Chapter 10-11 The Muscles and Muscle Tissue by yaofenji

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									        CHAPTER 10-11:
THE MUSCLES AND MUSCLE TISSUE
                       MUSCLE ATTACHMENT SITES:



•   origin: site of muscle's attachment to more stationary bone
•   insertion: site of muscle's attachment to more movable bone
•   belly: fleshy part of muscle between tendons of origin & insertion
•   tendonitis (tenosynovitis): painful inflammation of tendons, tendon
    sheaths & synovial membranes of a joint
• most commonly affected tendons are those of: elbow (tennis elbow), wrists,
  shoulders, finger joints (trigger finger), ankles & feet
• accompanied by swelling (fluid accumulation), tenderness & pain
• can be caused by trauma, strain or excessive exercise
                 LEVER SYSTEMS & LEVERAGE



• bones act as levers & joints act as fulcrums in producing
  movement
• lever: rigid structure that can move around a fixed
  point or fulcrum
• 2 forces act on lever: effort & load (resistance)
• when load is close to fulcrum, & effort is applied far
  away, the lever acts at a mechanical advantage (&
  vice-versa)
       LEVER SYSTEMS & LEVERAGE
                                          (a) First-class lever
                                  Arrangement of the elements is
                                        load-fulcrum-effort



 1st class levers: fulcrum is
 between effort & load
(e.g.: scissors & seesaws;
 atlanto-occipital joint)                      Fulcrum




                                        Load         Effort

                                In the body: A first-class lever system
                                raises your head off your chest. The
                                posterior neck muscles provide the effort,
                                the atlanto-occipital joint is the fulcrum,
                                and the weight to be lifted is the facial
                                skeleton.
   LEVER SYSTEMS & LEVERAGE
                                     (b) Second-class lever
                               Arrangement of the elements is
                                     fulcrum-load-effort



 2nd class levers: load is                                Effort

 between fulcrum &
       effort (e.g.:
wheelbarrow; probably
no examples in body)                                   Load

                                            Fulcrum

                             In the body: Second-class leverage is
                             exerted when you stand on tip-toe. The
                             effort is exerted by the calf muscles
                             pulling upward on the heel; the joints of
                             the ball of the foot are the fulcrum; and
                             the weight of the body is the load.
      LEVER SYSTEMS & LEVERAGE
                                         (c) Third-class lever
                                 Arrangement of the elements is
                                       load-effort-fulcrum



 3rd class levers: effort is                         Effort

between fulcrum & load
  (e.g.: forceps; elbow
            joint)
                                  Load
most common levers in                               Fulcrum
        body                   In the body: Flexing the forearm by the
                               biceps brachii muscle exemplifies
                               third-class leverage. The effort is exerted
                               on the proximal radius of the forearm, the
                               fulcrum is the elbow joint, and the load is
                               the hand and distal end of the forearm.
                   FASCICLE ARRANGEMENT



• Fascicle arrangement: affect a muscles range of
  motion & power
• 5 patterns: parallel, fusiform (spindle-shaped), circular,
  triangular or pennate (feather-shaped)
• longer fibers = greater range of motion; more fibers is
  usually associated with more power
Muscle Mechanics: Arrangement of Fascicles

                             (a)
                                                (g)
                             (b)

     Circular                                   (f)
        (orbicularis oris)                                (b) Convergent
                                                              (pectoralis major)



                             (c)
                                                (e)


                                                            (d) Unipennate
                             (d)
(c) Parallel                                                    (extensor
    (sartorius)                                                 digitorum
                                                                longus)




     (e) Bipennate                 (f) Fusiform
         (rectus femoris)              (biceps brachii)            (g) Multipennate
                                                                       (deltoid)
            COORDINATION WITHIN MUSCLE
                      GROUPS


• movements are often the result of several
  muscles acting as a group
• most muscles are arranged in opposing pairs:
• agonist (prime mover): contracts while
  antagonist stretches
• agonist & antagonist often located on opposite
  sides of bone (biceps brachii & triceps brachii)
              COORDINATION WITHIN MUSCLE GROUPS


