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75 Cards in this Set
- Front
- Back
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HOW MANY BONES IN THE BODY AND EXPLAIN THE FUNCTIONS OF THE AXIAL AND APPENDICULAR SKELETON
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Axial skeleton: protects vital structures. The skull – brain, verterbral columm –spinal cord, ribs – heart and lungs. The trunk made of the ribs, sternum, vertebrae and sacrum. Appendicular skeleton: provides body with mobility. The upper and lower limbs and the pectoral and pelvic girdles which attach them to the trunk. |
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Describe the functions of bone.
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Mechanical functions: support- rigid framework, protection of vital structures, allows movement by being site of attachment for muscles and acts as lever around joints
Physiological functions: haemopoesis – red marrow, mineral storage – calcium hydroxyapatate ( calcium homeostasis), emergency lipid store – yellow marrow. |
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List the types of bone with examples.
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Long bone – clavicle, humerus
Short bone – carpals and tarsals – cuboidal shape Irregular bone – vertebral column, bones of face Flat bone – skull – serve protection purposes, scapula Sesamoid bone – pisiform and patella – bones on tendons which cross the ends of long bone, protecting the tendon from excessive wear and changes the angle of the tendon. |
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List the types of tissue located between joints
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Bone, cartilage, fibrocartilage, ligaments, bursae, synovial membrane
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What does stability of joints depend on?
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- Ligaments – prevent excessive movement, can tear
- Muscle tone - Shape, size and arrangement of articulating bones ( the depth of bony articulation) |
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List factors that restrict movement around a joint.
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Ligaments, muscle tension ( harder to raise thigh if knee straight), interference from other structures, depth of bony articulation ( less stable, more mobile)
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How are joints classified?
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Structural classification – material in joint
Fibrous joint - sutures – tight union between bones of the adult skull, syndesmoses – bones held together by fibrous tissue eg interosseous membrane between radius and ulna and tibia and fibula. Cartilaginous joint – primary cartilaginous joint – epiphyseal growth plate in long bones, secondary cartilaginous joint – disc of fibrocartilage in the joint space eg pubic symphysis, intervertebral joint Synovial joint – protective fibrous joint capsule, articular surfaces covered by hyaline cartilage and separated by joint cavity, joint cavity lined by synovial membrane which secretes synovial fluid. Functional classification Synarthrosis – immovable Amphiarthrosis – slightly movable Diarthrosis – freely movable – synovial joint |
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Describe different types of synovial joint with examples.
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Hinge joint – flexion/extension – knee and elbow
Ball and socket joint – flexion/extension, abduction/adduction, external and internal rotation – shoulder and hip Pivot joint – rotation around another bone – top of neck Saddle joint – CMC joint of thumb – flexion/extension, abduction/adduction, circumduction Condyloid joint – wrist, MCP and MTP joints – flexion/extension, abduction/adduction, circumduction Gliding joint – intercarpal joints |
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What is Hiltons law?
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A nerve that supplies the joint will also supply the muscles moving the joint and the overlying skin.
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Describe the muscles of the anterior thoracic region
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Pectoralis major – lateral and medial pectoral nerves ( C7,C8,T1)
- Sternum intertubercular groove - Medial rotation, flexion, adduction Pectoralis minor – medial pectoral nerve ( C8, T1) - 3rd-5th rib corocoid process - Stabilises scapula - Depression and protraction Subclavius – nerve to subclavius (C5, C6) - Stabilises clavicle Seratus anterior – long thoracic nerve ( C5,C6,C7) - Lateral ribs medial border of scapula - Holds scapula close to thoracic wall - Rotation – boxers muscle - Abduction of arm above 90 degrees. - If paralysis – winged scapula - Medial border of axilla Deltoid – axillary nerve ( C5, C6) - Clavicle deltoid tuberosity - Abduction 15 – 90 degrees - Flexion/extension, - Medial and lateral rotation |
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List some injuries to joints
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Rheumatoid arthiritis – autoimmune disease attacking the synovium
Osteoarthritis – loss of cartilage, bones rub together ( may hear crepidis), pain Dislocation of joints Ligament tear Haemoarthrosis – blood in the synovial cavity Joint effusions –excessive synovial fluid in joint cavity |
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Describe sagital, coronal and transverse planes.
