Nervous System Anatomy - Al-Mustafa College PDF

General anatomy Dr.Samir Ali 1st academic year Al-Mustafa college Lecture 1 Nervous system The Brain The central nervous system (CNS) is composed of the brain and spinal cord. The peripheral nervous system...

General anatomy Dr.Samir Ali 1st academic year Al-Mustafa college Lecture 1 Nervous system The Brain The central nervous system (CNS) is composed of the brain and spinal cord. The peripheral nervous system (PNS) is composed of spinal nerves that branch from the spinal cord and cranial nerves that branch from the brain. The brain controls heart rate, respiratory rate, and blood pressure—and maintains the internal environment through control of the autonomic nervous system and the endocrine system. The average adult human brain weighs about 1500 g. Figure.1 1 Basic Parts of the Brain (figure 2 and 3 ) The brain is composed of the cerebrum, cerebellum, and brainstem Figure 2 : parts of the brain 2 Figure 3 (a and b) 3 Cerebrum: is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like vision and hearing, as well as speech, emotions, learning, and fine control of movement. Cerebellum (figure 4) : is located under the cerebrum. Its function is to coordinate muscle movements, and balance. Figure. 4 4 Brainstem (figure 5): acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, digestion, and swallowing. There are three regions of the brain stem are the medulla oblongata, pons, and midbrain. Figure. 5 5 The Diencephalon (figure 6) The diencephalon forms a central core of brain tissue just superior to the midbrain. It is almost completely surrounded by the cerebral hemispheres and contains numerous nuclei involved in a wide variety of sensory and motor processing between higher and lower brain centers. The diencephalon extends from the brain stem to the cerebrum and surrounds the third ventricle; it includes the thalamus, hypothalamus, and epithalamus. Projecting from the hypothalamus is the pituitary gland. Figure.6 6 Right brain – left brain The cerebrum is divided into two halves: the right and left hemispheres (Fig. 7). They are joined by a bundle of fibers called the corpus callosum that transmits messages from one side to the other. Each hemisphere controls the opposite side of the body. If a stroke occurs on the right side of the brain, your left arm or leg may be weak or paralyzed. Figure ( 7 ): The cerebrum is divided into left and right hemispheres Lobes of the brain The cerebral hemispheres have distinct fissures, which divide the brain into lobes. Each hemisphere has 4 lobes: frontal, temporal, parietal, and occipital (Fig. 8). Each lobe may be divided, once again, into areas that serve very specific functions. It’s important to understand that each lobe of the brain does not function alone. There are very complex relationships between the lobes of the brain and between the right and left hemispheres. 7 Figure ( 8 ): The cerebrum is divided into four lobes: frontal, parietal, occipital and temporal. Cortex The surface of the cerebrum is called the cortex. It has a folded appearance with hills and valleys. The cortex contains 16 billion neurons (the cerebellum has 70 billion = 86 billion total) that are arranged in specific layers. The nerve cell bodies color the cortex grey- brown giving it its name – gray matter (Fig. 9). Beneath the cortex are long nerve fibers (axons) that connect brain areas to each other — called white matter. Figure (9). The cortex contains neurons (grey matter), which are interconnected to other brain areas by axons (white matter). 8 Central sulcus (figure 10 ) : It separates the frontal lobe from the parietal lobe, and more specifically separates the primary motor cortex anteriorly from the primary somatosensory cortex posteriorly. Figure.10 9 Ventricles and cerebrospinal fluid The brain has hollow fluid-filled cavities called ventricles (Fig. 11). Inside the ventricles is a ribbon-like structure called the choroid plexus that makes clear colorless cerebrospinal fluid (CSF).There are two ventricles deep within the cerebral hemispheres called the lateral ventricles. They both connect with the third ventricle through opening called the interventricular foramen. The third ventricle connects with the fourth ventricle through a long narrow tube called cerebral aqueduct. From the fourth ventricle, CSF flows into the subarachnoid space where it cushions the brain. Figure ( 11 ): Ventricles of the brain. 10 Meninges ( figure 12 ): Meninges are three layers of membranes that cover and protect the brain and spinal cord. From the outermost layer inward they are: the dura mater, arachnoid mater, and pia mater. Dura mater: This is the outer layer, closest to the skull Arachnoid mater: This is the middle layer. The space between the dura and arachnoid membranes is called the subdural space Pia mater: This is the inner layer, closest to the brain tissue. The space between the arachnoid and pia is called the subarachnoid space. Figure ( 12): Meninges of the brain 11 12 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 2 Nervous system Spinal cord , spinal and cranial nerves Spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. 1  Figure 1. spinal cord The grey column , (as three regions of grey columns) in the center of the cord, is shaped like a butterfly. The white matter is located outside of the grey matter. Figure 2. cross section in the spinal cord 2 The spinal cord proper terminates in a region called the conus medullaris, while the pia mater continues as an extension called the filum terminale, which anchors the spinal cord to the coccyx. The cauda equina ("horse's tail") is a collection of nerves inferior to the conus medullaris that continue to travel through the vertebral column to the coccyx. The cauda equina forms because the spinal cord stops growing in length at about age four, even though the vertebral column continues to lengthen until adulthood. This results in sacral spinal nerves originating in the upper lumbar region. For that reason, the spinal cord occupies only two-thirds of the vertebral canal. Figure 3. spinal cord conus medullaris 3  Figure 4. MRI lumber spine sagittal view Figure 5. (A) conus medullaris sagittal view, (B) axial view 4 Spinal nerves : There are 31 spinal cord nerve segments in a human spinal cord: 8 cervical segments forming 8 pairs of cervical nerves , The cervical nerves are the spinal nerves from the cervical vertebrae in the cervical segment of the spinal cord. Although there are seven cervical vertebrae (C1–C7), there are eight cervical nerves C1–C8. C1–C7 emerge above their corresponding vertebrae, while C8 emerges below the C7 vertebra. Everywhere else in the spine, the nerve emerges below the vertebra with the same name. 12 thoracic segments forming 12 pairs of thoracic nerves 5 lumbar segments forming 5 pairs of lumbar nerves 5 sacral segments forming 5 pairs of sacral nerves 1 coccygeal segment forming 1 pair of coccygeal nerves Figure 6. axial view spinal cord and nerve 5 Figure 7. vertebral spine levels 6 Figure 8. nerves dermatological map 7 Brachial plexus (figure 9 ): The brachial plexus is a network (plexus) of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve (C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervico-axillary canal in the neck , over the first rib, and into the arm , it supplies nerve fibers to the chest, shoulder, arm, forearm, and hand. Figure 9. Brachial plexus 8 Lumber plexus ( figure 10) : The lumbar plexus is a web of nerves (a nervous plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Figure 10. lumber nerves and plexus 9 Sacral plexus ( figure 11) : In human