Science OLympiad cheat sheet, Cheat Sheet of Anatomy

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● The skin and its accessory organs like nails and hair form the integumentary system. The skin is composed of the epidermis, dermis, and hypodermis layers. ● - Epidermis: Made up of stratified squamous epithelium and keratinocytes, which produce keratin. It has five layers in thick skin and four layers in thin skin: ● ● - Stratum basale (deepest layer, responsible for new cell growth)- Stratum spinosum ● ● - Stratum granulosum- Stratum corneum (outermost layer, composed of dead cells) ● ● (^) - Keratinocytes are the main cells of the epidermis. Melanocytes produce melanin, which- Stratum lucidum (only found in thick skin, such as the palms and soles) gives skin its pigment. Merkel cells function as touch receptors, and Langerhans cells are immune cells found in the epidermis. ● - The dermis lies beneath the epidermis, connecting via the basal lamina, and contains collagen and elastic fibers. It also houses blood vessels, nerves, sweat glands, and ● sebaceous (oil) glands.- The hypodermis is the deeper layer that connects the skin to muscle and bone, serving ● as a storage area for adipose tissue (fat)### Hair and Nails ● ● - Hair shaft (visible part)- Hair bulb (surrounds the root under the skin) ● ● - Medulla (core of the hair)- Cuticle (outer layer) ● ● (^) - Phases of growth:- Anagen (growth phase) ● ● - Catagen (transitional phase)- Telogen (resting phase) ● ● - Nails grow from nail beds and are primarily composed of keratin.### Sweat and Oil Glands ● - Eccrine glands: Found throughout the body, these regulate temperature by releasing sweat. ● - Apocrine glands: Located in areas like the armpits and groin, these are activated by stress and emotions. ● - Sebaceous (oil) glands: Produce oil to waterproof and soften the skin. They become active during puberty. ● ● ### Skin Conditions- Melanoma is the most dangerous form of skin cancer, involving uncontrolled growth of ● melanocytes.- Basal cell carcinoma and squamous cell carcinoma are other types of skin cancers that ● affect different layers of the epidermis.- Common skin conditions include eczema, acne, and vitiligo. ● - Jaundice causes yellowing of the skin due to high levels of bilirubin. Approximately 24% of people aged 18 to 50 have tattoos. Meissner's corpuscles detect pressure and touch, while Merkel cells are located in the basal layer of the epidermis. Meissner's corpuscles are encapsulated, while Merkel cells are not. Arteries in the skin dilate during strenuous activity, causing the face to appear flushed. Basal cell carcinoma is a type of skin cancer that originates in the stratum basale and is the most common cancer in the U.S. Squamous cell carcinoma affects keratinocytes of the stratum spinosum and can metastasize. Melanoma is the uncontrolled growth of melanocytes and is the most fatal type of skin cancer. Eczema is often due to allergies, and acne results from clogged pores. Scars in the skin are rich in collagen. Keloid scars are raised above the surface of the skin. Bed sores are regions of skin that necrotize due to pressure from prolonged periods of time. Second-degree burns injure both the epidermis and the dermis. The hypodermis helps store adipose tissue. Langerhans cells are found in the stratum spinosum. The papillary and reticular layers of the dermis are composed of loose connective tissue. ● ### Skeletal System The epiphyseal plate is the growth plate. The medullary cavity is the hollow part of the diaphysis. Hyaline cartilage is a type of transparent cartilage. Inside the medullary cavity, there is a lining called the endosteum, where bone repair occurs. The outer layer of bone is covered in a fibrous membrane called the periosteum. The periosteum contains arteries, veins, and nerves. Articular cartilage absorbs shock. There are three classes of bone markings: articulations, projections, and holes. Articulations are used to join bones to create joints. Projections are raised areas of bone that serve as attachment points for tendons and ligaments. Holes are openings and grooves for arteries, veins, or nerves. Osteoblasts produce bone matrix during the process of calci the matrix of bone. Osteogenic stem cells are the precursor cells of bone and are the only bone cellsfication and become osteocytes, which maintain bone tissue. Osteoblasts form capable of mitosis. Osteocytes are located in spaces called lacunae and release enzymes to maintain bone. Canaliculi are small channels that allow osteocytes to receive nutrients and communicate with other cells. Osteogenic cells are located in the periosteum and the marrow. Osteoclasts are found at the surface of bone. The structural units of compact bone are osteons, also known as Haversian systems. The perforating canals, also called Volkmann's canals, connect the periosteum and endosteum. Osteocytes are found in the concentric circles of osteons. In spongy bone, osteocytes are found in the trabecular spaces. Sometimes, the cavities in spongy bone contain red marrow. Paget's disease is caused by overactive osteoclasts. Osteoporosis is more common in the femur, vertebrae, and wrist. Ossification (or osteogenesis) is the process of creating bone. Fetuses first create a template of cartilage, which is then replaced by bone as the cartilage is gradually broken down. Cartilage is avascular, meaning it is not easy to repair. The two types of ossification are endochondral ossification and intramembranous ossi spongy bone. The ossification. Intramembranous