Anatomy Book PDF

## Introduction of anatomy ### Lymphatic system - The lymphatic system consists of lymph nodes and lymph vessels as well as the spleen and tonsils. - It is an important part of the **immune system**. - The fluid circulating inside lymph vessels is called lymph, which is rich in lymphocytes that co...

## Introduction of anatomy ### Lymphatic system - The lymphatic system consists of lymph nodes and lymph vessels as well as the spleen and tonsils. - It is an important part of the **immune system**. - The fluid circulating inside lymph vessels is called lymph, which is rich in lymphocytes that combat infection and contain large particles in the tissue fluid. - Lymph formation starts in the intercellular tissue spaces and flows inside the lymph vessels, which are interrupted at various sites by masses of lymphoid tissues called lymph nodes. ### Introduction of anatomy - The lymph vessels have valves. - The **thoracic duct** is the largest and longest lymphatic vessel, which drains the body except the upper right quadrant of the body, which drains into the right lymph trunk. - These lymph vessels drain into large veins in the root of the neck. - Lymph drains eventually into the venous blood. - Lymph vessels are absent in the CNS, cornea, epidermis, and cartilage. - Cisterna chyli drains the lower 1/2 of the body below the diaphragm. - The thoracic duct begins at the upper end of cisterna chyli and ends in the beginning of the left brachiocephalic vein. ### Introduction of anatomy - Their walls are permeable due to the presence of microscopic gaps between the endothelial lining allowing exchange between blood and extracellular fluid. #### Sinusoids - The sinusoids are similar to capillaries, but have the following features: - The sinusoids have large irregular lumens. - Their wall, containing pores, is surrounded by an incomplete basement membrane. - They are present in the liver, spleen, and bone marrow. #### Capillary or Sinusoid? - A table describing the differences between capillaries and sinusoids is presented here. ### Introduction of anatomy - Arteriovenous shunt: between small arteries and accompanying veins. #### Capillaries - The capillaries have the following features: - They are microscopic vessels that form a network immediately following arterioles and connecting them with the venules. - The wall is formed of one layer of cells surrounded by a continuous basement membrane with no muscle layer. - The capillaries are of uniform narrow diameter and form anastomotic networks in all tissues called the capillary bed. ### Introduction of anatomy #### End Arteries - They are arteries that do not anastomose with adjacent arteries. - They are called the end arteries, and their obstruction will lead to death (necrosis) of the tissues that are supplied by them, e.g.: - Central retinal artery, which supplies the retina. - Renal artery, which supplies the kidney. - Splenic artery, which supplies the spleen. - Central branches of cerebral arteries. - Pulmonary arteries. #### Veins - They are vessels that carry the blood from all regions of the body to the heart. - They carry deoxygenated blood except the pulmonary and umbilical veins, which carry oxygenated blood. - The veins are classified into superficial and deep veins (according to the relation to deep fascia). #### Factors Which Help Venous Return 1. From the upper part of the body, venous blood is drained mainly by gravity. 2. From the lower part of the body: - Venous valves - Arterial pulsations - Muscular contractions (muscle pump) - Deep fascia surrounding the muscle groups - Negative intrathoracic pressure drawing blood from the abdomen, head, and neck into the thorax. ### Introduction of anatomy #### Blood vessels ##### Arteries - They are vessels that carry the blood from the heart to other regions of the body. - They carry oxygenated blood except the pulmonary and umbilical arteries, which carry deoxygenated blood. - They are classified according to their size and structure into: large, medium-sized, and small arteries. ##### Arterial Anastomosis - Definition: It is the connection between the arteries, which is present mainly around the joints. - Functions: - It increases the blood supply to some organs, e.g., the stomach. - It equalizes pressure in the communicating arteries. - It maintains the blood flow to an area or part of the body, if its main artery is obstructed. ##### Types of Arterial Anastomoses 1. **End to End Anastomosis:** - The 2 ends of 2 arteries are connected together forming an arch. - Example: Anastomosis in the hand and foot. ### Introduction of Anatomy - Exchange of gases occurs. - Oxygenated blood returns to the left atrium via the four pulmonary veins, then to the left ventricle, where a new cycle occurs. #### Portal Circulation - This circulation transmits venous blood from GIT to the liver in order to metabolize digested nutrients, and to detoxify the blood.  - The venous blood from the stomach, spleen, pancreas, and intestine is collected into the portal vein, which enters the liver (through the porta hepatis) and divides into many branches which end in liver sinusoids. - The blood leaves the liver sinusoids by the hepatic veins which end in the inferior vena cava. ### Introduction of anatomy #### Blood circulation - Left ventricle → aortic valve → aorta and its branches which supply upper and lower parts of the body → venous blood returns via S.V.C and I.V.C → Rt. atrium → tricuspid valve → Rt. ventricle → pulmonary valve → pulmonary trunk → Rt. and Lt. pulmonary arteries to Rt. and Lt. lungs, where oxygenation of blood occurs. - The oxygenated blood returns via four pulmonary veins → Lt. atrium → mitral valve → Lt. ventricle #### Types of circulation 1. Systemic circulation: - Oxygenated blood in the left ventricle passes through the aorta and its branches to reach all the tissues of the body, where exchange of gases and nutrients occur. - Deoxygenated blood is collected by small veins, then by large veins and finally by superior and inferior venae cava into the right atrium.  - The blood passes from the right atrium to the right ventricle, where this circulation ends and a new cycle starts. 2. Pulmonary circulation: - Deoxygenated blood from the right ventricle passes through the pulmonary artery and its two branches to reach both lungs, where oxygenation of blood occurs. - Oxygenated blood returns from the lungs to the left atrium through pulmonary veins. ### Introduction of anatomy #### Right ventricle: - Sends the deoxygenated blood through the pulmonary valve to the pulmonary trunk, which divides into two pulmonary branches (right and left), one for each lung where oxygenation of the blood occurs. #### Left atrium: - Receives the oxygenated blood from both lungs through four pulmonary veins, and pumps it to the left ventricle via the mitral valve. #### Left ventricle - Pumps its oxygenated blood to all parts of the body through the aortic valve to the aorta and its branches. #### Types of blood in the heart: 1. Right 1/2 of the heart contains deoxygenated (venous) blood. 2. Left 1/2 of the heart contains oxygenated (arterial) blood. - The heart is covered by the pericardial sacs. ### Introduction of anatomy #### Heart - It lies behind the sternum and costal cartilages, extending from the 2nd to the 6th costal cartilages. - About 2/3 of the heart lies to the left and 1/3 of the heart is to the right of the median plane. #### Chambers of the heart - It is formed of two atria and two ventricles ##### Right atrium - Receives the deoxygenated blood from all parts of the body by two large veins: the superior vena cava (SVC) and the inferior vena cava (IVC). It sends its blood to the right ventricle through the tricuspid valve. ### Introduction of anatomy #### Attachment of skeletal muscles: - Each muscle has two attachments. ##### Origin: - The most fixed attachment. ##### Insertion - The most mobile attachment. ### Introduction of anatomy #### Muscular system - Muscle tissue is characterized by the property of contraction, which is the ability of the muscle fibers to become short. #### Classification of the muscles - There are three types of muscles according to their structure and function. ##### Skeletal Muscles - Attached to the skeleton (bones) - Voluntary contraction - Striations present - Somatic nerve supply - Multinucleated muscle fibers - With peripheral nuclei ##### Smooth Muscles - In the walls of blood vessels and viscera. - Involuntary contraction - Striations absent - Autonomic nerve supply - Spindle-shaped muscle fibers - With a single nucleus ##### Cardiac Muscles - In the myocardium - Involuntary contraction - Striations present but less than skeletal muscle - Autonomic nerve supply - Branch and fuse together with a single nucleus ### Introduction of anatomy #### Summary of types of synovial joints ##### According to the axis of movement 1. **Uni-axial joints:** Movements occur around a single axis. - **Hinge joint:** The joint is uni-axial, with one transverse axis e.g., the elbow joint, where a convex trochlea articular surface articulates a deep concave surface. The movement is flexion and extension only, with no abduction or adduction due to strong collateral ligaments, e.g., elbow. - **Pivot joint**: The joint is uni-axial with one vertical axis, e.g., the superior radio-ulnar joint. The articulating surface consists of a central bony pivot (axis) surrounded by a fibro-osseous ring. The movement of this joint is rotation around the center of the pivot, i.e., pronation and supination. 2. **Bi-axial joints:** Movements take place around two axes perpendicular to each other. - **Condylar and bicondylar joint**: It consists of either two separate convex surfaces (condyles) which articulate with two concave surfaces, e.g., the knee joint. - **Ellipsoid joint**: It is formed by the articulation of an oval convex surface (carpal bones) with an elliptical concave surface (inferior surface of radius and the articular disc of ulna), e.g., wrist joint. - **Saddle joint**: The articulating surfaces of this joint are two concavo-convex surfaces, e.g., the carpo-metacarpal joint of the thumb. The movements of this joint are flexion, extension, abduction, abduction, opposition, and circumduction. 