Lecture 9 Muscular System COVID (2) PDF

Muscular System Classification of Skeletal Muscles By pattern of fascicles organization: parallel convergent circular By relationships of fascicles to tendons: pennate Parallel Muscles Fibers are parallel to the long axis of muscle: ̶e.g., sartorius If the center of the muscle is th...

Muscular System Classification of Skeletal Muscles By pattern of fascicles organization: parallel convergent circular By relationships of fascicles to tendons: pennate Parallel Muscles Fibers are parallel to the long axis of muscle: ̶e.g., sartorius If the center of the muscle is thick fusiform: ̶e.g., biceps brachii Convergent Muscles A broad area converges on attachment site (tendon, aponeurosis, or raphe) Muscle fibers pull in different directions, depending on stimulation e.g., pectoralis muscles Circular Muscles Also called sphincters Open and close to guard openings of the body e.g., orbicularis oris, external anal sphincter Pennate Muscles Fascicles form an angle with the tendon 3 Types: ̶ unipennate:  fibers on 1 side of tendon  e.g., extensor digitorum ̶ bipennate:  fibers on both sides of tendon  e.g., rectus femoris ̶ multipennate:  tendon branches within muscle  e.g., deltoid Origin, Insertion & Action Origin: fixed point of attachment Insertion: moving point of attachment Most muscles originate or insert on the skeleton Origin is usually proximal to insertion (exceptions) Action: movement produced by muscle contraction e.g., flexion, extension, adduction, … insertion is usually pulled towards origin (exceptions) Types of Muscles Based on Action Agonist (prime mover): ̶produces a particular action Synergist: ̶a smaller muscle that assists a larger agonist ̶helps start motion or stabilize origin of agonist (fixator) Antagonist: ̶opposes action of the agonist... Muscle Opposition Agonists and antagonists work in pairs: when 1 contracts, the other relaxes i.e., flexors–extensors, abductors–adductors, etc. Muscle Terminology Names of Skeletal Muscles Correct names of muscles include the term muscle Exceptions:  platysma  diaphragm Can be determined by one or more of… Naming Skeletal Muscles 1. Location in the body 2. Origin and insertion 3. Fascicle organization 4. Relative position 5. Structural characteristics 6. Action Location in the Body Identifies body regions e.g.: temporalis (temporal bone) frontalis (frontal bone) Origin & Insertion E.g., sternocleidomastoid muscle First part of name indicates origin Second part of name indicates insertion Fascicle Organization Describes fascicle orientation within muscle: i.e., rectus (straight), transversus, oblique Relative Position Externus (superficialis): ̶Superficial muscles Internus (profundus): ̶deep muscles Extrinsic: ̶muscles outside an organ Intrinsic: ̶muscles inside an organ Structural Characteristics Number of tendons (heads):  bi = 2, tri = 3, quadri = 4 Shape: deltoid (triangle), trapezius (trapezoid) Size: longus = long, brevis = short magnus = large, maximus = largest, minimus = smallest Action Movements: e.g., flexor, extensor, adductor, abductor Special actions: e.g., sartorius = like a tailor Combined Names (Example) Flexor Digitorum Superficialis Muscle Action Insertion Position (Location) Divisions of the Muscular System Axial muscles: ̶60% of skeletal muscles ̶position head and vertebral column ̶move thoracic cage Appendicular muscles: ̶40% of skeletal muscles ̶support pectoral and pelvic girdles ̶move upper and lower limbs Axial & Appendicular Muscles Axial Muscles Axial Muscles Axial Muscles Occipital belly of Frontal belly of occipitofrontalis occipitofrontalis Muscles of head and neck Temporalis Sternocleidomastoid Sternocleidomastoid Muscles of vertebral column Muscles of abdominal wall Rectus abdominis External oblique External oblique Muscles of pelvic floor Linea alba Anterior view Posterior view Muscles of Head & Neck 1 1. Muscles of facial expression: ̶ originate on skull 2. Muscles of mastication: ̶ move the mandible 3. Extrinsic eye (extraocular) muscles: ̶ originate on surface of orbit ̶ insert on the sclera of the eyeball ̶ control position