1. Membrane (dermal) bones ossify in membrane (intramembranous or mesenchymal ossification), and are thus derived from mesenchymal condensations. Examples: bones of the vault of skull and facial bones. Cartilaginous bones ossify in cartilage (intracartilaginous or endochondral ossification), and are thus derived from preformed cartilaginous models. Examples: bones of limbs, vertebral column and thoracic cage. Membrano-cartilaginous bones ossify partly in membrane and partly in cartilage. Examples: clavicle, mandible, occipital, temporal, sphenoid.  Skeleton I 37 2. Somatic bones: Most of the bones are somatic. Visceral bones: These develop from pharyngeal arches. Examples are hyoid bones, part of mandible and ear ossicles. C. Regional Classification 1. Axial skeleton includes skull, vertebral column, and thoracic cage. 2. Appendicular skeleton includes bones of the limbs. D. Structural Classification I. Macroscopically, the architecture of bone may be compact or cancellous (Fig. 2.8). 1. Compact bone is dense in texture like ivory, but is extremely porous. It is best developed in the cortex of the long bones. This is an adaptation to bending and twisting forces (a combination of compression, tension and shear). Filled with marrow - Spongy bone - Medullary cavity Thick compact bone Fig. 2.8: Structural components of a bone 2. Cancellous or spongy, or trabecular bone is open in texture, and is made up of a meshwork of trabeculae (rods and plates) between which are marrow containing spaces. The trabecular meshworks are of three primary types, namely: (a) meshwork of rods, 38 I Handbook of General Anatomy (b) meshwork of rods and plates, and (c) meshwork of plates (Singh, 1978). Cancellous bone is an adaptation to compressive forces. Bones are marvellously constructed to combine strength, elasticity and lightness in weight. Though the architecture of bone may be modified by mechanical forces, the form of the bone is primarily determined by heredity. According to Wolff's law (Trajectory Theory of Wolff, 1892), the bone formation is directly proportional to stress and strain. There are two forces, tensile force and compressive force. Both the tensile and compressive forces can stimulate bone formation in proper conditions. The architecture of cancellous bone is often interpreted in terms of the trajectorial theory. Thus the arrangement of bony trabeculae (lamellae) is governed by the lines of maximal internal stress in the bone. Pressure lamellae are arranged parallel to the line of weight transmission, whereas tension lamellae are arranged at right angles to pressure lamellae. The compact arrangement of pressure lamellae forms bony buttress, for additional support, like calcar femorale (Fig. 2.9). Compression lamellae from upper part of the head resist compression forces Tension lamellae from lower part of the head resist bending forces in the neck Calcar femorale resists shearing stresses between the neck and shaft Compression lamellae resist shearing stresses due to pull of muscles attached to greater trochanter Fig. 2.9: Diagrammatic representation of the compression (continuous lines) and tension (interrupted lines) lamellae in a sagittal section of the upper end of right femur.  Skeleton I 39 II. Microscopically, the bone is of five types, namely lamellar (including both compact and cancellous), woven, fibrous, dentine and cement. 1. Lamellar bone: Most of the mature human bones, whether compact or cancellous, are composed of thin plates of bony tissue called lamellae. These are arranged in piles in a cancellous bone, but in concentric cylinders (Haversian system or secondary osteon) in a compact bone. 2. Woven Bone: seen in fetal bone, fracture repair and in cancer of bone 3. Fibrous bone is found in young foetal bones, but are common in reptiles and amphibia. 4. Dentine and 5. Cement occur in teeth. Table 2.1: Comparison of compact and cancellous bones Compact bone Cancellous (spongy) bone Location In shaft (diaphysis) of long In the epiphyses of long bone bone Lamellae Arranged to form Haversian Arranged in a meshwork, so system Haversion systems are not present Bone marrow Yellow which stores fat after Red, produce RBCs, granular puberty. It is red before series of WBC and platelets puberty Nature Hard and ivory like Spongy GROSS STRUCTURE OF AN ADULT LONG BONE Naked eye examination of the longitudinal and transverse sections of a long bone shows the following features. 