anatomy, the sacral plexus is a nerve plexus which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis. It is part of the lumbosacral plexus and emerges from the lumbar vertebrae and sacral vertebrae (L4-S4). Figure 11. sacral plexus 10  Cranial nerves Cranial nerve Origin Component Function Notes I Olfactory Telencephalon Sensory Smell II Optic Retinal ganglion Sensory Vision cells III Oculomotor Midbrain Motor Moves eye Nerve with muscles the most actions on eye muscles IV Trochlear Midbrain Motor Moves eye muscles V Trigeminal pons Motor and Sensation in 3 branches: sensory face and ophthalmic , chewing maxillary and mandibular VI Abducent pons Motor Moves eye muscle VII Facial Pons Motor and Sensation Taste form the (cerebellopontine sensory near ear and anterior 2/3 angle) facial of the tongue expression VIII vestibulocochlear Pons Sensory Hearing and (cerebellopontine equilibrium angle) IX glossopharyngeal Medulla Sensory and Swallowing Taste form the motor posterior 1/3 of the tongue X Vagus Medulla Sensory and Mostly motor autonomic XI Accessory Cranial and spinal Motor Movement roots of head and pectoral girdle. XII Hypoglossal Medulla Motor Speech, manipulation of food, and swallowing 11 Olfactory (I) Nerve Optic (II) Nerve 12 Oculomotor (III) , Trochlear (IV) and Abducent (VI) nerves Trigeminal (V) nerve 13  Facial (VII) nerve Vestibulocochlear (VIII) nerve 14 Glossopharyngeal (IX) nerve Vagus (X) nerve 15  Accessory (IX) nerve Hypoglossal (XII) nerve 16 17 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 3 Respiratory system The respiratory system is divided into two main components: Upper respiratory tract: Composed of the nose, paranasal sinuses , the pharynx, and the larynx, the organs of the upper respiratory tract are located outside the chest cavity. -Nasal cavity: Inside the nose, the sticky mucous membrane lining the nasal cavity dust particles, and tiny hairs called cilia help move them to the nose to be sneezed. - Sinuses: These air-filled spaces alongside the nose help make the skull lighter. -Pharynx: Both food and air pass through the pharynx before reaching their appropriate destinations. -Larynx: The larynx is essential to human speech. Lower respiratory tract: Composed of the trachea, the lungs, and all segments of the bronchial tree (including the alveoli), the organs of the lower respiratory tract are located inside the chest cavity. - Trachea: Located just below the larynx, the trachea is the main airway to the lungs. -Lungs: Together the lungs form one of the body’s largest organs. They’re responsible for providing oxygen to capillaries and exhaling carbon dioxide. -Bronchi: The bronchi branch from the trachea into each lung and create the network of intricate passages that supply the lungs with air. 1 - Diaphragm: The diaphragm is the main respiratory muscle that contracts and relaxes to allow air into the lungs. The Larynx The larynx or voice box, extends from the level of the fourth to the sixth cervical vertebra. Superiorly, it attaches to the hyoid bone and opens into the laryngopharynx , inferiorly it is continuous with the trachea. 2 The larynx has three functions: Producing vocalizations. Providing an open airway. Acting as a switching mechanism to route air into the proper channels. During swallowing, the inlet (superior opening) to the larynx is closed. The framework of the larynx is an intricate arrangement of nine cartilages connected by membranes and ligaments (Figure 22.5). 1- The large thyroid cartilage is formed by two cartilage plates joined in the midline, lying in the anterior midline of the neck. This is the ridge like laryngeal prominence, which is obvious externally as the Adam’s apple. 2- Inferior to the thyroid cartilage is the cricoid cartilage. Three pairs of small cartilages lie just superior to the cricoid cartilage in the posterior part of the larynx (Figure 22.5c and d): the arytenoid cartilages , the corniculate cartilages , and the cuneiform cartilages.The ninth cartilage of the larynx, the leaf-shaped epiglottis, is composed of elastic cartilage and is almost entirely covered by a mucosa. Its attaches anteriorly to the internal aspect of the angle of the thyroid cartilage (Figure 22.5d). Within the larynx, paired vocal ligaments. These ligaments, composed largely of elastic fibers, form a pair of mucosal folds called the vocal folds or (true) vocal cords (Figure 22.5d and Figure 22.6). Another pair of horizontal mucosal folds that lies directly superior to the vocal folds, the vestibular folds, or false vocal cords, plays no part in sound production. However, they define a slit like cavity between themselves and the true vocal cords (see Figure 22.5d). 3 4 The Trachea The flexible trachea, descends from the larynx through the neck and into the mediastinum; it ends by dividing into the two main bronchi (primary bronchi) in the mid thorax (see Figure 22.1). the trachea is flexible enough to permit bending and elongation, but the cartilage rings prevent it from collapsing and keep the airway open despite the pressure changes that occur during breathing. Carina: - It is the ridge at the region of bifurcation of the trachea into right and left main bronchi The Bronchial Tree The right and left main bronchi , also called primary bronchi, are the largest in the bronchial tree, a system of respiratory passages that branches extensively 5 within the lungs (Figure 22.8). The two main bronchi are branches of the trachea in the mediastinum. This bifurcation occurs at the level of the sternal angle (T4). Each main bronchus runs obliquely through the mediastinum before plunging into the medial depression (hilum) of a lung. The main bronchi lie directly posterior to the large pulmonary vessels that supply the lungs. The right main bronchus is wider, shorter, and more vertical than the left (see Figure 22.12). The Respiratory Zone The respiratory zone is the end part of the respiratory tree in the lungs. The respiratory zone consists of structures that contain air-exchange chambers called alveoli (Figure22.9). The first respiratory zone structures, which branch from the terminal bronchioles of the conducting zone, are respiratory bronchioles. The respiratory bronchioles lead into alveolar ducts, straight ducts whose walls consist almost entirely of alveoli. The alveolar ducts then lead into terminal clusters of alveoli called alveolar sacs. Note that alveoli and alveolar sacs are not the same things: An alveolar sac is analogous to a bunch of grapes; the individual grapes are the alveoli. 6 The Lungs The paired lungs and their pleural sacs occupy all the thoracic cavity lateral to the mediastinum (Figure 22.11). Each lung is roughly cone-shaped. The anterior, lateral, and posterior surfaces of a lung contact the ribs and form a continuously curving costal surface. Just deep to the clavicle is the apex, the rounded, superior tip of the lung. The concave inferior surface that rests on the diaphragm is the base. On the medial surface of each lung is an indentation, the hilum, through which blood vessels, bronchi, lymphatic vessels, and nerves enter and exit the lung. Collectively, these structures attach the lung to the mediastinum and are called the root of the lung. The largest components of this 7 root are the pulmonary artery and veins and the main (primary) bronchus (Figure 22.11b). Because the heart is tilted slightly to the left of the median plane of the thorax, the left and right lungs differ slightly in shape and size. The left lung is somewhat smaller than the right and has a cardiac notch, a deviation in its anterior border that accommodates the heart (Figure 22.11a). Several deep fissures divide the two lungs into different patterns of lobes. The left lung is divided into two lobes, the superior lobe and the inferior lobe, by the oblique fissure. The right lung is partitioned into three lobes, the superior, middle, and inferior lobes, by the oblique and horizontal fissures. 