Medical brain notes 33

  History of Human anatomy   The term 'anatomy' is Greek in origin. It takes its root from 'ana' and 'tome' (ana-up ; tome-cutting). Thus anatomy is the science of physical structure of an animal or plant studied by dissection. The Human Anatomy provided the necessary knowledge for surgery and medicine.   The study of human anatomy dates back to 2500 BC, when the Egyptians prepared mummies. They removed internal organs of cadavers be-ing mummified. They also did surgery for wounds and broken bones. In India during 500 - 491 BC Susruta performed cataract operation. In 1 st  century AD, Celsus, a Roman physician wrote about surgical procedures.   The year 1543 AD was significant due to publication of an accurate book on Anatomy by Andreas Vesalius. In 1628 William Harvey described the functioning of heart and the movement of blood in animals. These earlier works were followed by the discovery and accurate account of each and every or-gan system and organs in human...

  The Integumentary System   The word integument means covering. The integumentary system cov-ers the outside of the body. It protects internal structures, prevents the entry of infectious agents, reduces water loss, regulates body temperature, produces vitamin D and detects stimuli such as touch, pain and temperature. Since the integument performs several functions, it is commonly referred to as  Jack of   all trades .   The skin or integument rests on layers of cells called  hypodermis . The hypodermis attaches the skin to underlying bones and muscles. It supplies blood vessels and nerves to the skin. The skin is composed of two major tissues, namely  dermis  and  epidermis . The dermis is mostly formed of connective tissue having fibro-blasts, adipose cells and macrophages. It provides the structural strength to the skin. The dermis accommodates nerve endings, hair follicles, smooth muscles and glands.   It is divided into two layers,...

  The Integumentary System   The word integument means covering. The integumentary system cov-ers the outside of the body. It protects internal structures, prevents the entry of infectious agents, reduces water loss, regulates body temperature, produces vitamin D and detects stimuli such as touch, pain and temperature. Since the integument performs several functions, it is commonly referred to as  Jack of   all trades .   The sk in or integument rests on layers of cells called  hypodermis . The hypodermis attaches the skin to underlying bones and muscles. It supplies blood vessels and nerves to the skin. The skin is composed of two major tissues, namely  dermis  and  epidermis . The dermis is mostly formed of connective tissue having fibro-blasts, adipose cells and macrophages. It provides the structural strength to the skin. The dermis accommodates nerve endings, hair follicles, smooth muscles and glands.   It is divided into two layers...

  Skeletal system   The skeletal system is constituted by bones, cartilages and ligaments. This system provides 'the shape' to the body. Further, bones remain as re-gions for the attachment of muscles. It also helps to hold weight. Structures like skull, protect inner organs. This system is also useful in locomotion. The bones remain as reservoirs of fat and certain minerals. The bone marrow is the site for the production of erythrocytes.   The bones can be long, short, flat or irregular in shape. Hands and legs have  long bones .  Short bones  are broad in shape. Carpals (wrist bones) and tarsals (antkle bones) are shorter.  Flat bones  are thin and flattened. Skull bones, ribs, sternum and scapula (shoulder blade) are  flat bones . Verterbral and facial bones are  irregular  in shape.     Structure of a typical long bone   A bone is covered by a double layered sheath called the  periosteum . The outer layer of ...

  Skull   :    The human cranial capacity is about 1500 cm 3 . It consists of 22 bones. It protects the brain. It supports the organs of vision, hearing, smell and taste. The lower jaw  or  mandible  remains specially attached to the skull. The skull or cranium is covered by eight bones. They are one pair each of  parietal  and temporal , individual bones as  frontal, sphenoid ,  occipital  and  ethmoid . These bones are joined by sutures to form a compact box like struc-ture.  The sutures  are immovable joints. In the front there are 14 facial bones. Of these  maxilla ,  zygomatic ,  palatine ,  lacrymal ,  nasal  and i nferior nasal koncha  remain as pairs. Mandible  or  lower jaw  and  vomer  are unpaired bones .   The  parietal  and  occipital  bones are major bones on the posterior side of the skull. The parietal bones are j...

  Vertebrae  -  The vertebrae make up the slighty S-shaped  vertebral   column  or  backbone . The vertebral column consists of 26 bones. They are   divided into 5 regions. They are the  cervical  (7),  thoracic  (12), l umbar  (5),  sacral  (1) and  coccygeal  (1) vertebrae. Vertrebra - Structure  : The main load - bearing portion of a vertebra is a   solid disc of bone called the  centrum . The centra of adjacent vertebrae are separated by intervertebral discs of cartilage. Projecting from the centrum dorsally is a  vertebral arch . It encloses the neural canal. This canal contains the spinal cord. Several bony projections are seen on the vertebral arch. On each side of the centrum ther are two  transverse processes . On the dorsal side there is a  neural spine . These bony projections are used for attachment of muscles. Further, there are two superior and two inferior pr...

  Rib cage -  There are 12 pairs of ribs. Each articulates with a thoracic vertebra. In the front, the first ten pairs are attached to the sternum (breast bone) by costal cartilages. The first seven are attached directly to the ster-num. They are called the  true ribs . Cartilages of  8 th ,  9 th  and  10 th  ribs are fused and attached to  7 th . They are called the  false ribs .  11 th   12 th  pairs are not attached to the sternum. They are called  floating ribs .     Vertebrae  - The vertebrae make up the slighty S-shaped  vertebral   column  or  backbone . The vertebral column consists of 26 bones. They are   divided into 5 regions. They are the  cervical  (7),  thoracic  (12), l umbar  (5),  sacral  (1) and  coccygeal  (1) vertebrae. Vertrebra - Structure  : The main load - bearing portion of a vertebra is a   solid d...

  Appendicular skeleton It consists of the bones of the  upper  and  lower limbs  and the  girdles  by which they are attached to the body.   Pectoral girdle  - The hands are attached to the pectoral girdle. Both of them   are attached loosely by muscles to the body. This arrangement facilitates free-dom of movement. Hence it is possible to place the hand in a wide range of positions.     The pectoral or shoulder girdle consists of two pairs of bones. Each pair has a  scapula  or shoulder blade and a  clavicle  or collarbone. The  scapula  is a flat, triangular bone. A  glenoid fossa  is located in the superior lateral region of the scapula. It articulates with the head of the humerus. The  clavicle  is a long bone. It has a slight S-shaped curve. It can be easily seen and felt. The clavicle holds the upper limb away from the body.       Pelvic girdle or pelvis...