1. Shaft: From without inwards, it is composed of periosteum, cortex and medullary cavity (Fig. 2.10). (a) Periosteum is a thick fibrous membrane covering the surface of the bone. It is made up of an outer fibrous layer, and an inner cellular layer which is osteogenic in nature. Periosteum is united to the underlying bone by Sharpey's fibres, and the 40 I Handbook of General Anatomy union is particularly strong over the attachments of tendons, and ligaments. At the articular margin the periosteum is continuous with the capsule of the joint. The abundant periosteal arteries nourish the outer part of the underlying cortex also. Periosteum has a rich nerve supply which makes it the most sensitive part of the bone. (b) Cortex is made up of a compact bone which gives it the desired strength to withstand all possible mechanical strains. (c) Medullary cavity is filled with red or yellow bone marrow. At birth the marrow is red everywhere with widespread active haemopoiesis. As the age advances, the red marrow at many places atrophies and is replaced by yellow, fatty marrow, with no power of haemopoiesis. Red marrow persists in the cancellous ends of long bones. In the sternum ribs, iliac crest, vertebrae and skull bones the red marrow is found throughout life. 2. The two ends of a long bone are made up of cancellous bone covered with hyaline (articular) cartilage (Fig. 2.10). Articular cartilage Cancellous bone Fibrous capsule Periosteum Cortex (compact bone) Medullary cavity Fig. 2.10: Naked eye structure of an adult long bone in longitudinal section  Skeleton I 41 PARTS OF A YOUNG BONE A typical long bone ossifies in three parts, the two ends from secondary centres, and the intervening shaft from a primary centre (Fig. 2.11). Before ossification is complete the following parts of the bone can be defined. - Epiphysis - Epiphysial plate of cartilage - Metaphysis Compact bone - Cancellous bone - Diaphysis - Metaphysis Fig. 2.11: Parts of a young long bone. 1. Epiphysis The ends and tips of a bone which ossify from secondary centres are called epiphyses. These are of the following types. (a) Pressure epiphysis is articular and takes part in transmission of the weight. Examples: head of femur; lower end of radius, etc. (Fig. 2.12) (b) Traction epiphysis is nonarticular and does not take part in the transmission of the weight. It always provides attachment to one or more tendons which exert a traction on the epiphysis. The traction epiphyses ossify later than the pressure epiphyses. Examples: trochanters of femur and tubercles of humerus (Figs 1.26 and 1.27). (c) Atavistic epiphysis is phylogenetically an independent bone which in man becomes fused to another bone. 42 I Handbook of General Anatomy Clavicle Scapula First rib Atavistic epiphysis Pressure epiphysis Traction epiphysis Sternum manubrium Xiphoid process Fig. 2.12: Types of epiphyses Examples: coracoid process of scapula and os trigonum or lateral tubercle of talus, (d) Aberrant epiphysis is not always present. Examples: epiphysis at the head of the first metacarpal and at the base of other metacarpal bones. 2. Diaphysis It is the elongated shaft of a long bone which ossifies from a primary centre (Fig. 2.11). 3. Metaphysis The epiphysial ends of a diaphysis are called metaphyses. Each metaphysis is the zone of active growth. Before epiphysial fusion, the metaphysis is richly supplied with blood through end arteries forming 'hair-pin' bends. This is the common site of osteomyelitis in children because the bacteria or emboli are easily trapped in the hair-pin bends, causing infarction. After the epiphysial fusion, vascular communications are established between the metaphysial and epiphysial arteries. Now the metaphysis contains no more end-arteries and is no longer subjected to osteomyelitis.  Skeleton I 43 4. Epiphysial Plate of Cartilage It separates epiphysis from metaphysis. Proliferation of cells in this cartilaginous plate is responsible for lengthwise growth of a long bone. After the epiphysial fusion, the bone can no longer grow in length. The growth cartilage is nourished by both the epiphysial and metaphysial arteries. BLOOD SUPPLY OF BONES 1. Long Bones The blood supply of a long bone is derived from the following sources (Fig. 2.13). (a) Nutrient artery It enters the shaft through the nutrient foramen, runs obliquely through the cortex, and divides into ascending and descending branches in the medullary cavity. Epiphysial arteries Epiphysial plate of cartilage Hair-pin bends of- Metaphysial arteries end arteries in the metaphysis before epiphysial fusion Nutrient a r t e r y — Periosteal arteries h Anastomosis between epiphysial and metaphysial arteries after fusion of epiphysis Fig. 2.13: Blood supply of a long bone in which the upper epiphysis (growing end) has not yet fused with the diaphysis. 