ossification center is a cluster of osteoblasts in the mesenchyme. Osteoblasts secrete anfication occurs when mesenchymal cells directly become compact and uncalci these trapped cells become osteocytes that maintain the bone. Trabecular bone results from mineralizedfied matrix called osteoid. Osteoid eventually traps osteoblasts in the matrix after it is calcified, and osteoid formed around capillaries. During intramembranous ossi capillaries and can condense to become red marrow. Capillaries can pass through spongy bone. The skull andfication, trabecular bone forms around collarbone are not fully ossi deformation. fied at birth to allow movement through the birth canal, permitting slight Six to eight weeks after conception, mesenchymal cells begin to differentiate into chondrocytes, and the perichondrium forms at this time. There are five main steps in endochondral ossification: Step One is when mesenchymal cells become chondrocytes; Step Two is when cartilage, which is a precursor to bone, forms; Step Three is when capillaries form inside and around the cartilage, and the perichondrium transforms into the periosteum; Step Four is the formation of the primary ossi the secondary ossification centers in the epiphyses. fication center; and Step Five is the formation of Epiphyseal plates are growth plates. Appositional growth is the widening of bones. The breaking down and rebuilding of bone is called bone remodeling. Closed reduction of a fracture is the process of setting the bone without surgery, while open reduction involves surgery. A fracture hematoma is the pooling of blood due to a fracture. An internal callus is a cartilage matrix between the two ends of a broken bone, while an external callus consists of hyaline cartilage and bone outside the break. Generally, if a bone heals well, there should be no evidence of the fracture. Calcium cannot be absorbed without vitamin D, and vitamin K also helps with bone mineralization. More than 60% of magnesium in the body is found in the skeleton. Parathyroid hormone increases calcium absorption in the small intestine and kidneys. Hypercalcemia refers to high calcium levels, while hypocalcemia refers to low calcium levels. Articular cartilage covers the epiphysis of bone. ● ● There are 206 bones in the human body, divided into:- Axial skeleton (80 bones): Skull, vertebrae, and rib cage. ● ● - Appendicular skeleton (126 bones): Limbs and their attachments.- Bone Structure: ● (^) cells) are found in lacunae. These cells receive nutrients via canaliculi.- Compact bone contains osteons (structural units), where osteocytes (mature bone ● ● (^) - Bone Growth and Repair:- Spongy bone is lighter and houses red marrow (site of blood cell production). ● ● - Osteoblasts build new bone, while osteoclasts break down bone tissue.- Endochondral ossification and intramembranous ossification are the two types of bone formation. The first replaces cartilage with bone, while the latter forms bone directly from mesenchymal cells. ● (^) development of an internal callus (cartilage) and external callus (bone and cartilage).- Bone repair involves the formation of a fracture hematoma, followed by the ● ● - Joints and Movement:- Articulations connect bones to form joints. ● ● - Projections are raised areas of bone for the attachment of muscles and tendons.- Holes in bones allow for the passage of blood vessels and nerves. ● ● - Each vertebra attaches to adjacent vertebrae or intervertebral discs.- The vertebral column originally develops with 33 vertebrae, but by adulthood, some fuse ● to form 24 distinct vertebrae.- Includes seven cervical vertebrae, 12 thoracic vertebrae (T1 to T12), and five lumbar ● vertebrae (L1 to L5).- The adult spine has four main curves, with two primary arches present from birth. ● ● - The vertebral arch is made up of the left and right pedicles and laminae.- Intervertebral discs, consisting of cartilage, attach to adjacent vertebrae. ● - The first cervical vertebra (C1) is known as the atlas and acts as an axis for head rotation. ● ● - The lumbar vertebrae are the largest and most load-bearing.- The sacrum forms from the fusion of five sacral vertebrae during adolescence. ● ● - The coccyx, or tailbone, is the final segment of the vertebral column.- Intervertebral discs are composed of two parts: ● - Annulus fibrosus (tough outer layer) ● ● (^) - Herniated discs occur when the nucleus pulposus deforms, often causing pain.- Nucleus pulposus (allows disc compression) ● ● - The anterior longitudinal ligament prevents excessive backward bending.- The posterior longitudinal ligament supports the vertebral column during forward ● bending.- The supraspinous ligament thickens near the cervical vertebrae and becomes the ● nuchal ligament.- The thoracic cage consists of 12 pairs of ribs. ● - Ribs attach to the thoracic vertebrae, with the sternum anchoring them at the front and the spine at the back. ● ● - The manubrium is the wide, upper part of the sternum, with the jugular notch at the top.- Ribs are numbered based on the thoracic vertebrae they attach to. ● ● - Costal cartilage (hyaline cartilage) connects ribs to the sternum.- The head of each rib connects to the costal cartilage. ● ● - The clavicle (collarbone) attaches to the sternum at the sternal angle.- The inferior part of the sternum, called the xiphoid process, becomes ossified by middle ● age.- Ribs 1 to 7 are known as true ribs (vertebrosternal ribs), while ribs 8 to 12 are false ribs ● (vertebrochondral ribs).