Muscles of the Body http www rad washington

Muscles of the Body

http: //www. rad. washington. edu/academics/academi c-sections/msk/muscle-atlas "Copyright 2003 -2004 University of Washington. All rights reserved including all photographs and images. No re-use, re-distribution or commercial use without prior written permission of the authors and the University of Washington. " "Musculoskeletal Images are from the University of Washington "Musculoskeletal Atlas: A Musculoskeletal Atlas of the Human Body" by Carol Teitz, M. D. and Dan Graney, Ph. D. " Other copies materials from Marieb, 5 th ed. , Martini, 6 th ed. or online with reference 2

Fascicles § Bundles of fibers *

Skeletal muscle Epimysium: surrounds whole muscle Perimysium is around fascicle Endomysium is around each muscle fiber

Different arrangements of fascicles

Arrangement of fascicles influences movement and power § Skeletal muscles can shorten by about 1/3 of their resting length § The more nearly parallel to the axis, the more they can shorten § This results in a larger distance of movement § The power depends on the total number of fibers § Stocky muscles (like bipennate vs parallel) have more fibers, therefore more powerful even though shorten very little

Interactions of Skeletal Muscles § Muscles can only pull, they can’t push § Actions must be “undone” by a different muscle § Muscles that produce opposite movements usually lie on opposite sides of a given joint

Interactions, continued § Agonist: prime mover, major responsibility for producing a specific movement § Antagonist: oppose or reverse a particular movement § Usually contract a little to prevent overshooting the mark or slow the agonist’s action near the end § Are being stretched or can remain relaxed when agonist works Antagonists for one movement can be agonists another for

§ Synergists help prime movers § Add a little extra force to the same movement § Or reduce undesirable extra movements (e. g. making a fist without flexing at wrist) § Fixators: hold a bone firmly so agonist has a stable base on which to move a body part (e. g. fixing scapula when arm moves)

Compartments Upper limb: 2 compartments Lower limb: 3 compartments § Contain muscles of similar developmental origin and function § Dense fibrous connective tissue separates

Naming skeletal muscles (examples) § Location: brachialis is in arm (brachium = arm) § Shape: deltoid is triangular (delta = triangle) § Size: minimus (smallest), longus (long), brevis (short) § Direction of fascicles and fibers: rectus (straight); transversus (right angle) and oblique (oblique) to midline § Number of origins: biceps (“two heads”), triceps (“three heads”), quadriceps (“four heads”) § Action: “flexor, ” “extensor, ” “adductor” or “abductor” appear in the name § Combinations of the above, e. g. extensor carpi radialis longus

Axial muscles § Lie anterior and posterior to body axis (vertebral column) § Move trunk; maintain posture § Skeletal muscles of thorax, abdomen, and pelvis § Many muscles of neck § A few muscles in head

Limb muscles § Arise from ventral region as limb buds § Muscles develop from lateral parts of myotomes § In general: dorsal (posterior) muscles become extensors and ventral (anterior) become flexors § Lower limb rotates during embryonic development: § Extensors on anterior (ventral) side: extend leg at knee, dorsiflex foot at ankle and extend toes § Flexors on posterior (dorsal) side: flex leg at knee, plantarflex foot at ankle, flex toes

to use for studying. . . anterior Text

posterior

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Muscles of the Head and Neck § Scalp Muscle: epicranius § frontal belly § occipital belly § gala aponeurotica § Muscles of Facial Expression: insert on skin or another muscle § Muscles of Mastication (chewing): all have insertions on the mandible § Anterior Neck Muscles § Posterior Neck Muscles 22

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Mastication: • Jaw closure: masseter and temporalis • Side to side grinding: pterygoids • Buccinator: compresses cheek “glossus” = tongue Extrinsic tongue muscles Tongue itself (instrinsic muscles): digestive tract section Deep chewing muscles 26 Pharyngeal constrictors

Muscles of the Anterior Neck Above hyoid (suprahyoid): form floor of oral cavity, anchor tongue, elevate hyoid, move larynx superiorly during swallowing Below hyoid (infrahyoid): depress hyoid and larynx during swallowing and speaking Right side (of slide) is deeper than left Sternocleodomastoid 27

Neck Anterolateral neck Scalenes elevate first 2 ribs Posterior neck Splenius’ (capitis and cervicis) extend head 28