8 The Pleurae Around each lung is a flattened sac whose walls consist of a serous membrane called pleura. The outer layer of this sac is the parietal pleura, whereas the inner layer, directly on the lung, is the visceral pleura (Figure 22.11a;). The parietal pleura covers the internal surface of the thoracic wall, the superior surface of the diaphragm, and the lateral surfaces of the mediastinum. From the mediastinum, it reflects laterally to enclose the great vessels running to the lung (root of lung, Figure 22.11d). In the area where these vessels enter the lung, the parietal pleura is continuous with the visceral pleura, which covers the external lung surface. 9 *Visceral pleura – covers the lungs. *Parietal pleura – covers the internal surface of the thoracic cavity. 10 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 4 Cardiovascular system The heart : The heart is relatively small, roughly the same size as your closed fist. The heart rests on the diaphragm, near the midline of the thoracic cavity. The heart lies in the mediastinum, an anatomical region that extends from the sternum to the vertebral column, from the first rib to the diaphragm, and between the lungs. Figure 1 1  Figure 2 Pericardium The membrane that surrounds and protects the heart is the pericardium. It consists of two main parts: (1) the fibrous pericardium (2) serous pericardium: The outer parietal layer of the serous pericardium The inner visceral layer of the serous pericardium They are separated by the fluid-filled pericardial cavity called pericardial cavity. Its function is to : Protects and anchors the heart Prevents over filling of the heart with blood Allows for the heart to work in a friction-free environment 2  Figure 3 Layers of the Heart Wall The heart wall is composed of endothelium, connective tissue, and cardiac muscle. The muscle that enables the heart to contract and allows for the synchronization of the heartbeat. The heart wall is divided into three layers: Epicardium— outer protective layer of the heart. Myocardium—muscular middle layer wall of the heart. Endocardium—inner layer of the heart 3  Figure 4 Heart chambers Heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle’s chamber walls have enough force to push blood through the aortic valve and into your body. 4 The Heart Valves Four valves regulate blood flow through your heart: The tricuspid valve regulates blood flow between the right atrium and right ventricle. The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen. The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle. The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body’s largest artery. Figure 5 5 Great vessels of the heart : Great vessel Where it connects to your heart Aorta. Left ventricle (via aortic valve). Main pulmonary artery. Right ventricle (via pulmonary valve). Pulmonary veins. Left atrium. Superior vena cava. Right atrium. Inferior vena cava. Right atrium. 6 Coronary arteries: The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of the body. Figure 6 Both coronary arteries originates from the aortic valve Left coronary artery : main branches are 1.Left anterior descending artery 2.Left circumflex artery 3.Posterior descending artery Right coronary artery : main branches are 1.Right marginal artery 2. Posterior descending artery 7  Figure 7 Artery Vein Tunica Interna Elastic Contain valves Tunica Media Thick Thin Tunica Externa Thin Thick The Pulmonary Circulation The pulmonary circulation carries deoxygenated blood from the right ventricle to the air sacs (alveoli) within the lungs and returns oxygenated blood from the air sacs to the left atrium (Figure 8. a and b). The pulmonary trunk emerges from the right ventricle then divides into two branches: the right pulmonary artery to the right lung and the left pulmonary artery to the left lung. On entering the lungs, the branches divide and subdivide until finally they form capillaries around the air sacs (alveoli) within the lungs. 8 CO2 passes from the blood into the air sacs and is exhaled. Inhaled O2 passes from the air within the lungs into the blood. The pulmonary capillaries unite to form venules and eventually pulmonary veins, which exit the lungs and carry the oxygenated blood to the left atrium. Two left and two right pulmonary veins enter the left atrium. Contractions of the left ventricle then eject the oxygenated blood into the systemic circulation. Figure 8. a and b 9 Figure 9 10 Figure 10 11 Ascending aorta branches : Right and left coronary arteries (aortic valve) Aortic arch braches : 1.brachiocephalic trunk 2. left common carotid 3.left subclavian Figure 11 Abdominal aorta branches : 1.inferior phrenic 2.celiac 3.superior mesenteric 4.renal 5.inferior mesenteric 6.common iliac divides into external iliac and internal iliac 12  Figure 12 Upper limb arteries : The arterial supply of the upper limb is derived from the subclavian artery. The right subclavian artery originates from the brachiocephalic artery, which is the first branch of the aortic arch. The left subclavian artery originates directly from the aortic arch, being the third branch. The subclavian artery ascends laterally to exit through the thoracic inlet. it becomes the axillary artery at the lateral border of the first rib. The axillary artery turns into the brachial artery just below the axilla 13 The brachial artery is the continuation of the main arterial supply in the upper arm as it travels medially towards the elbow. bifurcating into the radial artery and ulnar artery. Upper limb arteries : 1.subclavian 2.axillary 3.brachial 4.radial 5.ulnar Figure 13 14 Lower limb arteries: The common femoral artery is the direct continuation of the external iliac artery, beginning at the level of the inguinal ligament. The common femoral artery becomes the superficial femoral artery at the point where it gives off the profunda femoris. The popliteal artery is the direct continuation of the SFA in the adductor canal. The popliteal artery terminates into the anterior tibial artery and the tibioperoneal trunk. The anterior tibial artery passes through the interosseous membrane to reach the anterior compartment of the leg. It continues to the dorsum of the foot as the dorsalis pedis artery. The tibioperoneal trunk divides into the posterior tibial and peroneal arteries. Lower limbs arteries : 1.common femoral artery 2.superficial femoral 3.profunda femoris. 4.popliteal 5. anterior tibial 6.posterior tibial 7.peroneal 8.dorsalis pedis 15  Figure 14 Venous system Veins of the Head and Neck: Most blood draining from the head passes into three pairs of veins: the internal jugular , external jugular, and vertebral veins (Figure 15). 16  Figure 15 Upper limb venous system : Both superficial and deep veins return blood from the upper limbs to the heart (Figure 21.25). Superficial veins are located just deep to the skin and are often visible. They anastomose extensively with one another and with deep veins, and they do not accompany arteries. Superficial veins are larger than deep veins and return most of the blood from the upper limbs. Deep veins are located deep in the body. They usually accompany arteries and have the same names as the corresponding arteries. Both superficial and deep veins have valves, but valves are more numerous in the deep veins. 