- Parts of a rib include: ● ● - Head (attaches to spine)- Shaft (narrow, lengthened portion) ● ● - Tubercle (bump on the posterior rib surface)- Angle (point of greatest curvature) ● ● - Shaft (remaining part of the rib)- Costal cartilage (attaches rib to sternum) ● ● - Ribs 11 and 12 are floating ribs, not attaching to the sternum.- Fontanels are soft spots on an infant's skull that allow the head to pass through the birth ● canal.FIRST SEVEN RIBS ARE TRUE RIBS<LAST % RIBES ARE FALSE RIBS ● Floating ribs are 11-12Location because they are not attached to the sternum or to any other ribs in the front. They are: The last two pairs of ribs are called floating ribs ●^ attached only to the vertebrae at the back. 1. Cervical Vertebrae (C1 - C7) ● Location neck region.: The top portion of the spine, consisting of seven vertebrae (C1 to C7) in the ● Special Vertebrae vertebra, C2 (also called the: The first cervical vertebra, C1 (also called the Axis ), are specialized for head movement. Atlas ), and the second ● Function : ○ Support : The cervical vertebrae support the skull and neck, allowing ○ for a wide range of head movements. Flexibility : Enables the head to nod (C1) and rotate (C2) due to the ○ unique structure of the atlas and axis. Protection : Protects the upper part of the spinal cord and supports ○^ the blood vessels that travel to the brain. 2. Thoracic Vertebrae (T1 - T12) ● Location each connected to a pair of ribs.: The middle portion of the spine, consisting of twelve vertebrae (T1 to T12), ● Function : ○ Protection : Protects vital organs such as the heart and lungs by ○ forming part of the thoracic cage (rib cage). Support : Provides structural support for the upper body and ○ attaches to the ribs. Limited Movement : Allows limited flexibility compared to the cervical or lumbar spine, as the thoracic vertebrae must stabilize the rib cage. ● Location : The lower back region, consisting of five vertebrae (L1 to L5).^ ○^ 3. Lumbar Vertebrae (L1 - L5) ● Function : ○ Weight-bearing : The lumbar vertebrae are the largest and strongest ○ vertebrae because they support most of the body’s weight. Flexibility and Movement : These vertebrae allow for more flexibility and movement in the lower back, including bending, twisting, and lifting motions. ○ Protection region. : Protects the spinal cord and nerves in the lower back ● Location : The sacral vertebrae consist of five vertebrae (S1 to S5) that are fused^ ○^ 4. Sacral Vertebrae (S1 - S5) ● together to form a single bone called the Function :^ sacrum. ○ Support the pelvis (hip bones), enabling weight transfer from the upper body: Provides a strong foundation by connecting the spine to ○ to the lower limbs. Stability : The sacrum adds stability to the pelvis, which is crucial for ○ standing, walking, and other movements. Protection : Protects the lower spinal nerves and reproductive ○^ organs. 5. Coccygeal Vertebrae (Coccyx) ● Location together at the very base of the spine.: The coccyx, or tailbone , is made up of 3-5 small vertebrae that are fused ● Function : ○ Support : Provides support for the muscles, tendons, and ligaments ○ in the pelvic floor, helping in balance and posture. Attachment : Acts as an attachment site for various muscles that ○ contribute to the pelvic region’s function. Minimal Function : Although the coccyx has limited functional significance today, it represents a vestigial structure from when our ancestors had tails. ● ● - Fontanels decrease in size and disappear by age two. ● ● - Craniosynostosis occurs when skull sutures close prematurely, preventing brain growth.- The ethmoid bone forms the roof of the nasal cavity. ● ● (^) - Krista Galli is a projection in the nose cavity formed by the ethmoid bone. - There are 14 facial bones and 8 cranial bones. ● ● - The scapula (shoulder blade) joins with the humerus to form the shoulder joint.- The clavicle joins the scapula at the coracoclavicular ligament. ● ● - The acromioclavicular joint is the clavicle-to-scapula joint.- The glenohumeral joint connects the scapula and humerus. ● - The clavicle supports the scapula, allowing shoulder motion and protecting nerves and blood vessels beneath it. ● ● - Three parts of the clavicle include:- Medial (sternal end) ● ● - Lateral- Shaft ● - The medial end forms the sternoclavicular joint with the sternum, allowing clavicle and scapula motion. ● ● - The pectoral girdle is composed of the clavicle and scapula.- The scapula has three borders: superior, medial, and lateral. ● ● - The inferior angle of the scapula attaches to multiple muscles.- The glenoid cavity of the scapula forms the glenohumeral joint. ● ● - The acromion touches the clavicle, forming part of the shoulder joint.- The scapula has three indentations (fossa). ● ● - The acromioclavicular joint is supported by the coracoclavicular ligament.- The metacarpals form the palm (five bones in total). ● ● - The radius and ulna form the forearm.- The humerus forms the upper arm (single bone). ● ● (^) - The wrist contains eight carpal bones. - Fingers and thumbs contain 14 bones. ● ● - Each finger has three bones, while the thumb has two.- Phalanges are bones following the metacarpals. ● ● (^) - There are 30 bones in each upper extremity. - The proximal part of the humerus is called the head. ● ● - Below the head is the neck of the humerus.- The greater tuberosity is the upper part of the humerus and an attachment site for ● rotator muscles.- The deltoid is a V-shaped part of the humerus allowing attachment for the deltoid ● muscle.