Deep muscles of back Right side: deeper Quadratus lumborum (lateral flexion) Erector spinae (extend back): Iliocostalis Longissimus Spinalis Labeled cervicis, thoracics, lumborum depending on where they are 29

Per Marieb… (worthwhile to know) “During full flexion (i. e. when touching fingertips to floor), erector spinae are relaxed and strain is borne entirely by ligaments of back; on reversal of the movement, these muscles are initially inactive, and extension is initiated by hamstring muscles of thighs and gluteus maximus muscles of buttocks. As a result of this peculiarity, lifting a load or moving suddenly from a bent over position is potentially injurious to muscles and ligaments of back and intervertebral discs; erector spinae muscles readily go into painful spasms following injury to back structures. ” 30

Lift rib cage: inspiratory Depress rib cage: in forced expiration Deep muscles of the thorax: breathing § Intercostals Short: rib to rib § Diaphragm prime mover of inspiration Floor of thoracic cavity: when flattens, air moves in 31

Anterior Chest Muscles Superficial: Deeper: sternocleidomastoid pectoralis major pectoralis minor serratus anterior subclavius 32

Muscles of the abdominal wall From more superficial to deep: External oblique Internal oblique Transversus abdominis Nearer midline: Rectus abdominis Note inguinal ligament- from anterior superior iliac spine to pubic symphysis: lower border of external oblique rolls up on itself to form it * * The rectus abdominis is the medial pair of muscles; it is ensheathed by the aponeurosis of the lateral muscles, which don’t come to the midline

Muscles of the abdominal wall from the side

Muscles moving the scapula trapezius levator scapulae rhomboids posterior

9 Muscles crossing shoulder joint: movement of arm (humerus) Three most powerful of the nine and prime movers: pectoralis major latissimus dorsi deltoid 36

Rotator cuff supraspinatus, infraspinatus, subscapularis, teres minor 37 remaining 2 muscles : teres major and coracobrachialis

Forearm extensors (posterior) § Triceps brachii § Anconeus helps 38

Forearm flexors (anterior) Brachioradialis Brachialis Biceps brachii 3 muscle on 39 right from this site: http: //www. rad. washington. edu/atlas/

§ Retinaculae (retinaculum, singular) § “retainers, ” “wrist bands”, “ankle bracelets” § Bands of fascia holding tendons of wrist and ankle in place (prevent “bow-stringing”) § Tendons covered by slippery tendon sheets 40

Forearm muscles: movement of wrist, hand fingers § Many arise from distal humerus § Cross elbow, wrist and finger joints § Minimal action at elbow § At wrist joint: flexion, extension, abduction and adduction of the hand § At finger joints: mostly just flex and extend (other movements- by small muscles in the hand itself) 41

Forearm muscles, continued § Two compartments (each with superficial and deep muscle layers) §Anterior = flexor compartment ( except includes 2 pronators) §Most originate from a common tendon on the medial epicondyle of humerus §Posterior = extensor compartment (except includes supinator and brachioradialis) §Many arise from a common tendon from lateral epicondyle of humerus § Most muscles that move the palm and fingers are located in the forearm, not the hand itself §They operate by tendons like strings with puppets §There are some small muscles in the hand itself 42

Anterior wrist pronator and flexors Origin on medial epicondle of humerus: pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis Pronator teres Palmaris longus 43 http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Deep anterior hand muscles (some) § Flexor pollicis longus § Flexor digitorum profundus (only muscle that flexes DIPs) 44

Flexor digitorum superficialis Individually (this is right arm, anterior) Flexor digitorum profundus Flexor pollicis longus Pronator quadratus 45 http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

origin on lateral epicondyl of humerus § Extensor carpi radialis (longus & brevis) § Extensor digitorum § Extensor carpi ulnaris See individually in next slide

Superficial extensors Extensor carpi radialis longus Extensor digitorum Extensor carpi ulnaris Extensor carpi radialis brevis http: //www. rad. washington. edu/academics/academic-sections/msk/musc

Deep posterior muscles Abductor pollicis Extensor pollicis longus & brevis longus Supinator Extensor indicis http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Hand § Thenar § Hypothenar § Midpalmar § Lumbricals § Interossei Te

Thenar and hypothenar muscles http: //www. rad. washington. edu/academics/ academic-sections/msk/muscle-atlas

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Right forearm, anterior view, from superficial to deep 52

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Right forearm, posterior, from superficial to deep 54

