Skeletal Muscles Attach to bones Produce skeletal movement

Skeletal Muscles • • • Attach to bones Produce skeletal movement (voluntary) Maintain posture Support soft tissues Regulate entrances to the body Maintain body temperature

Properties of Skeletal Muscles Electrical excitability -ability to respond to stimuli by producing action potentials -two types of stimuli: 1. autorhythmic electrical signals 2. chemical stimuli – e. g. neurotransmitters Contractility -ability to contract when stimulated by an action potential -isotonic contraction: tension develops, muscle shortens -isometric contraction: tension develops, length doesn’t change Extensibility -ability to stretch without being damaged -allows contraction even when stretched Elasticity -ability to return to its original length and shape

Muscles: Gross Anatomy • muscles with similar functions are grouped and held together by layers of deep fascia e. g. biceps brachii and brachialis – forearm flexion • three layers of connective tissue surround a muscle – Epimysium – divides a muscle into fasicles – Perimysium – divides a fasicle into muscle fibers – Endomysium – divides a muscle fiber into myofibrils

Gross Anatomy • muscles are surrounded by a fascia (areolar tissue) • remove the fascia – epimysium that surrounds the muscle and divides it into groups called fascicles • each individual fascicle is surrounded by a perimysium • perimysium divides the fascicle into muscle fibers • muscle fiber = individual muscle cell • each muscle fiber/muscle cell is surrounded by an endomysium • endomysium divides the muscle fiber into protein filaments = myofibrils • myofibrils contain a “skeleton” of protein filaments (myofilaments) organized as sarcomeres

Muscles: Gross Anatomy • epimysium and perimysium extend off the muscle to become organized as a tendon – attaches to the periosteum of the bone

Dense regular connective tissue: Ligaments and Tendons

Microanatomy of Skeletal Muscle Fibers • • • large, multinucleated cells called fibers mature muscle fibers range from 10 to 100 microns in diameter typical length is 4 inches - some are 12 inches long muscle fibers increase in size during childhood = human GH & testosterone also increases muscle size

Skeletal Muscle vs. Smooth vs. Cardiac Muscle fibers

Microanatomy of Skeletal Muscle Fibers • embryonic development – stem cells (satellite cells) differentiate into immature myoblasts which begin to make the proteins of the myofibrils (i. e. the myofilaments) – myoblasts mature into myocytes – multiple myocytes fuse to form the muscle cell (muscle fiber) – muscle fibers cannot divide through mitosis – number of muscle cells predetermined before birth – they get larger as we grow – satellite cells can repair damaged/dying skeletal muscle cells throughout adulthood

Muscle Cell Anatomy • new terminology • cell membrane = sarcolemma • cytoplasm = sarcoplasm – large amounts of glycogen and myoglobin – surrounds the myofibrils • myofibrils made up of myofilaments – actin & myosin • transverse tubules – ingrowths of the sarcolemma – carry the action potential deep into the fiber – flanks the sarcoplasmic reticulum • novel internal membrane system = sarcoplasmic reticulum – for calcium storage

The Proteins of Muscle • contractile elements of the myofibrils = myofilaments -2 microns in diameter -give the muscle its striated appearance • myofilaments are built of 3 kinds of protein – contractile proteins • myosin and actin – regulatory proteins which turn contraction on & off • troponin and tropomyosin – structural proteins which provide proper alignment, elasticity and extensibility • titin, myomesin, nebulin, actinin and dystrophin

The Proteins of Muscle • two kinds of myofilaments • Thin - actin, troponin and tropomyosin • Thick – myosin only

Sarcomere Structure M line • sarcomere = regions bounded by two Z lines • thin myofilaments project out from Z line – actin attached via actinin (structural protein) • myosin/thick myofilaments lie in center of sarcomere – attached to the M line • thick and thin myofilaments overlap and connect via cross-bridges •

Sarcomere Structure • myosin/thick filament only region = H zone • thin filament only region = I band • length of myosin/thick filaments = A band

• contraction = “sliding filament theory” • thick and thin myofilaments slide over each other and sarcomere shortens

Contraction: The Sliding Filament Theory • Actin proteins in the thin filament have myosin binding sites • these sites are “covered up” by troponin and tropomyosin in relaxed muscle • “shifting off” of troponin/tropomyosin from these sites is required for contraction • shifting of troponin/tropomyosin is done through binding of calcium to troponin • calcium is released from the sarcoplasmic reticulum upon the action potential