of eye Muscles of Head & Neck 2 4. Muscles of the tongue: ̶ names end in glossus 5. Muscles of the pharynx: ̶ begin swallowing process 6. Muscles of the neck: ̶ anterior, posterior, and lateral groups Muscles of Facial Expression = Mimetic Supplied by the Facial Muscles Nerve (VII) Muscles of Facial Expression Occipitofrontalis (Epicranius): ̶frontal and occipital bellies ̶separated by epicranial aponeurosis (galea aponeurotica) Orbicularis oculi: ̶closes the eye and produces blinking Orbicularis oris: ̶constricts the mouth opening Buccinator: ̶moves food around the cheeks Muscles of Facial Expression 1 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ Muscles of Facial Expression 2 ✓ ✓ Muscles of Mastication Masseter: ̶strongest jaw muscle Temporalis: ̶helps lift the mandible Buccinator: ̶moves food around the cheeks(VII ) Pterygoids: ̶medial & lateral All supplied by the Trigeminal Nerve Muscles of Mastication ✓ ✓ ✓ ✓ Extrinsic Muscles of the Eye 4 recti muscles: ̶superior rectus ̶inferior rectus ̶medial rectus ̶lateral rectus Abduc ens 2 oblique muscles: (VI) ̶superior oblique Trochlea r ( ̶inferior oblique IV) All supplied by the Oculomotor Nerve (III) EXCEPT... Extrinsic Muscles of the Eye ✓ ✓ ✓ ✓ ✓ ✓ Muscles of the Neck Sternocleidomastoid: ✓ ̶exceptions:  origin is distal to insertion  insertion is pushed away from origin Muscles of the Abdominal Wall Oblique muscles: ̶compress underlying structures ̶rotate vertebral column Rectus muscles: ̶flex vertebral column ̶oppose erector spinae muscle (muscle of the vertebral column) Oblique Muscles Oblique Muscles External oblique muscle: ̶most superficial ̶fibers run downward and medially Internal oblique muscle: ̶underlies external oblique ̶fibers run upward and medially Transversus abdominis muscle: ̶deepest ̶fibers run horizontally Rectus Group: Rectus abdominis Between xiphoid process and symphysis pubis Separated in the middle line by linea alba Divided transversely by tendinous inscriptions Rectus Group: Diaphragm Divides thoracic and abdominal cavities Helps in respiration: main muscle of inspiration Muscles of the Abdominal Wall ✓ ✓ ✓ ✓ ✓ Muscles of the Pelvic Floor Functions of Pelvic Floor Muscles Support organs of pelvic cavity Flex sacrum and coccyx Control movement of: ̶urine through urethra (external urethral sphincter) ̶stool through anus (external anal sphincter) Perineum Area of skin anterior to the anus Extends to: ̶vaginal opening (female) ̶base of the testicles (male) Rich in nerve endings Site of episiotomy Appendicular Muscles Appendicular Muscles Appendicular Muscles Trapezius Trapezius Clavicle Deltoid Deltoid Sternum Pectoralis major Infraspinatus Teres minor Latissimus dorsi Teres major Serratus anterior Muscles of pectoral girdle Rhomboid major Biceps brachii Triceps brachii (long head) Triceps brachii Triceps brachii (lateral Brachialis Muscles head) of upper limbs Latissimus dorsi Pronator teres Brachioradialis Brachioradialis Extensor carpi radialis longus Extensor carpi radialis longus Muscles of pelvic girdle Anconeus Flexor carpi ulnaris Extensor digitorum Extensor carpi radialis brevis Palmaris longus Flexor carpi radialis Muscles Extensor carpi ulnaris of lower limbs Gluteus medius Tensor fasciae latae Gluteus maximus Flexor digitorum superficialis Flexor carpi ulnaris Gluteus medius Adductor magnus Tensor fasciae latae Iliopsoas Semitendinosus Pectineus Semimembranosus Adductor longus Gracilis Gracilis Biceps femoris Sartorius Sartorius Ractus femoris Plantaris Vastus lateralis Vastus medialis Gastrocnemius Gastrocnemius Soleus Fibularis longus Tibialis anterior Soleus Extensor digitorum longus Posterior view Lateral malleolus of fibula Anterior view Posterior view Calcaneal Medial malleolus of tibia tendon Calcaneus Muscles of Pectoral Girdle Trapezius: ̶superficial ̶covers back and neck ̶insertion: clavicle and scapular spine Rhomboids and levator scapulae: ̶deep to trapezius ̶origin: cervical and thoracic vertebrae ̶insertion: medial scapular border Muscles of Pectoral Girdle Serratus anterior: ̶on the chest ̶originates along ribs ̶inserts on anterior