Human Anatomy Lecture Notes PDF 2024-2025

HUMAN ANATOMY LECTURE NOTES (Clinically Seasoned for Medical Students) By Uğur Baran KASIRGA MD, PhD, MBA, DA Bahçeşehir University Faculty of Medicine Istanbul 2024 – 2025 Chapter 1: Ba...

HUMAN ANATOMY LECTURE NOTES (Clinically Seasoned for Medical Students) By Uğur Baran KASIRGA MD, PhD, MBA, DA Bahçeşehir University Faculty of Medicine Istanbul 2024 – 2025 Chapter 1: Basic Concepts and Descriptions Contents 1 Introduction to Anatomy Definition and Importance in Clinical Practice Morphology and Anatomy: Their Relationship 2 Anatomy Science Variations Gross Anatomy: Surface Anatomy Regional Anatomy Systemic Anatomy Microscopic Anatomy (Histology): Cytology Epithelial, Connective, Muscle, and Nervous Tissue Developmental Anatomy (Embryology): Early Development Fertilization and Cleavage Gastrulation and Organogenesis Fetal Development Clinical Anatomy: Radiological Anatomy Surgical Anatomy Anatomical Variations Comparative Anatomy Sectional Anatomy Topographic Anatomy 3 Anatomical Terminology Anatomical Position Anatomical Planes and Sections: Sagittal Plane Coronal Plane Transverse Plane Oblique Plane Anatomical Planes and Their Relationship to Radiologic Imaging Body Anatomical Axes: Longitudinal Axis Anteroposterior Axis Transverse Axis Synonyms for Anatomical Axes: 4 Directional Terms Superior, Inferior, Anterior, Posterior Medial, Lateral, Proximal, Distal 1  Superficial, Deep Ipsilateral, Contralateral Intermediate 5 Body Cavities and Membranes Dorsal and Ventral Body Cavities Cranial Cavity Vertebral Cavity Thoracic and Abdominopelvic Cavities Types of Body Membranes: Mucous Membranes Serous Membranes Cutaneous Membrane Synovial Membranes Fibrous Membranes 6 Movement Terms Flexion and Extension Abduction and Adduction Rotation (Medial and Lateral) Circumduction Supination and Pronation Dorsiflexion and Plantarflexion Inversion and Eversion Protraction and Retraction Elevation and Depression Opposition 7 Body Regions Axial and Appendicular Regions Head and Neck Region Thoracic, Abdominal, and Pelvic Regions Upper and Lower Limb Regions Back (Dorsal) Region 8 Quadrants and Regions of the Abdomen Four Quadrants Nine Regions of the Abdomen Chapter 2: The Skeleton in General and Its Derivatives 1 Overview of the Skeleton Division of the Skeleton: Appendicular Skeleton: 1. Pectoral Girdle 2  2. Upper Limbs 3. Pelvic Girdle 4. Lower Limbs Axial Skeleton: 5. Skull 6. Vertebral Column 7. Rib Cage 8. Hyoid Bone 2 Derivatives of the Skeleton Cartilage: Hyaline Cartilage Elastic Cartilage Fibrocartilage Joints (Articulations): Fibrous Joints Cartilaginous Joints Synovial Joints Bone Marrow: Red Bone Marrow Yellow Bone Marrow 3 Bones Compact Bone (Haversian Systems) Spongy Bone (Trabeculae and Bone Marrow) 4 Bone Cells Osteoblasts Osteocytes Osteoclasts Osteoprogenitor Cells 5 Bone Types and Their Functions Long Bones (e.g., Femur, Humerus) Short Bones (e.g., Carpals, Tarsals) Flat Bones (e.g., Skull, Ribs) Irregular Bones (e.g., Vertebrae, Facial Bones) Sesamoid Bones (e.g., Patella) 6 Bone Growth and Development Ossification Processes: Intramembranous Ossification Endochondral Ossification Growth Plates Bone Remodeling 3 7 Structure of a Long Bone Diaphysis Epiphysis Metaphysis Periosteum Endosteum 8 Bone Remodeling and Repair Bone Resorption and Formation Fracture Healing Stages: Hematoma, Soft Callus, Hard Callus, Remodeling 9 Clinical Aspects of Bone Health Osteoporosis Fractures Bone Infections (Osteomyelitis) Bone Tumors Chapter 3: Upper Extremity Bones Introduction to Upper Extremity Bones Overview of bones in the upper limb and their functional relevance. 1 Shoulder Girdle Scapula Anatomical landmarks: spine, acromion, coracoid process, borders, angles, fossae. Clinical correlations: fractures, winging of the scapula, muscular attachments. Clavicle Anatomical features: sternal end, acromial end, shaft. Clinical correlations: clavicular fractures, sternoclavicular joint dislocations. 2 Humerus Proximal Humerus Head, anatomical neck, surgical neck, greater and lesser tubercles, intertubercular sulcus. Clinical considerations: humeral head fractures, surgical neck fractures and axillary nerve injury. Shaft of Humerus Deltoid tuberosity, radial groove. Clinical considerations: humeral shaft fractures, radial nerve injury. 4  Distal Humerus Epicondyles (medial and lateral), capitulum, trochlea, olecranon fossa. Clinical considerations: supracondylar fractures, medial epicondyle fractures. 3 Radius and Ulna Proximal Radius and Ulna Radial head, neck, radial tuberosity, olecranon process, coronoid process. Shafts Interosseous borders, attachments, clinical significance. Distal Radius and Ulna Styloid processes, ulnar notch, dorsal tubercle of radius. Clinical considerations: Colles' fracture, Smith's fracture, Monteggia and Galeazzi fractures. 4 Bones of the Hand Carpal Bones Proximal and distal rows; scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate. Clinical correlations: scaphoid fractures, carpal tunnel syndrome. Metacarpals Bases, shafts, heads, articulations. Clinical relevance: Boxer's fracture, Bennet's fracture. Phalanges Proximal, middle, and distal phalanges, MCP, PIP, and DIP joints. Clinical relevance: phalangeal fractures, dislocations. Carpal Bones Overview of the carpal bones' arrangement and articulations. Specific details of each carpal bone: anatomy and clinical significance. Metacarpal Bones Anatomical features: bases, shafts, and heads. Articulation with carpal bones and phalanges. Common injuries: fractures, dislocations. Phalanges Anatomy of proximal, middle, and distal phalanges. Clinical relevance: fractures, joint pathologies. 5  Clinical Relevance of Carpal and Hand Bones Carpal Tunnel Syndrome Anatomy of the carpal tunnel and compression of the median nerve. Fractures and Dislocations Scaphoid fracture, Boxer's fracture, phalangeal injuries. Chapter 4: Lower Limb Bones 1 Introduction to Lower Limb Bones Overview of bones in the lower limb and their weight-bearing function. Comparison with upper limb bones in terms of structure and function. 2 Pelvic Girdle Hip Bone (Os Coxae) Components: ilium, ischium, and pubis. Landmarks: iliac crest, ischial tuberosity, pubic symphysis. Acetabulum Articulation with the head of the femur. Pelvic Inlet and Outlet Clinical implications in obstetrics. Clinical Correlations Pelvic fractures, acetabular fractures, sacroiliac joint dysfunction. 3 Femur Proximal Femur Head, neck, greater and lesser trochanters, intertrochanteric line and crest. Clinical considerations: fractures (neck, trochanters), avascular necrosis. Shaft of Femur Linea aspera, muscular attachments. Clinical considerations: femoral shaft fractures, intramedullary nailing. Distal Femur Medial and lateral condyles, intercondylar fossa, epicondyles. Clinical considerations: distal femoral fractures, knee joint involvement. 4 Patella Anatomy: base, apex, articular surface. Function in knee extension mechanism. Clinical relevance: patellar fractures, dislocations, patellofemoral pain syndrome. 5 Tibia and Fibula 6  Tibia Proximal end: medial and lateral condyles, tibial tuberosity. Shaft: anterior border, interosseous border. Distal end: medial malleolus, articulation with talus. Fibula Head, shaft, distal end (lateral malleolus). Clinical considerations: tibial fractures, fibular fractures, shin splints. 6 Foot Bones Tarsal Bones Overview of talus, calcaneus, navicular, cuboid, and cuneiforms. Clinical relevance: ankle fractures, calcaneal fractures. Metatarsal Bones Base, shaft, and head; common injuries (Jones fracture). Phalanges Proximal, middle, and distal phalanges. Clinical relevance: bunions, fractures. 7 Clinical Relevance in Lower Limb Bones Hip and Pelvic Fractures Management and implications of fractures. Knee Injuries Patellar fractures, dislocations. Leg and Ankle Fractures Tibial, fibular, and ankle joint injuries. Foot Pathologies Plantar fasciitis, tarsal fractures. 7 Chapter 1: Introduction to Anatomy Definition and Importance in Clinical Practice: Anatomy is the branch of science concerned with the study of the structure of organisms and their parts. In human anatomy, this focus is on the physical structure of the human body. The study of anatomy is a fundamental element in the education of health professionals, providing them with essential knowledge to understand the normal structure and function of the human body, as well as the changes that occur in disease. Morphology and Anatomy- Their Relationship: Morphology is the branch of biology that deals with the form and structure of organisms and their specific structural features. It encompasses both external appearance (shape, structure, color, pattern) and internal structures (like bones, muscles, and organs). Anatomy, on the other hand, is a subset of morphology that specifically focuses on the structure of organisms, particularly the human body in medical contexts. While morphology may include broader aspects like the overall shape and size of an organism, anatomy delves deeper into the internal structures, examining how tissues, organs, and systems are organized and interconnected. In essence, anatomy is a detailed and systematic study within the broader field of morphology. While morphology provides a general overview of form and structure across different organisms, anatomy provides the intricate details of these structures, particularly in humans, often with an emphasis on their function and clinical relevance. 