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Sagital plane divides right from left
Coronal place divides anterior from posterior Transverse plane divides superior from inferior |
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Draw the pectoral girdle and label all the bones, tuberosities and grooves.
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DRAW
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What is the metaphysis?
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The metaphysic is adjacent to the epiphyseal growth plate and is the part of bone that grows in length during childhood – endochondrous ossification.
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Can cartilage be converted to bone? Explain.
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No, cartilage is replaced by bone by endochondrous ossification. Cartilage can become calcified thus restricting nutrient and gaseous supply to the chondrocytes so that they eventually die. The calcified matrix is then used as a template, where osseous tissue can be laid down, eventually replacing all cartilage by bone.
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What factors are responsible for the appearance of tuberosities, tubercles, ridges and grooves on a typical long bone.
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Tuberosites, tubercles and ridges occur due to mechanical forces applied to the bone by the attachment of muscle, tendons and ligaments.
Grooves are formed from pressures exerted on the bone by adjacent nerves and vessels. |
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What is the function of erythropoietin?
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Erythropoietin is released from the kidneys in response to hypoxia and targets the bone marrow, accelerating release and production of erythrocytes. This increases oxygen carrying capacity of the blood so that oxygen levels are restored.
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An irregular, fixed lump is found on a patient’s breast what might this be?
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The lump may be a carcinoma which has attached to other chest tissues eg pectoral fascia and may invade the chest wall further to invade the pectoralis major muscle ( C7,C8,T1).
Surgical removal of the tumour will result in removing an extensive part of this muscle. Flexion, adduction and medial rotation of the arm will be compromised. |
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Describe intramembranous ossification and endochondral ossification.
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Intramembranous ossification takes place in flat bones eg scapula and bone is formed directly from mesenchymal tissue.
- Mesenchymal cells differentiate into osteoblasts which lay down osteoid - Osteiod ( bone matrix) becomes calcified - Extensive trabeculae form to produce spongy bone - Peripheral regions become compact bone ( series of haversian canals with trapped osteocytes) Endochondral ossification replaces hyaline cartilage for bone and takes place in long bones eg clavicle. - The mesenchymal cells in the perichondrium differentiate into osteoblasts and start laying down osteoid in the primary ossification site, the diaphysis. - The chondrocytes proliferate, mature and hypertrophy - The matrix becomes calcified which kills the chondrocytes ( loss of nutrients) and osteoblasts replace them - Growth in diameter occurs as the diaphysis - The secondary ossification site is the epiphysis - The epiphyseal growth plate remains during puberty until adulthood allowing growth in length as cartilage cells divide, mature and hypertrophy, the metaphysis grows. - The growth plate eventually ossifies and growth in length can no longer occur. |
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State how nutritional deficiency in calcium/phosphorous, vitamin A and vitamin C may affect bone.
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Calcium/phosphorous deficiency will cause brittle bones as they are essential for normal bone development and maintenance. Vitamin A deficiency may cause an inbalance in the ratio of osteoclasts and osteoblasts, thereby slowing growth rate.
Vitamin C deficiency would delay healing of broken bones. |
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Explain the cause of osteomalacia in the adult and rickets in children.
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Vitamin D deficiency causes osteomalacia and rickets which is a general weakening of bones and deformity ( bowed legs –varus). Vitamin D is acquired in the diet or by UV light and undergoes hydroxylation in the liver ( cholecalciferol -> 25 hydroxyvitamin D) and in the kidney ( 25 hydroxyvitamin D -> calcitriol using C1 hydroxylase (activated by PTH) to become hormonally active – calcitriol .
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What treatment is given to treat osteoporosis?
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Bisphosphates and calcitonin are given as they both inhibit osteoclast activity. Calcitonin also stimulate osteoblast activity and favours uptake into bones.
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What is paget’s disease?
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A progressive bone disease in which a pattern of excessive bone resorption is followed by bone formation contributing to thicker bones which are more porous and so more susceptible to fracture. Occurs mainly in the skull, pelvis and lower extremities, after age of 40, typical in 60s.
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Describe the structural and functional differences between cardiac, skeletal and smooth muscle.