scapular margin External Internal intercostals Innermost Muscles of Pectoral Girdle ✓ ✓ ✓ ✓ ✓ Muscles Move Upper Limbs Clavicle Deltoid Pectoralis major Latissimus dorsi Muscles move the arm Biceps brachii Muscles move the forearm Triceps brachii Brachialis Muscles move the hand and fingers Pronator teres Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Palmaris longus Flexor carpi radialis Flexor digitorum superficialis Flexor carpi ulnaris  Muscles Move the Arm Pectoralis major: ̶between sternum and greater + adduction & medial tubercle of humerus ̶flexes the shoulder Latissimus dorsi: ̶between thoracic & lumbar rotation vertebrae and intertubercular groove of humerus ̶extends the shoulder Muscles Move the Arm Deltoid: ̶ insertion: deltoid tuberosity ̶ major abductor Supraspinatus: ̶ assists deltoid (1st 15°) Infraspinatus and teres minor: ̶ produce lateral rotation at shoulder Subscapularis and teres major: ̶ produce medial rotation at shoulder Rotator Cuff j or i s N OT Teres ma included 4 muscles involved in moving shoulder: ̶subscapularis, supraspinatus, infraspinatus, and teres minor Originate from the scapula Combine to form a "cuff" over the humerus head Form a single tendon: ̶inserts on greater tubercle of the humerus Help lift and rotate the arm and stabilize the ball of the shoulder within the joint Rotator Cuff Tear Causes: ̶acute injury (sports) ̶repetitive overhead work Common cause of pain and disability in adults Muscles Move the Arm ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ Muscles Move Forearm & Hand Flexors & Extensors Flexors: mainly on anterior and medial surfaces of arm and forearm Extensors: mainly on posterior and lateral surfaces of arm and forearm Muscles Move the Forearm Origin: w- -- scapula: - o -- - l b  biceps brachii -- e  triceps brachii (long head) h e t humerus: on ct  rest of the muscles A int insertion: jo forearm bones Flexors of the Forearm Biceps brachii: ̶major flexor of the elbow ̶originates on scapula ̶2 heads: long and short ̶inserts on radial tuberosity Brachialis and brachioradialis: ̶assist biceps brachii (synergists) Prime mover of elbow flexion What is the difference between…? Chin & Pull Ups Ups Extensors of the Forearm Triceps brachii: ̶major extensor of the elbow ̶originates on scapula and humerus ̶3 heads: long, medial, and lateral ̶inserts on olecranon Pronators & Supinators of the Forearm Pronator teres and supinator: ̶originate on humerus and ulna ̶insert on the radius ̶rotate the radius Supinat or Muscles Move the Forearm ✓ ✓ ✓ ✓ ✓ ✓ Muscles Move Hand & Fingers Muscle Groups of the Hand Extrinsic muscles Intrinsic muscles Extrinsic Muscles of the Hand Are located entirely outside the hand (within the forearm) Only tendons cross the wrist (in tendon sheaths) Move hand and fingers Flexors of the Hand w - - r --i-s-t- o n the (from lateral to medial) Act Flexor carpi radialis: joint ̶flexes and abducts wrist Palmaris longus: ̶flexes wrist Flexor carpi ulnaris: ̶flexes and adducts wrist Extensors of the Hand wri s t o n the (from lateral to medial) Act joint Extensor carpi radialis longus Extensor carpi radialis brevis ̶extend and abduct wrist Extensor carpi ulnaris: ̶extends and adducts wrist Extrinsic Muscles of the Hand (Muscles moving the hand) ✓ ✓ Extrinsic Muscles of the Hand (Muscles moving the fingers) Intrinsic Muscles of the Hand e n Th othe ar Hyp nar ross Located within the hand I nt e ei bric Lum als Tendon Sheaths Wide bands of connective tissue Extensor retinaculum: ̶posterior surface of wrist ̶stabilizes tendons of extensor muscles Flexor retinaculum: ̶anterior surface of wrist ̶stabilizes tendons of flexor muscles Carpal Tunnel Syndrome Thickiening of flexor retinaculum Narrowing of the carpal tunnel Compression of the median nerve Numbness, pain and impaired nerve function All the following muscles contribute to the rotator cuff EXCEPT: A. Subscapularis muscle B. Teres major muscle C. Supraspinatus muscle D. Teres minor muscle E. Infraspinatus muscle All the following muscles contribute to the rotator cuff EXCEPT: A. Subscapularis muscle B. Teres major muscle