1 Anatomy Science Variations- Gross Anatomy: Surface Anatomy: The study of external features and the internal structures as they relate to the skin surface. For example, surface anatomy includes identifying palpable landmarks such as bones, muscles, and blood vessels that can be used in clinical practice for procedures like injections or assessments. Regional Anatomy: Examines specific regions of the body, such as the thorax, abdomen, or limbs, providing a detailed view of the interrelationships of structures within that area. This approach is particularly useful in surgery and radiology. Systemic Anatomy: Focuses on specific organ systems such as the cardiovascular, respiratory, or nervous systems. This method provides an understanding of how organs within a system work together to perform complex functions. Microscopic Anatomy (Histology): 8 Microscopic anatomy, also known as Histology, is the study of the structures of tissues and cells that are too small to be seen with the naked eye. Using microscopes, histologists examine the organization and function of cells, tissues, and organs at the microscopic level. Cytology: The study of individual cells, focusing on their structure, function, and the cellular processes that maintain life. Key cellular structures include the nucleus, mitochondria, endoplasmic reticulum, and cytoskeleton, each with specific roles that are crucial for cell function and survival. This field of study focuses on four main tissue types: Epithelial Tissue: Covers body surfaces and lines cavities, playing roles in protection, absorption, and secretion. Connective Tissue: Supports and binds other tissues, with subtypes including loose connective tissue, dense connective tissue, cartilage, bone, and blood. Muscle Tissue: Responsible for movement, with three types: skeletal muscle (voluntary control), cardiac muscle (heart), and smooth muscle (involuntary control, found in organs). Nervous Tissue: Composed of neurons and supporting cells, responsible for transmitting and processing information in the nervous system. Developmental Anatomy (Embryology): Developmental anatomy, also known as embryology, is the study of the development of an organism from the time of fertilization through to birth and sometimes extends to include postnatal development. This field focuses on how a single fertilized egg (zygote) transforms into a complex, multicellular human being with specialized organs and tissues. Key stages in developmental anatomy include: Early Development: Begins with fertilization, leading to the formation of a zygote. The zygote undergoes cleavage to form a blastocyst, which implants in the uterine wall. Gastrulation follows, forming three germ layers: ectoderm, mesoderm, and endoderm, which give rise to all tissues and organs. Fertilization: The union of sperm and egg to form a zygote, the first stage of a new organism. Cleavage and Blastulation: The zygote undergoes rapid cell divisions (cleavage) to form a multicellular structure called a blastocyst, which implants in the uterine wall. Gastrulation: The blastocyst reorganizes into three primary germ layers: ectoderm, mesoderm, and endoderm, each of which will give rise to different tissues and organs. Organogenesis: The process by which these germ layers differentiate into various organs and tissues, such as the heart, brain, limbs, and digestive system. The process by which the three germ layers differentiate into the various organs and systems. This 9  includes the development of the neural tube (future brain and spinal cord), the heart, and the primitive gut. Fetal Development: The phase where the body systems continue to develop and mature, preparing the fetus for survival outside the womb. After the embryonic period, the fetus continues to grow and mature, with organs refining their structures and functions in preparation for birth. Developmental anatomy is crucial for understanding congenital abnormalities, the impact of environmental factors on development, and the fundamental processes of life from conception to birth. Clinical Anatomy: Radiological Anatomy: Uses imaging techniques like X-rays, MRI, CT scans, and ultrasound to visualize and study the body's internal structures. Understanding radiological anatomy is essential for diagnosing diseases and planning treatments. Surgical Anatomy: Focuses on anatomical structures and their relationships as they pertain to surgery. Surgeons must have a detailed understanding of anatomy to avoid complications during procedures. Anatomical Variations: Recognition of normal anatomical variations, which can differ from person to person, is critical in clinical practice. For example, variations in the branching patterns of blood vessels can impact surgical approaches. Comparative Anatomy: Comparative anatomy is the study of similarities and differences in the anatomy of different species. By comparing the structures of various organisms, scientists can understand evolutionary relationships, functional adaptations, and developmental processes. For example, the study of homologous structures (like the forelimbs of humans, birds, and whales) reveals common ancestry, while analogous structures (like wings of birds and insects) demonstrate how different species have evolved similar functions independently. Sectional Anatomy: Sectional anatomy involves the study of the body through cross-sectional views, typically obtained by slicing the body along various planes (such as transverse, sagittal, or coronal planes). This approach is particularly important in imaging techniques like CT scans and MRIs, where internal structures are visualized in cross-section. Understanding sectional anatomy is crucial for interpreting these images accurately, as it reveals the relationships between different organs and tissues within a specific plane. Topographic Anatomy: Topographic anatomy, also known as surface anatomy, focuses on the relationships between internal structures and their external landmarks on the body’s surface. It is used to guide physical examinations, surgeries, and medical procedures by identifying palpable landmarks such as bones, muscles, and vessels. Topographic anatomy helps clinicians locate and assess underlying structures by observing or palpating the body’s surface, ensuring accurate and safe interventions. 10 2 Anatomical Terminology Anatomical terminology is a standardized language used by health professionals to describe the location and function of body parts accurately. This terminology is essential for clear communication and understanding in the medical field. Anatomical Position: The anatomical position is universally accepted as the standard starting point for describing the body. In this position, the body stands erect, feet together, arms at the sides, and head and eyes facing forward. The palms face forward (anteriorly), with the thumbs pointing away from the body. This position serves as a reference point for all directional terms and allows for consistent descriptions of structures regardless of the body’s actual position. Body Planes and Sections: Anatomical planes are essential in both the study and practice of anatomy because they provide a standardized way to describe locations, movements, and sections of the body. These planes divide the body into sections and serve as reference points for describing the relative positions of structures within the body. 11  The three primary anatomical planes are: Sagittal Plane: Divides the body into right and left portions. It’s crucial for describing movements like flexion and extension. Median (Midsagittal) Plane: A specific sagittal plane that lies exactly in the midline, dividing the body into equal right and left halves. Parasagittal Plane: Any sagittal plane that is offset from the midline, creating unequal right and left sections. Coronal (Frontal) Plane: Divides the body into anterior (front) and posterior (back) portions. It’s used to describe movements like abduction and adduction. Transverse (Horizontal) Plane: Divides the body into superior (upper) and inferior (lower) portions. It’s important for describing rotational movements. Oblique Plane: Cuts made along any plane that is not parallel to the standard planes (sagittal, coronal, or transverse), often used in imaging to visualize structures at angles that provide more information. These planes are necessary because they allow healthcare professionals to communicate about specific locations and directions in the body with precision and consistency, which is vital for diagnosing conditions, planning surgeries, and interpreting medical images. Anatomical Planes and Their Relationship to Radiologic Imaging: Anatomical planes are crucial in radiologic imaging because they provide a standardized method for capturing and interpreting images of the body’s internal structures. Radiologic imaging techniques, such as X-rays, CT scans, and MRI, often produce images in specific planes, allowing clinicians to visualize and analyze the body in detail. Sagittal Plane: In radiology, a sagittal plane image shows a side view of the body or organ, dividing it into right and left sections. This is particularly useful for examining structures like the brain, spine, and pelvic organs. Coronal (Frontal) Plane: A coronal plane image provides a front or back view of the body, dividing