Muscular System 24-25 Session II - CM edit v2 PDF

Body Structure and Processes Muscular System Introduction to Muscles Label the major muscles in the body Muscle: overview You are not expected to know all 700 muscles in the body. However, there are some major muscles it would be beneficial for you to be aware of by the time you enter Yea...

Body Structure and Processes Muscular System Introduction to Muscles Label the major muscles in the body Muscle: overview You are not expected to know all 700 muscles in the body. However, there are some major muscles it would be beneficial for you to be aware of by the time you enter Year 1 anatomy. Please use these slides as your revision guide. Muscle: overview Key axial and appendicular muscles in the anterior view. Muscle: overview Key axial and appendicular muscles in the posterior view. Muscular System Understand the difference between the point of origin and insertion Understand some of the rules used for naming skeletal muscles Label a diagram of the muscles of the upper arm Major skeletal muscles: overview There are >700 skeletal muscles o You DO NOT need to know them all o We will use a case study of the upper limb Skeletal muscles divide into two groups o Axial muscles  Position the head, spine and rib cage  Make breathing possible o Appendicular muscles  Stabilise and move lower and upper limbs Major skeletal muscles: origin and insertion All muscles have an origin o This is the site on a bone where a muscle begins o This is immovable All muscles have an insertion o This is a site on the bone where a muscle ends o This can move o E.g. the calf muscle (gastrocnemius) originates at the distal end of the femur and inserts at the calcaneus; during plantar flexion the insertion moves towards the origin Major skeletal muscles: naming muscles Muscles get their names from many places o Direction of the fascicle  E.g. ‘rectus’ means ‘straight’  Muscles that have ‘rectus’ run parallel to the long bones of the appendicular skeleton o Structural features  E.g. Biceps have two tendons at their origin  E.g. Triceps have three tendons at their origin Major skeletal muscles: naming muscles Muscles get their names from many places o Position within the body  E.g. Muscles named ‘externus’ and ‘superficialis’ are visible at the surface  E.g. Muscles named ‘profundus’ and ‘internus’ lie deeper within the body o Intrinsic versus extrinsic  ‘intrinsic’ muscles are found in organs  ‘extrinsic’ muscles stabilise organs externally Major skeletal muscles: naming muscles First part of the name relates to the point of origin Second part of the name relates to the point of insertion o E.g. the sternohyoid muscle  Originates at the sternum  Inserts at the hyoid bone N.B. when you see an ‘m’ on a diagram it means muscle Muscles of the pectoral girdle: trapezius muscles Two trapezius Trapezius muscles muscles have a diamond shape Cover the back… …neck… They perform a …and base of the large variety of skull movements Muscles of the pectoral girdle: trapezius muscles Muscles of the pectoral girdle: rhomboid muscles There are two They originate at rhomboid the cervical muscles vertebrae They are covered by the trapezius muscles They allow They insert at the shimmying scapula Muscles of the pectoral girdle: rhomboid muscles  Muscles of the pectoral girdle: levator scapulae There are two They originate at levator scapulae the cervical muscles vertebrae They are also covered by the trapezius muscles They allow They insert at the shrugging scapula Muscles of the pectoral girdle: levator scapulae  Muscles of the pectoral girdle: serratus anterior Serratus anterior Allows you to is a chest muscle swing your shoulder It inserts at the It originates on the border between the anterior surface of thoracic vertebrae the ribs and the scapula Muscles of the pectoral girdle: serratus anterior Muscles of the pectoral girdle: pectoralis minor …and it inserts at Allows you to the coracoid hunch process of the scapula Pectoralis minor originates at the ribs… Muscles of the pectoral girdle: pectoralis minor  Muscles that move the arm: deltoid Anterior view Posterior view Insert at the Originate at the deltoid lateral end of tuberosity on the clavicle the humerus The deltoid muscles abduct the arm  Muscles that move the arm: teres major Posterior view Lateral view Originate at the Insert at the top scapula of the humerus The teres major or ‘lats little helper’ often works with the latissimus dorsi to help adduct the arm. Rotator cuff muscles Four muscles: Supraspinatus Infraspinatus Teres minor Subscapularis Essential for shoulder stability and wide range of arm movements. Work together to keep head of humerus firmly in shallow socket.  Rotator cuff muscles: supraspinatus Posterior view Anterior view Originate at the Insert at the top scapula of the humerus The supraspinatus muscles assists the deltoids at the start of abduction  Rotator cuff muscles: subscapularis Posterior view Superior view Originate at the Insert at the top scapula of the humerus The subscapularis assists with internal rotation of the arm.  Rotator cuff muscles: infraspinatus Posterior view Lateral view Originate at the Insert at the top scapula of the humerus The infraspinatus muscles assist with external rotation of the arm.  Rotator cuff muscles: teres minor Posterior view Lateral view Originate at the Insert at the top scapula of the humerus The teres minor muscles also help with external rotation of the arm. Muscles that move the arm: pectoralis major Pectoralis major has …i.e. hands above two points of origin your head Pectoralis major produces flexion at 1. The clavicle the shoulder… Single point of 2. The sternum and insertion is at the top six ribs humerus  Muscles that move the arm: latissimus dorsi Anterior view Superior view Originate at the Insert at the thoracic middle of the vertebrae humerus The latissimus dorsi muscles produce extension at the shoulder; i.e. return arm to resting position after flexion Muscles that move the forearm and wrist Muscles that move the forearm and wrist all originate on the humerus There are two exceptions which both originate on the scapula and insert at the ulna or radius o Biceps brachii  Flexion of the elbow  Supination of the forearm o Triceps brachii  Extension of the elbow  Pronation of the forearm  Forearm and wrist: biceps brachii Biceps brachii have Heads converge at two heads; hence the belly BIcep Short head… …and long head… Insertion point is the …both originate at radial tuberosity on the scapula the radius  Forearm and wrist: triceps brachii Triceps brachii have …both originate at three heads; hence the humerus TRIcep …and lateral head… Long head originates at the scapula Medial head… Forearm and wrist: triceps brachii Three heads converge… …and insert at the ulna Forearm and wrist: brachialis and brachioradialis Brachialis and brachioradialis both create flexion at the elbow o They oppose the triceps brachii and counter their extension Brachialis provides 50% of elbow flexion o Origin = lower/distal humerus o Insertion = ulna Brachioradialis o Origin = lower/distal humerus o Insertion = radius Questions?