General Anatomy & Embryology 2025 PDF

General Anatomy & Embryology 2025 Contents Page number Introduction to Anatomy………………………………… 2 Skin & Fascia …………………………………………………. 6 Bone tissue…………………………………………............. 8 Joints………………………………...

General Anatomy & Embryology 2025 Contents Page number Introduction to Anatomy………………………………… 2 Skin & Fascia …………………………………………………. 6 Bone tissue…………………………………………............. 8 Joints…………………………………………………………….. 13 Muscles…………………………………………………………. 16 Appendicular skeletal system……………………….. 20 Cardiovascular system…………………………….……… 30 Gastro-intestinal tract………………………………….... 36 Nervous system…………………………………..………….. 43 Respiratory system…………………………..…………….. 50 Urinary system…………………………………….…………. 56 Reproductive system……………………………..………. 60 Gametogenesis………………………………………………. 66 Female cycle………………………………………………….. 70 1st week of pregnancy…………………………..………… 73 2nd week of pregnancy……………………………………. 79 3rd week of pregnancy………………………….…………. 83 4th week of pregnancy…………………………………….. 88 External appearance during second month of pregnancy………………………………………………………. 92 Monthly changes till birth time…………………….… 94 Fetal membranes (Amnion & umbilical cord)…… 96 Placenta & twins……………………………………………… 100 Birth defects……………………………………………………. 107 2  Introduction to Anatomy Anatomy: means cutting –up for studying the normal structure of organs in — living. — Types of study: — Macroscopic anatomy: Studying normal structure of organs by naked eye. Microscopic anatomy (Histology): studying of normal structure of cells under microscope. Developmental anatomy: Studying of intrauterine life. Applied anatomy: Application of anatomical facts in medicine and surgery. Surface anatomy: Identification of borders of organs on the skin surface. Radiographic anatomy: Studying of anatomy by using imaging techniques: CT, MRI, X-ray ….. Anatomical position & anatomical planes Anatomical position: human is standing erect. Face & eyes are looking forward. Arms are hanged beside the trunk. Palms of the hand are facing forward. Anatomical planes: Sagittal (Median) plane: a vertical plane which divides the body into right & left halves. If it is dividing two unequal parts, it’s called parasagittal (paramedian) plane. Coronal plane: a vertical plane which divides the body into front & back parts. Transverse plane: a horizontal plane which divides the body into upper & lower parts. Anatomical terms — Terms of relationship: Anterior  in front. Posterior  behind. Superior  above. Inferior  below. Medial  closer to median plane. 3  Lateral  away from the median plane. — Terms of comparison: Cranial  nearer to the head Caudal  nearer to the tail. Proximal  nearer to the trunk. Distal  away from the trunk. Ventral  nearer to the anterior abdominal wall. Dorsal  nearer to the backbone. — Terms of movements: Flexion  to bend. Extension  to straighten. Abduction  movement away from the median plane. Adduction movement towards the median plane. Circumduction  multi-axial movement in a sequence of flexion, abduction, extension & adduction or vice versa. Protraction (protrusion)  movement forward Retraction (retrusion) movement backward. Dorsiflexion of foot  movement to make toes approximate the front of leg. Planterflexion of foot  the reverse. Rotation  turning movement around a single axis.  Rotation in hand: supination  palm of the hand is facing forward. Pronation  palm of the hand is facing backward.  Rotation in foot: inversion  sole of the foot is facing inward. Eversion  sole of the foot is facing outward. — Body cavities Ventral body cavities — Thoracic cavity  containing lungs & heart. Abdominal & pelvic cavities  containing abdominal & pelvic viscera. These cavities are lined by serous membranes. — Dorsal body cavities — Cranial cavity  containing brain. Vertebral canal  containing spinal cord. These cavities are lined by meninges. 4  Skin & Fascia Introduction: The skin forms the external surface of the body. 5  The skin consists of two layers: o Epidermis  A superficial epithelial layer. o Dermis  A deeper connective tissue layer. The skin has four appendages that developed from ectoderm: Hairs, nails, sebaceous glands & Sweat glands. Functions of the skin: 1. It protects the underlying soft tissues from mechanical, osmotic & thermal damage. 2. It acts as a barrier against microorganisms. 3. It regulates heat exchange between the body & the external environment (Sweating). 4. The largest sensory organ for touch, pressure, pain & temperature. 5. Absorption of substances (drugs –toxins). 6. Activation of vitamin D by the effect of ultraviolet rays. Epidermis of skin: It is formed of stratified squamous epithelium – keratinized. It is composed of five layers: 1. Stratum coneum  non- nucleated cells, filled with water-retaining keratin protein. About 10- 30 layers. 2. Stratum lucidum found in thick skin (Palm of hand & sole of foot). Non-nucleated clear cells. 3. Stratum granulosum  with granular cytoplasm containing lipids. 4. Stratum spinosum  polyhedral cells connected tightly by desmosomes. 5. Stratum basale  proliferating basal layer on the basement membrane that give rise to all layers of epidermis. Dermis: It is consisted of connective tissue, in which the following structures are found: 1. Blood vessels. 2. Lymph vessels. 6  3. Sensory nerve endings. 4. Hair follicles, Sweat glands & Sebaceous glands. Flexure lines of skin (skin creases): Linear skin furrows lie opposite joints. Site: especially found in palm of hand, front of wrist joint. It is produced by firm attachment of the skin to the underlying deep fascia. Papillary ridges (Finger prints): They are narrow, slightly raised ridges that separated by fine parallel furrows to help perfect hand grip. They are found in the palm of hands, sole of feet as well as tips of fingers & toes. They are specific to the individuals which of medicolegal importance. Blood supply of skin: epidermis is avscular & receives its nourishment from vascular dermis. Nerve supply: 1. From the skin: sensory receptors for touch, temperature & pain. 2. To the skin: Autonomic sympathetic fibers that supply sweat glands, sebaceous glands & arrector pilorum muscles. Superficial fascia: Definition: A layer of loose areolar connective or adipose tissue that connects the skin to the underlying bones or deep fascia. It is known also by Hypodermis. Site & functions: It is well developed at these sites: trunk wall, abdominal wall, buttocks & face. It is absent in ear pinna, eye lids, penis & scrotum. It is condensed in scalp, palm of hand & sole of foot. Functions: 1. It facilitates skin movement. 2. It forms a soft bed for blood vessels & nerves of skin. 3. It retains body warmth. 4. It gives your body a smooth contour. Deep fascia: Definition: A dense connective tissue that is commonly arranged in sheets that form a stocking around the muscles and tendons beneath the superficial fascia. Site & functions: Deep fascia is absent in face, scalp & anterior abdominal wall. 7  Functions: 1. It invests muscles to make a degree of tension to help muscle action. 2. It sends septa between muscles. 3. It invests delicate structures: glands & blood vessels to keep their fixation in place. 4. It is thickened at the palm of hands (Palmar aponeurosis) & sole of feet (Planter aponeurosis) for protection of the underlying soft structures: vessels & nerves. 5. It helps venous return from the lower limbs by forming a closed compartments inside which the skeletal muscles contract to squeeze veins (Muscle Pump). Bones Bone tissue & functions — Bone tissue: Bones are hard forms of connective tissues. It forms 18% of body weight. The body is formed of 206 bones. Cells:  Osteocytes  mature bone cells.  Osteoblasts  young bone cells.  Osteoclasts  phagocytic cells for bone remodeling. Matrix:  Organic (collagen bundles type-1) 30% of dry bone.  Inorganic salts  calcium carbonate & calcium phosphate, 70%. Bone functions: 1. Gives body shape. 2. Forms joints for locomotion. 3. Protection of vital organs like brain & heart. 4. Containing bone marrow for blood cells formation. 5. Storage for calcium & phosphorus. 8 Types of bones — Histological classification: two types Compact bone  bony matrix contains tiny spaces with no bone marrow. Example: shaft of long bones. Spongy bone  bony matrix contains large spaces rich in bone marrow. Example: ends of long bones. — Developmental classification: two types Intra-membranous ossification  young bone cells are arranged in membrane like structure as in flat bones. Intra-cartilaginous ossification  young bone cells are developed from cartilaginous model as in long bones. Morphological classification: 1. Long bones: Present in limbs. They have a shaft & two articular ends. Growth of long bones:  They are developed by intra-cartilaginous ossification.  Primary centers of ossification appear at the shaft (diaphysis) of bones by 8th : 12th week of intra-uterine life.  Secondary centers of ossification appear at the ends (epiphysis) of bone around time of birth.  