Chapter 11 The Muscular System. Muscle Attachment Sites: Origin and Insertion

Transcription

1 Chapter 11 The Muscular System Skeletal muscle major groupings How movements occur at specific joints Learn the origin, insertion, function and innervation of all major muscles Important to allied health care and physical rehabilitation students 10-1 Muscle Attachment Sites: Origin and Insertion Skeletal muscles shorten & pull on the bones they are attached to Origin is the bone that does not move when muscle shortens (normally proximal) Insertion is the movable bone (some 2 joint muscles) Fleshy portion of the muscle in between attachment sites = belly 10-2 Muscular System 3 1

2 Tenosynovitis Inflammation of tendon and associated connective tissues at certain joints wrist, elbows and shoulder commonly affected Pain associated with movement Causes trauma, strain or excessive exercise 10-4 Lever Systems and Leverage Muscle acts on rigid rod (bone) that moves around a fixed point called a fulcrum Resistance is weight of body part & perhaps an object Effort or load is work done by muscle contraction Mechanical advantage the muscle whose attachment is farther from the joint will produce the most force the muscle attaching closer to the joint has the greater range of motion and the faster the speed it can produce 10-5 First - Class Lever Can produce mechanical advantage or not depending on location of effort & resistance if effort is further from fulcrum than resistance, then a strong resistance can be moved Head resting on vertebral column weight of face is the resistance joint between skull & atlas is fulcrum posterior neck muscles provide effort

3 Second - Class Lever Similar to a wheelbarrow Always produce mechanical advantage resistance is always closer to fulcrum than the effort Sacrifice of speed for force Raising up on your toes resistance is body weight fulcrum is ball of foot effort is contraction of calf muscles which pull heel up off of floor 10-7 Third - Class Lever Most common levers in the body Always produce a mechanical disadvantage effort is always closer to fulcrum than resistance Favors speed and range of motion over force Flexor muscles at the elbow resistance is weight in hand fulcrum is elbow joint effort is contraction of biceps brachii muscle 10-8 Types of levers (Fig. 11.2) Copyright 2009, John Wiley & Sons, Inc. 3

4 Fascicle Arrangements A contracting muscle shortens to about 70% of its length Fascicular arrangement represents a compromise between force of contraction (power) and range of motion muscles with longer fibers have a greater range of motion a short fiber can contract as forcefully as a long one Parallel Muscular System 11 Fan Muscular System 12 4

5 Pennate Muscular System 13 Bipennate Muscular System 14 Fusiform Muscular System 15 5

6 Muscular System 16 Muscular System 17 Muscular System 18 6

7 Muscular System 19 Muscular System 20 Muscular System 21 7

8 Sphincter = Ring of muscle surrounding tubular organ Smooth or skeletal Muscular System 22 Coordination Within Muscle Groups Most movement is the result of several muscle working at the same time Most muscles are arranged in opposing pairs at joints prime mover or agonist contracts to cause the desired action antagonist stretches and yields to prime mover synergists contract to stabilize nearby joints fixators stabilize the origin of the prime mover scapula held steady so deltoid can raise arm How Skeletal Muscle are Named Direction the muscle fibers run Size, shape, action, number of origins or locations Examples from Table 11.2 triceps brachii -- 3 sites of origin quadratus femoris -- square shape serratus anterior -- saw-toothed edge

9 Muscles of Facial Expression Arise from skull & insert onto skin Encircle eyes, nose & mouth Express emotions Facial Nerve (VII) Bell s palsy = facial paralysis due Muscles of Facial Expression Orbicularis oculi closes the eye Levator palpebrae superioris opens the eye Orbicularis oris puckers the mouth Buccinator forms the muscular portion of the cheek & assists in whistling, blowing, sucking & chewing Extrinsic Muscles of the Eyeballs Extrinsic muscles insert onto white of eye Fastest contracting & most precisely controlled Cranial nerves 3, 4 & 6 innervate the six muscles 4 Rectus muscles & 2 obliques Intrinsic muscles are found within the eyeball Levator palpebrae superioris raises eyelid

