Introduction To The MSK System PDF

Introduction to the MSK System 18/10/23, 11:51 PM Introduction to the MSK System The skeleton • Axial skeleton: bones of the skull, neck and trunk • Appendicular skeleton: bones of the pectoral and pelvic girdles, bones of the lower limbs AppendicularSkeleton AxialSkeleton Upper limbs • • • 1...

Introduction to the MSK System 18/10/23, 11:51 PM Introduction to the MSK System The skeleton • Axial skeleton: bones of the skull, neck and trunk • Appendicular skeleton: bones of the pectoral and pelvic girdles, bones of the lower limbs AppendicularSkeleton AxialSkeleton Upper limbs • • • 1 long bone in arm - humerus 2 long bones in forearm - radius and ulna Hand: carpal bones → metacarpals → phalanges Lower limbs • • • 1 long bone in thigh - femur 2 long bones in leg - tibia and fibula Foot: tarsal bones → metatarsals → phalanges Features of bone • Bony feature: functional hole, bump or groove found on bone which develops during bone growth ◦ ◦ • Adjacent structure applies force to bone, moulding its shape OR Adjacent structure develops at the same time as bone and the bone has to grow around the other structure - forms a foramen Tuberosity: rough area of bone where muscles attach e.g. ischial tuberosity Bone • Hard, connective tissue Cartilage • • Less rigid than bone Located where mobility is required - articulations Joints • Three types - synovial, cartilaginous and fibrous https://galvanized-borogovia-4fa.notion.site/Introduction-to-the-MSK-System-1f82fce6b6cd45b08e9a9daed6341784 Page 1 of 3 Introduction to the MSK System 18/10/23, 11:51 PM • Each is a compromise between mobility and stability - the more mobile a joint, the more easily it is dislocated • Joins have an excellent sensory nerve supply Skeletal muscle • Usually found deep to deep fascia • Usually two points of attachment to bone - ‘origin’ (usually most proximal part) and ‘insertion’ on the other side • During contraction, the origin and insertion are moved closer together ◦ Muscle fibres shorten along the long axis Tendon • Attach muscle (usually) to bone Aponeurosis • • • Flattened tendon Most commonly associated with flat muscles Attach muscle to soft tissue Biceps brachii • Attachments: ◦ ◦ ◦ • • Long head originates from the supraglenoid tubercle of the scapula Short head originates from the coracoid process of the scapula Both heads insert distally into the radial tuberosity and the fascia of the forearm via the bicipital aponeurosis Innervation: musculocutaneous nerve Actions: supination of the forearm (spans proximal radioulnar joint anteriorly) and flexion of the shoulder and elbow joint (spans shoulder and elbow joint anteriorly) Deltoid muscle • Attachments: originates from the lateral third of the clavicle, the acromion and the spine of the scapula, attaches to the deltoid tuberosity on the lateral aspect of the humerus • • Innervation: axillary nerve Actions: ◦ ◦ ◦ Anterior fibres: flexion and medial rotation of the shoulder Posterior fibres: extension and lateral rotation of the shoulder Middle fibres: the major abductor of the arm Clinical examination of skeletal muscle - reflexes • Reflexes are protective and automatic • Testing reflexes tests the ability to move and power of movement - testing muscle and nerve(s) supplying it • 2 main skeletal muscle reflexes - stretch and flexion withdrawal Stretch reflex - reflex arc 1. Sensory nerve (muscle) detects stretch and tells spinal cord 2. Motor nerve from spinal cord passes message to contract https://galvanized-borogovia-4fa.notion.site/Introduction-to-the-MSK-System-1f82fce6b6cd45b08e9a9daed6341784 Page 2 of 3 Introduction to the MSK System 18/10/23, 11:51 PM 3. Neuromuscular junction - synapse where motor nerve communicates with skeletal muscle Deep tendon relaxes • • Biceps jerk, triceps jerk, knee jerk and ankle jerk reflexes Hammer applies stretch → stretch reflex (if normal) Flexion withdrawal reflex • • Touch something potentially damaging Sudden flexion to withdraw from the danger Muscle damage • Muscle strain: overstretched, torn or twisted muscle • Paralysis: a muscle without a functioning motor nerve supply - can’t contract ◦ Muscle would have reduced tone • Spasticity: muscle has intact and functioning motor nerve but the descending controls from the brain aren’t working • • Atrophy: 'wasting’ of the muscles through inactivity, myocytes become smaller Hypertrophy: individual myocytes enlarge https://galvanized-borogovia-4fa.notion.site/Introduction-to-the-MSK-System-1f82fce6b6cd45b08e9a9daed6341784 Page 3 of 3