Epiphysial cartilage plate persists at junction between epiphysis & diaphysis for bone growth till time of 19th -25th years of age. Blood supply of long bones: i. Nutrient artery & vein. ii. Peri-osteal twigs of vessels. iii. Articular vessels near the joint ends. 9 2. Short bones: They are small cubical bones. Example: carpal & tarsal bones. 3. Flat bones: They have flat wide surface for protection & muscle attachment. Example: skull cap & scapula. 4. Irregular bones: They are of irregular configuration. Example: vertebrae. 5. Sesamoid bones: Small nodular bones present within muscle tendons to protect them against friction. Example: patella. 6. Pneumatic bones: Only in facial bone. Air spaces replace the bone marrow & communicate with nasal cavity. Example: Para-nasal sinuses. 10 11 Skeletal system — Axial skeleton: formed of: Skull & mandible. Vertebral column. Sternum. Ribs. — Appendicular skeleton: formed of: o Upper limb: which is formed of:  Shoulder girdle (clavicle & scapula).  Arm bone (Humerus).  Forearm bones (Ulna & radius).  Carpal bones (8 bones).  Metacarpal bones.  Phalanges ( 3 except for thumb, only 2) o lower limb: which is formed of:  Pelvic girdle (hip bones).  Thigh bone (Femur).  Leg bones (tibia & fibula).  Tarsal bones (7 bones).  Metatarsal bones.  Phalanges ( 3 except for big toe, only 2) 12  Joints Types of joints — Joints are junction or articulation between two or more bone. — Types: 1. Fibrous joints: bones are connected by an intervening fibrous tissue. Examples: sutures of skull & syndesmosis between lower ends of tibia & fibula. 2. Cartilaginous joints: bones are connected by cartilaginous tissue. 1. Primary cartilaginous joint  formed of hyaline cartilage as epiphysial cartilage plate. It allows no movement. 2. Secondary cartilaginous joint formed of fibro-cartilage as intervertebral disc. It allows compression & torsion movement (limited). 3. Synovial joints: — Joints are connected by a joint with a cavity which contains synovial fluid & enclosed inside a fibrous capsule. — Features: a) Articular cartilage: formed of hyaline cartilage, very smooth surface with no vessels or nerves. b) Fibrous capsule: fibrous sac enclosing the joint. It is perforated by vessels & nerves. 13  c) Synovial membrane: fine delicate membrane secreting synovial fluid. d) Synovial fluid: lubricating egg albumin like fluid to minimize friction between articular surfaces. e) Ligaments: strong fibrous bands connecting bones together. Structures could be found inside the synovial joint: Articular disc: formed of fibro-cartilage, compressible for shock absorbance & minimize friction. Examples: T/M joint, knee joint & sterno-clavicular joint. Intra-articular ligaments: ligaments inside the joint cavity. Example: cruciate ligaments inside the knee joint. Muscle tendons: found in shoulder joint, the tendon of long head of biceps. 14 Classification of synovial joints 1. Plane joints: — Flat articular surfaces allow minimal gliding movement. Example: intercarpal joint. 2. Uni-axial joints: Allow two movements around single axis. Hinge joints: with transverse axis. Example: elbow joint. Pivot joints: with longitudinal axis. Example: median Atlanto-axial joint. 3. Bi-axial joints: Allow four movements around two axes. Ellipsoid joint: an oval convexity is introduced into elliptical concavity. Example: Radio-carpal joint. Saddle joint: concavo-convex opposing surfaces of saddle shape. Example: carpo-metacarpal joint of thumb. 4. Multi-axial joints: Allow free movement. Ball & socket joints. Examples: hip & shoulder joints. — — — — — — — 15  Muscles — Muscles are bands of fibrous tissue that have the ability to contract producing a movement. — Types of muscles: 1. Skeletal muscles: They are attached to skeleton. They have voluntary action. Cut of its nerves produces paralysis. 2. Cardiac muscles: They are present in the heart. They have involuntary action. Cut of its nerves produces no paralysis (Autonomous). 3. Smooth muscles: They are present in the viscera (intestine & blood vessels). They have involuntary action. Cut of its nerves produces paralysis. Skeletal muscles — Structure: — Skeletal muscles form 43% of the body weight (39% in female). 16  — They are formed of 3 parts: Origin  the proximal fixed end of the muscle. Insertion  the distal mobile end of the muscle. Fleshy belly  the central main bulk of the muscle. — Muscle attachment to bone: Fleshy attachment  the muscle is attached to the bone by its fleshy belly. Muscle tendon  the muscle is attached to bone by rope-like, inelastic cord called muscle tendon. Aponeurosis  is a sheath like structure formed for wide muscle attachment as in abdominal muscles. Skeletal muscle forms — Muscle form is a description of the relationship between the line of pull of the muscle & direction of muscle fibers. — Types: a. Parallel form: muscle fibers are parallel to the line of pull. Example: Biceps brachii muscle. b. Oblique form (pinnate): i. Uni-pinnate  has a shape of half of feather. Example: Flexor pollices longus. ii. Bi-pinnate  has a shape of complete feather. Example: Rectus femoris. iii. Multipinnate  has a shape of multiple feathers. Example: Deltoid muscle. c. Convergent form  fan shaped. Example: Temporalis. d. Circular form  sphincter like. Example: Orbicularis oculi. 17  e. Segmented form  fused parts. Example: Rectus abdominis. Muscle action: — Muscle action is a description of the relationship between the line of pull of the muscle & joint movement. — Types: 1. Prime movers: muscles that act to perform specific action on the joint. Example: Brachailis in elbow flexion. 2. Antagonists: muscles that oppose the action of the prime movers. Example: 18  Triceps in elbow flexion. 3. Synergists & fixators: muscle that help prime movers to stabilize other joints to make smooth movement. Muscle related synovial membranes: — Synovial bursa: A closed fibrous sac which is lined by a synovial membrane for lubrication. It is present where the tendon of muscle is short & rubbing against a bony prominence. Example: Subscapular bursa beneath the Subscapularis muscle tendon. — Synovial sheath: A tubular fibrous sheath which is lined by a synovial membrane for lubrication. It is present where the tendon of muscle is long & rubbing against many bony prominences. Example: long flexor tendons of forearm. 19  Synovial sheaths of hand Subscapular bursa Appendicular Musculo-skeletal system Bones of the upper limb CLAVICLE - It lies horizontally in the root of the neck and covers the 1st rib. - It has 2 important functions: 1- To transmit forces from the upper limb to the bones of the axial skeleton (sternum). 2- To act as support holding the arm free from the trunk. - Clavicle is a long bone (“S” shaped), it consists of: 1- Medial (sternal) end: quadrilateral in shape, articulate with sternum forming the sterno- clavicular joint. 2- Body (shaft): - Its medial 2/3 convex forward and its lateral 1/3 concave forward. 3- Lateral (acromial) end: flat and articulate with the acromial process of the scapula forming the acromio- clavicular joint. SCAPULA 20 - Flat bone, triangular in shape; has 2 surfaces, 3 borders, 3 angles, 3 processes. - Angles: superior, inferior and lateral. o Superior angle: at level of 2nd rib. o Inferior angle: thick, at level of 7th rib. o Lateral angle carry head (glenoid cavity or fossa) which articulates with head of humerus to form shoulder joint. - Surfaces: anterior and posterior. o Anterior (costal) surface: has subscapular fossa. o Posterior surface: divided by spine of scapula into suprasinous fossa and infraspinous fossa. - Borders: superior, medial, lateral. o Lateral (axillary) border: thick. o Medial (vertebral) border. o Superior border: has suprascapular notch. - Processes: spine, acromion, coracoid. o Spine (spinous process): triangular bony shelf, on the dorsal surface; at level of 3rd rib, continues laterally as acromion. o Acromion: continuation of spine, forms tip of shoulder. o Coracoid process: bent like finger, directed forward, thick and very strong. HUMERUS Long bone consists of upper end, body (shaft) and lower end. Upper end: Consists of: - Head. - 2 necks (Anatomical neck: for attachment of the shoulder joint capsule & Surgical neck: in a direct contact with Axillary nerve that supplies deltoid muscle) - 2 tubercles, greater tubercle [directed laterally] & lesser tubercle [directed anterior]. - Intertubercular (bicipital) groove between the two tubercles. It forms a passage for long head biceps muscle. Body (shaft): has: 21 - Deltoid tuberosity for deltoid insertion. - Spiral groove, for passage Radial nerve on the back of the arm. Lower end: consists of: - Trochlea - Capitulum - Medial epicondyle - Lateral epicondyle - 3 fossae (coronoid, radial, and olecranon). ULNA Medial bone of forearm, long bone, consists of upper end, body (shaft) and lower end. Upper end: - 2 curved processes: olecranon and coronoid - 2 concave articular cavities, the tochlear and radial notches. Body (shaft): triangular in transverse section. Lower end: formed of: - Head of ulna - Styloid process which is present medially to the head. RADIUS Lateral bone of forearm, Long bone, has upper end, body (shaft) and lower end. Upper end: Consists of: head, neck and radial tuberosity. 