HBS Exam Study Guide PDF

1.2 HBS exam study guide What are muscles - The essential function of the muscles is contraction/shortening - Muscles are responsible for essentially ALL the body movement Similarities of all the 1. Skeletal and smooth muscle cells are elonga...

1.2 HBS exam study guide What are muscles - The essential function of the muscles is contraction/shortening - Muscles are responsible for essentially ALL the body movement Similarities of all the 1. Skeletal and smooth muscle cells are elongated. For this reason, these type of muscle cells are called muscle fibers (not muscles cardiac) 2. The ability of the muscles to shorten are because 2 types of myofilaments 3. Myo- means muscle Skeletal muscle fibers - Skeletal muscle fibers are packaged into organs called skeletal muscles - Attached to the bones or, for some facial muscles, to the skin - Single celled, very long, cylindrical, multinucleate cells with obvious striations - Voluntary contraction (only muscle subject to control) by nervous system - No rhythmic contraction which can range from slow to fast Connective tissue - Skeletal muscle are not ripped apart as they exert force because thousands wrappings of skeletal of fibers are bundled together by connective tissue, which provides muscle strength and support to the muscle - Each muscle fiber is enclosed in a connective sheath known as endomysium - Several sheathed fibers are wrapped by coarser fibrous membrane called perimysium to form a bundle of fibers called fascicle - Many fascicles are bound together by epimysium, which covers the entire muscle - The epimysia blend into the strong, cordlike tendons, or into sheetlike aponeuroses, which attach muscles indirectly to bones, cartilages, or connective tissue covering of each other Why is connective tissue necessary at each layer of muscle? - It is necessary for each sarcomere contraction to be connected so that the contraction is able to move the bone Tendon function - Tendons connect bones to muscles but also provide durability and conserve space - They are mostly tough collagenic fibers, so they can cross rough bony projects, which would tear the more delicate muscles tissues Smooth Muscle - No striations and is involuntary - Found mainly in the walls of hollow visceral organs (stomach, urinary bladder, respiratory passages) - Single celled, spindle shaped, uninucleated, no striations - Arranged in layers with one running circularly and the other longitudinally. As the two layers contract, it changes the shape/size of the organ - Contraction is very slow and constrained Cardiac Muscle - Cardiac muscle is found in the walls of the heart - Striated appearance & cardiac fibers are arranged in spiral bundles - Has branching chains of cells; uninucleated, striations, intercalated discs - Involuntary contractions because the heart has a pacemaker - Slow & rhythmic contractions Functions of muscle 1. Maintain posture 2. Stabilizing joints – skeletal muscles pull on bones to cause movements but also stabilize joints of the skeleton 3. Generate heat – generation of body heat as byproduct of muscle activity which is essential for maintaining body temperature Microscopic Anatomy of - The plasma membrane is called sarcolemma in muscle Skeletal Muscle cells - The long, ribbon-like organelles are called myofibrils - The striped appearance is because of the alternating light (I) and dark (A) bands - Myofibrils are made of contractile units called sarcomeres, which are then made of myofilaments. - Sarcomeres are the contractile unit of cardiac and skeletal muscle - This ultimately creates the bonding pattern. - There are two types of myofilaments: thick filaments and thin filaments Thick filament: - Also called myosin filaments which are made of protein called myosin - Also contain ATPase enzymes, which split ATP to generate the power for muscle contraction - Midparts are smooth but ends are studded with projections which are called myosin heads/cross bridges that link the thick and thin filaments together during contraction Thin filament: - Made of the contractile protein actin and regulatory proteins Sarcoplasmic Reticulum: - The role is to store calcium and release it on demand when the muscle fiber is stimulated to contract Contraction of muscle - The “all or none” law of muscle physiology ONLY applies to the muscle cell, not the whole muscle. It states that a as whole muscle cell will contract to