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Skeletal muscle- striations, peripheral nuclei, multinucleated muscle fibres with long cylindrical myofilaments arranged adjacently. Regeneration - Has satellite cells which can differentiate to form muscle fibres (hyperplasia) or can add to muscle fibres (hypertrophy). Voluntary control – somatic nervous system. The diaphragm can be under voluntary control via the phrenic nerve but is usually controlled automatically. Skeletal muscle can be controlled unvoluntary eg shivering – heat generation. T tubule in line with AI junction, forms triad.
Cardiac muscle : striations, short branched cyclinders, single central nucleus, myofilaments less ordered, intercalated discs for electrical and chemical communication between cells, t tubule in line with Z line, forms diad. Under involuntary control – sympathetic – increases heart rate and force of contraction - +ve ionotrophic and chronotrophic effect. Parasympathetic – decrease heart rate - -ve chronotrophic effect. Can’t regenerate. Smooth muscle: fusiform shaped cells with single central nucleus, actin filaments twist in cork screw shape, involuntary control, non-striated, can regenerate. |
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Describe the structure and organisation of skeletal muscle
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Myofilaments – actin and myosin form adjacent sarcomeres which make up myofibrils. Columns of myofibrils make up a muscle fibre. Muscle fibres are surrounded by endomysium ( CT). Bundles of muscle fibres form a fascicle and are surrounded by perimysium. Many fascicles are surrounded by epimysium which is neurovascular and dense connective tissue.
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Explain the mechanism of contraction of skeletal muscles
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An action potential passes along the sarcolemma, depolarising it. Depolarisation spreads down the T tubule and activates VOCC to open and extracellular calcium to enter muscle fibre. The calcium then binds to ryanodine receptors on SR to open the calcium channel by CICR. Calcium enters cytosol from SR and binds to troponin complex, changing its conformation so that it moves away from the actin helix. As it is attached to tropomyosin, it moves it away too, exposing the myosin head binding site on the actin helix. Myosin head binds to binding site and releases ADP + Pi. The release of Pi powers the power stroke and so the myosin head bends forwards and pulls the actin filament towards to M line ( I and H bands thin, A band stays the same). ATP binds to myosin head, releasing myosin from actin. The active transport of calcium ions back into SR by SERCA causes relaxation of muscle.
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What is fasciculation.
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Normal muscle twitch but can be associated with diseases such as motor neurone disease.
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What are the functions of skeletal muscle?
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Movement, stability over joints eg deltoid over glenohumeral joint, posture, heat generation.
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Describe agonists, antagonists, synergists, fixators.
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Agonists – prime mover
Antagonist – opposes prime mover Synergist – assists prime mover Fixators – fixes non moving joint when prime mover is acting over 2 joints. |
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Describe 1st class, 2nd class and 3rd class levers.
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1st class – load and force on opposite sides of the fulcrum.
2nd class – load and force on same side of fulcrum, load in the middle 3rd class – load and force on same side of fulcrum, force in the middle – most common, most inefficient |
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What is compartment syndrome?
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Muscles, nerves and vessels are arranged into compartments eg anterior and posterior compartments. Damage to the compartment can cause internal bleeding which could compress the nerves and vessels in the compartment.
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Define a motor unit and explain the basis of muscle tone in relation to causes of hypotonia.
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A motor unit is the functional unit of a muscle consisting of a motor neuron and the muscle fibres it controls. The number of muscle fibres in a motor unit can change greatly.
Muscle tone is a baseline tone that is present in resting muscle due to muscle elasticity and motor neurone activity. Hypotonia is a lack of skeletal muscle tone that can result from: - Damage to motor neurone central, cerebellum, spinal cord - Myopathy – degeneration of muscle - Lesions of sensory afferents from muscle fibres ( prevent proprioception – brain knowing what’s going on with muscles - Lesions of motor neurones eg polyneuritis – simultaneous impairment of function of lots of peripheral nerves |
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Describe simply the physiological mechanisms which underlie variation in force of contraction of a muscle
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Isotonic contraction – same constant force is exerted with varying muscle length. If the muscles shorten it is concentric contraction eg holding a load and if they lengthen it is eccentric contraction – eg walking down a hill – can cause delayed onset muscle soreness DOMS
Isometric contraction – constant muscle length, varying force – eg hand grip Rigor mortis – continuous contraction occurs in absence of ATP to remove myosin head from actin. Can be used by pathologists to estimate time of death. In order to increase force generated by a muscle, more motor units can be activated by recruitment. This is called spatial summation and uses reflex mechanisms from golgi tendon, joint receptors and muscle spindles. Temporal summation – increased frequency of action potentials to muscle fibres causes summation of contraction. When a high enough frequency is reached, a fused tetanus will occur which is continuous contraction of muscle. Clostridium tetani is a toxin which blocks inhibitory motor feedback control leading to constant contraction. |
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Differentiate the sources of energy for muscle contraction and relate these to muscular fatigue and muscle fibre type.