22 Body (shaft): triangular (in cross section) Lower end: carry styloid process of radius. BONES OF THE HAND They consist of: carpus, metacarpus and phalanges. The carpal bones - they are 8 short bones arranged in 2 rows (proximal & distal), from lateral to medial: 1- The proximal row: scaphoid, lunate, triquetral & pisiform. 2- The distal row: trapezium, trapezoid, capitate & hamate. Metacarpal bones: - 5 long bones (one for each finger). Phalanges - ALL fingers have 3 phalanges (proximal, middle, and distal) EXCEPT thumb (has 2 ONLY; proximal and distal). LOWER LIMB BONES Hip bone - Two bones, each consists of three bones that fuse together: ilium, pubis and ischium. - The two hip bones are joined anteriorly by the pubic symphysis and joined posteriorly by the sacrum forming the sacroiliac joints. Femur - The longest, heaviest, and strongest bone in the body. It has upper, lower end and shaft. The upper end: - contains the head, neck, the two trochanters (Greater & lesser) - The head; composes two-thirds of a sphere, it articulates with the acetabulum of the pelvic bone, The lower end: 23 - It has the medial and lateral condyles that articulate with the condyles of the tibia and back of patella forming the knee joint. Body (shaft): is long, slender and almost cylindrical in form. It has a prominent longitudinal ridge on its posterior surface, called the linea aspera that forms the insertion line for adductors of the thigh. Patella - Largest sesamoid bone in the body located within the tendon of quadriceps muscle. - Triangular in shape, with the apex of the patella facing downwards. - It gives attachment to the patellar ligament. - It articulate with femur to forms the patello-femoral joint (part of knee joint). Tibia - The larger, medial weight-bearing bone of the leg has: The upper end: - widened by the medial and lateral condyles. - Between the condyles is the inter-condylar eminence for attachment of cruciate ligament. - Tibial tuberosity is a prominent rounded elevation at the anterior aspect of the upper end that forms site of attachment of patellar ligament. The lower end: shows; medial malleolus: medially & fibular notch: laterally. The shaft: is thick and appears triangular in cross section. Fibula - The smaller, non-weight bearing and laterally placed bone of the leg. - The interosseous membrane connecting the fibula to the tibia - Lateral malleolus is located at the lower end. - It has a superior and an inferior tibio-fibular articulation. Skeleton of the Foot 24 Tarsal bones: - 7 tarsal bones - talus (articulates with tibia and fibula), calcaneus (heel bone, largest and strongest), navicular, cuboid and 3 cuneiforms Metatarsal bones: 5 long bones (one for each toe). Phalanges: ALL toes have 3 phalanges (proximal, middle, and distal) EXCEPT the big toe (has 2 ONLY; proximal and distal). ARCHES OF THE FOOT Function of the arches of the foot: - It distributes the body weight. - Give foot elasticity during movement. - Absorption of shocks falling on the foot. - Adaptation to irregular surfaces. - Protection of the nerves and vessels of foot. 1. Muscles of the upper limb: They connect the arm to the trunk. They are supplied by brachial plexus which is formed by ventral primary rami of spinal nerves (C5 :T1). They are grouped according to region, as: o Muscles of pectoral region & shoulder. o Muscles of the arm. o Muscles of the forearm. o Muscles of the hand. At each region, muscles are classified as flexors & extensors. 25 Muscles of shoulder & pectoral region: The muscle Origin Insertion Nerve supply action Pectoralis Front of the Bicipital Pectoral shoulder major upper chest groove of nerves flexion & wall & Humerus adduction clavicle. 26  Deltoid Clavicle & Deltoid Axillary nerve shoulder scapula tuberosity of abduction Humerus Muscles of the arm region Muscles of the forearm: Flexors of the forearm Extensors of the forearm They are present at the ventral aspect They are present at the dorsal aspect of the forearm and act as flexors for of the forearm and act as extensors wrist joint & fingers. for wrist joint & fingers. They have a common origin from the They have a common origin from the front of the medial epicondyle of the front of the lateral epicondyle of the humerus humerus They are supplied mainly by the They are supplied by the radial nerve median nerve & partly by ulnar nerve. Muscles of the hand - They are concerned with grasping & writing functions in human. 27  - They are supplied by ulnar nerve except thenar muscles that are supplied by median nerve. 2. Muscles of the lower limb: They connect the lower extremities to the trunk. They are supplied by lumbo-sacral plexus which is formed by ventral primary rami of spinal nerves (L1  S4). They are grouped according to region, as: o Gluteal muscles. o Muscles of the thigh. o Muscles of the leg. o Muscles of the foot. At each region, muscles are classified as flexors & extensors. Muscles of gluteal region: The muscle Origin Insertion Nerve supply action Gluteus Back of Gluteal Inferior Hip extension maximus sacrum & hip. tuberosity of gluteal nerve femur 28  Gluteus Lateral side of Greater Superior Hip abduction medius & hip bone. trochanter of gluteal nerve minimus femur Muscles of the thigh region: Muscles of the leg: Flexors of the leg (planter- flexors) Extensors of the leg (dorsi- flexors) They are present at the back aspect of They are present at the front aspect of the leg and act as planter- flexors for the leg and act as dorsi- flexors for ankle joint & toes. The most ankle joint & toes. prominent muscles are the group of Calf that forms the tendon Achillis which is inserted into the back of Calcaneus. They are supplied mainly by the tibial They are supplied mainly by the deep nerve. peroneal nerve Muscles of the foot - They are concerned with keeping foot arches in human. - they are supplied by medial & lateral planter nerves which are the terminal branches of tibial nerve 29  Cardiovascular system Heart Heart is a conical, hollow, muscular blood pump. It lies in the middle mediastinum in chest cavity inside the pericardium. Pericardium is formed of an outer fibrous layer (Fibrous pericardium) & an inner serous sac (Serous pericardium). Fibrous pericardium is made of connective tissue that prevents the heart from expanding too much.it is fused with the upper surface of central tendon of diaphragm. Serous pericardium is formed of two layers; visceral layer is adherent to heart & parietal layer which lines the inner surface of fibrous pericardium. Pericardial cavity is present between visceral & parietal layers containing serous fluid for lubrication of cardiac contraction. 30 External features of Heart Sterno-costal surface: o The surface of the heart which facing the inner surface of the sternum & ribs. o It is formed of ventricles (mainly right ventricle), right atrium with its auricle & left auricle but not the left atrium. Diaphragmatic surface: o The surface of the heart which facing the upper surface of diaphragm. o It is formed of both ventricles (mainly left ventricle) Cardiac apex: which is formed of left ventricle only Cardiac base: o The surface of the heart which facing the middle four thoracic vertebrae. o It is formed of both atria (mainly the left atrium). 31 Internal features of Heart Heart is formed of 4 chambers: 2 Atria & 2 Ventricles. Right atrium: o It has anterior rough part of muscle ridges (called Musculi Pectinati) & posterior smooth part. o It receives openings of SVC (superior vena cava), IVC (inferior vena cava)& Coronary sinus. Left atrium: o It receives openings of the four pulmonary veins which carry oxygenated blood from lungs. Right ventricle: o It has a rough inflow part of muscle ridges (called trabeculae carneae) & papillary muscles that attached to the margins of atrio-ventricular (A/V) cusps. o It receives blood from right atrium through the right A/V opening which is guarded by a Tri-cusped valve. o It pumps the blood to the pulmonary artery, through pulmonary orifice which is guarded by 3 semi-lunar cusps. — Left ventricle: o It is thicker by about 3 times than the right one. o It receives blood from left atrium through the left A/V opening which is guarded by a Bi-cusped (Mitral) valve. o It pumps the blood to the Ascending Aorta, through Aortic orifice which is guarded by 3 semi-lunar cusps. — 32 Blood circulation — Pulmonary circulation: o It aimed for oxygenation of blood. o It starts by pumping of right ventricle  pulmonary trunk right & left pulmonary branches (one for each lung)  gas exchange (release of Co2 & acquiring O2)  return of oxygenated blood to left atrium via four pulmonary veins (two from each lung). — Systemic circulation: o It aimed for oxygen supply of different body tissues. o It starts by pumping of left ventricle  Aorta  supplying tissues by oxygen  return of deoxygenated blood (Co2- loaded) to right atrium via SVC & IVC. Blood supply of Heart o Blood vessels are present in atrio-ventricular (coronary) sulcus, between atria & ventricles. o Arteries: (from Ascending Aorta). 