Muscular System PDF

The Muscular System  Muscles Muscle types Functions Clinical Considerations Structure Muscles (functional groups) Muscle Types  Function of Skeletal Muscles Produce movement (articulation) – Ambulation (movement of bones at joints) – S...

The Muscular System  Muscles Muscle types Functions Clinical Considerations Structure Muscles (functional groups) Muscle Types  Function of Skeletal Muscles Produce movement (articulation) – Ambulation (movement of bones at joints) – Stop movement – Posture – Stabilize joints – Facial expression Control movement of various substances – Sphincters – Voluntary Respiration – diaphragm Protection – Underlying organs Homeostasis – Heat production  Structure of Skeletal Muscles Anatomy – M. fibre – Endomysium – Fascicle/fasciculus – Perimysium – Epimysium – aa., vv., nn. Fascicle Arrangement/Shapes – Parallel – Convergent – Pennate Unipennate Bipennate Multipennate – Sphincters – Spiral – Fusiform  Naming of Muscles Shape Orbicularis, serratus, trapezius, quadratus Size Maximus, medius, minimus, major, minor, vastus Length Brevis, longus Position relative to midline Lateralis, medialis Direction Rectus, oblique Location in body (frontalis, capitis, carpi, oculi, oris) of attachments to skeleton (sternocleidomastoid) # of origins/mm. Biceps, triceps, quadriceps Actions Flexor, extensor, abductor, adductor, levator, erector  Naming of Muscles Direction of muscle fibres Relative size Location Number of origins Location of origin/insertion Shape Action  Functional Groups Agonist Antagonist Synergist Fixator  Origins and Insertions Origin Insertion  Muscles of Facial Expression Emotions/non-verbal communication Originate from bone/flat tendons and insert onto the hypodermis of the skin. Facial n. (CN VII)  Platysma Tenses skin of neck Depresses lower lip  Orbicularis Oris Purses lips Compresses lips against the teeth Articulation Mastication  Buccinator Pushes food against teeth Whistling and sucking Taut cheeks  Orbicularis Oculi – Orbital* – Palpebral* – Lacrimal Facial Paralysis  Muscles of Mastication Temporalis Masseter  Temporalis & Masseter mm. Temporalis m. – Powerful biting mm. – Floor of temporal fossa [O] – Coronoid process [I] – Elevation, retraction of mandible [A] Masseter m. – Medial surface of zygomatic arch [O] – Ramus of mandible [I] – Elevation, retraction of mandible  Sternocleidomastoid Sternum and clavicle [O] Mastoid process [I] Flexion, rotation [A] Torticollis Muscles of the Abdominal Wall  Anterolateral Abdominal Wall Muscles Internal Abdominal Oblique & Rectus Abdominis mm. External Abdominal Oblique m. Transversus Abdominis m. Median Incisions  Erector Spinae m. Iliocostalis m. Longissimus m. Spinalis m. Actions – Extend head and back when both are contracted – Laterally flexes head and vertebral column when one is contracted – Rotation of head  Latissimus dorsi Inferior six T-vertebrae, iliac crest, inferior 3-4 ribs [O] Intertubercular groove [I] Extends, adducts, rotates humerus medially @ shoulder joint [A]  Serratus Anterior Large m. that overlies the lateral aspect of the thorax and the intercostal mm. External surfaces of lateral parts of 1-8th rib [O] Anterior surface of medial border of scapula [I] Protracts the scapula and holds/fixes it against the thorax [A] Winged Scapula  Trapezius Large, flat, triangular m. cover the posterior aspect of the neck External occipital protuberance, spinous processes of C7-T12 [O] Lateral 1/3 of clavicle, acromion, spine of scapula [I] Elevates (superior fibers), retracts (middle fibers), depresses scapula Weakness causes drooping of shoulders  Deltoid Lateral 1/3 clavicle, acromion, spine of scapula [O] Deltoid tuberosity [I] Abduction of humerus @ shoulder, flexion and medial rotation (ant), extensor and lateral rotation (post) [A] Antagonists: pectoralis major and latissimus dorsi m. Intramuscular Injection  Rotator cuff mm. Supraspinatus m. Infraspinatus m. Teres minor m. Subscapularis m. SITS mm.  Supraspinatus, Infraspinatus & Teres Minor mm. Supraspinatus m.: – Supraspinous fossa [O] – Superior aspect of greater tubercle [I] – Initiates and assists deltoid in abduction (first 15◦ of abduction) [A] Infraspinatus m. – Infraspinous fossa [O] – Greater tubercle [I] – Lateral rotation of humerus [A] Teres minor m. – Lateral border of scapula [O] – Greater tubercle [I] – Laterally rotates humerus [A]  Subscapularis m. Subscapular fossa [O] Lesser tubercle [I] Medially rotates humerus [A] Adducts arm [A]  Rotator Cuff Injuries Commonly injured – Repetitive use of upper limb above the horizontal – Supraspinatus m. often affected – Baseball, racquet sports, swimming, weightlifting – Complete abduction followed by rapid and forceful rotation  Biceps brachii m. Short head – Coracoid process [O] Long head – supraglenoid tubercle [O] Radial tuberosity – both long and