17 Superficial system : Two major veins are cephalic , basilic and Median cubital vein Cephalic : ascends along the radial (lateral) side of the arm before emptying into the axillary vein. At the elbow, it communicates with the basilic vein via the median cubital vein Basilic : It originates on the medial (ulnar) side of the hand , it terminates by uniting with the brachial veins. Median cubital vein : It lies in the cubital fossa. It connects the cephalic vein and the basilic vein. It becomes prominent when pressure is applied. It is routinely used for venipuncture (taking blood) and as a site for an intravenous cannula. Deep system : Subclavian , axillary , brachial , radial and ulnar veins , similar to the arterial system. 18 Figure 16 19 Veins of the Abdomen and Pelvis: Blood from the abdominal and pelvic viscera and lower half of the abdominal wall returns to the heart via the inferior vena cava. Many small veins enter the inferior vena cava. Most carry return flow from parietal branches of the abdominal aorta, and their names correspond to the names of the arteries (see also Figure 17). 1.inferior vena cava 2.inferior phrenic nerve 3.hepatic 4.suprarenal 5.renal 6.common iliac 7.internal iliac 8.external iliac. 20 Figure 17 21 The Hepatic Portal Circulation The hepatic portal circulation carries venous blood from the gastrointestinal organs and spleen to the liver. The hepatic portal vein receives blood from capillaries of gastrointestinal organs and the spleen and delivers it to the sinusoids of the liver (Figure 18 and b ). The superior mesenteric and splenic veins unite to form the portal vein. At the same time the liver is receiving nutrient-rich but deoxygenated blood via the hepatic portal vein, it is also receiving oxygenated blood via the hepatic artery, a branch of the celiac trunk. The oxygenated blood mixes with the deoxygenated blood in sinusoids. Eventually, blood leaves the sinusoids of the liver through the hepatic veins, which drain into the inferior vena cava. 22 23  Figure 18 a and b Veins of the Lower Limbs: As with the upper limbs, blood from the lower limbs is drained by both superficial and deep veins. The superficial veins often anastomose with one another and with deep veins along their length. Deep veins, for the most part, have the same names as corresponding arteries (Figure 19 ). All veins of the lower limbs have valves, which are more numerous than in veins of the upper limbs. Deep system : Common iliac , external iliac , femoral , popliteal , anterior and posterior tibial veins. Superficial system : Great saphenous vein : Longest veins in body; ascend from foot to groin in subcutaneous layer. Begin at medial end of dorsal venous arches of foot. Pass anterior to medial malleolus of tibia and then superiorly along medial aspect of leg and thigh just deep to skin. Empty into femoral veins at groin. 24 Clinical note: These veins are more likely to be subject to varicosities than other veins in the lower limbs. The great saphenous veins are often used for prolonged administration of intravenous fluids. In coronary artery bypass grafting, if multiple blood vessels need to be grafted, sections of the great saphenous vein are used along with at least one artery as a graft. Small saphenous veins: Begin at lateral aspect of dorsal venous arches of foot. Pass posterior to lateral malleolus of fibula and ascend deep to skin along posterior aspect of leg. Empty into popliteal veins in popliteal fossa, posterior to knee. Figure 19 25 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 5 Digestive system 1 The various organs of the digestive system (Figure 23.1) can be divided into two main groups: the alimentary canal and the accessory digestive organs. The alimentary canal, also called the gastrointestinal (GI) tract, is the muscular digestive tube, extend from the mouth to the anus. The organs of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine (small bowel), and large intestine (large bowel), the last of which leads to the terminal opening, or anus. The accessory digestive organs are the teeth and tongue, plus the gallbladder and large digestive glands—the salivary glands, liver, and pancreas—that lie external to and are connected to the alimentary canal by ducts. The accessory digestive glands secrete saliva, bile, and digestive enzymes, all of which contribute to the breakdown of food. Abdominal Regions To mark the surface anatomy of the viscera, the abdomen is divided into nine regions by two transverse planes and two parasagittal (or vertical) planes. (Figure 23.2). 2  The superior three regions are the right and left hypochondriac region and the central epigastric region. The middle three regions are the right and left lumbar regions and the central umbilical region. The inferior three regions are the right and left iliac regions, and the central hypogastric region. The Peritoneal Cavity and Peritoneum All divisions of the ventral body cavity contain serous membranes, which is called peritoneum The digestive organs in the abdomino-pelvic cavity all surrounded by peritoneum and the peritoneal cavity. The visceral peritoneum covers the external surfaces of most digestive organs. The parietal peritoneum lines the body wall and is continuous with the visceral peritoneum. The peritoneal cavity is a space between the visceral and parietal peritoneum. 3  Figure 23.3 The Peritoneal Cavity and Peritoneum Mesenteries A mesentery is a double layer of peritoneum— two serous membranes fused together— that extends from the body wall to the digestive organs (Figure 23.4). Mesenteries hold organs in place, store fat, and, most important, provide a route for circulatory vessels and nerves to reach the organs in the peritoneal cavity. 4 5 The Mouth Food enters the alimentary canal through the mouth, where it is chewed, manipulated by the tongue, and moistened with saliva. The Pharynx From the mouth, swallowed food passes posteriorly into the oropharynx (Figure 23.11a), which are passageways for food, fluids, and inhaled air. The Esophagus The esophagus is a muscular tube that propels swallowed food to the stomach. Its lumen is collapsed when it is empty. The esophagus begins as a continuation of the pharynx in the mid neck, descends through the thorax (see Figure 23.1), and passes through the esophageal hiatus (opening) in the diaphragm to enter 6 the abdomen. Its join with the stomach at the cardial orifice, where a cardiac sphincter acts to close off the lumen and prevent regurgitation of acidic stomach juices into the esophagus. The Stomach The stomach extends from the esophagus to the small intestine. The stomach lies in the superior left part of the peritoneal cavity, in the left hypochondriac, epigastric, and umbilical regions of the abdomen (Figure 23.2). It is directly 7 inferior to the diaphragm. Its upper part is hidden behind the left side of the liver. The main regions of the stomach are (Figure 23.17a): 1- The cardia encircling the cardial orifice at the junction with the esophagus. 2- The fundus, the stomach’s dome, is tucked under the diaphragm. 3- The body the large mid portion of the stomach, 4- Ends at pyloric part, composed of the wider pyloric antrum and the narrower pyloric canal. The convex left surface of the stomach is its greater curvature, and the concave right margin is the lesser curvature. The Small Intestine The small intestine is a convoluted tube that runs from the pyloric sphincter, to the first part of the large intestine. It is (2.7–5 meters). The small intestine has three subdivisions (see Figure 23.1): 1- The duodenum 2- The jejunum 3- The ileum While the duodenum is C-shaped, the jejunum and ileum form sausage like coils that hang from the posterior abdomen by the mesentery and are framed by the large intestine. 