• synergists: contract & stabilize intermediate joints (joint in between
  agonist & primary joint) to prevent unwanted movement
• wrist extensors contract to prevent wrist from flexing when fingers
  flex
• fixators: stabilize origin of prime mover so it acts more efficiently
• fixators hold scapula steady while arm moves
• static stretching: holding a muscle in lengthened position (to point of
  slight discomfort; 15-30 sec.) to increase range of motion
• benefits may include improved performance, decreased risk of injury,
  reduced soreness & improved posture
                   NAMING SKELETAL MUSCLES



• Location—bone or body region associated with the muscle
• Shape—e.g., deltoid muscle (deltoid = triangle)
• Relative size—e.g., maximus (largest), minimus (smallest),
  longus (long)
• Direction of fibers or fascicles—e.g., rectus (fibers run
  straight), transversus, and oblique (fibers run at angles to an
  imaginary defined axis)
• Number of origins—e.g., biceps (2 origins) and triceps (3
  origins)
• Location of attachments—named according to point of origin
  or insertion
• Action—e.g., flexor or extensor, muscles that flex or extend,
  respectively
            Head             Facial
            Temporalis       Epicranius, frontal belly
            Masseter         Orbicularis oculi
Shoulder                     Zygomaticus
                             Orbicularis oris
 Trapezius                            Neck
 Deltoid                               Sternohyoid
Arm                                    Platysma
 Triceps brachii                       Sternocleidomastoid
 Biceps brachii                       Thorax
 Brachialis
Forearm                                Pectoralis minor
 Pronator teres                        Serratus anterior
 Brachioradialis                       Pectoralis major
 Flexor carpi radialis                 Intercostals
 Palmaris longus                      Abdomen
Pelvis/thigh                           Rectus abdominis
 Iliopsoas                             Internal oblique
 Pectineus                             Transversus abdominis
Thigh                                  External oblique
 Rectus femoris                       Thigh
 Vastus lateralis                      Tensor fasciae latae
 Vastus medialis                       Sartorius
                                       Adductor longus
Leg                                    Gracilis
 Fibularis longus             Leg
 Extensor digitorum longus     Gastrocnemius
 Tibialis anterior
                               Soleus




                                                               Figure 10.4
                          Neck
                          Epicranius, occipital belly
Arm                       Sternocleidomastoid
                          Trapezius
Triceps brachii               Shoulder
Brachialis
Forearm                        Deltoid
                               Infraspinatus
Brachioradialis                Teres major
Extensor carpi              Rhomboid major
radialis longus             Latissimus dorsi
Flexor carpi ulnaris          Hip
Extensor carpi
                               Gluteus medius
ulnaris                        Gluteus maximus
Extensor digitorum
    Iliotibial tract      Thigh
                          Adductor magnus
                          Hamstrings:
      Leg                  Biceps femoris
      Gastrocnemius        Semitendinosus
      Soleus               Semimembranosus
      Fibularis longus
      Calcaneal
      (Achilles) tendon
                                                    Figure 10.5
        MUSCLES OF FACIAL EXPRESSION



               Insert into the skin
     Important in nonverbal communication
All innervated by cranial nerve VII (facial nerve)
                 MUSCLES OF FACIAL EXPRESSION



• Epicranius (occipitofrontalis)
• Bipartite muscle consisting of the
•   Frontalis
• Occipitalis

• Galea aponeurotica—cranial aponeurosis connecting above
  muscles
• The two muscles have alternate actions of pulling the scalp
  forward and backward
                        Galea
                        aponeurotica
Corrugator
supercilii              Frontal belly
Orbicularis oculi       Occipital
Levator labii           belly
superioris
Zygomaticus
                        Temporalis
minor and major
Buccinator
                        Masseter
Risorius
                        Sternocleidomastoid
Orbicularis oris
                        Trapezius
Mentalis
Depressor               Splenius capitis
labii inferioris
Depressor anguli oris
Platysma




                             Figure 10.7; Table 10.3
                       MUSCLES OF MASTICATION AND
                           TONGUE MOVEMENT




• Four pairs involved in mastication
• Prime movers of jaw closure
• Temporalis and masseter
• Grinding movements
• Medial and lateral pterygoids
                 MUSCLES OF MASTICATION AND
                     TONGUE MOVEMENT