it into anterior and posterior portions. This plane is commonly used in imaging to assess the chest, abdomen, and musculoskeletal system, including the heart and lungs. Transverse (Horizontal) Plane: A transverse plane image, often referred to as a cross- sectional view, divides the body into upper and lower portions. This is the most commonly used plane in CT and MRI scans, as it allows for detailed visualization of the internal organs, blood vessels, and other structures. It is particularly useful in diagnosing abdominal and pelvic conditions, as well as in trauma assessments. By using these planes, radiologists and clinicians can accurately describe the location of abnormalities, plan surgical interventions, and monitor the progress of diseases. The 12 consistent use of anatomical planes in imaging ensures clear communication and precise interpretation across different medical disciplines. Body anatomical Axes: Anatomical axes are imaginary lines around which the body or body parts move. These axes are essential for understanding movements and describing the orientation of anatomical structures in relation to the planes of the body. The three primary anatomical axes correspond to the three anatomical planes: Longitudinal Axis: Also known as the vertical axis, this axis runs vertically from head to toe. It is associated with rotational movements around the transverse plane. For example, when you rotate your head or trunk to the left or right (as in shaking your head "no"), you are rotating around the longitudinal axis. Anteroposterior Axis: This axis runs from the front (anterior) to the back (posterior) of the body. It is associated with movements in the coronal (frontal) plane, such as abduction and adduction of the limbs. For example, raising your arms sideways away from your body involves movement around the anteroposterior axis. Transverse Axis: Also known as the horizontal axis, this axis runs horizontally from side to side, perpendicular to the sagittal plane. It is associated with movements in the sagittal plane, such as flexion and extension. For instance, bending forward at the waist or flexing the elbow involves movement around the transverse axis. These axes are crucial for describing and analyzing body movements, particularly in fields like kinesiology, physical therapy, and sports science, where understanding the direction and type of movement is vital for diagnosis, treatment, and performance enhancement. 13 Here are some common synonyms for the anatomical axes: Longitudinal Axis: Vertical Axis Cranio-Caudal Axis Superior-Inferior Axis Anteroposterior Axis: Sagittal Axis Dorsoventral Axis Front-Back Axis Transverse Axis: Horizontal Axis Mediolateral Axis Left-Right Axis These synonyms are often used interchangeably in anatomical and clinical contexts to describe the orientation and movement of the body or its parts relative to different planes. 3 Directional Terms: Directional terms in anatomy are standardized words used to describe the locations of structures in relation to other structures or locations in the body. These terms provide a clear and consistent way to communicate about the human body, which is essential in both clinical practice and anatomical studies. Here are the key directional terms: Superior (Cranial): Toward the head or the upper part of a structure. Example: The heart is superior to the liver. Inferior (Caudal): Away from the head or toward the lower part of a structure. Example: The stomach is inferior to the lungs. Anterior (Ventral): Toward the front of the body. Example: The sternum is anterior to the heart. Posterior (Dorsal): Toward the back of the body. Example: The spine is posterior to the heart. Medial: Toward the midline of the body. Example: The nose is medial to the eyes. Lateral: Away from the midline of the body. Example: The arms are lateral to the chest. Proximal: Closer to the point of attachment of a limb to the trunk or closer to the origin of a structure. Example: The elbow is proximal to the wrist. 14  Distal: Farther from the point of attachment of a limb to the trunk or farther from the origin of a structure. Example: The fingers are distal to the elbow. Superficial: Toward or at the body surface. Example: The skin is superficial to the muscles. Deep: Away from the body surface; more internal. Example: The lungs are deep to the ribcage. Ipsilateral and Contralateral: Ipsilateral refers to structures on the same side of the body, while contralateral refers to structures on the opposite side. These terms are often used in neurological assessments. Intermediate: A term used to describe a structure lying between two other structures, e.g., the collarbone is intermediate between the breastbone and shoulder. These terms are essential for precisely describing the locations of structures and guiding medical procedures, ensuring that healthcare professionals have a shared understanding when discussing the human body. Regional Terms: Cephalic: Head. Cervical: Neck. Thoracic: Chest. Abdominal: Abdomen. Pelvic: Pelvis. Brachial: Arm. Carpal: Wrist. Femoral: Thigh. Patellar: Knee. Plantar: Sole of the foot. 4 Body Cavities and Membranes: Dorsal Body Cavity: Comprises the cranial cavity (housing the brain) and the vertebral cavity (enclosing the spinal cord). The dorsal body cavity protects the central nervous system. Ventral Body Cavity: Larger and contains the thoracic and abdominopelvic cavities. These cavities are separated by the diaphragm. The ventral body cavity houses the internal organs (viscera). 15  Cranial Cavity: Contains the brain. Vertebral (Spinal) Cavity: Contains the spinal cord. Thoracic Cavity: Contains the lungs and heart, divided into the pleural cavities (each containing a lung) and the mediastinum (containing the heart, esophagus, trachea). Abdominopelvic Cavity: Contains the digestive organs, kidneys, and other abdominal organs in the abdominal cavity and the bladder, reproductive organs, and rectum in the pelvic cavity. Body Membranes: Body membranes are thin layers of tissue that cover surfaces, line cavities, and separate or protect different areas of the body. They play essential roles in protection, secretion, absorption, and sensation. There are five primary types of body membranes: Mucous Membranes (Mucosa): These membranes line body cavities that open to the exterior, such as the digestive, respiratory, urinary, and reproductive tracts. Mucous membranes secrete mucus, which keeps the surfaces moist and helps trap pathogens and particles, providing protection and facilitating absorption and secretion. The epithelial layer of the mucosa varies depending on the location and function, ranging from simple columnar epithelium in the intestines to stratified squamous epithelium in the mouth. Serous Membranes (Serosa): Serous membranes line body cavities that do not open to the exterior and cover the organs within these cavities. They consist of two layers: the parietal layer, which lines the cavity walls, and the visceral layer, which covers the organs. The 16  serous fluid between these layers acts as a lubricant, reducing friction between the organs and the body wall during movement. Examples include the pleura (around the lungs), pericardium (around the heart), and peritoneum (lining the abdominal cavity and covering abdominal organs). Cutaneous Membrane: The cutaneous membrane, commonly known as the skin, is the body’s largest organ. It covers the entire body surface and consists of a stratified squamous epithelium (epidermis) overlying a layer of connective tissue (dermis). The skin provides protection against environmental hazards, helps regulate body temperature, and contains sensory receptors for touch, pain, and temperature. Synovial Membranes: These membranes line the cavities of synovial joints (freely movable joints such as the knee, elbow, and shoulder). Synovial membranes secrete synovial fluid, which lubricates the joint surfaces, reducing friction and allowing for smooth movement. Unlike the other body membranes, synovial membranes are composed solely of connective tissue and do not contain an epithelial layer. Fibrous membranes: Fibrous membranes are a type of connective tissue membrane characterized by their dense fibrous tissue composition. These membranes provide structural support and protection, often surrounding organs or lining cavities. They are not as commonly discussed as mucous or serous membranes but are crucial in specific anatomical and physiological contexts. Examples of fibrous membranes include: Fascia: Fascia is a fibrous membrane that envelops muscles, groups of muscles, blood vessels, and nerves, binding them together while allowing movement. There are three layers: superficial fascia (beneath the skin), deep fascia (surrounding muscles, bones, and nerves), and visceral fascia (covering internal organs). 17 Periosteum: The periosteum is a dense fibrous membrane covering the outer surface of bones, except at the joints. It provides a surface for the attachment of tendons and ligaments and contains osteoblasts that are essential for bone growth and healing. Perichondrium: The perichondrium is a fibrous membrane that surrounds cartilage. It supplies nutrients to the cartilage, which lacks its own blood supply, and also plays a role in the growth and repair of cartilage tissue. Dura Mater: The dura mater is a tough, fibrous membrane that forms the outermost layer of the meninges, the protective coverings of the brain and spinal cord. It provides critical protection and structural support for the central nervous system. Fibrous membranes are essential for maintaining the integrity of organs and tissues, providing protection, and facilitating movement and healing. Their dense fibrous nature makes them particularly suited to withstanding tension and stress. Each type of body membrane has a specific function related to its location in the body, contributing to the overall protection, function, and maintenance of homeostasis. 