- Main grip strength muscles include the brachioradialis and flexor carpi radialis. ● - The trochlea connects the humerus to the ulna, while another part connects it to the radius. ● ● - The interosseous membrane runs between the radius and ulna.- The arm has a 5-15° angle, called the carrying angle, to prevent the arms from hitting ● the hips while walking.- Carpal bones and flexibility form the carpal tunnel. ● - Carpal tunnel syndrome results from compression of the median nerve, causing pain in the hand. ● - The pelvic girdle is formed by the hip bone (coxal bone) and provides attachment for the lower extremities. ● The carpal bones, along with the flexor retinaculum, form the carpal tunnel. Carpal tunnel syndrome is caused by the compression of the median nerve, leading to pain in the hand. The pelvic girdle is formed by a pair of hip bones, also known as coxal bones, which provide attachment points for the lower extremities. The pelvis is extremely strong, immobile, and serves as a weight-bearing structure. The bony pelvis is the complete ● structure made up of the two hip bones, sacrum, and coccyx.The ilium is the upper part of the hip bone, while the ischium is the lower part. The ischium contributes to the bottom of the coxal bone, and the pubis completes the rest of the coxal bone structure. The sacrotuberous ligament connects the sacrum to the coxal bone. The cavity of the pelvis contains the acetabulum, which is the socket for the hip joint. The opening between the ischium and the pubis is known as the obturator foramen. The posterior sacroiliac ligament supports the sacroiliac joint. ● ● The subpubic angle is larger in females than in males. Female pelvises are generally lighter and thinner than male pelvises, with the subpubic angle being greater than 80 degrees in females and less than 70 degrees in males. ● The lower limb is composed of three parts: the thigh (between the hip joint and the knee joint), the leg (between the knee and the ankle joints), and the foot. The femur is the single bone in the thigh and is roughly one-quarter of a person's height. The head of the femur articulates with the acetabulum to form the hip joint. The fovea capitis is an indentation on the head of the femur that serves as the attachment point for the ligamentum teres and allows the medial femoral circumflex artery to pass through, ● supplying blood to the femur.The neck of the femur is located between the head and the greater trochanter, and fractures commonly occur in this region. The bottom of the femur is the lateral epicondyle. The linea aspera is a ridge on the posterior side of the femur. The lesser trochanter serves as the attachment point for two muscles: the psoas major and the ● iliacus.The tibia is known as the shinbone, while the patella (kneecap) does not articulate with the fibula. The proximal epiphysis of the tibia is expanded to facilitate its articulation with the femur. The side of the proximal epiphysis facing the other leg is the medial condyle, while the side facing away is the lateral condyle. ● ● The patella is the largest sesamoid bone, and the fibula is not weight-bearing; its primary purpose is to provide muscle attachment. The anatomy of the foot is similar to that of the hand, but it contains tarsal bones instead of carpal bones. The talus is the ankle bone, and the big toe is called the hallux. The upper bones of the toes are also known as phalanges. ● Each limb develops from a limb bud, and all limb bones are formed by endochondral ossification. The ossification of the clavicle occurs by around age 25. The greater tubercle is located on the lateral side of the proximal humerus. MUSCULAR ● Frontalis: Origin: Galea aponeurotica, Insertion: Skin of the forehead, Function: Raises ● eyebrows, wrinkles forehead, Role: SynergistOrbicularis oris: Origin: Maxilla and mandible, Insertion: Skin around the lips, Function: Closes and puckers lips, Role: Agonist ● Orbicularis oculi: Origin: Frontal bone and medial palpebral ligament, Insertion: Lateral palpebral raphe, Function: Closes eyelids, Role: Agonist ● Occipitofrontalis: Origin: Occipital and frontal bones, Insertion: Skin of the forehead, Function: Moves scalp, raises eyebrows, Role: Synergist ● Zygomaticus major: Origin: Zygomatic bone, Insertion: Corner of the mouth, Function: Elevates lips (smiling), Role: Agonist ● Masseter: Origin: Zygomatic arch, Insertion: Mandible, Function: Closes jaw, Role: ● AgonistSternocleidomastoid: Origin: Manubrium of sternum and clavicle, Insertion: Mastoid ● process of temporal bone, Function: Rotates and flexes neck, Role: AgonistTrapezius: Origin: Occipital bone, vertebral column, Insertion: Clavicle, scapula, Function: ● Moves, stabilizes scapula, Role: SynergistBuccinator: Origin: Alveolar processes of maxilla and mandible, Insertion: Orbicularis oris, Function: Compresses cheek, Role: Agonist ● Pectoralis major: Origin: Clavicle, sternum, ribs, Insertion: Humerus, Function: Adducts, flexes arm, Role: Agonist ● Latissimus dorsi: Origin: Vertebrae, iliac crest, Insertion: Humerus, Function: Extends, ● adducts arm, Role: AgonistDeltoid: Origin: Clavicle, scapula, Insertion: Humerus, Function: Abducts arm, Role: ● AgonistTeres major: Origin: Scapula, Insertion: Humerus, Function: Medial rotation, adduction of ● arm, Role: SynergistBiceps brachii: Origin: Scapula, Insertion: Radius, Function: Flexes elbow, supinates forearm, Role: Agonist ● Triceps brachii: Origin: Scapula, humerus, Insertion: Ulna, Function: Extends elbow, Role: Agonist ● ● Brachialis: Origin: Humerus, Insertion: Ulna, Function: Flexes elbow, Role: SynergistBrachioradialis: Origin: Humerus, Insertion: Radius, Function: Flexes elbow, Role: ● SynergistPalmaris longus: Origin: Humerus, Insertion: Palmar aponeurosis, Function: Flexes wrist, Role: Synergist ● Flexor carpi radialis: Origin: Humerus, Insertion: Metacarpals, Function: Flexes wrist, abducts hand, Role: Agonist ● Flexor digitorum superficialis: Origin: Humerus, radius, ulna, Insertion: Middle phalanges, Function: Flexes fingers, Role: Agonist ● Extensor carpi radialis: Origin: Humerus, Insertion: Metacarpals, Function: Extends wrist, abducts hand, Role: Agonist ● Extensor digitorum: Origin: Humerus, Insertion: Phalanges, Function: Extends fingers, ● Role: AgonistExtensor digiti minimi: Origin: Humerus, Insertion: Phalanges, Function: Extends little ● finger, Role: AgonistExtensor carpi ulnaris: Origin: Humerus, Insertion: Metacarpal, Function: Extends wrist, ● adducts hand, Role: AgonistInfraspinatus: Origin: Scapula, Insertion: Humerus, Function: Lateral rotation of arm, Role: Synergist ● Supraspinatus: Origin: Scapula, Insertion: Humerus, Function: Abducts arm, Role: Synergist ● Subscapularis: Origin: Scapula, Insertion: Humerus, Function: Medial rotation of arm, Role: Synergist ● Teres Minor: Origin: Scapula, Insertion: Humerus, Function: Lateral rotation of arm, Role: Synergist ● External intercostals: Origin: Inferior border of ribs, Insertion: Superior border of next rib, ● Function: Elevates ribs for inhalation, Role: AgonistInternal intercostals: Origin: Superior border of ribs, Insertion: Inferior border of previous rib, Function: Depresses ribs for exhalation, Role: Antagonist ● Transverse abdominis: Origin: Iliac crest, ribs, Insertion: Linea alba, pubis, Function: Compresses abdomen, Role: Synergist ● Rectus abdominis: Origin: Pubis, Insertion: Ribs, xiphoid process, Function: Flexes vertebral column, Role: Agonist ● Serratus anterior: Origin: Ribs, Insertion: Scapula, Function: Protracts scapula, Role: Synergist ● Diaphragm: Origin: Sternum, ribs, vertebrae, Insertion: Central tendon, Function: ● Increases thoracic cavity volume, Role: AgonistIliopsoas: Origin: Iliac fossa, vertebrae, Insertion: Femur, Function: Flexes thigh, Role: ● AgonistSartorius: Origin: Iliac spine, Insertion: Tibia, Function: Flexes, abducts, laterally rotates ● thigh, Role: SynergistGluteus maximus: Origin: Ilium, sacrum, coccyx, Insertion: Femur, Function: Extends thigh, Role: Agonist ● ● Gluteus medius: Origin: Ilium, Insertion: Femur, Function: Abducts thigh, Role: SynergistTensor fasciae latae: Origin: Iliac crest, Insertion: Iliotibial tract, Function: Flexes, abducts ● thigh, Role: SynergistAdductor longus: Origin: Pubis, Insertion: Femur, Function: Adducts thigh, Role: Agonist ● Gracilis: Origin: Pubis, Insertion: Tibia, Function: Adducts thigh, flexes knee, Role: Synergist ● Semimembranosus: Origin: Ischial tuberosity, Insertion: Tibia, Function: Extends thigh, ● flexes knee, Role: AgonistSemitendinosus: Origin: Ischial tuberosity, Insertion: Tibia, Function: Extends thigh, flexes ● knee, Role: AgonistBiceps femoris: Origin: Ischial tuberosity, femur, Insertion: Fibula, tibia, Function: Extends ● thigh, flexes knee, Role: AgonistRectus femoris: Origin: Iliac spine, Insertion: Patella, tibia, Function: Extends knee, flexes thigh, Role: Agonist ● Vastus lateralis: Origin: Femur, Insertion: Patella, tibia, Function: Extends knee, Role: Agonist ● Vastus intermedius: Origin: Femur, Insertion: Patella, tibia, Function: Extends knee, Role: Agonist ● Vastus medialis: Origin: Femur, Insertion: Patella, tibia, Function: Extends knee, Role: Agonist ● Tibialis anterior: Origin: Tibia, Insertion: Metatarsals, Function: Dorsiflexes, inverts foot, ● Role: AgonistGastrocnemius: Origin: Femur, Insertion: Calcaneus, Function: Plantar flexes foot, Role: Agonist ● Soleus: Origin: Tibia, fibula, Insertion: Calcaneus, Function: Plantar flexes foot, Role: Synergist ● Peroneus longus: Origin: Fibula, Insertion: Metatarsal, Function: Everts foot, Role: Synergist ● Peroneus brevis: Origin: Fibula, Insertion: Metatarsal, Function: Everts foot, Role: Synergist Skeletal muscle moves the skeleton, which is why it is called skeletal muscle. Smooth muscles are involuntary. Skeletal muscle has elastic fibers to return to its original length. Cardiac muscle cells have one to two nuclei and are striated. Skeletal muscle cells have multiple nuclei and are also striated. Smooth muscle has one nucleus and is not striated. Each skeletal muscle is surrounded by three layers of connective tissue called the mysia. The epimysium is a single layer that prevents loss of muscle shape. The perimysium organizes muscle fibers into fascicles. Sarcomeres are enclosed by the endomysium. The whole muscle is enclosed by the epimysium. Muscle fibers can be up to 30 cm long. The membrane of a sarcomere is called the sarcolemma, and its cytoplasm is called the sarcoplasm. The thin line in the middle of a sarcomere is the M-line. Z-lines separate adjacent sarcomeres. The sarcomere is the functional unit of muscle contraction. Tropomyosin blocks actin from interacting with myosin until muscle contraction is promoted. The troponin-tropomyosin complex allows actin and myosin to interact and return to their original positions. Actin is thinner than myosin, and together with the troponin-tropomyosin complex, they are referred to as thin filaments. Myosin strands form the thick filaments of the sarcomere. Z-lines are the boundaries of