44 I Handbook of General Anatomy Each branch divides into a number of small parallel channels which terminate in the adult metaphysis by anastomosing with the epiphysial, metaphysial and periosteal arteries. The nutrient artery supplies medullary cavity, inner 2/3 of cortex and metaphysis. The nutrient foramen is directed away from the growing end of the bone; their directions are indicated by a jingle, 'To the elbow I go, from the knee I flee' (Fig. 2.14). Upper limb Lower limb Fig. 2.14: Direction of nutrient foramen in the limb bones The details and variations in the diaphysial nutrient foramina are described by a number of authors (Ujwal, 1962; Mysorekar, 1967; Chhatrapati and Misra, 1967; Kate, 1971; Patake and Mysorekar, 1977; Mysorekar and Nandedkar, 1979; Longia et al, 1980). The growing ends of bones in upper limb are upper end of humerus and lower ends of radius and ulna. In lower limb, the lower end of femur and upper end of tibia are the growing ends. (b) Periosteal arteries These are especially numerous beneath the muscular and ligamentous attachments. They ramify beneath the periosteum and enter the Volkmann's canals to supply the outer 1/3 of the cortex.  (c) Epiphysial arteries These are derived from periarticular vascular arcades (circulus vasculosus) found on the nonarticular bony surface. Out of the numerous vascular foramina in this region, only a few admit the arteries (epiphysial and metaphysial), and the rest are venous exits. The number and size of these foramina may give an idea of the relative vascularity of the two ends of a long bone (Tandon, 1964). (d) Metaphysial arteries These are derived from the neighbouring systemic vessels. They pass directly into the metaphysis and reinforce the metaphysial branches from the primary nutrient artery. In miniature long bones, the infection begins in the middle of the shaft rather than at the metaphysis because, the nutrient artery breaks up into a plexus immediately upon reaching the medullary cavity. In the adults, however, the chances of infection are minimized because the nutrient artery is mostly replaced by the periosteal vessels. 2. Other Bones Short bones are supplied by numerous periosteal vessels which enter their nonarticular surfaces. In a vertebra, the body is supplied by anterior and posterior vessels; and the vertebral arch by large vessels entering the bases of transverse processes. Its marrow is drained by two large basivertebral veins. A rib is supplied by : (a) the nutrient artery which enters it just beyond the tubercle; and (b) the periosteal arteries. Veins are numerous and large in the cancellous, red marrow containing bones (e.g., basivertebral veins). In the compact bone, they accompany arteries in the Volkmann's canals. Lymphatics have not been demonstrated within the bone, although some of them do accompany the periosteal blood vessels, which drain to the regional lymph nodes. NERVE SUPPLY OF BONES Nerves accompany the blood vessels. Most of them are sympathetic and vasomotor in function. 46 I Handbook of General Anatomy A few of them are sensory which are distributed to the articular ends and periosteum of the long bones, to the vertebra, and to large flat bones. DEVELOPMENT AND OSSIFICATION OF BONES Bones are first laid down as mesodermal (connective tissue) condensations. Conversion of mesodermal models into bone is called intramembranous or mesenchymal ossification, and the bones are called membrane (dermal) bones. However, mesodermal stage may pass through cartilaginous stage by chondrification during 2nd month of intrauterine life. Conversion of cartilaginous model into bone is called intracartilaginous or endochondral ossification, and such bones are called cartilaginous bones (Fig. 2.15). Ossification takes place by centres of ossification, each one of which is a point where laying down of lamellae (bone formation) starts by the osteoblasts situated on the newly formed capillary loops. The centres of ossification may be primary or secondary. The primary centres appear before birth, usually during 8th week of intrauterine life; the secondary centres appear after birth, with a few exceptions of lower end of femur and upper end of tibia. Many secondary centres appear during puberty. A primary centre forms diaphysis, and the secondary centres form epiphyses. Fusion of epiphyses with the diaphysis starts at puberty and is complete by the age of 25 years, after which no more bone growth can take place. The law of ossification states that secondary centres of ossification which appear first are last to unite. The end of a long bone where epiphysial fusion is delayed is called the growing end of the bone. GROWTH OF A LONG BONE 1. Bone grows in length by multiplication of cells in the epiphysial plate of cartilage (Fig. 2.15). 