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Muscles crossing the hip and knee joints § Three groups separated by fascia; all three enclosed by deep fascia of thigh (fascia lata) 1. Anterior § Flex femur at hip; extend leg at knee (e. g. foreswing phase of walking) 2. Posterior § Mostly extend thigh and flex leg (backswing phase of walking) 3. Adductor (medial) § Move thigh only, not leg

Muscles that flex thigh at hip Originate from vertebral column and pelvis and pass anterior to hip joint § § § Sartorius Iliopsoas Tensor fasciae lata Rectus femoris (only quad with origin on pelvis) Pectineus (medial compartment)

Muscles that flex thigh at hip: individually (go between last slide and this one) Iliopsoas Pectineus Tensor fascia lata Sartorius Rectus femoris Inserts on tibial tuberosity via patellar tendon http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Thigh extensors (posterior) Arise posterior to hip joint _______ § Gluteus maximus § Hamstrings (cross hip and knee joints: extend thigh & flex knee) § Biceps femoris § Semitendinosus § Semimembranosus (antagonists of quads) http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Hamstrings Biceps femoris long head cross hip and knee joints: extend thigh and flex knee Biceps femoris short head Semitendinosus Semimembranosus http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Abductors of thigh Buttocks muscles that lie lateral to hip joint § Gluteus medius § Gluteus minimus (under medius) § Tensor fascia lata

Thigh abductors Buttocks muscles that lie lateral to the hip joint Gluteus medius Gluteus minimus http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Lateral rotators § Piriformis § Also shown are other rotators and the gluteus muscles Piriformis laterally rotates hip; also helps abduct hip if it is flexed http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Adduction of thigh Muscles originate medial to hip joint § § § Gracilis Adductor magnus Adductor longus Adductor brevis Pectineus

Adductor magnus Thigh adductors (originate medial to hip joint) Pectineus Adductor brevis Gracilis Adductor longus http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Knee extensors Quadraceps femoris – the only extensors of the leg (lower leg) at the knee § Rectus femoris (only quad with origin on pelvis) Rectus § Vastus lateralis femoris § Vastus intermedius § Vastus medialis Antagonized by hamstrings http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Rectus femoris (only quad with origin on the pelvis) Quadriceps Vastus lateralis, intermedius, and medialis Note “o” and “i” Insert: tibial tuberosity via patellar ligament _____ http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Leg (lower leg) § 3 compartments § Anterior § Posterior § Lateral § Movements at joints: § Ankle § Dorsiflex § Plantarflex § Intertarsal § Inversion of foot § Eversion of foot § Toes § Flex (point) § Extend

Posterior compartment of leg § Superficial: these plantarflex foot § Gastrocnemius § Soleus § Plantaris

Posterior leg Plantaris Soleus Gastrocnemius http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Posterior leg continued § Deep § Popliteus § Flexor digitorum longus § Flexor hallucis longus § Tibilialis posterior

Deep posterior leg Popliteus Flexor digitorum longus Flexor hallucis longus Tibialis posterior http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Anterior leg extensors Mainly extend toes and dorsiflex foot § Tibialis anterior § Extensor digitorum longus § Extensor hallucis longus

More pics Extensor hallucis longus Tibialis anterior Extensor digitorum longus http: //www. rad. washington. edu/academics/academic-sections/msk/muscle-atlas

Lateral compartment of leg § Fibularis (peroneus) longus: § to first metatarsal and cuneiform § Fibularis (peroneus) brevis: § to fifth metatarsal

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Sole – third (deepest) layer

Addendum: some rotator cuff tests (FYI) FIGURE 2. Apley scratch test. The patient attempts to touch the opposite scapula to test range of motion of the shoulder. (Left) Testing abduction and external rotation. (Right) Testing adduction and FIGURE 3. Supraspinatus examination ("empty can" test). The patient attempts to elevate the arms against resistance while the elbows are extended, the arms are abducted and the thumbs are pointing downward. internal rotation. http: //www. aafp. org/afp/20000515/3079. html

FIGURE 4. Infraspinatus/teres minor examination. The patient attempts to externally rotate the arms against resistance while the arms are at the sides and the elbows are flexed to 90 degrees. FIGURE 5. Neer's test for impingement of the rotator cuff tendons under the coracoacromial arch. The arm is fully pronated and placed in forced flexion. FIGURE 6. Hawkins' test for subacromial impingement or rotator cuff tendonitis. The arm is forward elevated to 90 degrees, then forcibly internally rotated.