1. Right coronary artery  supplies mainly the right side of the heart. 33  2. Left coronary artery  mainly to the left side. o Veins: Coronary sinus is the main venous channel of the heart which ends into the right atrium. Blood vessels — Arteries: Thick walled tubes carry blood from heart to tissues. They are pulsating with cardiac systole. Contain no valves. They branch into smaller branches, arterioles to end by blood capillaries. Three types of arteries that have slightly different functions: o Elastic: Have more elastic tissue than muscular arteries and are located close to the heart. They make continuous blood flow. Examples: Aorta and pulmonary artery. o Muscular: Have more smooth muscle than elastic arteries. They control the amount of blood to the organ according to its activity. Examples: Femoral and Axillary arteries. o An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the primary site of vascular resistance. The greatest change in blood pressure and velocity of blood flow occurs at the transition of arterioles to capillaries. Arteries have three layers: 1. Tunica intima, or inner layer: lined with very smooth surface of endothelium to prevent blood clotting. 2. Tunica media, or middle layer: This is mostly smooth muscle that lets arteries get tighter or more open as needed. 3. Tunica externa, or outer layer: Interacts with other tissues, including nerves that send commands to pull in or expand. Veins: Thin walled tubes carry blood from tissues to heart. They are non-pulsating. Contain valves. They start from capillaries into venules to end by large veins. — Blood capillaries: Microscopic vessels (about 7 µm in diameter). They connect between arteries & veins for slow circulation to allow oxygen & nutrient supply to tissues. 34  — Avascular tissues: They are tissues with no blood capillaries & take their supply by diffusion from neighboring. They are: Cartilage, Cornea of eye & Epithelium. Lymphatic system Lymph: colorless collection of the extra fluid that drains from cells and tissues (that is not reabsorbed into the capillaries). It’s rich in WBCs. Sites which contain no lymph: CNS, bone marrow & Avascular tissues. Lymph vessels: o They carry lymph from tissues to lymph nodes. o They contain a huge amount of valves. o Lymph capillaries: blind end microscopic vessels, larger than blood capillaries with wide pores. o Afferent lymph vessels: formed by collection of lymph capillaries & they carry lymph to lymph nodes. o Efferent lymph vessels: carry lymph after its filtration in lymph nodes. o Lymph trunk: formed by union of efferent vessels & carry lymph from an entire organ. o Lymph ducts: the largest. Two lymph ducts are present: 35  1. Right lymphatic duct  carry lymph from right ½ of head & neck, right hemi-thorax & right upper limb  pours it into right innominate vein. 2. Thoracic duct  carry lymph from the greater remaining parts of the body  pours it into left innominate vein. — Lymphoid tissues: Lymphoid tissues are organized structures that support immune responses. The bone marrow and thymus are primary lymphoid tissues and the sites of lymphocyte development. The lymph nodes, spleen, tonsils and Peyer's patches are examples of secondary lymphoid tissue. — — — — — — — — — — — — Digestive system Introduction Digestive system is a group of organs working together to convert food into energy & basic nutrients to feed the entire body. Alimentary tract is the organs that food and liquids travel through when they are swallowed, digested, absorbed, and leave the body as feces. These organs include the mouth, pharynx (throat), esophagus, stomach, small intestine, large intestine, and anus. Digestive glands contributing digestive juices include the salivary glands, the gastric glands in the stomach lining, the pancreas, and the liver and its adjuncts—the gallbladder and bile ducts. The peritoneum: is a continuous membrane which lines the abdominal cavity and covers the abdominal organs (abdominal viscera). Formed of visceral layer 36  which is adherent to abdominal viscera, parietal layer which lines the abdominal wall with a peritoneal cavity in between containing thin film of serous fluid. Alimentary tract — Mouth cavity: Mouth vestibule: it is bounded between lips & cheeks on the outer side & alveolar process on the inner side. Mouth cavity proper: the deeper part next to alveolar process. The floor lodges the tongue & the roof is made by palate. The palate is formed of anterior 2/3 bony hard palate & posterior 1/3 which is muscular, called soft palate. The tongue is a muscular organ which is covered by mucus membrane with tongue papillae contain taste buds. Salivary glands: 3 major salivary glands. o Parotid gland  lies below ear & opens by its duct into the inner side of the cheek opposite upper 2nd molar tooth. o Submandibular & sublingual glands pour their secretion to the mouth floor. — Pharynx: A common muscular tube for food & air entry. It is formed of 3 divisions: o Naso-pharynx   It lies behind nasal cavity, opposite the basilar part of the occipital bone of skull & Atlas (C1).  It lodges on its lateral wall the opening of the Eustachian tube which connects the pharynx to the middle ear (Tympanic) cavity. o Oro-pharynx   It lies behind the oral cavity, opposite 2nd & 3rd cervical vertebrae.  It lodges on its lateral wall the palatine tonsils and the tonsillar fossa. o Laryngo-pharynx   It lies behind the laryngeal inlet, opposite 4th, 5th & 6th cervical vertebrae.  Bounded superior by the upper border of epiglottis & inferior down to the cricoid cartilage of larynx.  Piriform fossa is located on each side of the laryngeal inlet. A common place for food particles to become trapped (e.g. fish bone) During swallowing the soft palate is raised to close the posterior nasal aperture, epiglottis descends to close larynx & constrictors of the pharynx contract to move food down to esophagus. 37  Esophagus: 10 inches muscular tube connects pharynx down to stomach. It is formed of 3 parts: o Cervical part  in the neck, behind trachea. o Thoracic part  is the main part, it descends in the posterior mediastinum between both lungs. o Abdominal part  short, it pierces diaphragm at level of T10 vertebra to end into the cardiac end of the stomach — Stomach: o Stomach is a dilated part of alimentary tract which is present at the upper part of the left side of the abdominal cavity. o Shape: J-shaped. o Borders: two borders  Right border  is the lesser curvature.  Left border  is the greater curvature. o Surfaces: two surfaces  Anterior surface  related to the anterior abdominal wall & left lobe of liver. 38   Posterior surface  related to structures of stomach bed: left kidney, left suprarenal, pancreas, spleen, splenic artery & diaphragm. o Parts: three parts  Fundus of stomach  the upper convex part.  Body of stomach the main part of stomach.  Pyloric part  the lower part connected to duodenum. o Ends: two ends:  Cardiac end  joins the lower end of esophagus.  Pyloric end  joins the upper end of duodenum. — Small intestine: — It is the longest part of Alimentary tract (about 6 meters), adapted for food digestion & absorption. o Duodenum:  10 inches C-shaped tube around the head of pancreas.  It is formed of four parts.  The common bile duct & the main pancreatic duct open into the middle of the 2nd part of duodenum. o Jejunum:  It forms the proximal 2/5 of small intestine.  It has a thick muscular wall & very vascular.  The mucosa is highly folded (circular folds or plicae circularis) to increase surface are for absorption. o Ileum: 39   It forms the distal 3/5 of small intestine.  It has a thin muscular wall & less vascular.  Submucosa is rich in lymphoid aggregation, called Peyer’s patches — Large intestine: It is about 1.8 meters of length. It has 3 specific features: 1. Its wall has dilatations, called Sacculations. 2. The outer muscle layer forms 3 longitudinal bands, called Taeniae Coli. 3. Its outer surface has fat pouches of peritoneum, called Appendices epiploicae. It is formed of 10 parts: 1. Caecum  the 1st dilated part of large intestine, lies in the right iliac region & joins ileum at the Ilio-caecal junction. 2. Vermifrom appendix  the narrowest part of large intestine, connected to caecum below the ilio-caecal juction. Its common position is retrocaecal (behind caecum). 3. Ascending colon. 4. Right colic flexure  in front of right kidney. 5. Transverse colon  in front of pancreas. 6. Left colic flexure  in front of left kidney. 7. Descending colon. 8. Sigmoid colon  in the pelvic cavity. 9. Rectum. 10. Anal canal. Liver It is the largest abdominal organ, very vascular & friable. 