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1. Short term supply of ATP – lasts a few seconds – muscle fibre type IIb
2. Creatine phosphate + ADP ATP - phosphorylation by creatine kinase – lasts 15 seconds 3. Anaerobic glycolysis – from glucose in blood or muscle glycogen – lasts 20-40 seconds muscle cramp - > acidosis 4. Aerobic oxidative phosphorylation – endurance – muscle fibre type I Muscle fatigue – peripheral fatigue, may be caused by depletion of muscle glycogen stores. This occurs in intermittent claudication – pain in leg during exercise which goes away at rest – ischaemia resulting from atherosclerosis. |
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Describe muscle fibre types
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Type I – slow oxidative
- Lots of mitochondrial, resistant to fatigue, - Posture and endurance Type IIa – fast oxidative - Lots of mitochondria, moderate fatigue resistant - Walking, sprinting Type IIb – fast anaerobic - Glycolysis - Few mitochondria, rapidly fatigued - Short, intense movements |
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How can muscles be tested.
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Patient performs movements against resistance.
EMG –electromyography – electrodes places over a muscle and patient carries out certain movements. The activity of an individual muscle during different movements can be analysed. |
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When is avascular necrosis seen in bones?
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After a fracture small areas of adjacent bone undergo necrosis due to loss of blood supply eg avascular necrosis of scaphoid.
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DESCRIBE THE BOUNDARIES OF THE AXILA AND ITS CONTENTS.
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The axilla is a square pyramid shape located in the armpit.
The apex : cervicoclavicular canal, clavicle, 1st ribs, superior scapula Medial border: thoracic wall,(ribs and intercostals muscles) and overlying seratus anterior Anterior border: pectoralis major and minor and pectoral fascia Inferior border: skin Lateral border: intertubercular groove of humerus Posterior border: suscapularis, scapula, teres major and latissimus dorsi The axial is a passageway for nerves and vessels supplying the upper limb. The cords and terminal branches of the brachial plexus, the axillary artery and vein, lymphatic vessels and lymph nodes are found in the axila. The coracobracialis and long head tendon of the biceps brachii pass through the axilla to the corocoid process. |
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How is the axillary artery and vein formed?
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Braciocephalic artery subclavian artery at lateral border of 1st rib becomes axillary artery as it passes teres major becomes brachial artery.
Vena comitantes of bracial artery join basilic vein at inferior border of teres major axillary vein at lateral border of first rib becomes subclavian vein. |
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What happens to the axilla when the arm is raised above the head? Why would you have venous distension?
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The structures passing through the axilla are compressed against the corocoid process of the scapula and the tendon of the pectoralis minor muscle. This results in pain running down the arm, numbness and parathesia – neurological signs.
The compression of axillary vessels causes ischaemia and distension of superficial veins. The axillary artery is the main blood supply to the upper limb, the axillary artery bracial artery which bifurcates at the cubital fossa -> radial and ulnar nerves. |
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What is cyanosis?
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Development of bluish skin colour due to build up of deoxygenated haemoglobin.
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Describe malignant hyperthermia.
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Malignant hyperthermia is an inherited disease where general anaesthetics increase the release of calcium from SR. The increase in intracellular calcium activates cross bridge cycle, promoting contraction. The high level of calcium release prevents the calcium uptake back into SR thus prevents relaxation of skeletal muscle. This increases the metabolic activity of skeletal muscle causing a significant rise in temperature, sweating, tachycardia, increased ventilation, fall in blood oxygen, fall in blood ph.
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In a female why would you be concerned with enlarged lymph nodes.
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Axillary nodes are the most common side of metastases of cancer of the breast.
However they could be due tp lymphangitis – inflammation of lymphatic vessels, become tender and enlarged due to infection in upper limb, pectoral region, breast and superior abdomen. |
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What is the function of the clavicle? What would happen if the clavicle was fractured?