2. Bone grows in thickness by multiplication of cells in the deeper layer of periosteum. 3. Bones grow by deposition of new bone on the surface and at the ends. This process of bone deposition by osteoblasts is called appositional growth or surface accretion. However, in order to maintain the shape the unwanted bone must be removed. This  Skeleton I 47 process of bone removal by osteoblasts is called remodelling. This is how marrow cavity increases in size. Cancellous bone Primary centre of ossification Calcified cartilage^ Cartilage Compact bone Secondary centre of ossification Mature bone Fig. 2.15: Growth of a long bone MEDICOLEGAL AND ANTHROPOLOGICAL ASPECTS When a skeleton or isolated bones are received for medicolegal examination, one should be able to determine: (a) whether the bones are human or not; (b) whether they belong to one or more persons; (c) the age of the individual; (d) the sex; (e) the stature; and (f) the time and cause of death. For excellent details of all these points consult Modi (1977). 1. Estimation of Skeletal Age Up to the age of 25 years, the skeletal age can be estimated to within 1-2 years of correct age by the states of dentition and ossification, provided the whole skeleton is available. From 25 years onwards, the skeletal age can be estimated to within ± 5 years of the correct age by the state of cranial sutures and of the bony surfaces of symphysis pubis. In general, the appearance of secondary centres and fusion of epiphyses occur about one year earlier in females than in males. These events are also believed to occur 1-2 years (Bajaj et al, 1967) or 2-3 years (Pillai, 1936) earlier in India than in Western countries. 48 I Handbook of General Anatomy However, Jit and Singh (1971) did not find any difference between the eastern and western races. 2. Estimation of Sex Sex can be determined after the age of puberty. Sexual differences are best marked in the pelvis and skull, and accurate determination of sex can be done in over 90% cases with either pelvis or skull alone. However, sexual dimorphism has been worked out in a number of other bones, like sternum (Jit et al, 1980), atlas (Halim and Siddiqui, 1976), and most of the limb bones. 3. Estimation of Stature (Height) It is a common experience that trunk and limbs show characteristic ratios among themselves and in comparison with total height. Thus a number of regression formulae have been worked out to determine height from the length of the individual limb bones (Siddiqui and Shah, 1944; Singh and Sohal, 1952; Jit and Singh, 1956; Athawale, 1963; Kolte and Bansal, 1974; Kate and Majumdar, 1976). Height can also be determined from parts of certain long bones (Mysorekar et al), from head length (Saxena et al, 1981), and from foot measurements (Charnalia, 1961; Qamra et al, 1980). CR length has been correlated with diaphysial length of foetal bones (Vare and Bansal, 1977) and with the neonatal and placental parameters (Jeyasingh et al, 1980; Saxena et al, 1981). 4. Estimation of Race It is of interest to anthropologists. A number of metrical (like cranial and facial indices) and non metrical features of the skull, pelvis, and certain other bones are of racial significance (Krogman, 1962; Berry, 1975). CARTILAGE Synonyms 1. Chondros (G); 2. Gristle. Compare with the terms chondrification, chondrodystrophy, synchondrosis, etc.  Skeleton I 49 Definition Cartilage is a connective tissue composed of cells (chondrocytes) and fibres (collagen or yellow elastic) embedded in a firm, gel-like matrix which is rich in a mucopolysaccharide. It is much more elastic than bone. General Features 1. Cartilage has no blood vessels or lymphatics. The nutrition of cells diffuses through the matrix. 2. Cartilage has no nerves. It is, therefore, insensitive. 3. Cartilage is surrounded by a fibrous membrane, called perichondrium, which is similar to periosteum in structure and function. The articular cartilage has no perichondrium, so that its regeneration after injury is inadequate. 