40  Position: it occupies the whole right hypochondriac & extends to the epigastric region. Lobes: two main lobes, right lobe is large, left lobe is smaller, and two accessory lobes (caudate & quadrate). Surface: o Anterior surface  related to the anterior abdominal wall. o Superior surface  related to the diaphragm. o Posterior surface  related to vertebral column & IVC. o Right surface  related to right ribs (7th : 11th). o Inferior surface  lies on viscera, mainly stomach & right kidney. It contains:  Fossa for gall bladder.  Liver hilum (porta hepatis). Porta hepatis: deep, transverse fissure on the undersurface of the right lobe of the liver. It contains: portal vein, hepatic artery & hepatic duct. Portal circulation & biliary passages — Portal circulation: This circulation of nutrient-rich blood between the gut and liver is called the portal circulation. It enables the liver to remove any harmful substances that may have been digested before the blood enters the main blood circulation around the body. It starts by collection of venous blood from Alimentary tract  collected to portal vein  ends into liver for metabolism. 41  — Biliary passages: The biliary tract refers to the path by which bile is secreted by the liver then transported to the duodenum. It started by right & left hepatic ducts from corresponding liver lobes  united to common hepatic duct  with cystic duct of gall bladder forms common bile duct (CBD)  ends with the main pancreatic duct into 2nd part of duodenum. Pancreas — Pancreas is a mixed gland which lies horizontally at the level of 2nd lumbar vertebra. — Parts: The head  lies in the concavity of C-shaped duodenum. The neck  the next constricted part of pancreas. The body  is the main part which is related posteriorly to abdominal Aorta & IVC. The tail  extends to left side till the hilum of spleen. — Structure: (Mixed gland) Endocrine contains islets of Langerhans cells secreting insulin & glucagon into blood stream. Exocrine  secreting digestive enzymes via the main pancreatic duct into the 2nd part of duodenum. Blood supply of digestive system The digestive system is supplied by the celiac artery. The celiac artery is the first major branch from the abdominal aorta, and is the only major artery that nourishes the digestive organs. There are three main divisions – the left gastric artery, the common hepatic artery and the splenic artery. The celiac artery supplies the liver, stomach, spleen and the upper 1/3 of the duodenum (to the sphincter of Oddi) and the pancreas with oxygenated blood. Most of the blood is returned to the liver via the portal venous system for further processing and detoxification before returning to the systemic circulation via the hepatic veins. 42  The next branch from the abdominal aorta is the superior mesenteric artery, which supplies the regions of the digestive tract derived from the midgut, which includes the distal 2/3 of the duodenum, jejunum, ileum, cecum, appendix, ascending colon, and the proximal 2/3 of the transverse colon. The final branch which is important for the digestive system is the inferior mesenteric artery, which supplies the regions of the digestive tract derived from the hindgut, which includes the distal 1/3 of the transverse colon, descending colon, sigmoid colon, rectum, and the anus above the pectinate line. Blood flow to the digestive tract reaches its maximum 20–40 minutes after a meal and lasts for 1.5–2 hours — The nervous system Structure of nerve cell (Neuron)  Cell body.  Dendrites which receive the nerve impulse  Axon (only one) which transmits the nerve impulse away from the nerve cell.  The axon is surrounded by Schwann cells forming myelin sheath.  Definitions: ◦ Nucleus: the nerve cell collection inside CNS of specific function. ◦ Ganglion: the nerve cell collection in the PNS of specific function. ◦ Synapse: the point of functional contact but not cell continuity that activation of nerve cell propagated to the next one though a synaptic cleft and mediated by chemical neurotransmitter. 43 Central nervous system 1. Brain: (components): - Cerebrum. - Cerebellum. - Brainstem (Medulla oblongata, Pons and midbrain). 2. Spinal cord  Cerebrum:  Present inside the cranial cavity.  Formed of two cerebral hemispheres connected together by thick band of nerve fibers, called corpus callosum.  Each cerebral hemisphere controls an opposite side of the body.  Its total volume (1250: 1550 cc).  It is formed of 4 lobes: ◦ Frontal lobe: for motor activity, thinking & decision making. ◦ Parietal lobe: for somatosensory functions. ◦ Occipital lobe: for vision. ◦ Temporal lobe: for hearing, smell, memory and facial recognition.  Structure in cut sections: ◦ Outer grey matter (Cerebral cortex): composed of neuronal cell bodies and unmyelinated axons. Due to its large area, cerebral cortex makes involutions or folds (Called Gyri) separated by grooves (Called Sulci) that give it its wrinkled appearance. ◦ Inner white matter: It contains myelinated nerve fibers (axons), which are extensions of nerve cells. 44   Cerebellum: A structure that is located at the back of the brain, underlying the occipital and temporal lobes of the cerebrum. It is concerned with equilibrium & adjustment of motor activities.  Brainstem: ◦ It contains nuclei of lower 10 cranial nerves. ◦ It is composed of midbrain, pons & medulla oblongata.  Spinal cord: ◦ Cylindrical cord inside vertebral canal (about 45 cm). ◦ Structure:  Outer white matter: myelinated nerve fibers.  Inner grey matter: H –shaped, formed of: 1. Posterior horn  has a sensory function. 2. Anterior horn  has a motor function. 3. Lateral horn  has an autonomic function. Peripheral nervous system 1. Peripheral nerves: o Cranial nerves: 12 pairs. o Spinal nerves: 31 pairs 2. Autonomic nervous system: o Sympathetic component. o Parasympathetic component. 1. cranial nerves: i. Olfactory nerve. (Olfaction). ii. Optic nerve. (Vision). iii. Oculomotor nerve. 45  (Eye movement - parasympathetic) iv. Trochlear nerve. (Eye movement). v. Trigeminal nerve. (Sensations from face skin – motor to muscles of mastication) vi. Abducent nerve. (Eye movement). vii. Facial nerve. (Motor to facial muscles – parasympathetic). viii. Vestibulo-cochlear nerve (Hearing – equilibrium). ix. Glossopharyngeal nerve (Taste). x. Vagus nerve (Parasympathetic to heart, respiratory and GIT). xi. Accessory nerve (Motor to pharynx and larynx). xii. Hypoglossal (Motor to tongue). 2. Spinal nerves: They are 31 pairs of nerves. They are attached to the spinal cord by two roots (dorsal sensory and ventral motor). They are: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and one pair of coccygeal nerves. They are all mixed nerves (motor, sensory and autonomic fibers). Structure of spinal nerve: o Typical spinal nerves are attached to spinal cord by dorsal (sensory) root with dorsal root ganglion & ventral motor root. o Both roots unite to form the spinal nerve. o The spinal nerve leaves the vertebral canal through the corresponding inter-vertebral foramen. 46  Autonomic nervous system  This division of nervous system controls the organs of involuntary functions (Heart, smooth muscles and exocrine gland secretions).  The sympathetic centers are located in the spinal cord in LHCs (lateral horn cells) of all thoracic and first two lumbar segments.  The parasympathetic division is located in brain stem nuclei of cranial nerves (III, VII, IX & X) and also LHCs of sacral segments (S 2, 3, 4).  Functions of sympathetic division: 1. Its activity increases in stress conditions 2. It decreases GIT gland secretions and GIT motility… 3. It decreases the respiratory secretion, dilates bronchi and it increases the respiratory rate. 4. It increases the heart rate.  Functions of parasympathetic division: 1. Its activity increases in rest conditions 2. It increases GIT gland secretions and GIT motility. 3. It increases the respiratory secretion, constricts bronchi and it decreases the respiratory rate. 4. It decreases the heart rate. Brain coverings: 1. Dura mater: the tough outermost membrane. 2. Arachnoid mater: delicate spider web -like memrane. 3. Pia mater: the innermost vascular membrane in adirect contact with nerve tissue. CSF: is the cerebrospinal fluid which circulates inside brain ventricles and subarachnoid space to protect the nervous system as a water cushion. Blood supply to the brain:  Cerebral circulation is the movement of blood through a network of cerebral arteries and veins supplying the brain. The rate of cerebral blood flow in an adult human is typically 750 milliliters per minute, or about 15% of cardiac output.  