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Function:
- Rigid support - Increases range of movement of upper limb by holding scapula and upper limb away from thorax - Protects neurovascular structures which run behind it - Provides attachment for muscles - deltoid, subclavius, sternomastoid, trapezius In a fracture, the trapezius can’t hold up the lateral part of the clavicle due to weight of the upper limb so the shoulder drops, the sternomastoid elevates the medial aspect of the clavicle, the adductor muscles of the arm pull the lateral fragment of the clavicle medially. Fracture usually occurs from fall on outstretched hand, mostly likely in children as clavicle isn’t ossified yet or fall on shoulder or direct blow. The weakest part is between the lateral and middle 3rd. |
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Describe the future of the paraxial, intermediate and lateral mesoderm.
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The paraxial mesoderm forms somites which occur in pairs, one on either side of the neural tube. Somites differentiate into sclerotomes, dermatomes and myotomes. They form the axial skeleton ( ribs, skull, vertebral column). The remnant of the notochord, the nucleus pulposus is found in an intervertebral disc and can bulge out in slip disc herniation.
The intermediate mesoderm forms the urogenital system. The lateral mesoderm is separated into the parietal and visceral layers by the intraembryonic cavity. - The parietal mesoderm forms the dermis of the skin, the bones and connective tissue of the limbs, limb and body wall muscles, costal cartilage - The visceral mesoderm forms the smooth musculature and vasculature of the gut wall and serous membrane layer around many organs. - Intraembryonic cavity becomes the pericardial sac, the peritoneal sac, the pleural sacs. |
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Which areas of mesoderm are important for limb development.
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Paraxial mesoderm – somites provide musculature
Lateral mesoderm – provide skeleton of limb |
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When and where does limb bud growth occur?
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Limb buds form after the 4th week on the ventro-lateral body wall and extend ventrally at first, until they rotate. Limb growth occurs cranio-caudal direction and so lower limbs development lags 2 days behind upper limb. The limb bud consists of mesenchymal core, derived from parietal layer of lateral mesoderm, covered by ectoderm. The ectoderm at the distal border of the limb thickens to form the apical ectoderm ridge AER.
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Describe the importance of the AER.
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The AER is vital for limb development. It produces and inductive influence on the mesenchyme to proliferate and remain unspecialised. It controls growth in proximal to distal direction as mesenchyme further away from AER can differentiate into muscle and cartilage. When limb length is appropriate, paddles develop which are primordial of hands and feet.
Apoptosis of AER separates ridge into 5 digital rays. Digits then form as growth occurs where AER remains. The AER then regresses. Digital rays are cartilaginous models of digits. |
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Describe the 3 degrees of asymmetry and explain how they are brought about.
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Anterio-posterior axis – left and right hands are mirror images of eachother
ZPA- zone of polarising activity is a signalling centre at posterior base of limb bud, which controls both anterior-posterior patterning eg digits appear in the proper order, and maintenance of the AER Proximal-distal axis – eg shoulder and fingertips Controlled by the AER – proximal mesenchymal cells far away from AER begin to specialise into muscle and cartilage first Dorsal-ventral axis - eg palms aren’t hairy. The ectoderm exerts ventralising and dorsalilsing influences over mesenchymal core. the AER marks the difference between ventral and dorsal. |
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Describe syndactyly, polydactyly, Amelia and meromelia.
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Syndactyly – fusion of digital rays due to inadequate apoptosis. May be cutaneous syndactyly where only skin is involved or osseous syndactyly where bones are also fused.
Syndactyly usually is accompanied by club foot ( sole of foot turned inwards, foot adducted and plantar flexed) Polydactyly – additional digit Amelia – complete absence of one or more extremites. Meromelia – partial absence of a limb. - Thalidomide is a teratogen which interferes with the vasculature of AER and so elongation of the limb is not induced and the limb is much smaller - Phacomelia is a type of meromelia where long bones are absent and hands and feet are attached to the trunck via small irregular bones. |
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Describe osteogenesis imperfecta, mafans disease.
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Osteogenesis imperfecta is a disease where there is a defect in collagen synthesis. This results in shortening, bowing and hypomineralisation of the long bones of the limb, blue sclera, hyperflexibilty of the joints and frequent fractures.
