Muscular system Golden rules of skeletal muscles  All muscles cross at least one joint.  The muscle bulk lies proximal to the joint.  Muscles have origin and insertion.  Muscle can only pull.  During contraction insertion move towards origin.  The origin is attached to less movable bone, insertion to the movable one.

Types of body movements Flexion: bring two bones together. Hinge joint, knee, elbow. Extension: opposite of flexion, hyperextension, more than 180 degrees, like neck. Rotation: movement around longitudinal axis, shoulder, atlas around axis. Abduction: Moving a limb away from medial plane, faning of fingers, shoulder. Adduction: moving limb toward midline. Circumduction: combination of all movements, moving in a circle.

Supination and pronation: Supination occur when the forearm rotate laterally Palm anterior Radius and ulna are parallel. Pronation occur when forearm rotate medially. Palm face posteriorly Radius bone cross the ulna like X.

Dorsiflextion and planter flexion: up and down movements of ankle. Inversion and eversion: invert turn sole medially, eversion turn sole laterally. Opposition: the thumb touches the other fingers.

Types of muscles Antagonist: muscle that do the opposite function. Synergist: help other muscle to do the same function.

How to name the muscle?  Direction of muscle fiber e.g. rectus mean straight.  Size of muscle e.g. gluteus maximums i.e. largest.  Location of the muscle e.g. temporalis over temple.  Number of origins e.g. biceps, two, triceps three.  Location of origin and insertion e.g. sternomastoid  Shape of the muscle e.g. deltoid meaning triangular.  Action of the muscle e.g. flexor, extensor.

Important muscles of shoulder girdle Pectoralis major Fan shaped muscle, cover front of the chest. Origin: first 6 ribs and shoulder girdle Insertion: upper humerus Action: flex shoulder, adduct the arm.

Posterior muscles Trapezius: most superficial muscle of the back of the neck, and upper trunk. Origin: occipital bone of skull, back of neck back of chest. Insertion: scapular spine, and clavicle. Action: extend the head, elevate, and depress the shoulder adduct arm.

Latissimus dorsi: large, flat muscle. Important muscle in swimming Origin: lower spine, and ilium. Insertion: upper humerus Action: extend and adduct the arm.

Deltoid: fleshy, triangular shaped muscle, bulky. Favorite site for injection. Origin: spine of scapula, and clavicle. Insertion: deltoid tuberosity, upper humerus. Action: abduct the arm. Muscle of upper arm The anterior group cause elbow flexion. The posterior group cause elbow extension.

Action: it flexes and supinates the elbow. Brachialis lies deep to biceps. Biceps brachii: originate by two heads from the scapula and inserted into radial tuberosity of radius.

Triceps brachii: origin by three heads from scapula and humerus, inserted in olecranon process of ulna. Action: it extends the elbow.

Muscles of the lower limb  Largest and strongest muscles of the body.  Muscles causing movement at hip joint.  Lower limb is limb of stability, upper limb is for mobility  Anti gravity muscles, back of hip, front of thigh, back of leg  Act on two joints, hip and knee during walking  Movement appear to be done by pelvis, but done by lumbar vertebrae  Anterior abdominal wall muscles flex pelvis, by flexing lumbar vertebrae  Hamstring muscles back of thigh  Quadriceps front of the thigh

Gluteus maximus: origin, from sacrum and iliac bone, insertion into gluteal tuberosity of femur. Action the most important muscle of extension of the hip. Gluteus medius: lie under the gluteus maximus.itis the site for intra muscular injections. Stabilize pelvis during walking. The medial part of each buttock covers the important sciatic nerve. Action: it abducts the hip.

Iliopsoas: is two muscles, iliacus, and psoas major. Origin from lumbar vertebrae, and iliac bone Inserted into lesser trochanter of femur. Action it flex the hip. Adductor muscles Small muscles, they adduct the thigh. Muscles causing movement at knee joint Hamstring group Three muscles biceps femoris, semimembrenosus, semitendenosus. Origin: from ischial tuberosity Insertion: proximal medial tibia, and head of fibula. Action: it flexes the knee.

Quadriceps muscles: four muscles Rectus femoris, and three vastus(medialis,lateralis,intermedius).A nterior thigh Origin from femur Insertion: tibial tuberosity, via patellar ligament. Action: extend the knee. Can use vastus lateralis for intramuscular injections.

Muscles of the back of the leg Gasrocnemius Two bellies that form the curved calf Origin: two head from distal femur Insertion into calcaneus bone by tendon Achilles'. Soleus: lie deep to gastrocnemius. Origin: from tibia, back of fibula. Insertion: same Action of both muscles: planter flexion of the ankle.

Muscles of the abdominal wall Anterior abdominal muscles are: Rectus abdominis, external oblique, internal oblique, transverses abdominis. Their fibers run in three directions. Protect abdominal contents. Rectus abdominis: straplike, rectus muscles, most superficial. Run from pubis to rib cage, enclosed in aponeurosis.

Action: Flex the trunk Increase intra abdominal pressures in defecation, delivery, help respiration. Protect the viscera. External oblique: paired superficial lateral muscles. Fibers run downward and medially. Internal oblique: deep to Eo. Fibers run at right angle to Eo. Transversus abdominis.: deepest muscles, fibers run horizontal.

Point to remember Linea Alba is the medial border of rectus muscle. Linea semilunaris is the lateral border of rectus. Both are bloodless point used to open abdomen.

Head and neck muscles Two groups Facial muscles chewing muscles Facial muscles Frontalis: rise eye brow. Orbicularis oculi: close eyes, blink,wink and squint Orbicularis oris: close mouth, Buccinator: flattens check, whistle.

Chewing muscles Masseter, temporalis, and ptyregoid muscles. Neck muscles Sternocleidomastoid: Origin: sternum and clavicle Insertion: mastoid process of temporal bone Action: both flex the neck One side rotate head to other side

Intramuscular injections Intramuscular injections are used when rapid absorption is needed, because muscle has a good blood supply. Common sites are the buttock (gluteus medius), the lateral thigh (vastus lateralis), and the shoulder (deltoid). These sites are shown; also shown are the large nerves to be avoided when giving such injections.

ORGANIAZATION OF SKELETAL MUSCLE Endomysium – muscle fiber Perimysium – fascicle Epimysium – entire muscle The membrane of the muscle fiber is the sarcolemma. Within the muscle fiber are thousands of individual contracting units called sarcomeres, which are arranged end to end in cylinders called myofibrils. Myosin and actin are the contractile proteins of a muscle fiber.

ORGANIZATION OF SKELETAL MUSCLE

SKELETAL MUSCLE

CARDIAC MUSCLE

SMOOTH MUSCLE

COMPARISON BETWEEN THE THREE TYPES OF MUSCLES