Blood supply to the brain is normally divided into anterior and posterior segments, relating to the different arteries that supply the brain. The two main pairs of arteries are the Internal carotid arteries (supply the anterior brain) and vertebral arteries (supplying the brainstem and posterior brain). The anterior and posterior cerebral circulations are interconnected via bilateral posterior communicating arteries. They 47  are part of the Circle of Willis, which provides backup circulation to the brain. In case one of the supply arteries is occluded, the Circle of Willis provides interconnections between the anterior and the posterior cerebral circulation along the floor of the cerebral vault, providing blood to tissues that would otherwise become ischemic. The anterior cerebral circulation is the blood supply to the anterior portion of the brain including eyes. It is supplied by the following arteries: Internal carotid arteries: These large arteries are the medial branches of the common carotid arteries which enter the skull, as opposed to the external carotid branches which supply the facial tissues; the internal carotid artery branches into the anterior cerebral artery which supplies the medial surface of the cerebrum and continues to form the middle cerebral artery that supplies the lateral surface of the cerebrum. Posterior cerebral circulation is the blood supply to the posterior portion of the brain, including the occipital lobes, cerebellum and brainstem. It is supplied by the following arteries: Vertebral arteries: These smaller arteries branch from the subclavian arteries. Within the cranium the two vertebral arteries fuse into the basilar artery. Basilar artery: Supplies the midbrain, cerebellum, and usually branches into the posterior cerebral artery which supplies the occipital lobe of the cerebrum. Circle of Willis The circle of Willis is a part of the cerebral circulation and is composed of the following arteries: 1. Anterior cerebral artery (left and right). 48  2. Anterior communicating artery 3. Internal carotid artery (left and right). 4. Posterior cerebral artery (left and right). 5. Posterior communicating artery (left and right) The middle cerebral arteries are not considered part of the circle of Willis. Functional Areas of the brain (Brodmann areas) Definition: Mapping the cortex and its distinguished functions, pioneered by Korbinian Brodmann, from which the areas are named. Through using Brodmann's areas, the cortex of the brain can be divided into 52 areas which are numbered sequentially. Brodmann area Site function Primary motor area (area 4) Precentral gyrus concerned with execution of voluntary motor commands Premotor area (area 6) Anterior to Area 4 Planning of motor activity Motor speech area – Broca Lower part of the frontal Motor area of speech area (area 44, 45) lobe of the left cerebral hemisphere Sensory speech area – Junction between temporal Sensory area for Wernike area (40) and parietal lobes understanding language Primary somato-sensory Postcentral gyrus Receives sensation from skin, area (area 3, 1, 2) joints and muscles Primary visual area (area Occipital pole Receives image from eyes 17) 49 Primary auditory area (area Superior temporal gyrus Receives sounds from ears 41, 42) Respiratory system Structure of respiratory system:  Respiratory system is a biological system consisting of specific organs used for gas exchange.  Components: Nose. Nose Pharynx Pharynx. Larynx. Larynx Trachea. Bronchi and Bronchioles. Trachea Two lungs. Lung Muscles of respiration. Nose  It is formed of right & left cavities separated by nasal septum. Diaphragm  Parts: it is subdivided into 3 regions: 50  ◦ Nasal vestibule  the most anterior part, lined by skin & hairs ◦ Respiratory part  next to nasal vestibule, lined by pseudo-stratified ciliated epithelium with Goblet cells secreting mucus for humidification of inspired air. ◦ Olfactory part  forms the roof of nasal cavity & concerned with smell sensation.  The respiratory area of nasal cavity is connected with air cavities inside facial bones, called Para-nasal sinuses. They are 4 pairs: ◦ Frontal sinus. ◦ Ethmoid sinus. ◦ Sphenoid sinus. ◦ Maxillary sinus. Pharynx & larynx  Pharynx: 3 parts ◦ Naso-pharynx  behind nasal cavity. It receives the opening of Auditory (Eustachian) tube which connect it to middle ear. ◦ Oro-pharynx  behind the oral cavity. It lodges the palatine tonsils on its side wall. ◦ Laryngo-pharynx  it leads to laryngeal inlet.  Larynx: 51 ◦ Its wall is made up of cartilages to maintain its patency. ◦ Prominent cartilages are:  Thyroid cartilage  forms a prominence in the midline of neck (Adam’s Apple).  Cricoid cartilage  ring like, present below thyroid cartilage.  Epiglottis  leaf like elastic cartilage which prevents entry of food into respiratory passages.  Arytenoid cartilages  move the vocal cords for sound production. 52 Trachea & bronchial tree  Trachea: ◦ 10 cm tube, supported by C-shaped tracheal rings. ◦ Lined by ciliated epithelium to sweep up mucus. ◦ It ends by bifurcation into right & left main bronchi.  Bronchial tree: ◦ Main (primary) bronchi:  Right & left main bronchi, one for each lung. 53   The right bronchus is shorter, wider & more vertical, so inhaled foreign body tends to be trapped in the right main bronchus. ◦ Lobar (secondary) bronchi: two lobar bronchi on the left side & three on the right side. ◦ Segmental (tertiary) bronchi: – They are 10 in number & supply lung segments  subdivided in to about 20 subdivisions (bronchioles) terminal bronchioles  respiratory bronchioles  alveoli. Lungs  Features: ◦ They are right & left lungs, inside the chest cavity & form the main organ of respiration. ◦ The functional units are lung alveoli. ◦ Lung apex projects to the root of the neck. ◦ Lung base  rests on diaphragm. ◦ Anterior border of lung  behind the sternum. ◦ Posterior border of lung  related to the vertebral column. ◦ Lateral (costal) surface  related to the inner side of ribs. ◦ Medial surface  related to the mediastinum & contains lung root (hilum).  Lung hilum: contains main bronchus, pulmonary artery branch, 2 pulmonary veins, bronchial vessels, lymph nodes & autonomic nerve plexus.  Mediastinum: is the midline space of the chest between the two lungs, it contains heart, great vessels, trachea & esophagus.  Pleura: a closed serous sac surrounds lung, formed of: ◦ Visceral layer  adherent to lung. ◦ Parietal layer  lines chest wall. ◦ Pleural cavity  contains thin film of serous fluid with negative pressure. 54 Differences between right & left lungs  Right lung: ◦ It is larger & shorter due to elevated right copula of diaphragm by right lobe of liver. ◦ It has 3 lobes (upper, middle & lower), separated by 2 fissura (oblique & horizontal). ◦ It is formed of 10 broncho-pulmonary segments. ◦ The mediastinal surface of the right lung can be considered in terms of the lung root and surrounding surface characteristics. The root is considered to be approximately central upon the mediastinal surface, and the position of features is described with respect to this: 1. Superiorly:  Groove for azygous vein where it arches over the root of the right lung.  more superiorly, groove for esophagus vertically up to apex 2. Anteriorly: groove for superior vena cava progressing vertically; groove is joined by groove for azygous vein posteriorly. 3. Antero-inferiorly:  The cardiac impression: for right atrium.  A groove for the inferior vena cava running vertically down from the root. 4. inferiorly:  The pulmonary ligament  The lower part of a vertically-running groove for the esophagus. 5. posteriorly:  A groove for the esophagus running vertically downwards immediately posterior to the lung root. 55  Left lung: ◦ It is thinner due to shift of the ventricles of the heart to the left side, with a cardiac notch at its anterior border. ◦ It has 2 lobes (upper, & lower), separated by one oblique fissure. ◦ It is formed of 8 broncho-pulmonary segments. ◦ The mediastinal surface of the left lung can be considered in terms of the lung root and surrounding surface characteristics. The root is considered to be approximately central upon the mediastinal surface, and the position of features is described with respect to this: 1. Superiorly:  Deep groove for the arch of the Aorta  More superiorly is a vertical groove for the left subclavian artery 2. Antero-inferiorly:  Cardiac impression; deeper than on right side: for left ventricle. 3. inferiorly: pulmonary ligament 4. posteriorly: vertically descending groove for arch of Aorta — — 56  Urinary system Structure of urinary system  Group of organs serve to filter blood and create urine as a waste by-product.  The organs of the urinary system include the kidneys, renal pelvis, ureters, bladder and urethra. Kidneys  Size & position: ◦ A soft reddish organ (12×6×3 cm). ◦ It is present on each side of the vertebral column, fixed to the posterior abdominal wall, behind the peritoneum, (Retroperitoneal). ◦ At level between T12 to L3 vertebrae.  Structure: ◦ Renal cortex: containing about million nephrons (excretory units of the kidney). ◦ Renal medulla: containing the collecting tubules of urine. The take shape of pyramids and conduct urine to minor calyces  to major calyces  renal pelvis  finally, to ureter.  