18 5 Movement Terms: Movement terms in anatomy are used to describe the actions of muscles on the skeleton and the body’s joints. These terms help to precisely describe the direction and type of movement that occurs at different joints. Here are some key movement terms: Flexion and Extension: Flexion: A movement that decreases the angle between two body parts. For example, bending the elbow or knee brings the bones closer together, which is flexion. Extension: A movement that increases the angle between two body parts. Straightening the elbow or knee is an example of extension. Abduction and Adduction: Abduction: A movement away from the midline of the body. Raising the arm or leg sideways away from the body is an example of abduction. Adduction: A movement toward the midline of the body. Lowering the arm or leg back to the side of the body is an example of adduction. Rotation: Medial (Internal) Rotation: Rotating a limb toward the midline of the body. For example, turning the foot inward is medial rotation. Lateral (External) Rotation: Rotating a limb away from the midline of the body. Turning the foot outward is lateral rotation. Circumduction: A circular movement that combines flexion, extension, abduction, and adduction. It occurs at ball-and-socket joints, such as the shoulder or hip, allowing the limb to move in a circular path. Supination and Pronation: Supination: Rotating the forearm so that the palm faces upward or forward (as in holding a bowl of soup). Pronation: Rotating the forearm so that the palm faces downward or backward. Dorsiflexion and Plantarflexion: 19  Dorsiflexion: Bending the foot upward toward the shin. This movement occurs at the ankle joint. Plantarflexion: Bending the foot downward away from the shin, as in pointing the toes. Inversion and Eversion: Inversion: Turning the sole of the foot inward, toward the midline of the body. Eversion: Turning the sole of the foot outward, away from the midline of the body. Protraction and Retraction: Protraction: Moving a body part forward, such as jutting the jaw forward. Retraction: Moving a body part backward, such as pulling the jaw back. Elevation and Depression: Elevation: Lifting a body part upward, such as shrugging the shoulders. Depression: Lowering a body part downward, such as dropping the shoulders back down. Circumduction: A circular movement that combines flexion, extension, abduction, and adduction, commonly observed in ball-and-socket joints like the shoulder. Opposition: The movement that allows the thumb to touch the tips of the other fingers, enabling grasping, which is unique to humans and primates. These movement terms are essential for describing and understanding how the body moves, particularly in fields like physical therapy, sports medicine, and anatomy. They provide a clear and consistent way to discuss the mechanics of joints and muscles. 6 Body Regions: Body regions are specific areas of the body that are identified and named to facilitate the study, examination, and description of the human body. These regions are used to describe the location of anatomical structures, symptoms, and procedures in a clear and standardized way. Here’s an overview of the main body regions: Axial Region: The central part of the body, including the head, neck, and trunk. The axial region is crucial for supporting the appendicular region (limbs). Head and Neck Region: 20 Cephalic (Head): Includes the entire head. Cranial: Refers to the skull. Facial: Refers to the face, including the forehead (frontal), eyes (orbital), nose (nasal), mouth (oral), and chin (mental). Cervical: Refers to the neck. Thoracic Region: Thoracic (Chest): The chest area, which includes the heart and lungs. Pectoral: Refers to the chest muscles. Mammary: Refers to the breast. Sternal: Refers to the region of the sternum (breastbone). Axillary: Refers to the armpit. Abdominal Region: Abdominal: The area between the thorax and pelvis. Umbilical: Refers to the area around the navel. Epigastric: The upper central region above the stomach. Hypogastric (Pubic): The lower central region below the umbilical region. Right and Left Hypochondriac: Regions on either side of the epigastric region, beneath the ribs. Right and Left Lumbar: Regions on either side of the umbilical region. Right and Left Iliac (Inguinal): Regions on either side of the hypogastric region, near the groin. Pelvic Region: Pelvic: The area below the abdomen, containing the reproductive organs, bladder, and rectum. Inguinal: Refers to the groin. Pubic: Refers to the area over the pubic bone. Appendicular Region: Comprises the limbs, which are subdivided into upper limbs (arm, forearm, wrist, hand) and lower limbs (thigh, leg, ankle, foot). Each limb is further divided into specific regions for detailed study. Upper Limb Region: Brachial: The arm, from shoulder to elbow. Antebrachial: The forearm, from elbow to wrist. Carpal: The wrist. Manual: The hand. Palmar: The palm of the hand. Digital: The fingers. 21  Lower Limb Region: Femoral: The thigh, from hip to knee. Patellar: The front of the knee. Popliteal: The back of the knee. Crural: The leg, from knee to ankle. Sural: The calf (back of the leg). Tarsal: The ankle. Pedal: The foot. Plantar: The sole of the foot. Digital: The toes. Back (Dorsal) Region: Vertebral: Refers to the spinal column. Scapular: Refers to the shoulder blades. Lumbar: The lower back, between the ribs and pelvis. Sacral: The area over the sacrum, between the hips. Gluteal: The buttocks. These body regions help healthcare professionals, anatomists, and students to describe the body more precisely and are particularly useful in clinical settings to locate symptoms, diagnose conditions, and plan treatments. 7 Quadrants and Regions of the Abdomen: The abdomen is often divided into four quadrants: Clinicians often use quadrants to quickly locate pain or abnormalities. The division into right upper (RUQ), left upper (LUQ), right lower (RLQ), and left lower (LLQ) quadrants helps in diagnosis. Alternatively, the abdomen can be divided into nine regions: right hypochondriac (liver, gallbladder), epigastric (stomach), left hypochondriac (spleen), right lumbar, umbilical, left lumbar, right iliac, hypogastric, and left iliac. This helps to localize pain, discomfort, or other clinical findings and providing a precise anatomical location for internal organs. 22 Chapter 2: The Skeleton in General and Its Derivatives The Skeleton in General and Its Derivatives The human skeleton is a complex and dynamic structure that forms the framework of the body, providing support, protection, and enabling movement. It is composed of bones, cartilage, and joints, all of which work together to maintain the body's shape, protect vital organs, and facilitate locomotion. 1 Overview of the Skeleton: The human skeleton is divided into two main parts: Appendicular Skeleton: Comprising the bones of the limbs and girdles (shoulder girdle and pelvic girdle), the appendicular skeleton facilitates movement by acting as levers for muscles to act upon. This part of the skeleton includes the bones of the limbs and girdles that attach them to the axial skeleton: Pectoral Girdle: Consists of the clavicles (collarbones) and scapulae (shoulder blades). It connects the upper limbs to the axial skeleton. Upper Limbs: Includes the humerus, radius, ulna, carpals (wrist bones), metacarpals (palm bones), and phalanges (finger bones). Pelvic Girdle: Composed of the hip bones (ilium, ischium, and pubis), it supports the weight of the upper body and attaches the lower limbs to the axial skeleton. Lower Limbs: Includes the femur, patella (kneecap), tibia, fibula, tarsals (ankle bones), metatarsals (foot bones), and phalanges (toe bones). Axial Skeleton: This includes the bones that form the central axis of the body, consisting of the skull, vertebral column, and rib cage. It serves to protect the brain, spinal cord, and thoracic organs, as well as provide support for the body’s posture. This part of the skeleton forms the central axis of the body and includes: 23  Skull: Composed of the cranium and facial bones. It protects the brain and supports facial structures. Vertebral Column: Also known as the spine, it consists of vertebrae stacked in a column, providing support and protecting the spinal cord. Rib Cage: Includes the ribs and sternum. It encases and protects the thoracic organs such as the heart and lungs. Hyoid Bone: A small, U-shaped bone in the neck that supports the tongue and is involved in swallowing and speech. 