Contraction: The Sliding Filament Theory • thick myofilament is a bundle of myosin molecules • myosin looks like a “golf club” with a head, a hinge region and a shaft • each myosin protein has a globular “head” with a site to bind and breakdown ATP (ATPase site) and to bind actin (actin binding site) • binding of actin and myosin binding sites = cross-bridging

RESETTING of system Increase in Cai Removal of troponin-tropomyosin CONTRACTION Sliding of actin along myosin -for cross bridging- you will need two things: 1. calcium – uncovers the myosin binding sites on actin – “pushes aside” the troponintropomyosin complex 2. myosin head bound to ADP -for contraction – i. e. pivoting of the myosin head into the M line – the myosin head must be empty -to “reset” for a new cycle of cross-bridging – the myosin head must detach and pivot back -the myosin head must bind ATP -once the myosin head pivots back – the ATP is broken down to ADP – head is ready to cross-bridge again – if actin is “ready”

Some animations • http: //highered. mcgrawhill. com/sites/0072495855/student_view 0/chapter 10/animation__myofilam ent_contraction. html • https: //www. youtube. com/watch? v=ousflr. Oz. QHc • https: //www. youtube. com/watch? v=Ct 8 Ab. Zn_A 8 A

Muscle Metabolism • Production of ATP: -contraction requires huge amounts of ATP -muscle fibers produce ATP three ways: 1. Creatine phosphate 2. Anaerobic metabolism 3. Aerobic metabolism

Creatine Phosphate • Muscle fibers at rest produce more ATP then they need for resting metabolism • Excess ATP within resting muscle used to form creatine phosphate – creatine – arginine, glycine and methionine • made by kidneys and liver • phosphorylated by the enzyme creatine kinase • takes a phosphate off of ATP and transfers it creatine • takes the phosphate off of creatine phosphate and transfers it back to ADP – to make ATP

Creatine Phosphate • Creatine phosphate: 3 -6 times more plentiful than ATP within muscle • Sustains maximal contraction for 15 sec (used for 100 meter dash). • Athletes often use creatine supplementation – gain muscle mass but shut down bodies own synthesis (safety? )

Cellular Respiration -glycolysis -transition phase -citric acid cycle -electron transport chain http: //biology. about. com/gi/dynamic/offsite. htm? site=http: //www. sp. uconn. edu/%7 Eterry/images/anim/ETS. html http: //biology. about. com/gi/dynamic/offsite. htm? site=http: //www. biocarta. com/pathfiles/kreb. Pathway. asp http: //vcell. ndsu. nodak. edu/animations/etc/movie. htm

Anaerobic Cellular Respiration • Muscles deplete creatine – can make ATP in anaerobically or aerobically • for either process glucose is broken down via glycolysis – takes place in the cytosol of the cell • 2 ATP are produced from the breakdown of glucose into pyruvic acid during glycolysis – if no O 2 present (anaerobic) - pyruvic converted to lactic acid which diffuses into the blood • Glycolysis can continue anaerobically to provide ATP for 30 to 40 seconds of maximal activity (200 meter race) • If O 2 is present the pyruvic acid is converted into acetyl co. A (aerobic)

Aerobic Cellular Respiration • • ATP for any activity lasting over 30 seconds Provides 90% of ATP energy if activity lasts more than 10 minutes Each glucose = 36 ATP fatty acids and amino acids can also be used by the mitochondria – Fatty acid = ~100 ATP • Sources of oxygen – diffusion from blood, released by myoglobin

Aerobic Cellular Respiration • begins with the anaerobic process of glycolysis – – • if sufficient oxygen is available, pyruvic acid is imported into the mitochondria – • converted into acetyl co. A Acetyl co. A within the mitochondria enters the Kreb’s cycle – • • • creates 2 pyruvic acid if no oxygen available – pyruvic acid lactic acid acetyl co. A combines with oxaloacetate citric acid Kreb’s cycle takes place in the matrix of the mitochondria for every pyruvate, it generates 1 ATP, 3 NADH and 2 FADH 2 (electron carriers) The electrons are carried to an enzymes located on the inner mitochondrial membrane for the Electron Transport Chain