its fullest extent when it is stimulated. - Skeletal muscles are organs that consist of thousands of muscle cells, and they react to stimuli with graded responses, or different degrees of shortening. - Graded muscle responses can be produced by changing the frequency of the muscle stimulation and changing the number of muscle cells being stimulated For Rapid Stimulation: - Nerve impulses are delivered to the muscle at a very rapid rate, so the muscle does not get a chance to relax completely - When the muscle is stimulated so rapidly that no evidence of relaxation is seen and the contractions are sustained/smooth, the muscle is said to be complete, fused, or in a tetanic contraction. - Until this point, the muscle is unfused/incomplete Energy for muscle - As a muscle contract, the bonds of ATP molecules are hydrolyzed to release the energy contractions - ATP is the only energy source that can be used directly to power muscle activity 3 pathways for ATP regeneration: 1. Direct Phosphorylation of ADP by creatine phosphate - The unique high energy molecule creatine phosphate (CP) is found in muscle fibers. As ATP is depleted, interactions between CP and ADP result in the transfer of the phosphate group from CP to ADP 2. Aerobic Respiration - Occurs in mitochondria and involves metabolic pathways (known as oxidative phosphorylation) that use oxygen  - Glucose is broken down into carbon dioxide and water - Fairly slow, needs continuous delivery of oxygen and nutrient fuels to the muscle, high ATP yield 3. Anaerobic glycolysis and lactic acid formation - The initial steps of glucose breakdown occur in a pathway called glycolysis, which does not use oxygen - During glycolysis, which occur in the cytosol, glucose is broken down to pyruvic acid and small amounts of ATP are captured - As long as enough oxygen is present, the pyruvic acid enters the oxygen-requiring aerobic pathways that occur within mitochondria to produced ATP - If the activity is too intense or oxygen/glucose delivery is inadequate, the pyruvic acid is converted to lactic acid by a process called anaerobic glycolysis - Can cause muscle soreness, produces little ATP, much faster Muscle Fatigue - A muscle is fatigued when it is unable to contract even though it is still being stimulated - Without rest, an active or working muscle begins to tire and contract more weakly until it stops contracting altogether - It is believed to result from the oxygen debt that occurs during prolonged muscle activity: a person is not able to take in oxygen fast enough to supply the muscles - When there isn’t enough oxygen, the muscles start to get lactic acid → increasing acidity and lack of ATP causes muscles to stop contracting - Types of Muscle - The event that is common in ALL muscle contraction is that tension develops in the muscle as the actin and myosin Contractions myofilaments interact Isotonic Contractions: Muscle shortens and movement occurs - Bending the knee, rotating arms, smiling Isometric Contractions: Tension in the muscle is increasing, myosin myofilaments are trying to slide but the muscle is pitted against immovable object - Lifting 400 lb object, pushing against wall with bent elbows Muscle tone - Continuous partial contractions are called muscle tone - When muscle is relaxed, some of the fibers are contracting - As a result, the muscle remains firm and healthy Muscle Rules 1. With a few exceptions, ALL muscles cross at least one joint 2. The bulk of the muscle lies proximal to the joint crossed 3. All muscles have at least 2 attachments: origin and insertion 4. Muscles can only pull NEVER push 5. During contraction, the muscle insertion moves towards the origin Origin VS. insertion - Each one of our 600 skeletal muscles are attached to bone or connective tissue at no less than 2 points Origin: attached to the immovable or less movable bone Insertion: attached to the movable bone, and when the muscle contract it moves towards the origin Common movements of 1. Flexion joints - A movement, typically in the sagittal plane, that decreases the angle of the joint & brings two bones closer together - Typical of hinge joints (bending knee/elbow) but also common in ball-in-socket joints (bending forward at the hip) 2. Extension - Movement that increases the angle of the joint & brings two bones farther apart (straightening elbow) - If the extension is greater than 180 degrees (like when pointing chin to