Marfans syndrome is caused by a mutation in the fibrillin gene. This results in tall, thin individuals with long thin limbs and long thin face, sterna defects, dislocation of the lens of the eye, dilation/dissection of the aorta ( less elastin in wal), joint hyperflexibility. The symptoms and signs are very similar to those seen in homocysteinuria which is often misdiagnosed for marfans syndrome. |
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Describe congenital hip displacement.
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CHD is caused by the underdevelopment of the acetabulum and head of femur. The defect occurs before birth but the dislocation usually occurs after birth. CHD is associated with breech deliveries as the breech posture ( bum out) may put undue pressure on the hip joint, preventing complete development of the hip joint.
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Explain how the musculature of the limbs develops.
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Myogenic precursors migrate from the paraxial mesoderm into the limb and position around the skeletal elements into 2 common muscle masses: ventral – flexor compartment, dorsal – extensor compartment.
Upper limb: flexors = anterior, extensors = posterior Lower limb: flexors = posterior, extensors = anterior. This is because as the limbs elongate, the rotate from the original ventral position. The upper limb rotates laterally so that thumbs are lateral and the lower limbs rotate medially so the big toe is medial. |
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Explain how the limbs are innervated.
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The upper limb bud appears near the caudal cervical spinal roots and the lower limb bud appears near the sacral and lumbrical spinal roots. These roots innervate the limb buds early on in development as they are needed for development.
The upper limb is supplied by the brachial plexus – The anterior divisions supply the anterior muscle compartment. The anterior divisions arranged into medial and lateral cords. The posterior divisions supply the posterior muscle compartment. The posterior divisions form the posterior cord. |
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Explain the innervations of nail beds.
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Nails form from nail fields on the tips of fingers and then migrate to the dorsal surface, taking their nerve supply with them. Therefore on the dorsal side of the hand, the median nerve supplies to tops of the thumb, 2nd finger, 3rd finger and half of 4th finger. The ulnar nerve supplies the little finger and half of the 4th finger. The radial nerve supplies the rest of the dorsum.
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Describe the site, function and innervations of the trapezius, latissimus dorsi, serratus anterior, teres major and minor, levator scapulae, rhomboids, deltoid
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Trapezius
- Diamond shape on back, attaches to lateral clavicle, greater tuberosity of humerus, ribs. - Elevation and depression of shoulder, scapular rotation - swimming, abduction above 90 degrees with seratus anterior - Accessory nerve ( c3, c4 ) Latissimus dorsi - Biggest back muscle – ribs -> intertubercular groove - Adduction, medial rotation, tree climbing - when arms fixed, raises chest to arm - Thoracodorsal nerve ( c6-c8) Serratus anterior - Winged (penate) muscle, ribs to medial border of scapula - Internal rotation of scapula, holds scapula close to thorax, abduction above 90 degrees with trapezius - Long thoracic nerve ( c5- c7) – if damaged -> winged scapula – medial border moves laterally and posteriorly away from thoracic wall Teres major - Ribs -> intertubercular groove - Adduction and medial rotation - Lower subscapular nerve (c5, c6) Levator scapulae - Elevates scapula, tilts glenoid cavity inferiorly by rotating scapula - Dorsal scapular nerve ( c5) and cervical nerves Rhomboids - Attach to medial borders of scapula and ribs - Retracts scapula, rotates scapula to depress glenoid cavity, fixes scapula to thoracic wall - Dorsal scapular nerve ( c4,c5) |
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Describe the site, function and innervations of rotator cuff muscles.
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Rotator cuff muscles support the glenohumeral joint.
Supraspinatous - Found in supraspinous fossa, posterior and superior to spine of scapula an attaches to greater tuberosity of humerus - Abduction 0-15 degrees and external rotation - Suprascapular nerve ( c5,c6) Infraspinatous - Found in infraspinatous fossa, inferior to spine of scapula and attaches to greater tuberosity of humerus - external rotation of scapula - suprascapular nerve ( c5, c6) teres minor - lateral border of scapular to greater tuberosity - external rotation of scapula - axillary nerve ( c5, c6) subscapularis - subscapular fossa to lesser tuberosity - internal rotation of scapula - subscapular nerve ( c5,c6) all rotator cuff muscles and deltoid are supplied by superior brachial plexus |
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Draw a diagram of the shoulder joint including the ligaments and the bursae.