2 Derivatives of the Skeleton: Cartilage: A flexible connective tissue found in various parts of the skeleton. It provides cushioning and support and is crucial during bone development and growth. There are three types of cartilage: Hyaline Cartilage: The most common type, found in the joints, ribs, and nose. It provides smooth surfaces for joint movement. Elastic Cartilage: Found in the external ear and epiglottis, providing flexibility and shape. Fibrocartilage: Found in intervertebral discs and the pubic symphysis, providing strong support and cushioning. Joints (Articulations): Connections between bones that allow for movement and provide stability. They are classified based on their structure and function: Fibrous Joints: Connected by dense connective tissue and generally immovable, such as sutures in the skull. Cartilaginous Joints: Connected by cartilage and allow for limited movement, such as intervertebral discs. 24  Synovial Joints: Freely movable joints characterized by a synovial cavity filled with fluid. Examples include the knee, hip, and shoulder joints. Bone Marrow: A soft tissue found within the cavities of bones. There are two types: Red Bone Marrow: Involved in hematopoiesis (the production of blood cells) and found in the spongy bone of the axial skeleton, including the pelvis and sternum. Yellow Bone Marrow: Primarily composed of fat cells and found in the medullary cavities of long bones. 3 Bones Bones are a fundamental component of the human skeletal system, providing structure, protection, and support for the body. They also play a critical role in movement, mineral storage, and the production of blood cells. Bone tissue, or osseous tissue, is a specialized form of connective tissue. It is composed of cells and an extracellular matrix that provides strength and flexibility: Compact Bone: Dense and solid, it forms the outer layer of bones, providing strength and protection. Compact bone is organized into units called osteons or Haversian systems, which contain a central canal surrounded by concentric layers (lamellae) of bone tissue. Spongy Bone (Cancellous Bone): Lighter and less dense, it is found primarily at the ends of long bones and in the interior of other bones. Spongy bone consists of a network of trabeculae, which provide structural support and house the red bone marrow. 25 4 Bone Cells: There are four main types of cells involved in bone maintenance, growth, and remodeling: Osteoblasts: Cells responsible for bone formation. They secrete the bone matrix and initiate the process of mineralization. Osteocytes: Mature bone cells derived from osteoblasts that have become embedded in the matrix they produced. Osteocytes maintain bone tissue and communicate with other bone cells to regulate bone homeostasis. Osteoclasts: Large cells that break down bone tissue, a process known as bone resorption. This is crucial for bone remodeling and the release of calcium into the bloodstream. Osteoprogenitor Cells: Stem cells that differentiate into osteoblasts, playing a role in bone growth and healing. 5 Bone Types and Their Functions: Support: Bones provide the framework that supports the body and cradles soft organs. For example, the bones of the legs act as pillars to support the trunk of the body when standing. Protection: Bones protect vital organs. The skull encases the brain, the ribcage shields the heart and lungs, and the vertebrae protect the spinal cord. Movement: Bones act as levers that muscles pull on to produce movement. Joints between bones allow for flexibility and range of motion. Mineral Storage: Bones store minerals such as calcium and phosphate, which can be released into the bloodstream as needed to maintain essential mineral balances. Blood Cell Production: Bones contain marrow, where hematopoiesis (the production of blood cells) occurs. Red bone marrow produces red blood cells, white blood cells, and platelets. Energy Storage: The yellow marrow in bones stores lipids, which serve as an energy reserve. 26 Bones are classified based on their shapes and functions: Long Bones: These bones are longer than they are wide and primarily act as levers. These bones have a shaft with two ends. They are primarily found in the limbs and include bones like the femur, humerus, and tibia. Long bones are involved in movement and support. Examples include the femur, tibia, and humerus. Short Bones: Approximately equal in length, width, and thickness, these bones provide stability and support with limited movement. Examples include the carpals and tarsals. Examples include the bones of the wrist (carpals) and ankle (tarsals). Such as the carpals and tarsals, which provide stability and support. Flat Bones: Thin, flattened, and usually curved, flat bones protect internal organs and provide surfaces for muscle attachment. Examples include the sternum, ribs, and scapulae. Such as t he skull, ribs, and scapulae, which protect internal organs and provide muscle attachment sites. Irregular Bones: Bones with complex shapes that do not fit into the other categories, such as the vertebrae and some facial bones. They serve various functions, such as protection and support. Examples include the vertebrae and the bones of the pelvis. Such as the vertebrae and certain facial bones, which have complex shapes and functions. Sesamoid Bones: Small, round bones embedded in tendons, often found near joints. The patella is the most well-known and largest example sesamoid bone. It protects tendons from stress and wear. Such as the patella, which reduce friction and protect tendons 6 Bone Growth and Development: The skeleton begins as a cartilaginous framework in the embryo, which is gradually replaced by bone through a process called ossification. Bone growth continues through childhood and adolescence, driven by the activity at the growth plates (epiphyseal plates) in long bones. Bones grow in length at the epiphyseal plates through the division of cartilage cells, followed by ossification. Growth in diameter occurs through the addition of bone tissue by osteoblasts in the periosteum. 27 Ossification: The process by which bone tissue forms. It begins in the embryo and continues through adolescence. There are two main types: Intramembranous Ossification: Formation of bone directly from mesenchymal tissue, seen in the flat bones of the skull. Some bones, particularly flat bones of the skull, are formed directly from mesenchymal tissue without a cartilage precursor. The process by which flat bones, like those of the skull, are formed directly from mesenchymal tissue. Endochondral Ossification: The process by which most bones, including long bones, are formed from hyaline cartilage templates. This process involves the replacement of cartilage with bone tissue, allowing for the growth of the bone in length. Most bones of the body are formed through this process, where cartilage is gradually replaced by bone. Growth Plates: Areas of cartilage at the ends of long bones where lengthening occurs during growth. They eventually ossify and close after puberty, marking the end of bone growth in length. 28 Understanding the skeleton and its derivatives provides a foundation for exploring the detailed anatomy of individual bones, their relationships, and their roles in overall bodily function. 7 Structure of a Long Bone: Long bones serve as a model for understanding the basic structure of bones: Diaphysis: The shaft or central part of a long bone, composed of compact bone surrounding a central medullary cavity, which contains yellow marrow in adults. Epiphysis: The ends of the bone, composed of a thin layer of compact bone covering spongy bone. The epiphyses are involved in joint formation and are often covered with articular cartilage. Metaphysis: The region between the diaphysis and epiphysis, where the growth plate (epiphyseal plate) is located in growing bones. After growth, the plate becomes the epiphyseal line. Periosteum: A dense, fibrous membrane covering the external surface of bones, except at joint surfaces. The periosteum contains nerves and blood vessels that nourish the bone, as well as osteoblasts and osteoclasts for bone growth and repair. Endosteum: A thin membrane lining the medullary cavity and the surfaces of the spongy bone, also containing osteoblasts and osteoclasts for bone remodeling. 8 Bone Remodeling and Repair: Bone is a dynamic tissue that undergoes constant remodeling throughout life. This process involves the resorption of old bone by osteoclasts and the formation of new bone by osteoblasts. Bone remodeling is crucial for maintaining bone strength, adapting to stress, and repairing micro-damage. When a bone is fractured, the body initiates a repair process that includes the formation of a blood clot (hematoma), the development of a soft callus, the replacement with a hard callus, and finally the remodeling of the bone to its original shape. 29 9 Clinical Aspects of Bone Health: Osteoporosis: A condition characterized by a decrease in bone density, leading to fragile bones that are more prone to fractures. Fractures: Breaks in the bone that can occur due to trauma, overuse, or underlying medical conditions. The type of fracture and its location will dictate the treatment approach. Bone Infections (Osteomyelitis): Infections within the bone that can result from injuries, surgeries, or the spread of infection from other parts of the body. Treatment usually involves antibiotics and sometimes surgery. Bone Tumors: Abnormal growths of bone tissue that can be benign or malignant. Diagnosis and treatment depend on the type and location of the tumor. 