10 Muscles that Move the Mandible Masseter, temporalis & pterygoids Arise from skull & insert on mandible Cranial nerve V (trigeminal nerve) Protracts, elevates or retracts mandible Temporalis & Masseter elevate the mandible (biting) temporalis retracts Jaw Muscles -- Deep Dissection Lateral pterygoid protracts mandible sphenoid bone to condyle of mandible Medial pterygoid elevates & protracts mandible sphenoid bone to angle of mandible Together move jaw side to side to grind food Muscles that Move the Tongue 4 extrinsic mm arise elsewhere, but insert into tongue Genioglossus from inside tip of mandible Styloglossus from styloid process Palatoglossus from hard palate Hyoglossus from hyoid bone Together move tongue in various directions Intubation is necessary during anesthesia since Genioglossus relaxes & tongue falls posteriorly blocking airway

11 Muscles of the Floor of the Oral Cavity Suprahyoid muscles lie superior to hyoid bone. Digastric m. extends from mandible to mastoid process used to open the mouth Mylohyoid m. extends from hyoid to mandible supports floor of mouth & elevates hyoid bone during swallowing Stylohyoid & Geniohyoid elevate the hyoid during swallowing Muscles that Move the Head Sternocleidomastoid muscle arises from sternum & clavicle & inserts onto mastoid process of skull innervated by cranial nerve XI (spinal accessory) contraction of both flexes the cervical vertebrae & extends head contraction of one, laterally flexes the neck and rotates face in opposite direction Muscles of Abdominal Wall Notice 4 layers of muscle in the abdominal wall

12 Muscles of Abdominal Wall 4 pairs of sheetlike muscles rectus abdominis = vertically oriented external & internal obliques and transverses abdominis wrap around body to form anterior body wall form rectus sheath and linea alba Inguinal ligament from anterior superior iliac spine to upper surface of body of pubis Inguinal canal = passageway from pelvis through body wall musculature opening seen as superficial inguinal ring Inguinal hernia = rupture or separation of abdominal wall allowing protrusion of part of the small intestine (more common in males) Transverse Section of Body Wall Rectus sheath formed from connective tissue aponeuroses of other abdominal muscles as they insert in the midline connective tissue called the linea alba Muscles Used in Breathing Quadratus lumborum fills in space between 12th rib & iliac crest to create posterior body wall Breathing requires a change in size of the thorax During inspiration, thoracic cavity increases in size external intercostal lift the ribs diaphragm contracts & dome is flattened During expiration, thoracic cavity decreases in size internal intercostal mm used in forced expiration Diaphragm is innervated by phrenic nerve (C3-C5) but intercostals innervated by thoracic spinal nerves (T2-T12)

13 Female Pelvic Floor & Perineum Both the pelvic diaphragm ( coccygeus & levator ani) and the muscles of the perineum fill in the gap between the hip bones supports pelvic viscera & resists increased abdominal pressure during defecation, urination, coughing, vomiting, etc pierced by anal canal, vagina & urethra in females levator ani may be damaged during episiotomy during childbirth (urinary incontinence during coughing Muscles of Male Perineum Perineum contains more superficial layer of muscle urogenital triangle contains external genitals muscle arrangement forms urogenital diaphragm assists in urination (external urethral sphincter) and ejaculation (ischiocavernosus, bulbospongiosus) anal triangle contains anus external anal sphincter Stabilizing the Pectoral Girdle Anterior thoracic muscles Subclavius extends from 1st rib to clavicle Pectoralis minor extends from ribs to coracoid process Serratus anterior extends from ribs to inner surface of scapula Posterior thoracic muscle Trapezius extends from skull & vertebrae to clavicle & scapula Levator scapulae extends from cervical vertebrae to scapula Rhomboideus extends from thoracic vertebrae to vertebral border of scapula

14 Axial Muscles that Move the Arm Pectoralis major & Latissimus dorsi extend from body wall to humerus Muscles that Move the Arm Deltoid arises from acromion & spine of scapula & inserts on arm abducts, flexes & extends arm Rotator cuff muscles extend from scapula posterior to shoulder joint to attach to the humerus supraspinatus & infraspinatus : above & below spine of scapula subscapularis on inner surface of scapula Flexors of the Forearm (elbow) Cross anterior surface of elbow joint & form flexor muscle compartment Biceps brachii scapula to radial tuberosity flexes shoulder and elbow & supinates hand Brachialis humerus to ulna flexion of elbow Brachioradialis humerus to radius flexes elbow