sarcomeres. Muscle cells can Acetylcholine (ACh) improves the efficiency of signal transduction in sarcomeres. Muscle fatigue is due to the loss of ATP and the buildup of lactic acid. Troponin-tropomyosin complexes prevent muscle contraction until calcium ions (Ca² actin-myosin complex to form. Each thick filament is made up of about 300 myosin molecules. Creatine⁺) bind to troponin, which allows the phosphate can quickly regenerate ATP, but only provides roughly 15 seconds of energy. Creatine phosphate is a quicker but less efficient source of ATP than glucose. Pyruvic acid becomes lactic acid when used in anaerobic respiration.There are two main types of muscle contractions: isotonic and isometric. Isometric contractions do not change the length of the muscle, while isotonic contractions do. Concentric isotonic contractions involve the shortening of the muscle during load lifting, whereas eccentric contractions involve lengthening of the muscle under load. A motor unit is a group of sarcomeres innervated by a single nerve. A twitch is composed of three phases: latent, contraction, and relaxation. The latent phase is when the muscle receives the signal to contract, the contraction phase is when the muscle contracts, and the relaxation phase is when the muscle relaxes. The tension of a twitch can be measured by a myogram. Graded muscle response is the strength of a contraction based on the number of times the nerve fires. The rate at which nerves fire allows muscle twitches to be added together to create stronger contractions, which is known as wave summation. Wave summation is a gradual increase in contractile strength. Tetanus occurs when the frequency of nerve firing becomes so high that the relaxation period on the myogram disappears completely. Treppe refers to the increasing amplitude of muscle contractions on a myogram, indicating that muscle contraction is becoming more efficient. This is also known as the staircase effect. During the latent phase, calcium ions are released from the sarcoplasmic reticulum. All skeletal muscles are partially contracted to stabilize the skeleton and joints, a process known as muscle tone. Hypotonia is the absence of muscle tone, and hypertonia is too much muscle tone.There are three main types of skeletal muscle fibers: slow oxidative fibers, fast oxidative fibers, and fast glycolytic fibers. Slow oxidative (SO) fibers use ATP slowly, are aerobic, and are resistant to fatigue. Fast oxidative (FO) fibers contract quickly, are generally aerobic but can switch to glycolysis (anaerobic) under intense activity. Fast glycolytic (FG) fibers contract extremely quickly, are used for short bursts of power, and fatigue rapidly as they are anaerobic. SO fibers produce lower strength contractions but are ideal for endurance and joint stabilization. FO fibers are intermediate, while FG fibers are the most powerful but fatigue quickly. SO fibers produce more ATP than FG fibers, allowing them to sustain muscle activity for long periods. Hypertrophy refers to the thickening of myofibrils due to the addition of structural proteins, while the loss of structural proteins results in muscle atrophy. Age-related atrophy is called sarcopenia. SO fibers are commonly engaged during endurance exercises, which promote angiogenesis, the formation of a large capillary network around the myofibrils. Resistance exercises primarily engage FG fibers, which take up more space in the muscle, explaining why bodybuilders have more FG fibers. Anabolic steroids are synthetic forms of testosterone that enhance muscle growth. Sarcopenia is age-related muscle loss and is not reversible. Intercalated discs allow cardiac muscle cells to contract together by acting as junctions that relay contraction signals. These discs essentially make cardiac muscle cells function as a single unit, known as a functional including the eyes, skin, and internal organs. Smooth muscle in the skin, specifically the syncytiumSmooth muscle, known for its lack of striations, is found in various parts of the body erector pilly muscles, causes hair to stand up (piloerection) in response to cold or emotional stimuli. Unlike skeletal muscle, smooth muscle contains dense bodies, which function similarly to the Z discs in skeletal muscle but do not create striations. Smooth muscle lacks troponin, relying instead on contraction by binding to calcium ions. Dense bodies are attached to the sarcolemma (the plasma membrane calmadulin (not "eel monden") to regulate of the muscle cell), and calcium ions that regulate contraction come not just from the sarcoplasmic reticulum but also from extracellular sources. Calcium ions bind to light-chain kinase, leading to muscle contraction. Smooth muscle fibers are smaller in diameter than both calmadulin , initiating a cascade that activates myosin skeletal and cardiac muscle fibers. Intermediate filaments, connecting dense bodies, help transmit tension across the cell. Smooth muscle is not controlled voluntarily by the central nervous system but is instead regulated by the autonomic nervous system (ANS). Neurotransmitters are released from varicosities, which are swellings along autonomic nerve fibers, into the synaptic cleft to stimulate smooth muscle cells. This arrangement differs from the more precise neuromuscular junctions seen in skeletal muscle. Smooth muscle is categorized into two types: single-unit (visceral) smooth muscle, found in the walls of hollow organs, and multi-unit smooth muscle, found in the large airways, eyes (specifically the iris and ciliary muscles), and large blood vessels. Single-unit smooth muscle exhibits a stress-relaxation response, meaning