8 The Large Intestine This organ, which is wider than the small intestine but less than half as long (1.5 meters), has the following subdivisions: cecum, appendix, colon (ascending transverse and descending ) , rectum, and anal canal (Figure 23.21a). The large intestine begins with the saclike cecum in the right iliac fossa. (Figure 23.21a), The appendix is a tube that opens into the posteromedial wall of the cecum. The appendix has large masses of lymphoid tissue in its wall. The appendix functions as a safe for the beneficial bacteria that inhabit the large intestine. 9  Figure 23.21 Gross anatomy of the large intestine. (a) Entire large intestine. The colon has several distinct segments (Figure 23.21a). 1- From the cecum, the ascending colon ascends along the right side of the posterior abdominal wall and reaches the level of the right kidney, where it makes a right angle turn, the right colic flexure (also called the hepatic flexure because the liver lies directly superior to it). 2- From this flexure, the transverse colon extends to the left across the peritoneal cavity. Directly anterior to the spleen, it bends acutely downward at the left colic (splenic) flexure 3- Descends along the left side of the posterior abdominal wall again as the descending colon. 4- Inferiorly, the colon enters the true pelvis as the S-shaped sigmoid colon 10 The Rectum In the pelvis, the sigmoid colon joins the rectum (Figure 23.21a), which descends along the inferior half of the sacrum , it measures about 18-20 cm in length. The Anal Canal The last subdivision of the large intestine is the anal canal (see Figure 23.21b). About 3 cm long which end with anus. 11 Anatomy of the Accessory Organs The Liver The liver lies inferior to the diaphragm in the right superior part of the abdominal cavity (Figure 23.4). It lies almost entirely within the rib cage. The liver has two surfaces: the diaphragmatic and visceral surfaces (Figure 23.25 and Figure 23.26). The diaphragmatic surface faces anteriorly and superiorly, whereas the visceral surface faces posteroinferiorly. 12 The liver has a right lobe and a left lobe, which divided by the falciform ligament on the anterior part of the diaphragmatic surface (Figure 23.25) The falciform ligament is a vertical mesentery that binds the liver to the anterior abdominal 13 wall, Two other lobes, the quadrate lobe and the caudate lobe, are visible on the visceral surface just to the right of the fissure. The gallbladder The gallbladder is a muscular sac, resting in a depression on the visceral surface of the right lobe of the liver (Figure 23.26). It stores and concentrates bile produced by the liver. It is typically divided into three parts:- - Fundus : the rounded, distal portion of the gallbladder. It projects into the inferior surface of the liver. - Body : the largest part of the gallbladder. It lies adjacent to the posteroinferior aspect of the liver. -Neck : which continuous with the cystic duct, leading into the biliary tree. Figure 23.27 parts of gallbladder The gallbladder’s duct, the cystic duct (Figure 23.29), joins the common hepatic duct from the liver to form the bile duct. 14 The biliary tree A branching ductal system that collects bile from the hepatic parenchyma and transports it to the duodenum constitutes the biliary tree. the biliary tree is divided into intra- and extra-hepatic bile ducts Intrahepatic bile ducts The left and right hepatic ducts unite to form the common hepatic duct (CHD) Extrahepatic bile ducts The common hepatic duct is joined by the cystic duct (from the gallbladder) to form the common bile duct. The common bile duct travels initially in the free edge of the lesser omentum, then courses posteriorly to the duodenum and pancreas to unite with the main pancreatic duct to form the ampulla of Vater. Figure 23.29 the biliary tree 15 The Pancreas The pancreas, which lies in the epigastric and left hypochondriac regions of the abdomen (see Figure 23.2). It has head, body, and tail regions (Figure 23.28a), its head lies in the C-shaped curvature of the duodenum, and its tail extends to the left to touch the spleen. The main pancreatic duct extends through the length of the pancreas (Figure 23.19). This duct joins the bile duct to form the hepatopancreatic ampulla and empties into the duodenum. 16 Salivary Glands A salivary gland is a gland that releases a secretion called saliva into the oral cavity. The saliva is secreted to keep the mucous membranes of the mouth and pharynx moist and to cleanse the mouth and teeth. When food enters the mouth, however, secretion of saliva increases, and it lubricates, dissolves, and begins the chemical breakdown of the food. The mucous membrane of the mouth and tongue contains many small salivary glands that open directly, or indirectly via short ducts, to the oral cavity. There are three pairs of major salivary glands: the parotid, submandibular, and sublingual glands (Figure 24.6a). The parotid glands are located inferior and anterior to the ears. Each secretes saliva into the oral cavity via a parotid duct to open into the vestibule opposite the second maxillary (upper) molar tooth. The submandibular glands are found in the floor of the mouth; they are medial and partly inferior to the body of the mandible. Their ducts, the submandibular ducts, run under the mucosa on either side of the midline of the floor of the mouth and enter the oral cavity. The sublingual glands are beneath the tongue and superior to the submandibular glands. Their ducts, the lesser sublingual ducts, open into the floor of the mouth in the oral cavity proper. 17 Spleen The oval spleen is the largest single mass of lymphatic tissue in the body, measuring about 12 cm in length (Figure 22.7a). It is located in the left hypochondriac region between the stomach and diaphragm. The superior surface of the spleen is smooth and convex and conforms to the concave surface of the diaphragm. Neighboring organs make indentations in the visceral surface of the spleen. Like lymph nodes , the spleen has a hilum. Through it pass the splenic artery, splenic vein, and efferent lymphatic vessels. the parenchyma of the spleen consists of two different kinds of tissue called white pulp and red pulp (Figure 22.7b, c). the spleen performs three functions related to blood cells: (1) removal by macrophages of ruptured, worn out, or defective blood cells and platelets; 18 (2) storage of platelets, up to one-third of the body’s supply; and (3) production of blood cells (hemopoiesis) during fetal life. 19 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 6 Urinary system The urinary system consists of: 1.Two kidneys 2.Two ureters 3.Urinary bladder 4.Urethra The kidneys (figure 1) Kidneys are bean–shaped organs located just above the waist between the peritoneum and the posterior wall of the abdomen ( retroperitoneal ). The kidneys are located between the levels of the last thoracic (T12) and third lumbar vertebrae, a position where they are partially protected by ribs 11 and 12 , The right kidney is slightly lower than the left. 1  Figure 1 External anatomy of the kidney (figure 2) A typical adult kidney is 10–12 cm Long , 5–7 cm wide. The concave medial border of each kidney faces the vertebral column. 