Relations: ◦ Anterior:  Right kidney  right lobe of liver, 2nd part of duodenum & right colic flexure.  Left kidney  spleen, stomach & left colic flexure. ◦ Posterior: for both kidneys  muscles of the posterior abdominal wall.  Blood supply: ◦ Renal artery: from the abdominal Aorta. 57  ◦ Renal vein: ends into IVC.  Renal hilum: is the site of entrance of renal vessels & ureter. It is present on the medial border of kidney.  Renal coverings: from in-outwards: ◦ Fibrous capsule of the kidney. ◦ Peri-renal fat. Supra-renal gland is embedded at its upper part. ◦ Renal fascia is the outermost layer derived from fascia of muscles of posterior abdominal wall.  Ureter: ◦ A 25 cm narrow muscular tube connects the renal pelvis down to urinary bladder. ◦ It descends on the posterior abdominal wall to end into urinary bladder by oblique segment to prevent urine regurgitation back to the kidney. ◦ It has 3 constrictions in its course: 1. At its beginning (junction with renal pelvis). 2. At its middle (entrance to pelvic cavity). 3. At its termination (oblique segment within the bladder wall).  Urinary bladder: ◦ A muscular sac in the pelvic cavity, just above & behind pubic bones. ◦ The bladder stores urine & controls its evacuation. ◦ It is related posteriorly to the rectum in male & anterior vaginal wall in female. 58  ◦ It connects to urethra by internal urethral meatus, surround by smooth muscle, called internal urethral sphincter. Urethra  It is a tube which connects the urinary bladder to the external urethral meatus, for the removal of urine outside the body.  Female urethra: is 4 cm in length, embedded in the anterior vaginal wall & opens into vaginal vestibule.  Male urethra: ◦ It is 20 cm in length. ◦ Male urethra transmits urine & semen. ◦ Formed of 3 parts: 1. Prostatic urethra (3cm)  traverses prostate & receives 2 openings of ejaculatory ducts. 2. Membranous urethra (2 cm)  traverses the perineal membrane. 3. Penile urethra (15 cm)  traverses the corpus spongiosum of penis  Urethral sphincters: ◦ Internal urethral sphincter  smooth muscle surrounds the internal urethral meatus. ◦ External urethral sphincter  skeletal muscle surrounds the membranous urethra. 59 (a) Female urethra, (b) male urethra — — — 60  Reproductive system  The biological system made up of all the anatomical organs involved in sexual reproduction. Female genital system  General structure: ◦ External genital organs:  Valva: formed of labia majora, labia minora & clitoris  Breast (mammary gland). ◦ Internal genital organs:  Ovaries. (the primary sex organs).  Fallopian tubes.  Uterus.  Vagina.  ovaries: ◦ The primary sex organ in female. ◦ Size: 1× 2 × 3 cm. ◦ Almond shaped. ◦ Functions: (Mixed gland). 1. Endocrine: production of estrogen & progesterone hormones. 2. Exocrine: production of ova.  Fallopian tubes: ◦ 10 cm in length. ◦ Site of fertilization (its ampulla). ◦ Transport zygote to the uterine cavity by the ciliary action of its epithelium. ◦ Parts: i. Infundibulum: with its fimbriae with seeping action to pick up the ovum. ii. Ampulla: is the most dilated part. It is the site of fertilization. iii. Isthmus: is a narrow part of the tube. iv. Intramural part: the narrowest part within the uterine wall. 61  Uterus: ◦ Pear shaped pelvic organ, 1× 2 × 3 inches. Present in the pelvic cavity between the urinary bladder anteriorly, & rectum posteriorly. ◦ Parts: 3 parts 1. Fundus: the upper convex part of the uterus. 2. Body: the main part, about 2 inches in length. 3. Cervix: 1 inch, formed of 2 parts:  Supra-vaginal part  opens into uterine cavity by internal os.  Vaginal part  opens into the upper part of vagina by external os. It is surrounded by vaginal fornices. ◦ Layers: 3 layers ◦ Epimetrium: the outer peritoneal covering. ◦ Myometrium: the middle main part, formed of smooth muscles. ◦ Endometrium: the inner most layer, formed of 3 layers: 1. compact layer  the most superficial. 2. Spongy layer  contains endometrial blood vessels & endometrial glands. 3. Basal layer  adherent to myometrium. It forms the previous 2 layers. 62  – Compact & spongy layers are called the functional layer & shed during menstruation. Implantation occurs into the functional layer.  Vagina: ◦ A fibro-muscular tube connect uterus to outside external genitalia. ◦ It is related anteriorly to urethra & urinary bladder base & posterior to rectum. ◦ Vaginal fornices: the site of semen accumulation after intercourse. Male genital system  General structure: ◦ External genital organs: 1. Penis: is the copulatory organ. 2. Scrotum: skin sac contains both testes. 3. Testis: is the primary sex organ. ◦ Internal genital organs: i. Duct system: 1. Epididymis. 2. Vas deferens. 3. Ejaculatory duct. 4. Urethra. ii. Glands: 1. Prostate. 2. Seminal vesicles 3. Bulbo-urethral (Cowper’s) glands.  Testis: ◦ The primary sex organ, It is mixed gland: – Endocrine  secreting testosterone hormone. – Exocrine  secreting sperms. 63 ◦ Structure: Generally, testis is located outside the body in the scrotum as spermatogenesis requires lower temperature (34ºc) 1. Seminiferous tubules: ◦ They are highly convoluted tubules, (0.15mm in diameter & more than 500 meters in length in one testis). ◦ They are sites of sperm formation (spermatogenesis). 2. Rete-testis: Communicating tubules near the mediastinum testis. They receive the terminal ends of seminiferous tubules & send vasa efferentia to epididymis. 3. Supporting cells: Sertoli cells: present inside seminiferous tubules for nutrition of sperms. Interstitial cells of Leydig: present in between seminiferous tubules for secretion of testosterone. 64  ◦ Coverings: 1. Tunica Vaginalis: is the outer serous sac (an extension of peritoneum). 2. Tunica Albugenia: whitish fibrous capsule. It sends septa to divide the testis into about 200 lobules, that contain seminiferous tubules.  Epididymis: ◦ A highly convoluted duct (~ 6 meters), formed of head, body & tail. ◦ Epididymis receives vasa efferentia. ◦ Functions: site for sperm maturation.  Vas deferens: ◦ It starts from the tail of epididymis & ends into ejaculatory duct. ◦ Length: 45 cm & thickness: 1.5 mm, its lumen: 0.7 mm. ◦ Function: sperm transport  Male sex glands: ◦ Prostate: 1. Position: it surrounds the urinary bladder neck & prostatic urethra. 2. Functions: it secrets alkaline fluid to neutralize the vaginal acidity. 3. It forms ~ 40% of semen volume. ◦ Seminal vesicles: 1. Position: they are two glands, each one is related to the base of urinary bladder & opens into ejaculatory duct by union with the terminal part Vas deferens. 2. Functions: secret nutritive fluid to sperms. 3. It forms ~ 60% of semen volume. ◦ Bulbo-urethral (Cowper’s) glands: 1. Position: they are two glands, on each side of the membranous urethra. 2. Functions: lubricate urethra to allow smooth flow of semen. 65  — — — — — — — — — — — — Structure of — seminiferous tubules — — 66  Structure of testis Gametogenesis  Process of formation of gametes; sperms, in male & ova, in females.  Spermatogenesis: the process of sperms formation in male.  Oogenesis: the process of ova formation in female.  Significance of gametogenesis: 1. Reduction of chromosomal material by half (Meiosis). 2. Variations in human. 3. Change the shape of gamete cell to be suitable to its function Spermatogenesis:  Definition: the process of sperm formation.  Site: seminiferous tubules of the testis.  Time: it starts from the puberty till old age.  Duration: 70 days.  Steps: 1. Spermatogonia (mother cells) undergo several mitotic divisions to keep its function to produce primary spermatocytes. 2. Others transform into primary spermatocytes (2n) meiosis I  two secondary spermatocytes (n)  meiosis II  four spermatids (n). 3. Spermatids transform into mature sperm, a process called: Spermiogenesis. Spermiogenesis:  Definition: morphological changes that occurs in spermatids to be mature sperms.  Duration: 4 days.  Steps: 1. Formation of acrosomal cap (Golgi apparatus). 67 2. Condensation of the nucleus (n). 3. Mitochondria become spiral & form the middle piece. 4. Flagellum forms the tail for sperm motility. 5. Shedding of the most of cytoplasm. 68   Features of the mature sperm: Head: contains the nucleus with haploid number of chromosomes, covered by the acrosomal cap contains proteolytic enzymes for fertilization. Neck: formed of centerioles. Middle piece: made by spiral mitochondria. Tail: motile flagellum Abnormal forms of sperms: Giant sperm  large sized. Dwarf sperm  small sized. Double head  two heads & one tail. Double tail  two tails & one head. Seminal fluid  Volume: 3 -5 ml.  Sperm count: 60 -120 million/ml.  Composition: 60% secretion of seminal vesicles. 