it contracts when stretched but quickly relaxes to maintain tone without prolonged contraction. Multi-unit smooth muscle does not exhibit this behavior and is activated more precisely by neural input. Smooth muscle cells can divide and grow through a process called hyperplasia, unlike skeletal and cardiac muscle, which do not typically regenerate and instead form scar tissue, a process known as fibrosis. Specialized smooth muscle cells, known as pericytes, help regenerate smooth muscle in certain organs like blood vessels. Moving on to skeletal muscle mechanics: the origin of a muscle is the attachment point on the bone that remains stationary during contraction, while the insertion is the attachment point on the bone that moves. In the upper arm, the biceps brachii acts as the agonist (prime mover) in elbow flexion, while the triceps is the antagonist. The brachioradialis and brachialis act as synergists to help flex the forearm. The quads (quadriceps) and hamstrings are another example of agonist-antagonist muscle pairs, where quads are the agonists in knee extension and hamstrings are the antagonists. Stretching increases synovial fluid production, making the fluid less viscous and improving joint lubrication. Muscle fascicles (bundles of muscle fibers) are surrounded by connective tissue called the perimysium. Muscle fascicle arrangements include parallel, fusiform, unipennate, bipennate, multipennate, convergent, and circular configurations, which influence the range of motion and power of the muscle. The gluteus maximus is the largest muscle in the body, while the sartorius is the longest. Muscles like the biceps brachii have a fusiform shape, meaning they have a rounded belly and taper at the ends. Muscles with “brevis” in their name are typically short, such as the extensor carpi radialis brevis. The six extraocular muscles control eye movements: four rectus muscles (superior, inferior, medial, and lateral) and two oblique muscles (superior and inferior). The superior rectus moves the eye upward and inward, while the inferior rectus moves it downward and inward. The lateral rectus moves the eye outward, away from the nose, and the medial rectus moves it inward, toward the nose. The inferior oblique moves the eye upward and outward, and the superior oblique moves it downward and outward. Chewing (mastication) involves the masseter and temporalis muscles, which elevate the mandible, and the medial and lateral pterygoid muscles, which move the mandible side to side. Swallowing (deglutition) is controlled by several muscles, including the genioglossus, which allows the tongue to protrude, and the styloglossus, which pulls the tongue back into the mouth. The mylohyoid and stylohyoid muscles elevate the hyoid bone during swallowing, expanding the oral cavity. The sternocleidomastoid muscle rotates and tilts the head, while the scalene muscles (anterior, middle, and posterior) assist with flexion and lateral bending of the neck. The erector spinae muscles, including the spinalis, longissimus, and iliocostalis groups, stabilize the spine and are important for posture. In the torso, the four major abdominal muscles are the rectus abdominis, external obliques, internal obliques, and diaphragm and intercostal muscles (external and internal) are essential for breathing, while the levator ani and other pelvic floor muscles support pelvic organs. The muscles of the arm and forearm include the biceps brachii, brachialis, and brachioradialis as the main flexors, while the triceps brachii and anconeus are responsible for extension. The pronator teres and pronator quadratus muscles facilitate pronation (turning the palm downward), while the supinator muscle allows for supination (turning the palm upward). There are 33 vertebra in the human body,24 pre sacral vertebra Integumentary System ● Acne, Symptoms: Pimples, blackheads, whiteheads, oily skin, and possible scarring, Identifiable Factors: Hormonal changes, excess oil production, clogged hair follicles, bacteria, Cause: Hormonal changes during puberty, stress, certain medications, diet. ● Eczema (Atopic Dermatitis), Symptoms: Itchy, red, and dry skin, rashes, oozing or crusting, Identifiable Factors: Genetic predisposition, environmental triggers, allergens, ● Cause: Immune system dysfunction, skin barrier defects.Psoriasis, Symptoms: Red patches of skin covered with thick, silvery scales, dry, cracked skin, itching, Identifiable Factors: Genetic predisposition, immune system dysfunction, ● Cause: Overactive immune system, triggering skin cell production.Vitiligo, Symptoms: Loss of skin color in patches, white patches on the skin, hair turning white, Identifiable Factors: Autoimmune condition, genetic factors, Cause: Destruction of melanocytes (cells that produce skin pigment). ● Rosacea, Symptoms: Facial redness, swollen red bumps, visible blood vessels, eye irritation, Identifiable Factors: Genetic predisposition, environmental factors, blood vessel dysfunction, Cause: Unknown, but may involve immune system, mites, and bacteria. ● Athlete's Foot, Symptoms: Itchy, cracked, and peeling skin between the toes, burning sensation, Identifiable Factors: Fungal infection, warm, moist environments, Cause: ● Dermatophyte fungi.Impetigo, Symptoms: Red sores that quickly rupture, ooze, and form a yellow-brown crust, Identifiable Factors: Bacterial infection, poor hygiene, skin injuries, Cause: Staphylococcus or Streptococcus bacteria. ● Cellulitis, Symptoms: Red, hot, swollen skin, pain, fever, chills, Identifiable Factors: Bacterial