• All are innervated by cranial nerve V (trigeminal nerve)
• Buccinator muscles (of facial expression group) also help by
  holding food between the teeth
• Three muscles anchor and move the tongue
• All are innervated by cranial nerve XII (hypoglossal nerve)
                Temporalis



Orbicularis
oris          Masseter
Buccinator



(a)
                   Figure 10.7; table 10.3
                      MUSCLES OF THE HEAD & NECK



• orbicularis oris
• origin: muscle fibers surrounding mouth opening
• insertion: skin at corner of mouth
• action: closes & protrudes lips (assists in speech)
• zygomaticus major & minor
• origin: zygomatic bone
• insertion: skin at angle of mouth & orbicularis oris (z. major) & upper lip (z.
  minor)
• action: z. major draws mouth superiorly & laterally (smiling & laughing); z.
  minor raises upper lip
                      MUSCLES OF THE HEAD & NECK

• buccinator
• origin: alveolar processes of maxilla & mandible
• insertion: orbicularis oris
• action: presses cheeks against teeth & lips (whistling & blowing); draws
  corner of mouth laterally; assists in chewing
• platysma
• origin: fascia over deltoid & pectoralis major muscles
• insertion: mandible, muscles around mouth & skin of lower face
• action: draws outer lower lip inferiorly & posteriorly (pouting) & depresses
  mandible
                       MUSCLES OF THE HEAD & NECK

• orbicularis oculi
• origin: medial wall of orbit
• insertion: circular path around orbit
• action: closes eye
• muscles that move eyeballs (6 muscles): superior, inferior,
  lateral & medial rectus muscles, & superior & inferior oblique
  muscles
• masseter
• origin: maxilla & zygomatic arch
• insertion: angle & ramus of mandible
• action: elevates mandible (closes mouth) & retracts mandible
                       MUSCLES OF THE HEAD & NECK

• occipitofrontalis
• origin: epicranial aponeurosis (frontal belly); occipital bone & mastoid process
  of temporal bone (occipital belly)
• insertion: skin over orbit (frontal belly); epicranial aponeurosis (occipital belly)
• action: draws scalp anteriorly (frontal belly); draws scalp posteriorly (occipital
  belly)
• temporalis
• origin: temporal bone
• insertion: coronoid process & ramus of mandible
• action: elevates & retracts mandible
                      MUSCLES OF THE HEAD & NECK



• suprahyoid muscles: elevate hyoid bone
• infrahyoid muscles: depress hyoid bone
• sternocleidomastoid
• origin: sternum & clavicle
• insertion: mastoid process of temporal bone
• action: flex cervical portion of vertebral column; extend head & elevate
  sternum during forced inhalation; laterally flex & rotate head side to side
                     MUSCLES OF ABDOMINAL WALL

• rectus abdominis
• origin: pubic crest & pubic symphysis
• insertion: cartilage of ribs 5-7 & xiphoid process
• action: flexes vertebral column & compresses abdomen
• external oblique
• origin: lower 8 ribs
• insertion: iliac crest & linea alba
• action: compresses abdomen & flexes vertebral column
                   MUSCLES OF ABDOMINAL WALL

• internal oblique
• origin: iliac crest, inguinal ligament & thoracolumbar fascia
• insertion: cartilage of last 3 or 4 ribs; linea alba
• action: compresses abdomen & flexes vertebral column
• transverse abdominis
• origin: iliac crest, inguinal ligament, lumbar fascia & cartilage of
  lower 6 ribs
• insertion: xiphoid process, linea alba & pubis
• action: compresses abdomen
                          Pectoralis major
Serratus anterior

                          Linea alba

                          Tendinous
Transversus abdominis     intersection
Internal oblique          Rectus
                          abdominis
External oblique


Aponeurosis of the      Inguinal ligament
external oblique        (formed by inferior border
                        of the external oblique
                        aponeurosis)




                                         Figure 10.11a
                         MUSCLES USED IN BREATHING

• diaphragm
• origin: xiphoid process of sternum, costal cartilage of lower 6 ribs & lumbar
  vertebrae
• insertion: central tendon
• action: increases height & volume of thoracic cavity, resulting in inhalation
• external intercostals
• origin: superior rib
• insertion: inferior rib
• action: elevates ribs & increases width & depth of thoracic cavity, resulting in
  inhalation
                         MUSCLES USED IN BREATHING