Aerobic Cellular Respiration protons • • electrons the Electron Transport chain is comprised of three membrane complexes in the inner mitochondrial membrane • FADH 2 drops its pair of electrons to NADH drops off its pair of electrons to complex II complex I transfers them to complex III • complex II transfers them to complex III transfers them to complex IV III complex IV transfers them to oxygen to make water these complexes pump protons as the electrons flow through them creates a proton gradient

Aerobic Cellular Respiration [high H+] [low H+] • • • as the electrons diffused back to the matrix through an ATP synthase – the ATP synthase combines an ADP and a Pi to create ATP the use of the proton gradient to create ATP = chemiosmosis Check out these animations http: //www. youtube. com/watch? v=xb. J 0 nbzt 5 Kw&feature=relmf u http: //www. youtube. com/watch? v=3 y 1 d. O 4 n. Na. KY [low H+]

Types of Muscle Fibers • • • classified on how they make their ATP Fast fibers = fast glycolytic Slow fibers = slow oxidative Intermediate fibers = fast glycolytic-oxidative Percentage of fast versus slow fibers is genetically determined • Proportions vary with the muscle – neck, back and leg muscles have a higher proportion of postural, slow oxidative fibers – shoulder and arm muscles have a higher proportion of fast glycolytic fibers

Types of Muscle Fibers • Slow fibers: – – – Half the diameter of fast fibers; good blood supply plentiful mitochondria make ATP through aerobic cellular respiration Three times longer to contract vs. other fibers Continue to contract for long periods of time Take longest to fatigue • e. g. marathon runners

Types of Muscle Fibers • • • Fast Fibers: Large in diameter Contain densely packed myofibrils Large glycogen reserves produce powerful, explosive contractions fatigue quickly • Fast oxidative-glycolytic (fast-twitch A) – redder in color (lots of mitochondria, myoglobin & blood vessels) – split ATP at very fast rate; used for walking and sprinting • Fast glycolytic (fast-twitch B) – whiter in color (few mitochondria & BV, low myoglobin) – anaerobic movements for short duration; used for weight-lifting

Muscles and Hormones • muscle fibers respond to many hormones by producing more muscle proteins • 1. Testosterone – from the testes – has dramatic effects on the size of muscle fibers • 2. Human growth hormone – from the anterior pituitary – h. GH stimulates the liver to produce insulin-like growth factor – IGF-1 stimulates the production of muscle proteins (and bone proteins)

Classification • According to arrangement of fibers and fascicles – Parallel muscles • Parallel to long axis of muscle – Convergent muscles • Fibers converge on common attachment site – Pennate muscles • One or more tendons run through body of muscle • Unipennate, bipennate, multipennate – Circular muscles • Fibers concentrically arranged

Bones & Muscles: Origins and Insertions • Origin – portion of the skeletal muscle that attaches to the more stationary structure • Insertion - portion of the skeletal muscle that attaches to the more moveable structure • majority of muscles originate or insert from bony markings on the skeleton

Bones & Muscles: Origins and Insertions • markings: specific elevations, depressions, and openings of bones – bony markings provide distinct and characteristic landmarks for orientation and identification of bones and associated structures. • many markings come together to form a joint • many markings are often the sites for the origins or insertions of muscles, or a channel for the passage of nerves and vessels • 3 kinds of bony markings: – depressions – fossa, fissure – openings – foramen, canal, meatus – processes – condyles, spines, crests, heads, lines, ridges, trochanters, tubercles

Muscle Names • Yield clues to muscle orientation, location or function – Biceps brachii (two heads, arm) – Vastus femoris (large, femur) – Orbicularis oculi (circular, eye) – Rectus abdominis (erect, abdomen)

Musculoskeleton: Axial Division • Axial skeleton: 80 bones – main axis of the body – forms a framework for the protection of delicate organs • including the sense organs • Axial musculature – axial musculature arises from and inserts on the axial skeleton – responsible for positioning the head and spinal column – postural muscles – also moves the rib cage, assisting in breathing – grouped into 4 groups: – 1. muscles of the head and neck – 2. muscles of the vertebral column – 3. the abdominals - oblique and rectus muscles – 4. muscles of the pelvic floor

Muscles of the Head and Neck • Muscles of facial expression – know for practical • Extrinsic eye muscles – know for practical • Muscles of mastication – check your list for practical • Muscles of the tongue – check your list for practical • Muscles of the pharynx – don’t worry about these • Muscles of the anterior neck – know for practical