2 Near the center of the concave border is an indentation called the renal hilum , through which the ureter emerges from the kidney along with blood vessels, lymphatic vessels, and nerves. Three layers of tissue surround each kidney. The deep layer, the renal capsule, is a smooth, transparent sheet of dense irregular connective tissue , It serves as a barrier against trauma and helps maintain the shape of the kidney. The middle layer, the adipose capsule, is a mass of fatty tissue surrounding the renal capsule, It also protects the kidney from trauma and holds it firmly in place within the abdominal cavity. The superficial layer, the renal fascia, is another thin layer of dense irregular connective tissue that anchors the kidney to the surrounding structures and to the abdominal wall. Figure 2 3 Internal anatomy of the kidney (figure 3) A frontal section through the kidney reveals two distinct regions: a superficial, light red region called the renal cortex and a deep , darker reddish-brown inner region called the renal Medulla. The medulla consists of several cone-shaped renal pyramids. The base (wider end) of each pyramid faces the renal cortex, and its apex (narrower end), called a renal papilla , points toward the renal hilum. The renal cortex is the smooth-textured area extending from the renal capsule to the bases of the renal pyramids and into the spaces between them. Those portions of the renal cortex that extend between renal pyramids are called renal columns. Figure 3 4 Together, the renal cortex and renal pyramids of the renal medulla constitute the parenchyma or functional portion of the kidney. Within the parenchyma are the functional units of the kidney—about 1 million microscopic structures called nephrons. Filtrate (filtered fluid) formed by the nephrons drains into large papillary ducts , which extend through the renal papillae of the pyramids. The papillary ducts drain into cuplike structures called minor and major calyces. Each kidney has 8 to 18 minor calyces and 2 or 3 major calyces. From the major calyces, urine drains into a single large cavity called the renal pelvis and then out through the ureter to the urinary bladder. The hilum expands into a cavity within the kidney called the renal sinus, which contains part of the renal pelvis, the calyces ,and branches of the renal blood vessels and nerves. Adipose tissue helps stabilize the position of these structures in the renal sinus. Blood supply of the kidneys (Figure 4 ) The kidneys receive 20–25% of the resting cardiac output via the right and left renal arteries. Within the kidney, the renal artery divides into several segmental arteries , Each segmental artery gives off several branches that enter the parenchyma and pass through the renal columns between the renal lobes as the interlobar arteries. At the bases of the renal pyramids, the interlobar arteries arch between the renal medulla and cortex ; here they are known as the arcuate arteries. Then they produce a series of cortical radiate arteries. These arteries radiate outward and enter the renal cortex. Here, they give off branches called afferent arterioles. 5 Each nephron receives one afferent arteriole, which divides into a tangled, ball- shaped capillary network called the glomerulus. The glomerular capillaries then reunite to form an efferent arteriole that carries blood out of the glomerulus. Figure 4 6 The ureters Each of the two ureters transports urine from the renal pelvis of one kidney to the urinary bladder. Peristaltic contractions of the muscular walls of the ureters push urine toward the urinary bladder. The ureters are 25–30 cm long and are thick walled , narrow tubes that vary in diameter from 1 mm to 10 mm along their course between the renal pelvis and the urinary bladder. Like the kidneys, the ureters are retroperitoneal. At the base of the urinary bladder, the ureters curve medially and pass obliquely through the wall of the posterior aspect of the urinary bladder. Three layers of tissue form the wall of the ureters. The deepest coat is the mucosa , intermediate coat is the muscularis and the superficial coat is the adventitia. The urinary bladder ( figure 5) It is a hollow, distensible muscular organ situated in the pelvic cavity posterior to the pubic symphysis. In males, it is directly anterior to the rectum; in females, it is anterior to the vagina and inferior to the uterus. Folds of the peritoneum hold the urinary bladder in position. bladder is spherical. When it is empty, it collapses. As urine volume increases, it becomes pear-shaped and rises into the abdominal cavity. Urinary bladder capacity averages 700–800 mL. 7  Figure 5 Anatomy and Histology of the Urinary Bladder In the floor of the urinary bladder is a small triangular area called the trigone. The two posterior corners of the trigone contain the two ureteral openings ; the opening into the urethra , the internal urethral orifice , lies in the anterior corner. Three coats make up the wall of the urinary bladder. The deepest is the mucosa, a mucous membrane composed of transitional epithelium and an underlying 8 lamina propria similar to that of the ureters. Surrounding the mucosa is the intermediate muscularis , which consists of three layers of smooth muscle fibers. Around the opening to the urethra the circular fibers form an internal urethral sphincter; inferior to it is the external urethral sphincter , which is composed of skeletal muscle and is a modification of the deep muscles of the perineum. The most superficial coat of the urinary bladder on the posterior and inferior surfaces is the adventitia, a layer of areolar connective tissue that is continuous with that of the ureters. Over the superior surface of the urinary bladder is the serosa, a layer of visceral peritoneum. The urethra (figure 6) It is a small tube leading from the internal urethral orifice in the floor of the urinary bladder to the exterior of the body. In males, it discharges semen (fluid that contains sperm). The male urethra first passes through the prostate, then through the deep muscles of the perineum, and finally through the penis , a distance of about 20 cm. The male urethra is subdivided into three anatomical regions: (1) The prostatic urethra passes through the prostate. (2) The intermediate (membranous) urethra, the shortest portion ,passes through the deep muscles of the perineum. (3) The spongy urethra, the longest portion, passes through the penis. The epithelium of the prostatic urethra is continuous with that of the urinary bladder. 9  Figure 6 The female urethra is a simple short tube The female urethra measures approximately 4 cm in length , that transports urine out of the body, extending from the internal urethral orifice of the bladder to the external urethral orifice in the vestibule of the vagina. 10 Adrenal gland (figure 7) The paired adrenal glands or suprarenal glands , one of which lies superior to each kidney in the retroperitoneal space , have a flattened pyramidal shape. In an adult, each adrenal gland is 3–5 cm in height, 2–3 cm in width, and a little less than 1 cm thick. the adrenal glands differentiate into two structurally and functionally distinct regions: a large, peripherally located adrenal cortex, comprising 80–90% of the gland, and a small, centrally located adrenal medulla , A connective tissue capsule covers the gland. The adrenal cortex produces steroid hormones that are essential for life. The adrenal medulla produces three catecholamine hormones—norepinephrine, epinephrine, and a small amount of dopamine. 