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look in book
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Describe the function of the glenohumeral ligaments and the coracohumeral ligaments
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These ligaments are both intrinsic ligaments – part of the fibrous layer of the joint capsule.
The glenohumeral ligaments strengthen the anterior aspect of the joint capsule, extending from glenoid labrum at supraglenoid tubercle to fibrous layer of capsule at the anatomical neck of humerus The coracohumerual ligament passes from the corocoid process to the greater tuberosity of the humerus, strengthening the joint capsule superiorly. |
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Describe the function of the transverse humeral ligament.
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The transverse humeral ligament attaches from the Greater tubercle to lesser tubercle, crossing over the intertubercular groove. This ligament makes the groove into a canal which holds the synovial sheath and tendon of the long head of biceps brachii (inserts at supraglenoid tubercle) in place during movements of the glenohumeral joint.
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Describe the function of coraco-acromial arch.
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The coracoacromial arch is comprised of the corocoid process, the acromion and the coroacromial ligament which connects them. This forms a protective arch that overlies the humeral head and prevents superior displacement from the glenoid cavity.
The coraco-acromial arch is so strong that a forceful superior thrust of the humerus would not damage the coraco-acromial arch, but cause a fracture of the humerus or clavicle. |
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Describe the function of bursae around the glenohumeral joint
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Bursae are synovial fluid filled cavities that are present where tendons rub against bone, ligaments or other tendons and where skin moves over a bony prominence.
The subscapular bursa is located between the tendon of the subscapularis and the neck of the scapula. The bursa protects the tendon where it passes inferior to the corocoid process and over the neck of the scapula. The subscapular bursa communicates with the glenohumeral joint cavity. The subacromial bursa is located between the coracoacromial arch and the deltoid superiorly and the supraspinatous tendon and glenohumeral joint capsule inferiorly. It facilitates movement of the supraspinatous tendon under the coraco-acromial arch and of the deltoid over the glenohumeral joint capsule |
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Describe the vascular supply of the glenohumeral joint.
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The glenohumeral joint is supplied by the posterior and anterior humeral circumflex arteries and branches off the suprascapular artery
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Describe dislocations of sternoclavicular joint and acromioclavicular joint.
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Dislocation of sternoclavicular joint is very rare as it is very strong due to its ligaments, disc and the way forces are transmitted along the clavicle. Most dislocations of SV in people under 25 is at epiphyseal growth plate at the sterna end of the clavicle as it does not ossify until 23-25 years.
Dislocation of acromioclavicular joint is more common as although the extrinsic coracoclavicular ligament is strong, the AC joint is not. Dislocation arises from a direct blow, hard fall on a shoulder or on an outstretched upper limb. The injury is worse if both the AC and coracoclavicular ligament tear – the shoulder separates from the clavicle and falls due to the weight of the upper limb. The acromion becomes more prominent and the clavicle may move superior to it. |
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Describe calcific supraspinatous tendinitis.
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Calcific supraspinatous tendinitis is the inflammation and calcification of the subacromial bursa resulting in pain, tenderness and limited movement of glenohumeral joint.
Deposition of calcium in supraspinatous tendon is common and causes increased local pressure resulting in pain on abducting arm. The calcium deposit irritates the subacromial bursa causing an inflammatory reaction – subacromial bursitis. Subacromial bursitis causes pain on abduction of arm 50-130 degrees – PAINFUL ARC! This is because at this position the supraspinatous tendon is in contact with the acromion and no longer protected by the bursa. Usually occurs in males over 50 after unusual or excessive glenohumeral joint use. |
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Describe rotator cuff injuries.
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Degenerative tendinitis:
- impingement syndrome – supraspinatous tendon is impinged between the head of the humerus and the coracoacromial arch -> irritation of arch and inflammation and wear and tear of tendon - recurrent inflammation of rotator cuff, especially avascular area of supraspinatous tendon -> shoulder pan and tear!! TEST: ask patient to lower fully abducted arm, from 90 degrees the arm will suddenly drop OR won't be able to abduct arm from 0 degrees. - CAUSED BY: repetitive use of the upper limb above horizontal – throwing, swimming, weightlifting - shoulder pain and loss of function |
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Why does the humeral head dislocate so easily? What is the usual direction of dislocation and why?