Muscles of Facial Expression • Originate on surface of skull • Largest ones are associated with mouth – Orbicularis oris – Buccinator • Occipitofrontalis muscle – movement of eyebrows, forehead, scalp – two bellies – occipital belly and frontal belly – also known as Epicranius = Occipitalis and Frontalis • Platysma – Skin of neck, depresses mandible

Muscles of Facial Expression • • • Orbicularis oris - puckering Buccinator - whistling Occipitofrontalis muscle (Epicranius) – movement of eyebrows, forehead, scalp – Front belly = Frontalis (moves eyebrows and forehead) – Back belly = Occipitalis (moves back of scalp) • • Zygomaticus Major and Minor - smiling Risorius - grinning Orbicularis oculi – closes eye Depressor anguli oris - – lowers angle of mouth Depressor labii inferioris –depresses lower lip Levator labii superioris – raises upper lip Mentalis - pouting Platysma – pouting & depresses mandible originate on surface of skull – insert on the skin of the face

zygomaticus minor zygomaticus major

Muscles of Mastication • Act on the mandible • Temporalis – elevates mandible • Masseter – elevates mandible • Medial pterygoid & Lateral pterygoid – protract the mandible and move it side to side – Don’t need to know for practical

Six Extra-Ocular (Oculomotor) Muscles • • • Inferior rectus Superior rectus Medial rectus Lateral rectus Superior oblique Inferior oblique

Muscles of the Tongue • Necessary for speech and swallowing – – Genioglossus Hyoglossus Palatoglossus Styloglossus palatoglossus temporalis styloglossus hyoglossus mylohyoid

Anterior Muscles of the Neck • foundation for the muscles of the tongue and pharynx, move the hyoid up or down for swallowing & breathing, depress the mandible – Digastric – two bellies – Mylohyoid – Sternohyoid – Sternothyroid – Thyrohyoid – Omohyoid

Anterior Muscles of the Neck • Foundation for the muscles of the tongue and pharynx – – Digastric Mylohyoid Sternocleidomastoid omohyoid thyrohyoid sternohyoid thyroid gland

Anterior Muscles of the Neck • Sternocleidomastoid – two sites of origin – clavicle and sternum – insertion: onto mastoid process – contract both together – flexes head forward – individually – laterally flexes & rotates head to the opposite side

Anterior Muscles of the Neck

Muscles of the Vertebral Column • covered by a superficial layer of back muscles – Trapezius – Latissimus dorsi • superficial and deep layers • quite complex – multiple origins and insertions + overlapping • 5 Groups: – – – Splenius group Erector spinae group Scalenes Transversospinalis group Segmental group

Muscles of the Vertebral Column • Superficial muscles: • Splenius group – together they extend the head and neck, individually they laterally flex and rotate to the same side • Splenius capitis • Splenius cervicis

Muscles of the Vertebral Column • Superficial muscles: • Erector Spinae - spinal extensors – comprised of capitis, cervicis, thoracic and lumborum portions – Spinalis – medial group of muscles – capitis, cervicis and thoracis groups – Iliocostalis – lateral group of muscles – cervicis, thoracis and lumborum – Longissimus – in between these two (intermediate) – capitis, cervicis and thoracis – lumborum portion fuses with iliocostalis

Muscles of the Vertebral Column • Deep muscles: • Interconnect and stabilize the vertebrae • Scalenes – flexes and rotates neck, used in deep inspiration • Anterior • Medial • Posterior • Transversospinal group – extends the vertebral column and rotates it to the opposite side • Semispinalis – capitis, cervicis and thoracis portions • runs from transverse to spinous processes • Multifidus – below the ribcage semispinalis is called mutifidis • Rotatores

Muscles of the Vertebral Column • Deep muscles: • Quadratus lumborum - flexes the lumbar spine • Segmental group – extends and laterally flexes vertebral column • Interspinales – run between spinous processes • Intertransversarii – run between transverse processes

The Oblique and Rectus Muscles • 3 Abdominal Oblique muscles and Rectus Abdominis Muscle • Rectus abdominis – partitioned into 4 sections by fibrous “tendinous intersections” or “tendinous inscriptions”