• internal intercostals
• origin: superior rib
• insertion: inferior rib
• action: further decreases width & depth of thoracic cavity during forced
  exhalation
      External
      intercostal




(a)          Internal
             intercostal
                           Figure 10.10a
                           MUSCLES THAT MOVE THE
                         PECTORAL GIRDLE (PRIMARILY
                                 SCAPULA)
• pectoralis minor
• origin: 2nd or 3rd through 4th or 5th ribs
• insertion: coracoid process of scapula
• action: abducts & inferiorly rotates scapula; elevates 3rd through 5th ribs
  during forced inhalation (when scapula stabilized)
• serratus anterior
• origin: superior 8 or 9 ribs
• insertion: vertebral border & inferior angle of scapula
• action: abducts & superiorly rotates scapula; elevates ribs (when scapula
  stabilized)
                          MUSCLES THAT MOVE THE
                        PECTORAL GIRDLE (PRIMARILY
                                SCAPULA)
• trapezius
• origin: occipital bone (superior nuchal line & ligamentum nuchae) & spines of
  7th cervical & all thoracic vertebrae
• insertion: clavicle; acromion & spine of scapula
• action: elevates scapula & helps extend head; adducts & depresses scapula &
  rotates scapula upward; stabilizes scapula
                         MUSCLES THAT MOVE THE
                               HUMERUS
• pectoralis major
• origin: clavicle, sternum & costal cartilage of 2nd to 6th ribs (sometimes 1st to
  7th ribs)
• insertion: greater tubercle of humerus & intertubercular sulcus of humerus
• action: adducts & medial rotates arm at shoulder joint; flexes arm (clavicular
  head) & extends arm (sternocostal head)
• latissimus dorsi
• origin: spines of inferior 6 thoracic vertebrae & lumbar vertebrae; crests of
  sacrum & ilium & inferior 4 ribs
• insertion: intertubercular sulcus of humerus
• action: extends, adducts & medially rotates arm at shoulder joint; draws arm
  posteriorly & inferiorly
                         MUSCLES THAT MOVE THE
                               HUMERUS
• deltoid
• origin: acromial extremity of clavicle; acromion & spine of scapula
• insertion: deltoid tuberosity of humerus
• action: abducts arm at shoulder joint (lateral fibers); flexes & medially rotates
  arm at shoulder joint (anterior fibers); extends & laterally rotates arm at
  shoulder joint (posterior fibers)
• infraspinatus
• origin: inferior to spine of scapula (infraspinous fossa)
• insertion: greater tubercle of humerus
• action: laterally rotates & adducts arm at shoulder joint
                         MUSCLES THAT MOVE THE
                               HUMERUS
• teres major
• origin: inferior angle of scapula
• insertion: intertubercular sulcus of humerus
• action: extends arm & assists in adduction & medial rotation of arm at
  shoulder joint
• teres minor
• origin: inferior lateral border of scapula
• insertion: greater tubercle of humerus
• action: laterally rotates, extends & adducts arm at shoulder joint
Sternocleido-    Subclavius
mastoid          Clavicle
                 Subscapularis
Deltoid
                 Pectoralis minor
Pectoralis
major            Coracobrachialis
Sternum
                 Serratus anterior
Biceps brachii   Humerus


(a)




                              Figure 10.13a
             Levator
             scapulae
Trapezius    Supraspinatus
             Clavicle
Deltoid      Spine of
Rhomboid     scapula
minor        Infraspinatus
Rhomboid     Teres minor
major        Teres major


             Humerus


Latissimus
dorsi




(c)
                        Figure 10.13c
                        Clavicle



Deltoid
Sternum
Pectoralis major
Coracobrachialis
Triceps brachii:
 Lateral head
 Long head
 Medial head
Biceps brachii
Brachialis
Brachioradialis