4. When cartilage calcifies, the chondrocytes die and the cartilage is replaced by bone like tissue. Table 2.2 shows the comparison between bone and cartilage. Table 2.2: Comparison between bone and cartilage Bone Cartilage 1. Bone is hard Cartilage is firm 2. Matrix has inflexible material It has chondroitin providing flexibility called ossein 3. Matrix possesses calcium salt Calcium salts not present 4. Bone has rich nerve supply. It does not have nerve supply. It is vascular in nature It is avascular in nature 5. Bone marrow is present Bone marrow is absent 6. Growth is only by apposition Growth is appositional and interstitial (by surface deposition) (from within) Types of Cartilage There are three types of cartilages: 1. Hyaline cartilage (Fig. 2.16) 2. Fibrocartilage (Fig. 2.17) 3. Elastic cartilage (Fig. 2.16) 50 I Handbook of General Anatomy Table 2.3 reveals the comparison between three types of cartilages. Table 2.3: Comparison of three types of cartilages Hyaline Cartilage Fibrocartilage Elastic cartilage Location In the articular In the intervertebral In the pinna, external cartilages of long disc of pubic auditory meatus, bones, sternum, symphysis, Eustachian tubes, ribs, nasal and temporomandibular epiglottis, vocal some laryngeal joints, sterno- process of arytenoid cartilages clavicular joint cartilage Colour Bluish white Glistening white Yellowish Appearance Shiny or Opaque Opaque translucent Fibres Very thin, having Numerous white Numerous yellow same refractive fibres fibres index as matrix, so these are not seen Elasticity Flexible More firm strongest Most flexible Epiglottis (elastic) Hyoid bone Thyroid, cricoid (hyaline) Fig. 2.16: Hyaline and elastic cartilages  Skeleton I 51 Intervertebral disc - Fig. 2.17: Fibrocartilage: Intervertebral disc CLINICAL ANATOMY A defect in membranous ossification causes a rare syndrome called cleidocranial dysostosis. It is characterized by three cardinal features: (a) Varying degrees of aplasia of the clavicles; (b) increase 52 I Handbook of General Anatomy in the transverse diameter of cranium, and (c) retardation in fontanelle ossification (Srivastava et al, 1971). It may be hereditary or environmental in origin. A defect in endochondral ossification causes a common type of dwarfism called achondroplasia, in which the limbs are short, but the trunk is normal. It is transmitted as a Mendelian dominant character. Periosteum is particularly sensitive to tearing or tension. Drilling into the compact bone without anaesthesia causes only mild pain or an aching sensation; drilling into spongy bone is much more painful. Fractures, tumours and infections of the bone are very painful. Blood supply of bone is so rich that it is very difficult to interrupt it sufficiently to kill the bone. Passing a metal pin into the medullary cavity hardly interferes with the blood supply of the bone. Fracture is a break in the continuity of a bone. The fracture which is not connected with the skin wound is known as simple (closed) fracture. The fracture line may be (a) oblique or (b) horizontal. The fracture which communicates with the skin wound is known as (c) compound (open) fracture. A fracture requires "reduction" by which the alignment of the broken ends is restored (Fig. 2.18). (a) (b) (c) Closed and Closed and Open oblique line horizontal line Fig. 2.18: Types of fractures  Skeleton I 53 Healing (repair) of a fracture takes place in three stages: (a) Repair by granulation tissue; (b) union by callus; and (c) consolidation by mature bone. Axis or 2nd cervical vertebra may get fractured. If dens of axis gets separated from the body, it hits the vital centres in the medulla oblongata causing instantaneous death (Fig. 2.19). Even fracture of laminae may cause death. Fig. 2.19: "Hanging till death" occurs due to fracture of dens of axis vertebra In rickets (deficiency of vitamin D), calcification of cartilage fails and ossification of the growth zone is disturbed. Rickets affects the growing bones and, therefore, the disease develops during the period of most rapid growth of skeleton, i.e. 3 months to 3 years. Osteoid tissue is formed normally and the cartilage cells proliferate freely, but mineralization does not take place. This results in craniotabes, rachitic rosary at the costochondral junctions, Harrison's sulcus at the diaphragmatic attachments, enlarged epiphyses in limb bones (Fig. 2.20) and the spinal and pelvic deformities. For proper development of bones, a child requires adequate amounts of proteins, calcium, vitamin D, etc. Deficiency of calcium and vitamin D in growing children leads to widening of ends of bones with inadequate ossification. This condition is called as rickets (Fig. 2.20). 54 I Handbook of General Anatomy (a) (b) F i g. 2. 