11 Figure 7 12 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 7 Male reproductive system Include the testes, a system of ducts (epididymis, ductus deferens, ejaculatory ducts, and urethra), accessory sex glands (seminal vesicles , prostate, and bulbourethral glands) , and several supporting structures, including the scrotum and the penis (figure 1). Figure 1 1 The scrotum (figure2) It consists of loose skin and underlying subcutaneous layer that hangs from the root. Internally , the scrotal septum divides the scrotum into two sacs , each containing a single testis. The location of the scrotum and the contraction of its muscle fibers regulate the temperature of the testes. Normal sperm production requires a temperature about 2–3 C below core body temperature.This lowered temperature is maintained within the scrotum because it is outside the pelvic cavity. Figure 2 2 The testes (figure 3) They are paired oval glands in the scrotum measuring about 5 cm long and 2.5 cm in diameter. Each testis (singular) has a mass of 10–15 grams. The testes (male gonads) produce sperm and secrete hormones. The testes develop near the kidneys, in the posterior portion of the abdomen, and they usually begin their descent into the scrotum through the inguinal canals (passageways in the lower anterior abdominal wall) during fetal development. Figure 3 3 A serous membrane called the tunica vaginalis , which is derived from the peritoneum and forms during the descent of the testes, partially covers the testes. A collection of serous fluid in the tunica vaginalis is called a hydrocele.It may be caused by injury to the testes or inflammation of the epididymis. Internal to the tunica vaginalis the testis is surrounded by is a white fibrous capsule , the tunica albuginea; it extends inward, forming septa that divide the testis into a series of internal compartments called lobules. Each of the 200–300 lobules contains one to three tightly coiled tubules, the seminiferous tubules , where sperm are produced. In the spaces between adjacent seminiferous tubules are clusters of cells called interstitial cells or Leydig cells. These cells secrete testosterone , the most prevalent androgen. The sperm (figure 4) A sperm is about 60µm long and contains several structures that are highly adapted for reaching and penetrating a secondary oocyte. The major parts of a sperm are the head and the tail. The flattened, pointed head of the sperm is about 4–5 µm long. Covering the anterior two-thirds of the nucleus is the acrosome , a cap like vesicle filled with enzymes that help a sperm to penetrate a secondary oocyte to bring about fertilization most sperm do not survive more than 48 hours within the female reproductive tract. Figure 4 4 Ducts of the testes (figure 5 and 6) Seminiferous tublues : is formed between lobules Straight tubules : these are short ducts Rete testis : it is network of straight tubules Efferent ducts : extends to the epididymis head Ductus epididymis : at the head of the epididymis Ductus (vas) deferens : continuation from the tail of the epididymis , it is about 45 cm long , Functionally, the ductus deferens conveys sperm from the epididymis toward the urethra , Like the epididymis , the ductus deferens also can store sperm for several months. Ejacularoty ducts : it is about 2 cm long and is formed by the union of the duct from the seminal vesicle and the ampulla of the ductus (vas) deferens. They terminate in the prostatic urethra , where they eject sperm and seminal vesicle secretions. Figure 5 5 The epididymis Each epididymis consists mostly of the tightly coiled ductus epididymis. The efferent ducts from the testis join the ductus epididymis at the larger, superior portion of the epididymis called the head. The body is the narrow mid portion of the epididymis , and the tail is the smaller, inferior portion. At its distal end, the tail of the epididymis continues as the ductus (vas) Deferens. The ductus epididymis would measure about 6 m in length if it were uncoiled. The epididymis is the site of sperm maturation , the process by which sperm acquire motility and the ability to fertilize an ovum. This occurs over a period of about 14 days. The spermatic cord The spermatic cord is a supporting structure of the male reproductive system that ascends out of the scrotum. It consists of the ductus (vas) deferens as it ascends through the scrotum, the testicular artery, veins that drain the testes. The spermatic cord pass through the inguinal canal , the canal ends at the superficial (subcutaneous) inguinal ring, a somewhat triangular opening in the aponeurosis of the external oblique muscle. In females, the round ligament of the uterus pass through the inguinal canal. 6  Figure 6 Urethra It is reproductive and urinary systems; it serves as a passageway for both semen and urine. About 20 cm long, it passes through the prostate, the deep muscles of the perineum, and the penis, and is subdivided into three parts. 1.The prostatic urethra is 2–3 cm long and passes through the prostate. 2. Intermediate (membranous) urethra.is about 1 cm in length. it passes through the deep muscles of the perineum. 3. spongy urethra, which is about 15–20 cm As this duct passes through the corpus spongiosum of the penis. 7 Accessory sex glands Seminal vesicles (figure 6) They are convoluted pouch like structures, about 5 cm in length, lying posterior to the base of the urinary bladder and anterior to the rectum. Prostate (figure 6) The prostate is a single, doughnut-shaped gland about the size of a golf ball. It measures about 4 cm from side to side, about 3 cm from top to bottom, and about 2 cm from front to back. The normal prostate gland has approximately a volume of 25 ml , It is inferior to the urinary bladder and surrounds the prostatic urethra. The prostate slowly increases in size from birth to puberty. It then expands rapidly until about age 30, after which time its size typically remains stable until about age 45, when further enlargement may occur. The prostate secretes a milky, slightly acidic fluid (pH about 6.5) that contains several substances. Secretions of the prostate enter the prostatic urethra through many prostatic ducts. Prostatic secretions make up about 25% of the volume. Bulbourethral Glands (figure 6) They are called also Cowper’sglands , are about the size of peas. They are located inferior to the prostate on either side of the membranous urethra , and their ducts open into the spongy urethra. It secretes an alkaline fluid into the urethra that protects the passing sperm by neutralizing acids from urine in the urethra. 8 Semen is a mixture of sperm and seminal fluid, a liquid that consists of the secretions of the seminiferous tubules, seminal vesicles , prostate, and bulbourethral glands. The volume of semen in a typical ejaculation is 2.5–5 milliliters (mL), with 50– 150 million sperm per mL. When the number falls below 20 million/mL , the male is likely to be infertile. The penis (figure 7) The penis contains the urethra and is a passageway for the ejaculation of semen and the excretion of urine. It is cylindrical in shape and consists of a body, glans penis, and a root. The body of the penis is composed of three cylindrical masses of tissue, each surrounded by fibrous tissue called the tunica albuginea. The two dorsolateral masses are called the corpora cavernosa. The smaller mid ventral mass, the corpus spongiosum , contains the spongy urethra. The root of the penis is the attached portion (proximal portion). It consists of the bulb of the penis, the expanded posterior continuation of the base of the corpus spongiosum penis, and the crura of the penis. 