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The glenoid fossa (cavity) is relatively shallow; it accepts a little more than a third of the humeral head. Although the joint is strengthened on its superior, anterior and posterior aspects by the coracoacromial arch and muscles, it is weak on its inferior aspect. Hence, the head of the humerus usually dislocates inferiorly, but ends up as an anterior (subcoracoid location) i.e. anterior-inferior dislocation.
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Describe glenohumerual dislocations.
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Most dislocations occur inferiorly, often after an avulsion fracture of the greater tubercle – loss of flexor and adduction muscles pulling the arm anterosuperior.
Anterior dislocations are more common than posterior dislocations. - Young adults – athletes - Excessive extension and lateral rotation of humerus, direct blow to humerus - Humeral head lies anterior to infraglenoid tubercle and long head of triceps and inferior to the glenoid cavity - Flexors and adductors pull the arm in anterosuperiorly, The axially nerve may be damaged when the glenohumeral joint dislocates due to its close relation to the inferior part of the joint capsule. This may result in paralysis of deltoid and loss of sensation in regimental badge area. |
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Describe glenoid labrum tears.
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The glenoid labrum is a ring of fibrocartilage that surrounds the glenoid cavity and deepens it, making the articulation with the humeral head stronger.
Tearing of the fibrocartilage glenoid labrum often occurs from Shoulder instability - sudden contraction of the biceps or - forceful subluxation of the humeral head over the glenoid labrum. The tear usually occurs in the anterosuperior part of the labrum and pain is felt on throwing. |
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Describe adhesive capsulitis of glenohumeral joint.
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- Adhesive capsulitis is also called frozen shoulder.
Adhesive fibrosis and scarring between the inflamed joint capsule of the GH joint, rotator cuff, subacromial bursa and deltoid. Can be caused by: - Glenohumeral dislocations - Calcific supraspinatous tendinitis - Partial tearing of the rotator cuff - Bicipital tendinitis 40-60 years of age - Difficulty abducting arm – lack of movement of GH joint - Strain on AC joint causing pain on elevation, shrugging. |
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What is biceps tendinitis?
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Wear and tear of long head of biceps tendon in intertubercular groove causing shoulder pain and inflammation.
Can be caused by repetitive microtrauma in sports involving throwing. Biceps tendinitis can lead to rupture of tendon and so it is torn away from supraglenoid tubercle creating a snap/pop sound. The deatached muscle belly forms a ball distal, central anterior part of arm – POPEYE DEFORMITY. |
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Discuss the various types of fractures of the humerus
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Fracture at surgical neck
– fall on hand - axillary nerve and posterior/anterior circumflex humeral arteries wrap around surgical neck and so are damaged -> deltoid Avulsion fractures - Greater tuberosity – loss of rotator cuff muscles - Condyles -> medial – ulnar nerve Transverse mid shaft fractures of humerus – damaged radial nerve and deep brachial artery - wrist drop - loss of extension Supracondylar fracture - median nerve and brachial artery at wrist - hand of benediction - on doing a fist. Intercondylar fracture – olecrannon between |
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What factors contribute to the stability of the shoulder joint?
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The tonus of the rotator cuff muscles; the coracobrachialis, the short head of biceps and the long head of triceps assist the deltoid in resisting downward dislocation of the joint.
Capsular and extracapsular ligaments. Glenoid labrum helps to deepen the glenoid fossa (cavity). |
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In injuries of the shoulder joint, the humerus may fracture at its “surgical neck”. Where is the “anatomical neck” of the humerus and what is its significance?
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The anatomical neck is formed by the groove circumscribing and separating the head from the greater and lesser tubercles. The articular capsule of the joint is attached nearby. The anatomical neck also marks the region of the epiphyseal growth plate during the growth in length of the humerus.
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List all the movements of the scapula (six of them) and the principle muscles that produce them.
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Protraction – Serratus anterior
Retraction – (Middle fibres of) trapezius, rhomboids Elevation – (Upper fibres of) trapezius, levator scapulae Depression – (gravity) (relaxation of elevator muscles) Lateral rotation/upward rotation – upper and lower fibres of trapezius Medial rotation/downward rotation – Latissimus dorsi, levator scapulae, rhomboids (tilt glenoid cavity inferiorly) NB In lateral/upward rotation of the scapula, the glenoid cavity moving superiorly (ie when upper limb is abducted). Converse is true for medial/downward rotation. |