3. **Multi-axial joints:** Movements occur around three axes. The articular surface consists of globular rounded bone articulates with concave socket. According to the shape of the articular surfaces, they are called ball and socket joints, e.g., shoulder and hip joints. They are the most freely mobile joins in the body. The movements of this joint are around: - Transverse axis: Flexion and extension. - Antero-posterior axis: Abduction and adduction. - Vertical axis: Medial and lateral rotation, and circumduction. ##### According to the shape of the articular surface - **Hinge joint** - **Pivot joint** - **Condylar joint** - **Ellipsoid joint** - **Saddle joint** - **Ball and socket joint** - **Plane joint** ### Introduction of anatomy #### Classification of synovial joints ##### According to the number of articulating bones 1. **Simple joints:** Between two bones e.g., shoulder 2. **Compound joints:** Between more than two bones e.g., elbow 3. **Complex joints:** Contain intra-articular structures e.g., knee joint ### Introduction of anatomy - **Rotation:** Medial or lateral rotation of the limb around a vertical axis. - **Circumduction:** Combination of all above movements. - **Supination:** The lateral rotation of the forearm. - **Pronation:** The medial rotation of the forearm. - **Flexion:** Approximation of two ventral surfaces to each other (bending). - **Extension:** The two ventral surfaces move away from each other (straightening). - **Abduction:** Movement of the limb laterally away from the middle line (in fingers, moving away from the center of the middle finger, while in toes, moving away from the center of the second toe). - **Adduction:** Movement of the limb medially towards the middle line (in fingers, moving towards the center of the middle finger, while in toes, moving towards the center of the second toe.) - **Inversion:** The sole of the foot is directed inwards. - **Eversion:** The sole of the foot is directed outwards. - **Opposition:** The thumb comes into contact with the other four fingers. ### Introduction of anatomy #### Factors affecting the stability of the joint 1. Shape and fitting of articulating surfaces. 2. Thickness and strength of the capsule. 3. Position and strength of ligaments. 4. Strength of muscles surrounding the joint. ### Introduction of anatomy #### Synovial membrane - Thin, moist, smooth, and glistening membrane that covers all structures inside the joint except the articular surfaces. - It also lines the fibrous capsule. - It secretes and absorbs the synovial fluid. #### Synovial fluid - Pale yellow viscous fluid, similar to egg albumin. - It contains free cells (synovial cells, macrophages, and lymphocytes). - Functions: - Lubrication and nutrition of the articular cartilage. - Prevents erosion of articular cartilage. #### Ligaments - Extracapsular and intracapsular ligaments which support and strengthen the joint. #### Structures which may be present inside the cavity of synovial Joints 1. **Articular disc:** Disc of fibrocartilage which divides the joint cavity into two compartments (upper and lower), e.g., temporo-mandibular joint. 2. **Menisci (semilunar cartilages):** E.g., the two semilunar plates of fibrocartilage present inside the knee joint. 3. **Ligament:** E.g., the cruciate ligament inside the knee joint. 4. **Tendon:** E.g., the tendon of the long head of biceps muscle inside the shoulder joint. ### Introduction of anatomy #### Synovial joints - They are mobile joints present mostly in the limbs. ##### Structure of synovial joints 1. **Fibrous Capsule:** - The synovial joint is surrounded completely by a fibrous capsule, which is lined by synovial membrane. - This capsule is supported and strengthened by **ligaments**. - It is pierced by blood vessels and nerves which supply the joint. 2. **Articular cartilage:** - Hyaline cartilage covers the articular surfaces of bones. - It is very smooth and is lubricated by the synovial fluid. - **Nutrition:** From synovial fluid. - It has no blood or nerve supply. - Applied anatomy: In old age, it shows irregularities and erosions. The eroded areas do not repair with pain & limitation of movements. This disease is called **osteoarthritis**. 3. **Joint cavity:** - It is potential a cavity which appears if fluid, blood, or pus collect into it. - Normally it contains a very thin film of synovial fluid.  ### Introduction of anatomy #### Cartilaginous Joints (false joint) - In these joints, the surfaces of the articulating bones are connected together by a disc of cartilage. - They are two types: ##### Primary Cartilaginous joint - Temporary joint - Disappears by ossification of epiphyseal cartilage. - Site: at the ends of long bones - Fixed joint. - Structure: Epiphyseal plate of hyaline cartilage between the epiphysis and metaphysis in the developing long bones in children ##### Secondary Cartilaginous joint - Permanent joint. - Present in the midline, e.g., intervertebral discs & symphysis pubis. - **No, or limited movement**, which is allowed by the elasticity of the fibro-cartilaginous disc.  - The articulating bone is covered by a thin layer of hyaline cartilage, and are separated by white fibro-cartilaginous disc. It is strengthened by fibrous ligaments, which fuse with the periphery of the cartilaginous discs.  ### Introduction of anatomy #### Joints - The joint is the contact (articulation) between two or more bones together. #### Classification of joints - There are three types of joints. ##### Fibrous joints (false joint) - Fixed joints in which the surfaces of articulating bones are connected together by fibrous tissue.  - There are three types: ###### Syndesmosis - Present in the inferior tibio fibular joint. - The lower end of tibia and fibula are connected together by fibrous tissue called interosseous ligament. ###### Gomphosis - Present in teeth. - The roots of teeth are connected to their sockets in the bones by fibrous tissue called periodontal ligament. ###### Sutures - Present in the skull. - The bones of the skull are connected together by the thin layer of fibrous tissue called sutural ligament. - They are obliterated in old age.