    (a) Anterior view

                                   Figure 10.14a
                         MUSCLES THAT MOVE THE
                             RADIUS & ULNA
• Flexors:
• biceps brachii
• origin: tubercle above glenoid cavity of scapula (long head); coracoid process
  of scapula (short head)
• insertion: radial tuberosity of radius (& bicipital aponeurosis)
• action: flexes forearm at elbow joint; supinates forearm at radioulnar joints &
  flexes arm at shoulder joint
• brachialis
• origin: distal anterior surface of humerus
• insertion: ulnar tuberosity & coronoid process of ulna
• action: flexes forearm at elbow joint
                         MUSCLES THAT MOVE THE
                             RADIUS & ULNA
• brachioradialis
• origin: lateral border & distal end of humerus
• insertion: superior to styloid process of radius
• action: flexes forearm at elbow joint; supinates & pronates forearm at
  radioulnar joints
• Extensors:
• triceps brachii
• origin: inferior to glenoid cavity of scapula (long head); lateral & posterior
  surface of humerus (lateral head); posterior surface of humerus ( medial
  head)
• insertion: olecranon of ulna
• action: extends forearm at elbow joint & extends arm at shoulder joint
                         MUSCLES THAT MOVE THE
                             RADIUS & ULNA


• Pronators:
• pronator teres
• origin: medial epicondyle of humerus & coronoid process of ulna
• insertion: midlateral surface of radius
• action: pronates forearm at radioulnar joints & weakly flexes forearm at elbow
  joint
Superficial transverse
ligament of palm
Palmar aponeurosis

                          Flexor retinaculum
                          Pronator quadratus
Flexor digitorum
superficialis             Flexor pollicis longus
Flexor carpi ulnaris
Palmaris longus           Extensor carpi radialis longus
Flexor carpi radialis     Brachioradialis
Medial epicondyle         Pronator teres
of humerus                Tendon of biceps brachii
Medial head of
triceps brachii           Biceps brachii
                    (a)

                                                     Figure 10.15a
                        Tendon of flexor digitorum
Tendon of flexor        superficialis (cut)
digitorum profundus     Lumbricals
                        Tendon of flexor
                        pollicis longus
                        Thenar muscles of thumb
Tendon of flexor
                        Pronator quadratus
carpi ulnaris (cut)

                        Flexor pollicis longus



                        Flexor digitorum
                        profundus
Supinator



                  (c)

                                                  Figure 10.15c
Extensor
expansion
Tendons of
extensor
digitorum            Tendons of extensor carpi
Extensor pollicis    radialis brevis and longus
longus               Extensor indicis
Extensor pollicis    Extensor digiti
brevis               minimi
Abductor             Extensor carpi
pollicis longus      ulnaris
Extensor digitorum
                     Flexor carpi
Extensor carpi       ulnaris
radialis brevis      Anconeus
Extensor carpi       Insertion of
radialis longus      triceps brachii
                     Brachioradialis
(a)

                                                  Figure 10.16a
                            Interossei

Extensor indicis
Extensor pollicis brevis
Extensor pollicis longus
Abductor pollicis longus

Supinator
Anconeus
Olecranon process of ulna


(b)

                                         Figure 10.16b
                       MUSCLES THAT MOVE THE
                     WRIST, HAND, THUMB & FINGERS


• Flexors:
• flexor carpi radialis
• origin: medial epicondyle of humerus
• insertion: 2nd & 3rd metacarpals
• action: flexes & abducts hand at wrist joint
• palmaris longus
• origin: medial epicondyle of humerus
• insertion: flexor retinaculum & palmar aponeurosis
• action: weakly flexes hand at wrist joint
                       MUSCLES THAT MOVE THE
                     WRIST, HAND, THUMB & FINGERS


• flexor carpi ulnaris
• origin: medial epicondyle of humerus; coronoid process of ulna; ridge along
  anterior surface of radius
• insertion: pisiform, hamate & base of 5th metacarpal
• action: flexes & adducts hand at wrist joint
• Extensors:
• extensor carpi radialis
• origin: lateral supercondylar ridge of humerus
• insertion: 2nd metacarpal
• action: extends & abducts hand at wrist joint
                      MUSCLES THAT MOVE THE
                    WRIST, HAND, THUMB & FINGERS
• extensor digitorum
• origin: lateral epicondyle of humerus
• insertion: distal & middle phalanges of each finger
• action: extends distal & middle phalanges of each finger at interphalangeal
  joints; extends proximal phalanges of each finger at metacarpophalangeal
  joints; extends hand at wrist joint
•   extensor carpi ulnaris
• origin: lateral epicondyle of humerus & posterior border of ulna
• insertion: 5th metacarpal
• action: extends & adducts hand at wrist joint
                      MUSCLES THAT MOVE THE
                    WRIST, HAND, THUMB & FINGERS