2 0 : (a) Rickets, ( b ) N o r m a l In scurvy (deficiency of vitamin C), formation of collagenous fibres and matrix is impaired. Defective formation of the intercellular cementing substances and lack of collagen cause rupture of capillaries and defective formation of new capillaries. Haematoma in the muscles and bones (subperiosteal) cause severe pain and tenderness. The normal architecture at the growing ends of the bones is lost. Many skeletal defects are caused by genetic factors, or by a combination of genetic, hormonal, nutritional and pathological factors. The vertebral arch or laminae of the vertebral column may remain deficient, the spinal cord may be covered by skin, i.e. (a) spina bifida occulta. There may be protrusion of the meninges surrounding the spinal cord placed in the vertebral canal, i.e. (b) meningocele or there may be protrusion of the spinal cord as well as meninges, i.e. (c) meningo-myelocele (Fig. 2.21). (a) (b) (c) Fig. 2.21: Types of spina bifida: (a) Spina bifida occulta, (b) Meningocele, (c) meningo-myelocele  Skeleton I 55 If deficiency of calcium, vitamin D occurs in adult life, it leads osteomalacia. The bones on X-rays examination do not reveal enough trabeculae. Deficiency of calcium in bones in old age leads to osteoporosis, seen both in females and males. Due to osteoporosis, there is forward bending of the vertebral column, leading to kyphosis (Fig. 2.22). Nerves are closely related to bones in some areas. Fracture of the bones of those areas may lead to injury to the nerve, leading to paralysis of muscles supplied including the sensory loss (Fig. 2.23). Axillary Radial Ulnar- Fig. 2.22: Kyphosis due to Fig. 2.23: Nerves in contact with osteoporosis posterior surface of humerus Table 2.4: Comparison of osteoporosis and osteomalacia Calcium & Alkaline Osteo- Trabeculae phosphate phosphatase blast Osteoporosis Normal Normal Normal Thin and small Osteomalacia May be low Raised Increased Thick uncalcified osteoid 56 I Handbook of General Anatomy Bone marrow biopsy: Bone marrow can be taken either from manubrium sterni or iliac crest in various clinical conditions (Fig. 2.24). Bone tumour: Benign or malignant tumours can occur in the bone (Fig. 2.25). Fig. 2.24: Bone marrow biopsy - Malignant tumour Fig. 2.25: Malignant tumour of the bone  3 Joints Related Terms 1. Arthron (G. a joint). Compare with the terms arthrology, synarthrosis, diarthrosis, arthritis, arthrodesis, etc. 2. Articulatio (L a joint); articulation (NA). 3. Junctura (L a joint). 4. Syndesmology (G. syndesmosis = ligament) is the study of ligaments and related joints. Definition Joint is a junction between two or more bones or cartilages. It is a device to permit movements. However, immovable joints are primarily meant for growth, and may permit moulding during childbirth. There are more joints in a child than in an adult because as growth proceeds some of the bones fuse together, e.g. the ilium, ischium and pubis to form the pelvic bone; the two halves of the infant frontal bone, and of the infant mandible; the five sacral vertebrae and the four coccygeal vertebrae. CLASSIFICATION OF JOINTS A. Structural Classification 1. Fibrous joints (a) Sutures (b) Syndesmosis (c) Gomphosis 58 I Handbook of General Anatomy 2. Cartilaginous joints (a) Primary cartilaginous joints or synchondrosis (b) Secondary cartilaginous joints or symphysis 3. Synovial joints (a) Ball-and-socket or spheroidal joints (b) Sellar or saddle joints (c) Condylar or bicondylar joints (d) Ellipsoid joints (e) Hinge joints (f) Pivot or trochoid joints (g) Plane joints B. Functional Classification (according to the d e g r e e of mobility) 1. Synarthrosis (immovable), like fibrous joints (Fig.3.1). 2. Amphiarthrosis (slightly movable), like cartilaginous joints (Fig. 3.2). 3. Diarthrosis (freely movable), like synovial joints (Fig. 3.3). Synarthroses are fixed joints at which there is no movement. The articular surfaces are joined by tough fibrous tissue. Often the edges of the bones are dovetailed into one another as in the sutures of the skull. Amphiarthroses are joints at which slight movement is possible. A pad of cartilage lies between the bone surfaces, and there are fibrous ligaments to hold the bones and cartilage in place. The cartilages of such joints also act as shock absorbers, e.g. the intervertebral discs between the bodies of the vertebrae, where the cartilage is strengthened by extra collagen fibres. Suture Fig. 3.1: Synarthrosis: Fibrous joint  Joints i 59 -Intervertebral joint Fig. 3.2: Amphiarthrosis: Secondary cartilaginous joint -Capsule