infection, skin injuries, weakened immune system, Cause: Streptococcus or Staphylococcus bacteria. ● Hives (Urticaria), Symptoms: Red, itchy welts, swelling, burning sensation, Identifiable Factors: Allergic reactions, stress, infections, Cause: Release of histamine from mast ● cells.Cold Sores, Symptoms: Blisters around the mouth, tingling, itching, pain, Identifiable Factors: Herpes simplex virus type 1 (HSV-1), Cause: HSV-1 infection, triggered by ● stress, illness, or sun exposure.Ringworm, Symptoms: Red, itchy, circular rash, scaly skin, hair loss in affected area, Identifiable Factors: Fungal infection, close contact with infected individuals or animals, Cause: Dermatophyte fungi. ● Melanoma, Symptoms: New mole, changes in existing moles, asymmetry, irregular borders, color changes, Identifiable Factors: UV radiation exposure, genetic mutations, Cause: DNA damage from UV radiation. ● Basal Cell Carcinoma, Symptoms: Open sore, shiny bump, pink growth, scar-like area, Identifiable Factors: UV radiation exposure, fair skin, Cause: DNA damage from UV radiation. ● Squamous Cell Carcinoma, Symptoms: Rough, scaly patch, firm red nodule, ulceration, Identifiable Factors: UV radiation exposure, chronic sun exposure, Cause: DNA damage ● from UV radiation.Kaposi's Sarcoma, Symptoms: Purple patches, nodules, lesions on skin, mucous membranes, internal organs, Identifiable Factors: Human herpesvirus 8 (HHV-8), weakened immune system, Cause: HHV-8 infection, often seen in immunocompromised individuals. Skeletal System ● ● Pagets diseas is when osteocytes break down bone too fast with bone growing backOsteoporosis, Symptoms: Bone fractures, loss of height, stooped posture, back pain, pIdentifiable Factors: Low bone density on scans, history of fractures, Cause: Hormonal changes (e.g., menopause), calcium and vitamin D deficiency, inactivity. ● Osteoarthritis, Symptoms: Joint pain, stiffness, swelling, decreased range of motion, Identifiable Factors: X-ray showing joint space narrowing, bone spurs, Cause: Wear and tear of joints, aging, obesity. ● Rheumatoid Arthritis, Symptoms: Joint pain, swelling, morning stiffness, fatigue, Identifiable Factors: Blood tests showing rheumatoid factor or anti-CCP antibodies, joint ● swelling, Cause: Autoimmune disorder.Osteomalacia/Rickets, Symptoms: Bone pain, muscle weakness, difficulty walking, Identifiable Factors: Low levels of vitamin D, abnormal bone X-rays, Cause: Vitamin D ● deficiency.Gout, Symptoms: Sudden, severe joint pain, redness, swelling, warmth, Identifiable Factors: High levels of uric acid in blood, urate crystals in joint fluid, Cause: Build-up of uric acid crystals in joints. ● Osteosarcoma, Symptoms: Bone pain, swelling, noticeable mass, Identifiable Factors: X-ray showing bone lesions, biopsy confirming cancer, Cause: Genetic mutations, often in growing bones. ● Ewing Sarcoma, Symptoms: Bone pain, fever, swelling, palpable lump, Identifiable Factors: Imaging showing bone lesions, biopsy, Cause: Genetic mutations. ● Scoliosis, Symptoms: Uneven shoulders, waist, rib prominence, Identifiable Factors: ● Spine curvature on X-ray, Cause: Often idiopathic, genetic factors.Kyphosis, Symptoms: Humpback appearance, back pain, stiffness, Identifiable Factors: ● Abnormal spine curvature on X-ray, Cause: Aging, osteoporosis, spinal deformities.Lordosis, Symptoms: Excessive inward curve of the spine, back pain, Identifiable Factors: Abnormal spinal curve on physical exam, Cause: Obesity, poor posture, genetic factors. ● Tennis Elbow (Lateral Epicondylitis), Symptoms: Pain on the outside of the elbow, weak grip strength, Identifiable Factors: Pain with elbow movement, tenderness over the lateral epicondyle, Cause: Overuse, repetitive motion. ● Golfer's Elbow (Medial Epicondylitis), Symptoms: Pain on the inside of the elbow, weak grip strength, Identifiable Factors: Pain with wrist flexion, tenderness over the medial ● epicondyle, Cause: Overuse, repetitive motion.Meniscus Tears, Symptoms: Knee pain, swelling, locking or clicking of the knee, Identifiable Factors: MRI showing tear in meniscus, Cause: Injury, wear and ● ● MUSCULARMyasthenia Gravis : Muscle weakness, drooping eyelids, antibody tests; autoimmune ● disorder at neuromuscular junction. Polymyositis : Muscle weakness, muscle biopsy shows inflammation; autoimmune ● disorder. Dermatomyositis : Skin rash, muscle weakness, skin biopsy; autoimmune disorder. ● Muscular Dystrophy : Progressive muscle weakness, genetic testing; genetic mutations. ● Rhabdomyolysis medications. : Muscle pain, dark urine, elevated creatine kinase; muscle injury, ● Amyotrophic Lateral Sclerosis (ALS) mutations, environmental factors. : Muscle weakness, electromyography; genetic ● Fibromyalgia genetics or stress.: Widespread pain, tender points on exam; cause unknown, linked to ● Chronic Fatigue Syndrome : Severe fatigue, diagnosis based on symptoms; cause ● unknown, possibly viral infections. Carpal Tunnel Syndrome : Numbness, tingling, electromyography; median nerve ● compression in the wrist. Polymyalgia Rheumatica : Muscle pain, elevated inflammatory markers; cause ● unknown, possibly autoimmune. Duchenne Muscular Dystrophy : Progressive muscle weakness, genetic testing; genetic mutations affecting dystrophin. ● ● Myotonic DystrophyBotulism : Muscle weakness, toxin in blood or stool; Clostridium botulinum toxin.: Muscle stiffness, genetic testing; genetic mutations. ● Tetanus : Muscle stiffness, clinical diagnosis; Clostridium tetani toxin. ● Polio : Muscle weakness, virus detection; Poliovirus infection.