• abductor pollicis longus
• origin: posterior surface of middle of radius & ulna
• insertion: 1st metacarpal
• abducts & extends thumb at carpometacarpal joint & abducts hand at wrist
  joint
Tendons of:
 Flexor digitorum
 profundus
                                                      Fibrous sheath
 Flexor digitorum
 superficialis                                        Second lumbrical
                                                      Dorsal interossei
   Third
   lumbrical                                          First lumbrical

   Fourth                                             Adductor pollicis
   lumbrical                                          Flexor pollicis
   Opponens                                           brevis
   digiti minimi                                      Abductor pollicis
                                                      brevis
   Flexor digiti
   minimi brevis                                      Opponens pollicis
   Abductor
   digiti minimi                                      Flexor retinaculum
   Pisiform bone                                      Abductor pollicis
   Flexor carpi                                       longus
   ulnaris tendon                              Tendons of:
                                                Palmaris longus
   Flexor digitorum
   superficialis                                Flexor carpi radialis
                                                Flexor pollicis longus
   tendons       (a) First superficial layer

                                                                           Figure 10.18a
                                                    Flexor digitorum
                                                    profundus tendon

                                                    Flexor digitorum
                                                    superficialis tendon



                                                        Dorsal interossei
Palmar interossei
                                                        Adductor pollicis
Opponens digiti
minimi                                                  Flexor pollicis
                                                        brevis
Flexor digiti minimi
brevis (cut)                                            Abductor pollicis
                                                        brevis
Abductor digiti minimi
(cut)
                                            Opponens pollicis

                                            Flexor pollicis longus
                                            tendon
                         (b) Second layer

                                                                     Figure 10.18b
                         Palmar interossei




(c) Palmar interossei (isolated)

                                             Figure 10.18c
                          Dorsal interossei




(d) Dorsal interossei (isolated)
                                              Figure 10.18d
                         MUSCLES THAT MOVE THE
                                 FEMUR
• gluteus maximus
• origin: iliac crest, sacrum, coccyx & aponeurosis of sacrospinalis
• insertion: iliotibial tract & linea aspera under greater trochanter of femur
• action: extends thigh at hip joint & laterally rotates thigh
• gluteus medius
• origin: ilium
• insertion: greater trochanter of femur
• action: abducts thigh at hip joint & medially rotates thigh
                           MUSCLES THAT MOVE THE
                                   FEMUR
• tensor fasciae latae
• origin: iliac crest
• insertion: iliotibial tract (& tibia)
• action: flexes & abducts thigh at hip joint
• adductor longus
• origin: pubic crest & pubic symphysis
• insertion: linea aspera of femur
• action: flexes & adducts thigh at hip joint & medially rotates thigh
                         MUSCLES THAT MOVE THE
                                 FEMUR
• pectineus
• origin: superior ramus of pubis
• insertion: pectineal line of femur (between lesser trochanter & linea aspera)
• action: flexes & adducts thigh at hip joint
                         MUSCLES THAT ACT ON THE
                          FEMUR, TIBIA & FIBULA
• Extensors:
• sartorius
• origin: anterior superior iliac spine
• insertion: medial surface & body of tibia
• action: flexes leg at knee joint; flexes, abducts & laterally rotates thigh at hip
  joint
• Quadriceps femoris muscle group:
• rectus femoris
• origin: anterior inferior iliac spine
• insertion: patella (via quadriceps tendon) & tibial tuberosity (via patellar
  ligament)
• action: extends leg at knee joint; flexes thigh at hip joint
                        MUSCLES THAT ACT ON THE
                         FEMUR, TIBIA & FIBULA
• vastus lateralis
• origin: greater trochanter & linea aspera of femur
• insertion: patella (via quadriceps tendon) & tibial tuberosity (via patellar
  ligament)
• action: extends leg at knee joint
• vastus medialis
• origin: linea aspera of femur
• insertion: patella (via quadriceps tendon) & tibial tuberosity (via patellar
  ligament)
• action: extends leg at knee joint
                        MUSCLES THAT ACT ON THE
                         FEMUR, TIBIA & FIBULA
• Flexors:
• Hamstring muscle group:
• biceps femoris
• origin: ischial tuberosity (long head); linea aspera of femur (short head)
• insertion: head of fibula & lateral condyle of tibia
• action: flexes leg at knee joint & extends thigh at hip joint
• semitendinosus
• origin: ischial tuberosity
• insertion: proximal medial surface of shaft of tibia
• action: flexes leg at knee joint & extends thigh at hip joint
                        MUSCLES THAT ACT ON THE
                         FEMUR, TIBIA & FIBULA
• semimembranosus
• origin: ischial tuberosity
•   insertion: medial condyle of tibia
• action: flexes leg at knee joint & extends thigh at hip joint
       12th rib                    12th thoracic vertebra
       Quadratus lumborum
       Psoas minor
       Iliac crest
             Psoas major
Iliopsoas
             Iliacus               5th lumbar vertebra
Anterior superior iliac spine
Tensor fasciae latae
Pectineus