The Oblique and Rectus Muscles • 3 Abdominal oblique muscles: – External oblique (fibers down and in) – Internal oblique (fibers up and in) – Transversus abdominis (fibers side to side) – Compress underlying organs – all together – flex the vertebral column – singly - rotate the vertebral column to the opposite side -the oblique muscles are connected to their opposite partners via an aponeurosis (broad, flat tendon) -the 3 aponeuroses form an “envelope” that encloses the rectus abdominis = rectus sheath

The Diaphragm

The Pelvic Floor & Perineum • pelvic diaphragm or floor = coccygeus & levator ani & external anal sphincter – found in the anal triangle- contains the anus – supports pelvic viscera & resists increased abdominal pressure during defecation, urination, coughing, vomiting, etc – pierced by anal canal, vagina & urethra • additional muscles lie superficial to the pelvic floor = perineal muscles – found in the urogenital triangle - contains the external genitalia – also contains muscles – assist in the erection (male and female)

Muscles of the Pelvic Floor

Musculoskeleton: Appendicular Division • Appendicular skeleton: 126 bones – Bones of upper and lower limbs – Pectoral and pelvic girdles » connect limbs to trunk • Appendicular musculature • originates or inserts on the appendicular skeleton • stabilizes or moves components of the appendicular skeleton • stabilizes pectoral girdle (i. e. shoulder joint) • stabilizes pelvic girdle (i. e. hip joint) • moves the upper and lower limbs • grouped into 7 distinct groups: – 4 groups move the upper limb – 3 groups move the lower limb

Muscles that move the pectoral girdle • clavicle can be elevated or depressed or stabilized – subclavius muscle • movements of the scapula are quite complex – adduction/retraction – rowing – abduction/protraction – punching or ‘hunching’ of shoulders – elevation – shrugging – depression – pull-downs – superior rotation – jumping jack – inferior rotation – parallel bars

Muscles that move the pectoral girdle • POSTERIOR MUSCLES: • Trapezius muscle – one of the largest muscles on the back – affects position of pectoral girdle, neck, head -can perform a series of complex motions -in 4 legged animals - divided into clavo-, acromio- and spinosections (superior, medial and inferior fibers) -in humans – divided into superior, medial and inferior fibers

Muscles that move the pectoral girdle • Trapezius muscle – one of the largest muscles on the back -origin: occipital bone, C 7 vertebra & all thoracic vertebrae -insertion – spine of scapula and lateral 1/3 of clavicle -superior fibers – elevate and superiorly rotate scapula -e. g. jumping jacks -medial fibers – adducts scapula -e. g. rowing -inferior fibers – depresses scapula -e. g. pull-downs

Muscles that move the pectoral girdle • POSTERIOR MUSCLES • Rhomboid muscles: major and minor – adducts scapula – origin: C 7 to T 5 vertebrae – insertion: on medial border of scapula • Levator scapulae muscle – elevates scapula – origin: C 1 through C 4 – insertion: medial border of scapula (above the spine)

Muscles that move the pectoral girdle • ANTERIOR MUSCLES • Serratus anterior muscle – abducts scapula – origin: first 9 ribs – insertion: medial border of scapula • Subclavius – depresses the clavicle • Pectoralis minor – abducts scapula – Ppus - rotates it down (inferior) – origin: ribs 3 -5 – insertion: corocoid process of scapula

Muscles that Move the Arm • Deltoid – can be divided into anterior, lateral and posterior fibers – major arm abductor – anterior fibers: flex and medially rotate arm – lateral fibers: prime mover; abduction of arm – posterior fibers: extend and laterally rotate arm – origin: spine of scapula, acromion and lateral 1/3 of clavicle – insertion: deltoid tuberosity of humerus

Muscles that Move the Arm • Rotator Cuff muscles: – surround and stabilize the glenohumeral joint – origin: bony fossae and inferior angle of scapula – insertion: lesser or greater tubercle of humerus

Muscles that Move the Arm • Rotator Cuff muscles: – Supraspinatus • abducts the arm – Supscapularis • rotates arm medially – Infraspinatus • adducts and rotates arm laterally – Teres minor • adducts and rotates arm laterally

Muscles that Move the Arm • Coracobrachialis – flexion and adduction at shoulder – origin at corocoid process of scapula – insertion on the humerus • Pectoralis major muscle – flexes arm shoulder – adducts and medially rotates arm – origin: clavicle, sternum and costal cartilages – insertion: greater tubercle of humerus