4o% secretion of prostate 1 meter): can lead to formation of true knot or wind around fetal neck & result in fetal death. Abnormal short cord (< 40 cm): can lead to premature separation of the placenta & fetal death. Long cord - around fetal neck Long cord – true knot The Placenta — The functional unit of exchange between fetus and the mother. — structure: 100  — Fetal part: chorion frondosum. — Maternal part: decidua basalis. Decidua: — Definition: the endometrium after implantation (endometrium of pregnancy). — Parts: Decidua basalis: present deep to the implanted chorionic vesicle. Decidua capsularis: covers the implanted chorionic vesicle. Decidua parietalis: the remaining part of endometrium. — Fate: Decidua basalis remains as the maternal part of the placenta Decidua parietalis and capsularis become fused together with obliteration of the uterine cavity. Chorionic villi: — Definition: finger like projections from the trophoblast. — Classification: Depending on the structure: 1. Primary chorionic villi: formed by the beginning of the 3 rd week. It is formed of core of cytotrphobalst covered by syncytiotrophoblast. 2. Secondary chorionic villi: formed by the middle of the 3 rd week. It is formed of core extraembryonic mesoderm covered by cytotrphobalst & syncytiotrophoblast. 3. Tertiary chorionic villi: formed by the end of the 3 rd week. It contains fetal capillaries inside the core extraembryonic mesoderm covered by cytotrphobalst & syncytiotrophoblast. According to distribution: (by the 2nd month of gestation) 1. Chorion leave: the chorionic villi facing the decidua capsularis become degenerated. 2. Chorion frondosum: : the chorionic villi facing the decidua basalis become branched and more complex According to function: (by the 3 rd month of gestation), only at the site of the chorion frondosum: 1. Anchoring (stem) villi: large villi that extend to decidua basalis & become adherent to it by (cytotrophoblastic shell) for fixation of the placenta. 101  2. Absorbing (free): small villi arise from the stem villus into the inter-villus space for exchange process with maternal blood. Full term placenta: Discoid shaped. 15- 20 cm in diameter. About 500 gm in weight. Thickness: 2.5 cm at the center and thinned at its periphery. Maternal surface: covered by decidua basalis & divided by decidual septa into 15- 20 lobes (cotyledons). Fetal surface is smooth and covered by amnion. Umbilical cord is attached near to the center (eccentric). 102 Functions of the placenta: Gas exchange (respiratory): it supplies the fetus with oxygen. Nutrition: glucose, amino acids, fatty acids, vitamins, … Excretion: urea and creatinin. Hormonal: it produces estrogen, progesterone, hCG, somato-mammotropin ….. Protection: (placental barrier) o Placental barrier: all layers are separating between maternal and fetal blood. o It includes:  Syncytiotrophoblast.  Cytotrophoblast  Extra-embryonic mesoderm.  Endothelium of fetal capillaries. o After 4th month: it is only of two layers (syncytiotrophoblast and Endothelium of fetal capillaries). Anomalies of the placenta: Shape: 103  o Bi-lobed (bipartite): placenta is formed of two lobes. o Tri-lobed (tripartite): placenta is formed of three lobes. o Accessory lobe (placenta succenturiata): associated with small accessory lobe. Number: more than one in multiple pregnancy (twins). Position: in the lower uterine segment. o Placenta previa centralis: overlies the internal os. o Placenta previa marginalis: related to the margin of the internal os. o Placenta previa parietalis: beside the internal os. Attachment to the umbilical cord: o Marginal attachment (battledore placenta). o Velamentous attachment: the umbilical cord attached to the chorion some distance from the placenta. Invasion into the endomentrium: placenta increta. Velamentous cord Bipartite 104  Placenta succenturiata Twins Definition of twins: — Delivery of more than one baby at the same labor setting. — Incidence: Delivery of two babies is about 1/80 of deliveries. Delivery of three babies is about 1/800 of deliveries. Delivery of four babies is about 1/8000 of deliveries. Types of twins: 1. dizygotic twins (fraternal): It is formed when two different ova are fertilized by two different sperms. It accounts about 2/3 of cases. Sex: they are of the same or different sexes. Genetic features: they are different. Fetal membranes: each fetus has its own chorion, placenta and amniotic sac (they have separate membranes). 2. Monozygotic twins (identical): It is formed when a single ovum is fertilized by one sperm. It accounts about 1/3 of cases. Sex: they are of the same sex. Genetic features: they are the same (they are different in finger and iris prints). Fetal membranes: according to the stage of division of the Zygote. 105  1. Division at two cell stage: Each fetus has its own chorion, placenta and amniotic sac (like dizygotic twins). 2. Division at blastocyst stage: It occurs after formation of chorion (outer cell mass). They have separate amniotic sac but common chorion and placenta. — 3. Division at chorionic vesicle stage: It occurs after formation of embryonic disc. They are characterized by common chorion, placenta and amniotic sac. If division of the two embryonic discs is incomplete, conjoined (siamese) twins could be the result. According to the point of fusion, conjoined twins are classified into: cranio-pagus, thoraco-pagus, pygo-pagus. 106  Cranio-pagus twins: fusion at the site of the head. Thoraco-pagus twins: fusion at the site of thorax. Pygo-pagus twins: fusion at the site of pelvis. 107  Parasitic twins: Remnant fetal parts fused to the other normal partner. These parts may be inside or outside the body of the normal one. Birth defects & prenatal diagnosis Birth defects (congenital anomalies): It’s a description of structural, functional & metabolic disorders since birth. Teratology: is the science that studies these disorders. Major structural anomalies: o 4-6% of live born infants. o Considered as a major contributor to disability. o Chromosomal anomalies account for 15% of these anomalies. Minor structural anomalies: 108  o 15% of live born infants. o Examples: microtia (small ears) & short palpebral fissure. o Presence of one minor anomaly increases the chance to 3% to have a major one. Two minor anomalies increase the chance up to 10% to have a major one. Three minor anomalies increase the chance up to 20% to have a major one. Types of anomalies: 1. Malformations: — The disorder occurs during the organ formation (embryonic period: 3 rd to 8th weeks). — The organ is not formed, partially formed or abnormally formed (examples: renal aplasia & polyductyly). 2. Disruptions: — Morphological alterations of already formed structures. — Example: amniotic band syndrome. 3. Deformations: — Abnormality due to a mechanical force. — Example: club foot due to compression in the amniotic cavity. 4. Syndromes: — Group of anomalies occurring together by a specific cause. — Example: VACTERL = vertebral, anal, cardiac, tracheo-esophageal, renal, limb defects). 109  Club foot polyductyly Teratogens: — Definition: an agent that can produce a congenital anomaly or birth defect. — Causes of birth defects: 50 – 60 % of unknown cause. Genetic (15 %): due to chromosomal abnormalities. Environmental (10 %): due to teratogens. Combined genetic & environmental (25 % of cases). Types of teratogens (environmental causes): 1. Infectious agents: Exposure to infections like: rubella virus & cytomegalovirus produces cardiac & neural tube defects. 2. Physical agents: like X- ray can kill rapidly dividing cells. 3. Drugs: a. Thalidomide (sedative) produces limb defects. b. Valproic acid (anti-epileptic) produces neural tube defects. 4. Hormones: synthetic progesterone (norethistrone) can produce masculinization of female fetus genital organs. 5. Maternal diseases: maternal diabetes increases the risk for cardiac & nervous defects. Prevention of birth defects: 1. Supplementation of salt supplies with iodine eliminates mental retardation & bone deformities resulting from cretinism. 2. Metabolic control of maternal diabetes by using insulin. 3. Folic acid supplementation lowering the incidence of neural tube defects by 70%. 4. Avoidance of teratogenic drugs during child bearing period. 110 Methods for prenatal diagnosis of birth defects: 1. Ultrasonography: A technique that uses high-frequency sound waves reflected from tissues to create images. Used for detection of placental position, amniotic fluid & fetal growth. 2. Maternal serum screening: For searching of biochemical markers of fetal growth. Alpha fetoprotein (AFP) is produced by fetal liver & leaks to maternal blood. High levels of AFP are produced in neural tube defects & low levels are produced in Down syndrome. 3. Amniocentesis: o A needle is inserted trans-abdominally into the amniotic cavity, guided by ultrasound. o Approximately, 30 ml of fluid are withdrawn for analysis. o Uses:  Analysis for biochemical markers (AFP).  Karyotype for sloughed fetal cells. 4. Chorionic villi sampling: A needle is inserted trans-abdominally into the placenta, guided by ultrasound. Approximately, 30 mg of chorionic villi are aspirated for analysis. Uses: karyotype for fetal cells. It is better than amniocentesis but two fold higher risk of fetal loss. 111  Amniocentesis Chorionic villi sampling End of book 112