30 Chapter 3: Upper Extremity Bones The upper extremity consists of the bones of the shoulder girdle, arm, forearm, and hand. This chapter will explore each of these bones in detail, starting from the shoulder girdle and moving distally through the humerus, radius, ulna, and the bones of the hand (carpals, metacarpals, and phalanges). 1 Shoulder Girdle: Scapula and Clavicle Scapula The scapula, or shoulder blade, is a flat, triangular bone located on the posterior aspect of the thorax extending from the second to the seventh ribs. It plays a critical role in shoulder function, serving as a site of attachment for multiple muscles and providing the foundation for upper limb movements. It is a triangular, flat bone, which serves as a site for attachment for many (17) muscles. Proximal (Medial) Border: Medial Border: This long, straight edge of the scapula runs parallel and closest to the vertebral column. The medial border is clinically significant because it is often involved in muscle attachment, particularly for the rhomboid muscles and the serratus anterior. Any disruption in these muscles or their attachment can lead to scapular winging, a condition where the scapula protrudes abnormally from the back. Superior Angle: The superior-medial corner of the scapula, where the levator scapulae muscle attaches. This region can be a source of pain in conditions like levator scapulae syndrome, where muscle spasm or strain occurs. Inferior Angle: The inferior-medial tip of the scapula is palpable and serves as an important landmark in physical examination. It is involved in the upward rotation of the scapula, a movement essential for full abduction of the arm. Clinically, this area is examined for abnormalities in scapular movement and alignment. Body and Surface: Spine of Scapula: The spine is a prominent bony ridge on the posterior surface of the scapula, dividing it into the supraspinous and infraspinous fossae. The 31  trapezius and deltoid muscles attach to the spine, making it a crucial structure for shoulder movement. Fractures of the scapular spine, although rare, can significantly impact shoulder function and require careful management. Acromion Process: The acromion is the lateral extension of the scapular spine, forming the highest point of the shoulder. It articulates with the clavicle at the acromioclavicular (AC) joint, a common site of injury, particularly in contact sports. It is crucial for shoulder abduction and serves as an attachment for the deltoid muscle. Acromion fractures or AC joint separations can lead to pain, instability, and limited shoulder mobility. Coracoid Process: This hook-like projection on the anterior surface of the scapula is a major site for muscle and ligament attachment, including the pectoralis minor, coracobrachialis, and the short head of the biceps brachii. Clinical conditions such as coracoid process fractures or impingement syndromes, where the coracoid process impinges on surrounding soft tissues, can cause significant shoulder pain and dysfunction. Distal (Lateral) Border: Glenoid Cavity (Fossa): The glenoid cavity is a shallow socket that articulates with the head of the humerus, forming the glenohumeral joint. This joint is highly mobile but inherently unstable, making it prone to dislocations. The surrounding labrum deepens the socket and provides additional stability, and tears to the labrum can cause pain, clicking, and shoulder instability. Clinical Anatomy: Scapular Fractures: Scapular fractures are typically associated with high- energy trauma, such as motor vehicle accidents or falls. These fractures can involve the body, spine, acromion, or glenoid, each presenting specific challenges. For example, fractures involving the glenoid cavity may lead to shoulder instability and require surgical intervention to restore joint congruency. 32 Clavicle The clavicle, or collarbone, is a long, S- shaped bone that serves as a strut between the scapula and the sternum, acting as a strut to hold the upper limb away from the thorax. It plays a key role in maintaining the position of the shoulder and providing attachment for muscles. Proximal (Medial) End: Sternal End: This rounded end of the clavicle articulates with the manubrium of the sternum at the sternoclavicular (SC) joint. This joint allows for a range of movements, including elevation, depression, protraction, and retraction of the shoulder. The SC joint is critical for the movement of the shoulder girdle, and dislocations here, though rare, can lead to significant impairment and require careful management, sometimes necessitating surgical intervention. Costoclavicular Ligament Attachment: The medial end of the clavicle is the attachment site for the costoclavicular ligament, which stabilizes the SC joint. Injuries to this ligament can result in SC joint instability. Body (Shaft): Medial Two-Thirds: The shaft is convex anteriorly in the medial two-thirds, providing attachment for muscles such as the pectoralis major, sternocleidomastoid, and subclavius. Fractures in this region are common, particularly in the middle third of the clavicle. These fractures often occur due to falls onto the shoulder or outstretched hand and can result in significant pain and deformity. 33  Lateral One-Third: The lateral third of the clavicle is concave anteriorly and serves as the attachment for the deltoid and trapezius muscles. Fractures in this region can be complicated by damage to the surrounding structures, including the coracoclavicular ligaments, which can lead to acromioclavicular joint dislocation. Distal (Lateral) End: Acromial End: This flattened end of the clavicle articulates with the acromion of the scapula at the acromioclavicular joint. AC joint injuries, such as separations or arthritis, are common, especially in athletes, and can result in pain and a visible bump at the shoulder. Clinical Anatomy: Clavicle Fractures: Clavicle fractures are among the most common fractures, particularly in children and young adults. The midshaft is the most frequent site of fracture, often resulting from falls or direct trauma. Treatment typically involves immobilization with a sling or, in some cases, surgical fixation to ensure proper alignment and healing. 2 Humerus The humerus is the long bone of the upper arm, connecting the shoulder to the elbow. It is crucial for a wide range of movements and is frequently involved in fractures. Proximal End: The important anatomical features of the proximal humerus are the head, anatomical neck, surgical neck, greater and lesser tubercles and intertubercular sulcus. A tubercle is a round nodule, and signifies an attachment site of a muscle or ligament. Head: The head of the humerus is a large, rounded structure that articulates with the glenoid cavity of the scapula to form the glenohumeral joint. 34 This ball-and-socket joint allows for extensive mobility. The head is larger than the glenoid cavity, allowing for a wide range of motion. Dislocations of the shoulder commonly involve the humeral head, particularly anterior dislocations, which may damage the surrounding capsule and labrum. Anatomical Neck: A slight constriction immediately below the head, marking the border between the articular surface and the rest of the bone. Surgical Neck: The region humerus is just below the head and tubercles of the humerus. It is a common site for fractures, especially in older individuals, and may lead to injury to the axillary nerve, affecting shoulder function. It is called the "surgical neck" of the humerus because fractures in this area are relatively common and often require surgical intervention. This distinguishes it from the "anatomical neck," which is located more proximally and is less frequently involved in fractures. Greater and Lesser Tubercles: Bony prominences located lateral and anterior to the head, respectively. The greater tubercle serves as the attachment for the supraspinatus, infraspinatus, and teres minor, while the lesser tubercle is the attachment site for the subscapularis muscle. Intertubercular Groove (Bicipital Groove): 35  A groove between the tubercles, housing the tendon of the long head of the biceps brachii muscle. MAJOR LIEUTENANT MAJOR Shaft: The shaft of the humerus contains some important bony landmarks such as the deltoid tuberosity and radial groove, and is the site of attachment for various muscles. On the lateral side of the humeral shaft is a roughened surface where the deltoid muscle attaches. This is known is as the deltoid tuberosity. Deltoid Tuberosity: A roughened area on the lateral surface of the shaft, providing attachment for the deltoid muscle. Radial Groove: A shallow groove running obliquely down the posterior aspect of the shaft, accommodating the radial nerve and deep brachial artery. Distal End: The lateral and medial borders of the humerus form medial and lateral supra-epicondylar ridges. The lateral supra-epicondylar ridge is more roughened, as it is the site of attachment for many of the extensor muscles in the posterior forearm. 