Muscles that Move the Arm • Latissumus dorsi muscle – extends arm at shoulder – adducts and medially rotates arm – origin: all lumbar vertebrae, sacrum and coccyx – insertion: intertubercular groove of humerus

Summary: Muscle Actions at the Shoulder Joint Abduction: 1. Deltoid (middle) 2. Supraspinatus Flexion: 1. Pectoralis Major 2. Deltoid (anterior) 3. Coracobrachialis Lateral Rotation: 1. Infraspinatus 2. Teres minor 3. Deltoid (posterior) prime movers in bold Adduction: 1. Latissimus dorsi 2. Pectoralis major 3. Coracobrachialis 4. Teres major 5. Teres minor 6. Infraspinatus Extension: 1. Latissimus dorsi 2. Deltoid (posterior) 3. Teres major 4. Triceps brachii (long) Medial Rotation: 1. Subscapularis 2. Pectoralis Major 3. Latissimus dorsi 4. Teres major 5. Deltoid (anterior)

Muscles that Move the Forearm • 3 Flexors of the elbow joint: – all insert either onto the radius or the ulna • 1. biceps brachii – “two heads” of humerus – long & short heads – flexes elbow joint & supinates forearm – origin: short head - corocoid process of scapula; long head – scapula above the glenoid cavity – insertion: radial tuberosity of radius • 2. brachioradialis – origin: humerus – insertion: radius (styloid process) • 3. brachialis – major flexor of the elbow joint – origin: humerus – insertion: coronoid process of ulna

Muscles that Move the Forearm • 4 Extensors of the elbow joint: – different origins – but all insert onto the olecranon process of ulna • 1. triceps brachii – “three heads” of humerus – long, medial & lateral heads – extends elbow joint – origin: short & medial heads – back of humerus; long head – scapula (below glenoid cavity) – insertion: olecranon process of ulna • 2. anconeus – 4 th extensor of the elbow joint – origin: lateral epicondyle of humerus – insertion: olecranon process of ulna

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 – longus – brevis

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 11 -78

Intrinsic Muscles, Tendons and Ligaments of the Hand

Retinaculum • • Tough connective tissue band that helps hold tendons in place Flexor retinaculum runs from pisiform/hamate to scaphoid/trapezium – lies over 10 tendons + median nerve – flexor carpi radialis, pollicis longus, digitorum superficialis & digitorum profundus – carpal tunnel syndrome = painful compression of median nerve due to narrowing of the passageway under flexor retinaculum

Muscles of the pelvic girdle and lower limbs • Three groups – Muscles that move thighs – Muscles that move the leg – Muscles that move the foot and toes

Muscles that Move the Thigh at the Hip Joint • muscles that move thigh can perform multiple movements – e. g. sartorius – “tailor muscle” • • hip flexion lateral rotation of femur flexion of knee medial rotation of leg • these muscles span the hip joint – another ball-in-socket joint capable of multiple planes of motion • movements at the hip joint – – – – abduction adduction flexion extension medial rotation lateral rotation circumduction

Muscles that Move the Thigh at the Hip Joint • can categorize the muscles of the thigh & their movements this way – – – Medial compartment – hip adductors Lateral compartment – hip abductors Anterior compartment – hip flexors (knee extensors) Posterior compartment – hip extensors & knee flexors Gluteal region – hip extensors and abductors Deep Gluteal region – lateral rotators

Muscles that Flex the Thigh • 9 Hip flexors: – these muscles also either adduct or abduct the thigh – iliopsoas – made up two muscles: iliacus & psoas major • the 2 major hip flexors • origin – lumbar vertebrae and iliac fossa • insertion – lesser trochanter of femur – sartorius - longest muscle in the body • origin – anterior superior iliac spine • insertion - tibia – tensor fascia latae – also abducts the thigh by pulling on its tendon; medially rotates thigh • origin – iliac crest • insertion – tibia by way of the iliotibial tract or IT band – rectus femoris – part of the quadriceps – 3 adductors + pectineus