ceiling), it is hyperextension 3. Rotation - Movement of bone around longitudinal axis - Common movement in ball-in-socket joints and describes movement of the atlas around the dens of the axis (like shaking head no) 4. Abduction - Moving limb away from the midline or median plane of the body - Also applies to fanning of toes or fingers  5. Adduction - Movement of limb towards the midline of the body 6. Circumduction - Combination of flexion, extension, abduction, and adduction commonly seen in ball-in-socket joints such as the shoulder - Proximal end is stationary and distal end moves in circle - The whole limb outlines a cone Special Movements of 1. Dorsiflexion and plantar flexion joints - Up and down movements of the foot at the ankle are given special names - Lifting the foot so that the super surface approaches shin (standing on heels) is called dorsiflexion - Depressing the foot (Pointing toes) is called plantar flexion - Each of these movements also corresponds to the wrists Prime Mover - Muscles can’t push – they can ONLY pull as they contract – so most body movements are the result of the activity of Antagonists two or more muscles acting together or against each other Synergists - Muscles are arranged in a way that whatever one muscle (or group of muscles) can do, other muscles can reverse Fixators Prime Mover: muscles that has major responsibility for causing a particular movements Antagonists: Muscles that oppose or reverse a movement Synergists: help prime movers by producing the same movement or by reducing undesirable movements - Ex: Making wrist without bending wrist because synergist muscles stabilize wrist joints Fixators: Specialized synergists that hold a bone still or stabilize the origin of prime mover so all the tension can be used to move the insertion bone Naming Skeletal Direction of Muscle Fibers Muscles - Some muscles are named in reference to some imaginary line, usually the midline of the body or long axis of a limb bone - When a muscle’s name includes the term “rectus” (straight), its fibers run parallel to that imaginary line - Oblique tells you that the muscle fibers run obliquely (at slant) to imaginary line Relative Size of Muscle - Maximus (largest), minimus (smallest), and longus (long) are often used in the names of muscles Location of Muscle - Some muscles are named for the bone with which they are associated - Temporalis and frontalis muscles overlie the temporal and frontal bones of the skull respectively Number of Origins - When biceps, triceps, or quadriceps form part of a muscle name, one can assume that the muscle has 2, 3, or 4 origins respectively Location of the muscle’s origin and insertion - Can be named for insertion site - Ex: Sternocleidomastoid muscle has its origin on the stern (sterno) and clavicle (cleido) and inserts on the mastoid process Shape of muscle - Some muscles have a shape which makes it easily identifiable - Ex: Deltoid muscle is roughly triangular Action the Muscle - When muscles are named for their actions, terms like flexor, extensor, and adductor appear in their names Serratus Anterior Pec Muscles Pectoralis Major: 3 types - clavicular, sternal, abdominal heads 1. Clavicular (upper) - O: inferior border of the medial half of the clavicle - I: lateral edge, proximal humerus - A: underhand motions 2. Sternal (medial) - O: ribs 1-5, lateral edge sternum - I: lateral edge, proximal humerus - A: adducts arm across chest 3. Abdominal head (lower) - O: ribs 5-7 - I: lateral edge, proximal humerus - A: pulls the arm down Pectoralis Minor: - O: anterior surface of ribs 3-5 - I: coracoid process of scapula - A: rotates shoulder forward Briachialis ○ Triceps Brachii - 3 parts i. O: Long head: infraglenoid tubercle of scapula ii. O: Lateral head: humerus, above radial groove iii. O: Medial head: humerus, below radial groove iv. I: olecranon of ulna v. A: extends elbow ○ Briachialis i. Deep to the biceps brachii, distal to its tendon ii. O: anterior lower half of humerus and medial, lateral intermuscular septa iii. I: coronoid process and tuberosity of ulna iv. A: flexes elbow Intercostal Muscles 3 layers - external, internal, innermost intercostal muscles - O: ribs 1-11 - I: ribs 2-12 - A: raise the ribs, expand the chest cavity when breathing A bit more: - Intercostal muscles are situated between the ribs and move the chest wall - External intercostal muscles are responsible for forced and quiet inhalation - Internal intercostal muscles are responsible for exhalation Joints - Every bone in the body form a joint with at least one other bone Functions of joints/articulations: 1. They hold the bones together 2. Give the rigid skeleton mobility Classification of joints - Joints are classified either functionally or structurally Functional: - The functional classification focuses on the amount of movement allowed by the joint - Synarthroses: Immovable joints - Amphiarthroses: slightly movable joints - Diarthroses: Freely movable joints - Freely movable joints are found the limbs where mobility is important - Immovable and slightly movable joints are found in the axial skeleton, where firm attachments and protection of the internal organs are priorities Structure: - Fibrous, cartilaginous, and synovial joints based on whether fibrous tissue, cartilage, or a joint cavity separates the bony regions at the joint - Fibrous joints are immovable and synovial joints are freely movable - Cartilagneous joints are amphiarthrotic Fibrous Joints - The bones are united by fibrous tissues - Best examples are the sutures of the skull. In sutures, the irregular edges of the bones interlock and are bound together by connective tissue fibers, allowing no movement to occur. - In syndesmoses, the connecting fibers are longer than those of sutures (like the distal ends connecting tibia and fibula) Cartilaginous Joints - The bone ends are connected by cartilage - Examples that are slightly movable (amphiarthrotic) are the pubic symphysis of the pelvis and intervertebral joints of the spinal column, where the articulating bone surfaces are connected by discs of fibrocartilage - Examples that are immovable (synarthrotic) are hyaline-cartilage epiphyseal plates of growing long bones and cartilaginous joints between first ribs and sternum Synovial Joints - Synovial joints are those where the articulating bone ends are separated by joint cavity containing synovial fluid - Account for all joints in the limbs ALL synovial joints have 4 distinguishing features: 1. Articular cartilage – Articular (hyaline) cartilage covers the ends of the bones 2. Fibrous articular capsule – Enclosed by a sleeve or capsule of fibrous connective tissue, and the capsule is lined with a smooth synovial membrane 3. Joint Cavity – The articular capsule encloses a cavity, called the joint cavity, which contains synovial fluid 4. Reinforcing Ligaments – Fibrous capsule is reinforced by ligaments Bursae: flattened fibrous sacs lined with synovial membrane and containing a thin  film of synovial fluid - Common where ligaments, muscles, skin, tendons or bones rub together. Tendon Sheath: elongated bursa that wraps around a tendon subjected to friction Type of Synovial Joints Plane Joint: - Articular surfaces are flat - Only short slipping or gliding movements are allowed - Movement of plane joints are nonaxial (gliding does not involve rotation around ANY axis) - Ex: intercarpal joints of wrist Hinge Joint: - Cylindrical end of one bone fits into the trough-shaped surface of another bone - Angular movement is allowed in just one plane, like mechanical hinge - Ex: elbow joint, ankle joint, and joints between phalanges - Hinge joints are classified as uniaxial Pivot Joint: - Rounded end of one bone fits into the sleeve or ring of another bone or ligament - Pivot joints are also uniaxial Condyloid Joint: - Both articular surfaces are oval shaped and fit into each other - Condyloid joints allow the moving bone to travel from side to side & back and forth - Has biaxial movement Saddle Joint: - Each articular surface has convex and concave areas - These biaxial joints allow same types of movement as condyloid joints - Ex: carpometacarpal joints in the thumbs Ball and Socket Joints: - Spherical head of one bone fits into a round socket in another - These multiaxial joints allow movement in all axes including rotation - Most freely moving synovial joints Knee Anatomy Explain basic knee - Knee is held/stabilized by soft tissues anatomy - Ligament - bands of strong, soft tissue that attach bone to bone - Tendons - attach muscle to bone  4 principle ligaments in the knee - gives the joint stability and strength, connects to the femur and tibia - Medial collateral ligament (MCL) - inside side - gives stability to inner knee - Lateral collateral ligament (LCL) - outside side - gives stability to outer knee - Anterior cruciate ligament (ACL) - in front - controls forward motions of tibia - Posterior cruciate ligament (PCL) - in the back - controls backward motions of tibia Knee tests - Laxity - looseness of a limb or muscle, if laxity increases drastically compared to the uninjured state, the test is positive, indicating a torn or injured ligament Anterior Drawer Test (ACL) Purpose: To assess the integrity of the anterior cruciate ligament (ACL). Position: The patient lies supine (on their back) with the affected knee flexed at 90 degrees. The patient's foot is flat on the table, stabilized by the examiner (PT). Procedure: The PT sits on the patient’s foot to stabilize the leg. The examiner grasps the proximal tibia just below the knee joint with both hands. The PT ensures that the patient's hamstring muscles are relaxed (as tensing can affect the results). The examiner then applies an anterior force by pulling the tibia forward (toward them) while stabilizing the femur. Positive Test: If the tibia moves forward excessively compared to the opposite leg or lacks a distinct endpoint, it indicates an ACL injury. Posterior Drawer Test (PCL) Purpose: To evaluate the integrity of the posterior cruciate ligament (PCL), which prevents the tibia from moving too far backward relative to the femur. Position: The patient should lie supine (on their back) on the examination table. The knee is flexed to 90 degrees, with the hip flexed to about 45 degrees. The patient's foot should rest flat on the table. The PT can sit on the patient’s foot to ensure the leg remains stable. Procedure: The PT grasps the proximal tibia just below the knee joint with both hands, positioning the thumbs on the tibial plateau (the front of the tibia, just below the kneecap). Ensure that the patient’s hamstrings are relaxed since tense muscles can interfere with the results. Apply a posterior force by pushing the tibia backward (toward the table) relative to the femur, while keeping the femur stationary. The motion should be smooth and controlled. Positive Test: If the tibia moves excessively posteriorly (backward) relative to the femur, or if there is no firm endpoint, it suggests a PCL injury. Valgus stress test (MCl) Purpose: To assess the medial collateral ligament (MCL), which provides stability on the inner side of the knee. Position: The patient lies supine on the examination table. The affected knee is flexed to about 30 degrees to isolate the MCL (testing at 0 degrees tests both the MCL and joint capsule). The examiner holds the patient's ankle with one hand, while the other hand is placed on the lateral (outer) side of the knee to stabilize the femur. Procedure: Apply a valgus force by pushing the tibia laterally (away from the body) while stabilizing the femur with the other hand. The movement creates tension on the medial side of the knee, stressing the MCL. Ensure that the tibia is rotated slightly laterally to open the medial joint space. Positive Test: If there is excessive gapping or pain along the medial side of the knee, or if the movement feels “soft” without a distinct endpoint, this indicates an MCL injury. Varus Stress Test  Purpose: To assess the lateral collateral ligament (LCL), which stabilizes the outer side of the knee. Position: The patient lies supine on the table. The knee is flexed at about 30 degrees to isolate the LCL (testing at 0 degrees evaluates both the LCL and joint capsule). The examiner holds the patient’s ankle with one hand, and places the other hand on the medial side of the knee (inner side) to stabilize the femur. Procedure: Apply a varus force by pushing the tibia medially (toward the midline) while stabilizing the femur with the other hand. This creates tension on the lateral side of the knee, stressing the LCL. The tibia should be rotated slightly medially during the test to ensure proper force distribution. Positive Test: If there is excessive lateral gapping or pain along the lateral side of the knee, it suggests an LCL injury 3 types of cartilage 1. Articular (hyaline) cartilage - attached to articular bone structures; covers the ends of bones (condyles) to cushion joint; allows easy bending/straightening, protects joint from weight-bearing stress 2. Elastic cartilage - spongy, yellow, elastic network of fibers that provide support to body structure - Ear, upper respiratory tract 3. Fibrocartilage - stronger type of cartilage that provides support, rigidity and cushioning to parts