Male s u r f a c e — -Articular cartilage -Synovial Female s u r f a c e — membrane Fig. 3.3: Diarthrosis: Simple synovial joint Diarthroses or synovial joints are known as freely movable joints, though at some of them the movement is restricted by the shape of the articulating surfaces and by the ligaments which hold the bones together. These ligaments are of elastic connective tissue. A synovial joint has a fluid-filled cavity between articular surfaces which are covered by articular cartilage. The fluid, known as synovial fluid, produced by the synovial membrane which lines the cavity except for the actual articular surfaces and covers any ligaments or tendons which pass through the joint. Synovial fluid acts as a lubricant. The form of the articulating surfaces controls the type of movement which takes place at any joint. The movements possible at synovial joints are: Angular flexion : decreasing the angle between two bones; 60 I Handbook of General Anatomy extension : increasing the angle between two bones; abduction : moving the part away from the mid-line; adduction : bringing the part towards the mid-line. Rotary rotation : turning upon an axis; circumduction: moving the extremity of the part round in a circle so that the whole part inscribes a cone. Gliding one part slides on another. C. Regional Classification 1. Skull type: immovable. 2. Vertebral type: slightly movable. 3. Limb type: freely movable. D. According to number of articulating bones 1. Simple joint: When two bones articulate, e.g. interphalangeal joints (Fig. 3.3). 2. Compound joint: More than two bones articulate within one capsule, e.g. elbow joint, wrist joint (Fig. 3.4). 3. Complex joint: When joint cavity is divided by an intra-articular disc, e.g., temporomandibular joint (Fig. 3.5) and sternoclavicular joint. Intercarpal joint Triquetral Lunate Scaphoid bone - — Wrist joint Ulna Radius Fig. 3.4: Compound joint: Wrist joint  Joints i 61 Mandibular fossa Squamotympanic fissure Intra-articulardisc Articular tubercle Head of mandible Tympanic plate Fibrous capsule Fig. 3.5: Complex joint: Temporomandibular joint The structural classification is most commonly followed, and will be considered in detail in the following paragraphs. FIBROUS JOINTS In fibrous joints the bones are joined by fibrous tissue. These joints are either immovable or permit a slight degree of movement. These can be grouped in the following three subtypes. 1. Sutures: These are peculiar to skull, and are immovable. According to the shape of bony margins, the sutures can be: (i) Plane, e.g. internasal suture (ii) Serrate, e.g. interparietal suture (iii) Squamous, e.g. temporo-parietal suture (iv) Denticulate, e.g. lambdoid suture (v) Schindylesis type (Fig. 3.6), e.g. between rostrum of sphenoid and upper border of vomer. Neonatal skull reveals fontanelles which are temporary in nature. At six specific points on the sutures in new born skull are membrane filled gaps called "fontanelles". These allow the underlying brain to increase in size. Anterior fontanelle is used to judge the hydration of the infant. All these fontanelles become bone by 18 months (Fig. 3.7). 2. Syndesmosis: The bones are connected by the interosseous ligament. Example: inferior tibiofibular joint (Fig. 3.8). 3. Gomphosis (peg and socket joint). Example: root of the tooth in its bony socket (Fig. 3.9).  1 62 H a n d b o o k of G e n e r a l A n a t o m y Pericranium Suture ligament (sutural membrane) — Skull bone Endocranium (i) Plane suture (ii) Serrate suture (iii) Squamous suture Ala of- Rostrum of vomer sphenoid (v) Schindylesis (iv) Denticulate suture (wedge and groove suture) F i g. 3.6: T y p e s of s u t u r e s Anterior Anteroinferior Posterior Posteroinferior Fig. 3.7: Fontanelles - Interosseous tibiofibular ligament Inferior transverse tibiofibular ligament F i g. 3. 8 : Inferior t i b i o f i b u l a r j o i n t  Joints I 63 - Incisor line Clinical crown - Pulp cavity Gum Cemento-enamel junction Root with arteriole Cement Periodontal membrane F i g. 3.9: G o m p h o s i s Alveolar bone C A R T I L A G I N O U S JOINTS In this type of joints the bones are joined by cartilage. These are of the following two types: 1. Primary cartilaginous joints (synchondrosis, or hyaline cartilage joints): The bones are united by a plate of hyaline cartilage so that the joint is immovable and strong. These joints are temporary in nature because after a certain age the cartilaginous plate is replaced by bone (synostosis). Examples: (a) Joint between epiphysis and diaphysis of a growing long bone