Muscles that Extend the Thigh • 5 Hip extensors: – originate from pelvis & sacrum and insert into the femur, tibia and fibula – some also laterally rotate thigh – 3 Hamstrings – also flexors of the knee – hamstring part (lowest part) of adductor magnus – Gluteus maximus • • • major hip extensor extension and lateral rotation of hip pulls on iliotibial tract origin – iliac crest, sacrum and coccyx insertion – gluteal tuberosity on femur

Muscles that Adduct the Thigh • 5 adductors of the hip – originate from pubis and insert onto the linea aspera of femur – Adductor magnus – biggest of the adductors – divided into an adductor part and a hamstring part – hamstring part also extends the hip – adductor part also flexes the hip – Adductor brevis – Adductor longus – Pectineus – pectineus, adductor longus and brevis are also hip flexors – Gracilis – also flexes the knee

Muscles that Abduct the Thigh • 4 Hip Abductors: • originate from pelvis • all insert onto the greater trochanter of femur • Gluteus Medius • origin – iliac crest • Gluteus Minimus • origin - anterior gluteal line • Sartorius • Tensor fascia latae

Muscles that Rotate the Thigh • 9 lateral rotators of the thigh (hip joint): • most insert onto the greater trochanter of the femur • Piriformis • Obturator internus • Obturator externus • Superior gemellar muscle • Inferior gemellar muscle • Quadratus femoris • Gluteus maximus (medius and minimus) • Adductor magnus • Sartorius

Muscles that Rotate the Thigh • 3 medial rotators of the thigh (hip joint): • Gluteus medius and minimus – when hip is extended • Adductor brevis • Tensor fascia latae

Summary: Muscle Actions at the Hip Joint Abduction: 1. Gluteus medius 2. Gluteus minimus 3. Tensor fascia latae 4. Sartorius Flexion: 1. Iliopsoas 2. 3 adductors 3. Pectineus 4. Sartorius 5. Rectus femoris 6. Gracilis Lateral Rotation: 1. Adductor magnus (hamstring) 2. Gluteus maximus 3. Sartorius 4. 2 Obturators 5. 2 Gemellars 6. Quadratus femoris 7. Piriformis prime movers in bold Adduction: 1. Adductor longus 2. Adductor brevis 3. Adductor magnus 4. Pectineus Extension: 1. Gluteus maximus 2. Adductor magnus (ham. ) 3. Biceps femoris (long head) 4. Semimembranosus 5. Semitendinosus Medial Rotation: 1. Gluteus medius 2. Gluteus minimus 3. Adductor brevis 4. Tensor fascia latae

Muscles that Extend the Leg • 4 Extensor muscles of the knee join = Quadriceps femoris – “four heads” of the femur – found on the anterior and lateral surfaces of the thigh – originate from the pelvis (rectus femoris) and femur ( 3 vastus muscles) – all insert onto the tibial tuberosity on the tibia via the patellar ligament – Rectus femoris – because of its origin on the anterior inferior iliac spine – also a hip flexor – Vastus lateralis – Vastus medialis – Vastus intermedius

Muscles that Flex the Leg • 11 Flexors of the knee joint • some also extend the hip (hamstrings) • found in the posterior compartment of the thigh • originate from the pelvis and insert onto the tibia and fibula • 3 Hamstrings: all originate on the ischial tuberosity – Biceps femoris (long and short heads) heads – both heads insert onto head of fibula – Semimembranosus & Semitendinosus – common insertion with semimembranosus onto tibia • • • 3 Adductor muscles Sartorius Gracilis

Muscles that Flex the Leg • 11 Flexors of the knee joint • Gastrocnemius • gastroc = belly • kneme = leg • also plantar flexes foot together with soleus • origin – femoral condyles • insertion – calcaneus via the Achilles tendon • Popliteus – poplit = back of knee – unlocks knee joint – origin – lateral condyle of femur – insertion - tibia • Plantaris • weak knee flexor

Muscles that Plantar Flex the Foot • Gastrocnemius, soleus and plantaris are also plantar flexors of the foot • Tibialis posterior – also inverts the foot (turn in) • Fibularis/Peroneus – longus and brevis – also evert the foot (turn out) • Flexor digitorum longus and flexor hallicis longus – also curl the toes

Muscles that Dorsiflex the Foot • 4 muscles are responsible for dorsiflexion of foot (toes up) • Tibialis anterior – also inverts the foot • Fibularis/Peroneus tertius – everts the foot with the other 2 fibularis muscles • Extensor digitorum and hallicis longus