C. Supraspinatus muscle D. Teres minor muscle E. Infraspinatus muscle Muscles of Pelvic Girdle Pelvic girdle is tightly bound to axial skeleton: permits little movement has few muscles Muscles Move Lower Limbs Muscles move the thigh Muscles move the leg Muscles move the foot and toes Muscles Move the Thigh Gluteal muscles: cover lateral surface of ilium Lateral rotators: extend from the acetabulum to the greater trochanter Adductors: along the medial aspect of the thigh Iliopsoas muscle: 2 in 1 muscle Gluteal Muscles Gluteal Muscles Gluteus maximus: ̶ largest, most posterior gluteal muscle ̶ inserts on the iliotibial tract ̶ produces extension and lateral rotation at hip Gluteus medius and minimus: ̶ anterior to gluteus maximus ̶ insert on greater trochanter of femur Tensor fasciae latae: ̶ works with gluteus maximus ̶ stabilizes iliotibial tract Muscles Move the Thigh (Gluteal muscles) ✓ ✓ ✓ ✓ Adductors Adductor magnus: ̶ adduction, flexion and medial rotation (superior part) ̶ adduction, extension and lateral rotation (inferior part) Adductor longus Adductor brevis Pectineus Gracilis ̶ adduction, flexion and medial rotation Iliopsoas Muscle 2 hip flexors: ̶psoas major ̶iliacus Origin: lumbar vertebrae and iliac fossa Share one tendon Insertion: lesser trochanter Muscles Move the Thigh (Adductors & iliopsoas muscles) ✓ ✓ Muscles Move the Leg. e... Extensors: k...e.n ̶originate on the femoral surface the t on ̶prime: quadriceps femoris Ac t oi n  front of the thigh j Flexors: ̶originate on the pelvic girdle ̶prime: hamstrings  back of the thigh  Anterior superior iliac spine Inguinal ligament Extensors of the Knee Gluteus medius Iliacus Iliopsoas Psoas major Pubic tubercle Tensor fasciae Quadriceps femoris (4 muscles): latae Pectineus rectus femoris muscle Adductor longus Gracilis 3 vasti muscles: Sartorius  vastus medialis Extensors of the Knee  vastus lateralis Iliotibial tract (Quadriceps muscles) Rectus femoris  vastus intermedius Vastus lateralis Share one tendon → Vastus medialis Enclose the patella Quadriceps tendon Insertion: tibial tuberosity Patella Patellar ligament  Iliac crest Gluteus medius Flexors of the Knee Tensor fasciae latae Hamstring Gluteus maximus Semitendinosus (medial Semimembranosus) s Adductor magnus Sartorius Biceps femoris (lateral) Gracilis Iliotibial tract Sartorius: Flexors of the Knee Biceps femoris, long head ̶origin: anterior superior iliac spine Biceps femoris, short head Semitendinosus ̶flexes both hip & knee Semimembranosus Popliteus: Sartorius Popliteus ̶rotates the tibia to unlock the knee Muscles Move the Leg ✓ ✓ Muscles Move Foot & Toes Extensors of the ankle (plantar flexion) Flexors of the ankle (dorsiflexion) Extensors of the toes Flexors of the toes Extensors (Plantarflexors) of the Ankle Gastrocnemius Soleus calcaneal (achilles) tendon Peroneus (fibularis): ̶longus ̶brevis Tibialis posterior Flexors (Dorsiflexors) of the Ankle Tibialis anterior: ̶opposes the extensors Muscles Move Foot ✓ ✓ ✓ ✓ ✓ ✓ Extensors of the Toes Extensor digitorum longus Extensor hallucis longus Extensor Retinacula Fibrous sheaths Hold tendons of toes as they cross the ankle Include: ̶superior extensor retinaculum ̶inferior extensor retinaculum Flexors of the Toes Flexor digitorum longus Flexor hallucis longus ̶oppose the extensors Muscles Move Toes ✓ ✓ Intrinsic Muscles of the Foot Hernia Protrusion of an organ through an abnormal opening Due to muscle defect Common types: ̶inguinal ̶umbilical ̶incisional ̶diaphragmatic (hiatus) Effects of Aging on Skeletal Muscles Skeletal muscle fibres become: ̶smaller in diameter ̶less elastic (due to fibrosis) Decreased tolerance for exercise Decreased ability to recover from muscular injuries Integration with Other Systems Summary  Organization of skeletal muscle fibers: ̶ parallel, convergent, circular, pennate  Actions of skeletal muscles: ̶ agonist, antagonist, synergist  Naming of skeletal muscles  Axial muscles: Appendicular muscles: ̶ head & neck ̶ vertebral column – shoulder & upper limb ̶ abdominal wall – pelvis & lower limb ̶ pelvic floor  Hernia  Effects of aging on skeletal muscles