Sartorius                       Adductor longus
                                Gracilis
Quadriceps femoris
                                Adductor magnus
• Rectus femoris
• Vastus lateralis
• Vastus medialis
                                Tendon of quadriceps femoris
                                Patella
                                Patellar ligament
(a)
                                                         Figure 10.19a
      Gluteus medius



      Gluteus maximus


      Adductor magnus
      Gracilis
      Iliotibial tract

      Long head Biceps
      Short head femoris
                           Hamstrings
      Semitendinosus
      Semimembranosus



(a)

                                        Figure 10.20a
Pectineus
(cut)
Adductor
brevis          Adductor
                magnus
Adductor
longus


Femur


              O = origin
              I = insertion
        (b)


                              Figure 10.19b
                  Gluteus medius (cut)

                  Gluteus minimus

Superior
gemellus          Piriformis
Obturator
                  Obturator
internus
                  externus
Inferior          Quadratus
gemellus          femoris
                  Gluteus
                  maximus
                  (cut)



            (c)

                                     Figure 10.20c
       12th rib                    12th thoracic vertebra
       Quadratus lumborum
       Psoas minor
       Iliac crest
             Psoas major
Iliopsoas
             Iliacus               5th lumbar vertebra
Anterior superior iliac spine
Tensor fasciae latae
Pectineus

Sartorius                       Adductor longus
                                Gracilis
Quadriceps femoris
                                Adductor magnus
• Rectus femoris
• Vastus lateralis
• Vastus medialis
                                Tendon of quadriceps femoris

                                Patella
                                Patellar ligament
(a)


                                                         Figure 10.19a
      Gluteus medius



      Gluteus maximus


      Adductor magnus
      Gracilis
      Iliotibial tract

      Long head Biceps
      Short head femoris
                           Hamstrings
      Semitendinosus
      Semimembranosus



(a)


                                        Figure 10.20a
      Fibularis longus
      Gastrocnemius
      Tibia
      Tibialis anterior
      Extensor digitorum longus
      Soleus
      Extensor hallucis longus
      Fibularis tertius
      Superior and inferior
      extensor retinacula
      Extensor hallucis brevis
      Extensor digitorum brevis

(a)

                                  Figure 10.21a
                         Patella
                         Head of fibula
                         Gastrocnemius
                         Soleus
                         Fibularis longus
                         Extensor digitorum longus
                         Tibialis anterior
                         Extensor hallucis longus
                         Fibularis tertius
Fibularis brevis             Superior and inferior extensor
Flexor hallucis longus       retinacula
                               Extensor hallucis brevis
Fibular retinaculum              Extensor digitorum brevis
Lateral malleolus
(a)                                5th metatarsal