15 Extensors of the Forearm (elbow) Cross posterior surface of elbow joint & forms extensor muscle compartment Triceps brachii long head arises scapula medial & lateral heads from humerus inserts on ulna extends elbow & shoulder joints Anconeus assists triceps brachii in extending the elbow Cross-Section Through Forearm If I am looking down onto this section is it from right or left arm? Muscle that Pronate & Flex Pronator teres medial epicondyle to radius so contraction turns palm of hand down towards floor Flexor carpi muscles radialis ulnaris Flexor digitorum muscles superficialis profundus Flexor pollicis

16 Muscles that Supinate & Extend Supinator lateral epicondyle of humerus to radius supinates hand Extensors of wrist and fingers extensor carpi extensor digitorum extensor pollicis extensor indicis Retinaculum Tough connective tissue band that helps hold tendons in place Extensor & Flexor retinaculum cross wrist region attaching from bone to bone (carpal tunnel syndrome = painful compression of median nerve due to narrowing passageway under flexor retinaculum Intrinsic Muscles of the Hand Origins & insertions are within the hand Help move the digits Thenar muscles move the thumb Hypothenar muscles move the little finger Opposition, flexion, extension, abduction & adduction

17 Muscles that Move the Vertebrae Quite complex due to overlap Erector spinae fibers run longitudinally 3 groupings spinalis iliocostalis longissimus extend vertebral column Smaller, deeper muscles transversospinalis group semispinalis, multifidis & rotatores run from transverse process to dorsal spine of vertebrae above & help rotate vertebrae Scalene Muscle Group Attach cervical vertebrae to uppermost ribs Flex, laterally flex & rotate the head Muscles Crossing the Hip Joint Iliopsoas flexes hip joint arises lumbar vertebrae & ilium inserts on lesser trochanter Quadriceps femoris has 4 heads Rectus femoris crosses hip 3 heads arise from femur all act to extend the knee Adductor muscles bring legs together cross hip joint medially see next picture Pulled groin muscle result of quick sprint activity stretching or tearing of iliopsoas or adductor muscle

18 Adductor Muscles of the Thigh Adductor group of muscle extends from pelvis to linea aspera on posterior surface of femur pectineus adductor longus adductor brevis gracilis adductor magnus (hip extensor) Muscles of the Butt & Thigh Gluteus muscles maximus, medius & minimus maximus extends hip medius & minimus abduct Deeper muscles laterally rotate femur Hamstring muscles semimembranosus (medial) semitendinosus (medial) biceps femoris (lateral) extend hip & flex knee Pulled hamstring tear of origin of muscles from ischial tuberosity Cross-Section through Thigh 3 compartments of muscle with unique innervation anterior compartment is quadriceps femoris innervated by femoral nerve medial compartment is adductors innervated by obturator nerve posterior compartment is hamstrings innervated by sciatic nerve

19 Muscles of the Calf (posterior leg) 3 muscles insert onto calcaneus gastrocnemius arises femur flexes knee and ankle plantaris & soleus arise from leg flexes ankle Deeper mm arise from tibia or fibula cross ankle joint to insert into foot tibialis posterior flexor digitorum longus flexor hallucis longus flexing ankle joint & toes Muscles of the Leg and Foot Anterior compartment of leg extensors of ankle & toes tibialis anterior extensor digitorum longus extensor hallucis longus tendons pass under retinaculum Shinsplits syndrome pain or soreness on anterior tibia running on hard surfaces Lateral compartment of leg peroneus mm plantarflex the foot tendons pass posteriorly to axis of ankle joint and into plantar foot Muscles of the Plantar Foot Intrinsic muscles arise & insert in foot 4 layers of muscles get shorter as go into deeper layers Flex, adduct & abduct toes Digiti minimi muscles move little toe Hallucis muscles move big toe Plantar fasciitis (painful heel syndrome) chronic irritation of plantar aponeurosis at calcaneus improper shoes & weight gain

20 Running injuries Compartment syndrome