9 Figure 7 ( a and b ) 10 General anatomy Dr.Samir Ali 1st academic year Al-Mostafa college Lecture 8 Female reproductive system It includes the ovaries , the uterine tubes, the uterus; the vagina; and external organs (which are collectively called the vulva). The mammary glands are Considered as part of both integumentary and reproductive systems. Ovaries They are paired glands that resemble unshelled almonds in size and shape ; They are one on either side of the uterus. A series of ligaments holds them in position. The broad ligament of the uterus, which is a fold of the parietal peritoneum, attaches to the ovaries by a double layered fold of peritoneum called the mesovarium. The ovarian ligament anchors the ovaries to the uterus , and the suspensory ligament attaches them to the pelvic wall. Each ovary contains a hilum , the point of entrance and exit for blood vessels and nerves along which the mesovarium is attached. The ovaries functions are : 1.gamtes production 2.hormones release such as estrogen and progesterone. 1 Oogenesis and Follicular Development Each month after puberty until menopause, gonadotropins (FSH and LH) secreted by the anterior pituitary further stimulate the development of several primordial follicles , although only one will typically reach the maturity needed for ovulation. primordial follicles → primary follicles → secondary follicle → mature follicle (before ovulation) 2 The mature follicle soon ruptures and releases its secondary oocyte, a process known as ovulation. Normally these cells are swept into the uterine tube. If fertilization does not occur, the cells degenerate. If sperm are present in the uterine tube and one penetrates the secondary oocyte, however, The secondary oocyte splits into two cells, again of unequal size. The larger cell is the ovum, the sperm cell and the ovum unite, forming a zygote. The Zygote begins to undergo cell divisions while moving toward the uterus. It arrives in the uterus 6 to 7 days after ovulation. 3 Uterine tube (Fallopian tubes ) There are two uterine tubes, that extend laterally from the uterus. The tubes, which measure about 10 cm long , lie within the folds of the broad ligaments of the uterus. They provide a route for sperm to reach an ovum and fertilized. The funnel-shaped portion of each tube, called the infundibulum , is close to the ovary but is open to the pelvic cavity. It ends in a fringe of finger like projections called fimbriae. the uterine tube extends medially and eventually inferiorly and attaches to the superior lateral angle of the uterus. The ampulla of the uterine tube is the widest, longest portion, making up about the lateral two-thirds of its length. The isthmus of the uterine tube is the more medial, short, narrow ,thick-walled portion that joins the uterus. Histologically, the uterine tubes are composed of three layers: Mucosa , muscularis , and serosa. 4 Uterus It is the site of implantation of a fertilized ovum, development of the fetus during pregnancy, and labor. During reproductive cycles when implantation does not occur, the uterus is the source of menstrual flow. It Situated between the urinary bladder and the rectum, the uterus is the size and shape of an inverted pear. In females who have never been pregnant, it is about 7.5 cm long , 5 cm wide , and 2.5 cm thick. The uterus is larger in females who have recently been pregnant, and smaller (atrophied) when sex hormone levels are low, as occurs after menopause. 5 Histology of the Uterus The outer layer—the perimetrium or serosa—is part of the visceral peritoneum it covers the urinary bladder and forms a shallow pouch, the vesicouterine pouch. Posteriorly, it covers the rectum and forms a deep pouch between the uterus and rectum, the rectouterine pouch or pouch of Douglas—the most inferior point in the pelvic cavity. The middle layer of the uterus, the myometrium of smooth muscle. The inner layer of the uterus, the endometrium Branches of the internal iliac artery called uterine arteries supply blood to the uterus Anatomical subdivisions of the uterus 1) a portion superior to the uterine tubes called the fundus, (2) a tapering central portion called the body (3) an inferior narrow portion called the cervix that opens into the vagina. The interior of the body of the uterus is called the uterine cavity, and the interior of the cervix is called the cervical canal. The cervical canal opens into the uterine cavity at the internal os and into the vagina at the external os. Normally, the body of the uterus projects anteriorly and superiorly over the urinary bladder in a position called anteflexion. The cervix projects inferiorly and posteriorly and enters the anterior wall of the vagina at nearly a right angle. 6 Cervical Mucus: The secretory cells of the mucosa of the cervix produce a secretion called cervical mucus. The vagina is a tubular, 10-cm long fibromuscular canal. Histology :The mucosa of the vagina is continuous with that of the uterus. The muscularis ,and The adventitia, the adventitia anchors the vagina to adjacent organs such as the urethra and urinary bladder anteriorly and the rectum and anal canal posteriorly. A thin fold of vascularized mucous membrane, called the hymen ( membrane), forms a border around and partially closes the inferior end of the vaginal opening to the exterior, the vaginal orifice. Sometimes the hymen completely covers the orifice, a condition called imperforate hymen. Surgery may be needed to open. Vulva the external genitals of the female , two longitudinal folds of skin, the labia majora.Medial to the labia majora are two smaller folds of skin called the labia minora. Perineum The perineum is the diamond-shaped area medial to the thighs and buttocks of both males and females. It contains the external genitals and anus. The perineum is bounded anteriorly by the pubic symphysis, laterally by the ischial tuberosities , and posteriorly by the coccyx. A transverse line drawn between the ischial tuberosities divides the perineum into an anterior 7 urogenital triangle that contains the external genitals and a posterior anal triangle that contains the anus. 8 Mammary Glands Each breast is a hemispheric projection of variable size anterior to the pectoralis major and serratus anterior muscles and attached to them by a layer of fascia composed of dense irregular connective tissue. Each breast has one pigmented projection, the nipple, that has a series of closely spaced openings of ducts called lactiferous ducts. The circular pigmented area of skin surrounding the nipple is called the areola ; it appears rough because it contains modified sebaceous (oil) glands. Strands of connective tissue called the suspensory ligaments of the breast (Cooper’s ligaments) run between the skin and fascia and support the breast. Within each breast is a mammary gland , a modified (sweat) gland that produces milk. A mammary gland consists of 15 to 20 lobes, or compartments, separated by a variable amount of adipose tissue. 9 In each lobe are several smaller compartments called lobules, composed of grapelike clusters of milk-secreting glands termed alveoli embedded in connective tissue. When milk is being produced, it passes from the alveoli into a series of secondary tubules and then into the mammary ducts. Near the nipple, the mammary ducts expand slightly to form sinuses called lactiferous sinuses , where some milk may be stored before draining into a lactiferous duct. Each lactiferous duct typically carries milk from one of the lobes to the exterior. 10 The functions of the mammary glands are the synthesis, secretion, and ejection of milk; these functions, called lactation, are associated with pregnancy and childbirth. Milk production is stimulated largely by the hormone prolactin from the anterior pituitary, with contributions from progesterone and estrogens. The ejection of milk is stimulated by oxytocin, which is released from the posterior pituitary in response to the sucking of an infant on the mother’s nipple (suckling). 11