short heads [I] Flexion at elbow [A] Flexion at shoulder [A] Supinator [A]  Rupture of Biceps Can involve distal insertion or long head of biceps brachii proximal biceps rupture more common than distal results in approximately 20% forearm flexion loss but more significant loss of forearm supination Causes: – Injury: a fall on to an outstretched arm sudden heavy lifting causing forced contraction of the biceps. – Impingement: gradual fraying of the tendon which can occur as a result of impingement which is contact between the tendon and the acromion bone above it. Overuse with repetitive shoulder motion causing accelerated rubbing and wear. – Degeneration: age related degeneration may be preceding degeneration of impingement and then tearing as a result of the relatively minor injury  Brachioradialis m. Origin: – Lateral supracondylar ridge Insertion: – Lateral surface of distal end of radius proximal to styloid process Actions: – Weak flexion of forearm – Strong flexor of forearm when in neutral (mid- pronated) position  Triceps Brachii m. Long head Lateral head Medial head Olecranon process of ulna [I] Extension at elbow [A] Extension at shoulder [A]  Anatomical Snuffbox extensor pollicis longus m. extensor pollicis brevis m. Scaphoid Styloid process of radius Trapezium Base of 1st metacarpal Radial a. Cephalic v.  Gluteal Muscles Gluteus maximus m. Gluteus medius m. Gluteus minimus m.  Gluteus Maximus m. Largest & heaviest gluteal m. Covers all other gluteal mm. Used only briefly when walking Actions: Chief extensor of thigh Assists in lateral rotation  Gluteus Medius & Minimus mm. Fan shaped Gluteus Medius & Minimus mm. Origin: External aspect of ilium Insertion: Greater trochanter Actions: Abduction at thigh Medial rotation at thigh Stabilizes pelvis when weightbearing – preventing pelvic tilt Intramuscular Gluteal Injections  Positive Trendelenburg Which nerve?  Anterior (Thigh) Compartment Anterior Compartment – Extensors Flexion of thigh Extension of leg Femoral nerve Muscles – Iliopsoas m. – Pectineus m. – Sartorius m. – Quadriceps femoris m. Rectus femoris m. Vastus lateralis m. Vastus intermedius m. Vastus medialis m.  Quadriceps Femoris m. Four heads Largest and one of most powerful in body Origin: Rectus femoris m.: AIIS Vastus lateralis m.: linea aspera Vastus intermedius m.: anterior surface of femur Vastus medialis m.: linea aspera Insertion: tibial tuberosity Actions: All extend at knee Rectus femoris m: flex at thigh  Iliopsoas m. L. mm. of the loins Iliacus & psoas mm. Origin: Transverse processes of T12-L5 (psoas major m.) Iliac fossa (iliacus m.) Insertion: Lesser trochanter Actions: Flex thigh at hip Stabilize joint  Medial (Thigh) Compartment Muscles – Adductor longus m. – Adductor brevis m. – Adductor magnus m. – Gracilis m. Actions: – Adduction of thigh – Medial rotation of thigh  Posterior (Thigh) Compartment Muscles – Semitendinosus m. – Semimembranosus m. – Biceps femoris m. Actions: – Flexion of leg at knee – Extension of thigh  Muscles of the Leg (Compartments) Anterior Compartment – Dorsiflexion – extension of toes Lateral Compartment – Plantarflexion – eversion of ankle Posterior Compartment – Superficial and deep – Plantarflexion – flexion of toes  Anterior (Leg) Compartment Muscles Tibialis anterior m. Extensor hallucis longus m. Extensor digitorum longus m. Actions: Dorsiflexion Extension of toes  Anterior Compartment Syndrome occurs when the tissue pressure within a closed muscle compartment exceeds the perfusion pressure and results in muscle and nerve ischemia. It typically occurs subsequent: – Trauma (fractures) – arterial injury – Exertion – prolonged limb compression Edema – hemorrhage accumulation Elevated compartment pressure Compartment tamponade – Muscle ischemia – Neural injury Foot drop  Foot Drop inability or difficulty dorsiflexion the leg must be lifted higher than usual to prevent the foot from dragging. Causes: nerve damage muscle damage abnormal anatomy a combination Deep fibular (peroneal) n. Abnormal gait  Lateral (Leg) Compartment Muscles Peroneus longus m. Peroneus brevis m. Actions Plantar flexion Eversion of ankle  Avulsion Fracture Fibularis (peroneus) brevis tendon Tuberosity (base) of 5th metatarsal violent and sudden inversion of foot my result in tuberosity fracturing and may be pulled off by tendon of peroneus brevis  Posterior (Leg) Compartment Muscles of superficial compartment Gastrocnemius m. Soleus m. Plantaris m. Actions Plantarflexion at ankle flexion of toes  Ruptured Calcaneal Tendon More common in men Ages 30-40 years old Weekend warriors Fluoroquinolone antibiotics Steroid injections usually traumatic injury during a sporting event may occur with: – sudden forced plantar flexion – violent dorsiflexion in a plantar flexed foot rupture usually occurs 4-6 cm above the calcaneal insertion in hypovascular region