of the body - Intervertebral discs, pubic symphysis What are - Hyperextended joints mean they have been bent past their ROM, causing damage to ligaments - when a ligament is hyperextended joints? injured/torn, the joint becomes unstable Goniometer steps Goniometer - instrument used for measuring angles of a joint - Line up fulcrum (axis) of goniometer with the fulcrum of the joint - Line the stationary arm of the goniometer with the fixed segment of the joint, align moving part with the moving part of the body in its neutral position - Direct the patient to move the joint in the desired direction to the fullest extent possible - Follow the motion of the patient with the moveable arm of the goniometer, keep stationary arm straight - Look at goniometer before removing it from body - Record ROM for joint Sliding Filament Theory 1. Calcium Binding: Calcium ions bind to the troponin complex, causing a change in its shape. This moves tropomyosin, which was blocking the myosin-binding sites on actin. 2. Cross-Bridge Formation: Myosin heads (on thick filaments) attach to the now-exposed binding sites on actin (thin filaments), forming a cross-bridge. 3. Power Stroke: Using energy from ATP, the myosin heads pivot, pulling the actin filaments toward the center of the sarcomere. This shortens the muscle and causes contraction. 4. Cross-Bridge Detachment: A new ATP molecule binds to the myosin head, causing it to detach from the actin filament. 5. Reactivation of Myosin: ATP is hydrolyzed (broken down) into ADP and phosphate, re-cocking the myosin head into its original position. 6. Repeat: The cycle repeats as long as calcium ions remain elevated and ATP is available, allowing the muscle to continue contracting. 7. Relaxation: When the nerve signal stops, calcium ions are pumped back into the sarcoplasmic reticulum, tropomyosin moves back to block the binding sites on actin, and the muscle relaxes Where is the The meniscus is a C-shaped piece of cartilage located in the knee joint, acting as a cushion between the femur (thigh bone) meniscus? and the tibia (shin bone) How to repair cartilage vs ligament Cartilage Repair 1. Microfracture: - A surgical technique where small holes are made in the bone near the damaged cartilage to stimulate the growth of new cartilage. 2. Autologous Chondrocyte Implantation (ACI): - Cartilage cells are harvested from the patient, cultured in a lab, and then implanted back into the damaged area to promote cartilage regeneration. 3. Osteochondral Autograft Transplantation (OAT): - Healthy cartilage and underlying bone are taken from a non-weight-bearing area of the patient’s knee and transplanted to the damaged area Ligament Repair 1. Surgical Ligament Reconstruction: - The damaged ligament is replaced with a graft (often taken from the patient’s hamstring, patellar tendon, or a donor), typically used for ACL injuries. 2. Ligament Repair (Direct Suturing): - In cases of partial tears, the damaged ligament may be sutured back together directly, restoring its integrity. 3. Bracing and Rehabilitation: - For minor ligament injuries, a combination of bracing and physical therapy is often the first line of treatment to strengthen the surrounding muscles and restore function Rigor Mortis and Sliding Filament theory Rigor mortis is a post-mortem condition that occurs after death and is characterized by the stiffening of muscles. This phenomenon is directly related to the sliding filament theory and involves several key processes: Mechanism of Rigor Mortis 1. ATP Depletion: ○ After death, the body stops producing adenosine triphosphate (ATP) because cellular metabolism ceases. ATP is essential for muscle function and is required for the detachment of myosin heads from actin filaments. 2. Myosin Binding: ○ In a living muscle, when ATP binds to the myosin head, it causes the myosin to detach from the actin filament after a power stroke. However, in rigor mortis, the lack of ATP means that myosin heads cannot detach from actin. 3. Stiffening of Muscles: ○ As a result of the myosin heads remaining attached to the actin filaments, the muscle fibers become rigid. This leads to the characteristic stiffness seen in rigor mortis, as the muscle cannot relax. 4. Timeframe: ○ Rigor mortis typically begins within 2 to 6 hours after death, peaks at about 12 hours, and can last for 24 to 48 hours before gradually dissipating as the muscle proteins start to break down.