36  Capitulum and Trochlea: The capitulum articulates with the head of the radius, and the trochlea articulates with the trochlear notch of the ulna, forming part of the elbow joint. Medial and Lateral Epicondyles: Bony projections on either side of the distal humerus. The medial epicondyle is the site of attachment for the common flexor tendon, while the lateral epicondyle serves as the attachment for the common extensor tendon. Olecranon Fossa: A deep depression on the posterior surface that accommodates the olecranon process of the ulna during elbow extension. Immediately distal to the supra-epicondylar ridges are the lateral and medial epicondyles projections of bone. Both can be palpated at the elbow (the medial more so, as it is much larger). The ulnar nerve passes into the forearm along th posterior side of the medial epicondyle, and can also be palpated there. Clinical Anatomy: Humerus Fractures: Fractures of the humerus can occur at various sites, with proximal humeral fractures common in elderly individuals due to falls, and midshaft fractures often associated with radial nerve injury. Fractures of the humerus are categorized based on their location along the bone: the proximal region (head), the shaft, and the distal regions, including the medial epicondyle and the medial supracondylar area. Each type of fracture has distinct mechanisms, clinical presentations, and management considerations. 37 Proximal Humerus Fractures (Head of the Humerus) The proximal humerus includes the head, anatomical neck, and surgical neck. Fractures in this region are common, particularly in elderly individuals with osteoporotic bones. These fractures typically occur due to direct trauma from falls or high-energy impacts such as motor vehicle accidents. Common Fracture Types: Surgical Neck Fracture: The most common type, often treated non- operatively if minimally displaced. Anatomical Neck Fracture: These are more severe and may compromise the blood supply to the humeral head, increasing the risk of avascular necrosis. Humeral Shaft Fractures Fractures of the humeral shaft typically result from direct trauma (such as a blow or fall onto the arm) or from indirect forces (such as a twisting injury). These fractures account for a significant proportion of humeral fractures and can vary widely in presentation. Types of Fractures: These fractures may be transverse, spiral, or oblique, depending on the mechanism of injury. Transverse fractures are often caused by direct trauma. Spiral fractures usually result from twisting forces. Medial Epicondylar Region Fractures 38  The medial epicondyle, located on the distal humerus, serves as an important attachment point for muscles and ligaments, particularly those involved in flexion and pronation of the forearm. Fractures in this region often occur due to direct trauma or avulsion injuries, particularly in young athletes who engage in throwing sports. Medial Supracondylar Region Fractures The supracondylar region is located just above the condyles of the distal humerus and is a common site for fractures in children, often resulting from falls on an outstretched hand (FOOSH injury). Medial supracondylar fractures can have serious complications due to their proximity to neurovascular structures, including the brachial artery and the median and ulnar nerves Clinical Importance and Complications Each region of humeral fractures comes with unique clinical challenges. Proximal humerus fractures can compromise shoulder function and blood supply, shaft fractures risk radial nerve injury, and distal fractures, particularly in the medial epicondyle and supracondylar regions, risk neurovascular injury. The choice of treatment depends on the type of fracture, the degree of displacement, and associated complications, with options ranging from conservative immobilization to surgical fixation. 3 Forearm Bones: Radius and Ulna Radius The radius is the lateral bone of the forearm, playing a crucial role in the movement of the wrist and elbow. Proximal End: Head: A disc-shaped structure that articulates with the capitulum of the humerus and the radial notch of the ulna, allowing for rotation during pronation and supination. Neck: A narrow region just distal to the head, providing attachment for the annular ligament, which stabilizes the proximal radioulnar joint. Radial Tuberosity: A bony prominence on the anterior aspect of the proximal radius, providing attachment for the biceps brachii tendon. Shaft: Interosseous Border: The medial edge of the shaft, where the interosseous membrane attaches, connecting the radius and ulna. 39  Distal Surface: The shaft expands distally to form the broad distal end of the radius, which plays a key role in wrist joint formation. Distal End: Styloid Process: A pointed projection on the lateral side of the distal radius, providing attachment for ligaments of the wrist. Ulnar Notch: A concave surface on the distal radius that articulates with the head of the ulna, forming the distal radioulnar joint. Dorsal Tubercle: A small prominence on the posterior aspect, serving as a pulley for the extensor pollicis longus tendon. Clinical Anatomy: Colles' Fracture: A common fracture of the distal radius, typically occurring due to a fall on an outstretched hand. It results in a characteristic "dinner fork" deformity. Smith's fracture; It is a fracture of the distal radius, often referred to as a reverse Colles' fracture. It occurs when the distal fragment of the radius is displaced anteriorly (towards the palm), typically caused by a fall on a flexed wrist. Ulna The ulna is the medial bone of the forearm, primarily involved in forming the elbow joint and providing stability to the forearm. Proximal End: Olecranon Process: A large, curved projection at the proximal end, forming the point of the elbow and providing attachment for the triceps brachii muscle. Coronoid Process: A triangular eminence projecting forward from the upper and front part of the ulna, fitting into the coronoid fossa of the humerus during elbow flexion. Trochlear Notch: A deep notch between the olecranon and coronoid processes that articulates with the trochlea of the humerus, forming the hinge part of the elbow joint. Radial Notch: A shallow depression on the lateral side of the coronoid process that articulates with the head of the radius. Shaft: 40  Interosseous Border: The lateral edge of the shaft where the interosseous membrane attaches, linking the ulna to the radius. Distal End: Head: A small, rounded structure at the distal end of the ulna, articulating with the ulnar notch of the radius at the distal radioulnar joint. 41 Carpal and Hand Bones The human hand, composed of a complex arrangement of bones, joints, ligaments, and muscles, provides the capacity for a wide range of motions, from fine dexterous movements to powerful grasping actions. The skeletal structure of the hand consists of three main groups of bones: Carpal Bones – Forming the wrist. Metacarpal Bones – Supporting the palm. Phalanges – Making up the fingers. These bones are intricately connected to ensure stability and flexibility, essential for performing complex hand movements. 1 Carpal Bones (Wrist) The carpal bones are a set of eight small bones arranged in two rows (proximal and distal). They form the wrist joint and provide the base for hand movement. They articulate with both the radius and ulna proximally and the metacarpal bones distally. Proximal Row (from lateral to medial) Scaphoid: A boat-shaped bone that articulates with the radius. It is the largest bone in the proximal row and serves as a bridge between the proximal and distal rows of carpal bones. Clinical Note: Fractures of the scaphoid are common and may result in avascular necrosis due to its limited blood supply. Lunate: A crescent-shaped bone that also articulates with the radius. It is centrally located in the proximal row and plays a key role in wrist articulation. Clinical Note: The lunate is prone to dislocation, leading to a condition called Kienböck's disease, which can cause avascular necrosis. Scaphoid Fractures are the most common carpal bone fracture, often occurring after a fall onto an outstretched hand. Diagnosis can generally be made by dedicated radiographs but CT or MRI may be needed for confirmation. Treatment may require a prolonged period of cast immobilization, percutaneous surgical fixation, or open reduction and internal fixation. 42 Triquetrum: A pyramidal-shaped bone located medially, articulating with the pisiform and distal row of carpals. It is positioned posterior to the pisiform. Clinical Note: Triquetral fractures can occur, typically involving the dorsal surface due to direct trauma. Pisiform: A small, pea-shaped bone that sits on top of the triquetrum. It is considered a sesamoid bone within the tendon of the flexor carpi ulnaris. Clinical Note: The pisiform acts as a sesamoid bone to increase the leverage of the tendon. Distal Row (from lateral to medial) Trapezium: A saddle-shaped bone that articulates with the first metacarpal, forming the carpometacarpal joint of the thumb, which allows for a wide range of thumb movements. Clinical Note: The trapezium is important for thumb mobility, and arthritis in this joint is a common condition known as basal thumb arthritis. Trapezoid: A wedge-shaped bone, smaller and more centrally located. It articulates with the second metacarpal and provides stability for the index finger. Clinical Note: Fractures of the trapezoid are rare but can affect hand stability. 43  Capitate: The largest of all carpal bones, located centrally in the distal row. It articulates with the third metacarpal and plays a major role in wrist stability and movement. Clinical Note: Due to its central position, capitate fractures can disrupt the function of both rows of carpal bones. Hamate: A hook-shaped bone, which has a prominent projection called the hamulus or hook of the hamate. It articulates with the fourth and fifth metacarpals. Clinical Note: The hook of the hamate can be fractured, often due to sports injuries (such as in golfers or baseball players), leading to ulnar nerve compression. Articulations and Ligaments The carpal bones articulate with each other through a series of joints and are stabilized by multiple ligaments: Intercarpal Ligaments: Connect the carpal bones to each other, maintaining the integrity of the carpal rows. Radiocarpal Joint: Formed by the articulation of the radius with the scaphoid and lunate bones. Midcarpal Joint: Lies between the proximal and distal rows of the carpal bones, allowing for gliding and additional wrist movements. Carpometacarpal Joints: These are the articulations between the distal row of carpal bones and the bases of the metacarpals. 2 Metacarpal Bones (Bones of the Palm) The metacarpals are five long bones that form the skeleton of the palm. Each metacarpal is numbered from I to V from the thumb to the little finger. Metacarpal I (Thumb): Shorter and thicker than the others, and articulates with the trapezium. Its mobility allows for the wide range of thumb movements. 44  Metacarpal II (Index Finger): Longest of the metacarpals and articulates primarily with the trapezoid. Metacarpal III (Middle Finger): Features a prominent styloid process at its base and articulates with the capitate. The styloid process of the third metacarpal bone is a bony projection located on the dorsal aspect of the base of the third metacarpal. It serves as an important attachment site for the extensor carpi radialis brevis tendon, which plays a key role in wrist extension and stability during hand movements. This process can be palpated externally on the dorsum of the hand and is clinically significant in cases of trauma to the hand or wrist, as fractures involving the styloid process may lead to complications in hand function and mobility. Its anatomical position and relation to surrounding tendons also make it a landmark during surgical interventions involving the dorsal wrist and hand. Metacarpal IV (Ring Finger): Smaller and articulates with the hamate. Metacarpal V (Little Finger): Articulates with the hamate and is most flexible, contributing to the cupping movement of the hand. Each metacarpal has a base (proximal end), a shaft, and a head (distal end), which forms the knuckles at the metacarpophalangeal joints. 3 Phalanges (Bones of the Fingers) The phalanges are the bones of the fingers. Each finger contains three phalanges – proximal, middle, and distal, except the thumb, which has only two phalanges (proximal and distal). Proximal Phalanges: These are the longest and articulate proximally with the heads of the metacarpals. Middle Phalanges: Present only in the second to fifth fingers and articulate proximally with the proximal phalanges. 45  Distal Phalanges: The smallest of the phalanges, these bones form the tips of the fingers. Each phalanx has a base, shaft, and head: Base: Articulates with the metacarpals or the preceding phalanx. Shaft: The central portion of the bone. Head: Rounded and forms the joint with the subsequent phalanx. The phalangeal joints include: Metacarpophalangeal Joints (MCP): Between the heads of the metacarpals and the bases of the proximal phalanges, allowing for flexion, extension, abduction, and adduction. Proximal Interphalangeal Joints (PIP): Between the proximal and middle phalanges, permitting flexion and extension. Distal Interphalangeal Joints (DIP): Between the middle and distal phalanges, also allowing flexion and extension. Clinical Relevance Carpal Tunnel Syndrome: Compression of the median nerve as it passes through the carpal tunnel formed by the carpal bones and the flexor retinaculum. Fractures: Carpal and metacarpal fractures, such as a scaphoid fracture or a boxer's fracture (fracture of the fifth metacarpal), can severely affect hand function. 46 Chapter 4: Lower Limb Bones 1 Introduction to Lower Limb Bones The lower limb bones form the critical structure that supports the body's weight, enables balance, and facilitates movement. Unlike the bones of the upper limb, which are more adapted for a wide range of motion and dexterity, the bones of the lower limb are designed to bear weight, provide stability, and withstand mechanical stress. This chapter will provide an in-depth analysis of the bones of the lower limb, starting with the pelvic girdle and extending to the bones of the foot, with a particular focus on their clinical implications. 2 Pelvic Girdle The pelvic girdle is the basin-like structure that connects the lower limb to the axial skeleton. It is formed by the two hip bones (os coxae), the sacrum, and the coccyx. The hip bone is composed of three regions: the ilium, ischium, and pubis, which fuse during development to form a single structure. Prior to puberty, the triradiate cartilage separates these parts –and fusion only begins at the age of 15-17. Ilium: The superior and largest portion of the hip bone. The iliac crest, palpable under the skin, serves as a significant landmark for lumbar punctures and injections. The anterior superior iliac spine (ASIS) and anterior inferior iliac spine (AIIS) are prominent bony landmarks for muscle attachment, such as the sartorius and rectus femoris, respectively. Ischium: The posterior-inferior part of the hip bone. The ischial spine is a sharp projection that serves as an attachment for ligaments like the sacrospinous ligament. The ischial tuberosity, often referred to as the "sit bone," bears weight when sitting and serves as an attachment point for the hamstring muscles. 47  Pubis: The anterior portion of the hip bone. It consists of the body, superior ramus, and inferior ramus. The two pubic bones meet anteriorly at the pubic symphysis, a cartilaginous joint that allows slight movement, especially during childbirth. Acetabulum and Pelvic Inlet / Outlet The acetabulum is the concave socket that articulates with the head of the femur to form the hip joint. The lunate surface is the weight-bearing area of the acetabulum, while the acetabular fossa provides space for ligamentous and vascular structures. The pelvic inlet and outlet define the boundaries of the true pelvis. The dimensions of these regions are clinically relevant, particularly in obstetrics for determining the passage of the fetus during childbirth. Clinical Correlations 48 Pelvic Fractures: High-energy trauma (e.g., motor vehicle accidents) can lead to fractures in the pelvic ring. Stable fractures often involve one side of the pelvis, while unstable fractures involve multiple disruptions of the pelvic ring and may require surgical fixation. There are two broad groups of pelvic fractures: LOW and HIGH energy injuries. Low energy injuries: For example, a simple fall from standing height in an osteoporotic patient resulting in pubic rami fracture. These are usually ‘stable’ injuries, not requiring surgery. Higher energy injuries can be associated with soft tissue and vascular injury. In particular, the bladder and urethra are at high risk of damage. Vascular injury can result in life threatening hemorrhage. Sacroiliac Joint Dysfunction: The sacroiliac joint, which connects the sacrum to the ilium, plays a key role in transferring weight from the upper body to the lower limb. Inflammation, degeneration, or instability of this joint can lead to chronic pain and impaired mobility. Functions of the Pelvis The strong and rigid pelvis is adapted to serve a number of roles in the human body. The main functions being: Transfer of weight from the upper axial skeleton to the lower appendicular components of the skeleton, especially during movement. Provides attachment for a number of muscles and ligaments used in locomotion. Contains and protects the abdominopelvic and pelvic viscera. The Greater and Lesser Pelvis 49 The osteology of the pelvic girdle allows the pelvic region to be divided into two: Greater pelvis (false pelvis) – located superiorly, it provides support of the lower abdominal viscera (such as a ileum and sigmoid colon). It has little obstetric relevance. Lesser pelvis (true pelvis) –located inferiorly. Within the lesser pelvis reside the pelvic cavity and pelvic viscera. The junction between the greater and lesser pelvis is known as the pelvic inlet. The outer bony edges of the pelvic inlet are called the pelvic brim. Pelvic inlet The pelvic inlet marks the boundary between the greater pelvis and lesser pelvis. Its size is defined by its edge, the pelvic brim. The borders of the pelvic inlet: Posterior – sacral promontory (the superior portion of the sacrum) and sacral wings (ala). Lateral – arcuate line on the inner surface of the ilium, and the pectineal line on the superior pubic ramus. Anterior – pubic symphysis. 50  The pelvic inlet determines the size and shape of the birth canal, with the prominent ridges key areas of muscle and ligament attachment. Some alternative descriptive terminology can be used in describing the pelvic inlet: Linea terminalis – the combined pectineal line, arcuate line and sacral promontory. Iliopectineal line – the combined arcuate and pectineal lines. This represents the lateral border of the pelvic inlet. Pelvic outlet The pelvic outlet is located at the end of the lesser pelvis, and the beginning of the pelvic wall. Its borders are: Posterior: The tip of the coccyx Lateral: The ischial tuberosities and the inferior margin of the sacrotuberous ligament