                                                       Figure 10.22a
                 Plantaris


Gastrocnemius Medial head
              Lateral head




         Tendon of
         gastrocnemius

         Calcaneal tendon
         Medial malleolus
                                        Lateral malleolus
                                       Calcaneus
(a) Superficial view of the posterior leg.
                                                            Figure 10.23a
                         Plantaris (cut)
                         Gastrocnemius
                         lateral head (cut)
Gastrocnemius            Popliteus
medial head (cut)        Soleus (cut)
                         Tibialis posterior
                         Fibula
                         Fibularis longus
Flexor digitorum
longus                   Flexor hallucis longus

Tendon of tibialis       Fibularis brevis
posterior
Medial malleolus
Calcaneal tendon (cut)
                         Calcaneus



                                              Figure 10.23c
                      MUSCLES THAT MOVE THE FOOT
                                & TOES

• tibialis anterior
• origin: lateral condyle & body of tibia (& interosseus membrane between tibia
  & fibula)
• insertion: 1st metatarsal & medial cuneiform
• action: dorsiflexes foot at ankle joint & inverts foot at intertarsal joints
• extensor digitorum longus
• origin: lateral condyle of tibia, anterior surface of fibula & (& interosseus
  membrane between tibia & fibula)
• insertion: middle & distal phalanges of toes 2-5
• action: dorsiflexes foot at ankle joint; extends distal & middle phalanges of
  each toe at interphalangeal joints; extends proximal phalanx of each toe at
  metatarsophalangeal joint
                      MUSCLES THAT MOVE THE FOOT
                                & TOES


• fibularis (peroneus) longus
• origin: head & body of fibula & lateral condyle of tibia
• insertion: 1st metatarsal & medial cuneiform
• action: plantar flexes foot at ankle joint & everts foot at intertarsal joints
• gastrocnemius
• origin: lateral & medial condyles of femur & capsule of knee
• insertion: calcaneus (via calcaneal tendon)
• action: plantar flexes foot at ankle joint & flexes leg at knee joint
                      MUSCLES THAT MOVE THE FOOT
                                & TOES


• soleus
• origin: head of fibula & medial border of tibia
• insertion: calcaneus (via calcaneal tendon)
• action: plantar flexes foot at ankle joint
      Fibularis longus
      Gastrocnemius
      Tibia
      Tibialis anterior
      Extensor digitorum longus
      Soleus
      Extensor hallucis longus
      Fibularis tertius
      Superior and inferior
      extensor retinacula
      Extensor hallucis brevis
      Extensor digitorum brevis

(a)

                                  Figure 10.21a
                    Tendon of flexor hallucis longus
                    Lumbricals
                    Flexor hallucis brevis
                    Flexor digiti minimi brevis
                    Abductor hallucis
                    Flexor digitorum brevis

                    Flexor accessorius
                    Abductor digiti minimi



                    Calcaneal tuberosity

(a) First layer (plantar aspect)

                                                       Figure 10.24a
                  Lumbricals
                  Flexor hallucis brevis
                  Flexor hallucis longus tendon
                  Flexor digitorum longus (tendon)
                  Flexor digiti minimi brevis
                  Abductor digiti minimi
                  Flexor accessorius
                  Fibularis longus (tendon)
                  Flexor digitorum longus (tendon)
                  Flexor hallucis longus (tendon)



(b) Second layer (plantar aspect)
                                                     Figure 10.24b
                   Adductor hallucis (transverse head)
                   Adductor hallucis (oblique head)

                   Interosseous muscles
                   Flexor hallucis brevis
                   Flexor digiti minimi brevis
                   Fibularis longus (tendon)
                   Flexor accessorius
                   Flexor digitorum longus (tendon)

                   Flexor hallucis longus (tendon)


(c) Third layer (plantar aspect)
                                                         Figure 10.24c
                            Plantar interossei




(d) Fourth layer (plantar aspect): plantar interossei


                                                        Figure 10.24d
                                    MUSCLE TYPES


• Skeletal muscle tissue: attach to & cover bony skeleton
•   longest of muscle types; striated; under voluntary control
• Cardiac muscle tissue: occurs only in walls of heart
•   striated; involuntary
•   pacemaker cells set rate of contraction
• Smooth muscle tissue: occurs in walls of visceral organs (stomach,
  bladder), respiratory passageways & blood vessels
•   forces fluids & other substances through body channels
•   nonstriated; involuntary
•   slow & sustained contractions
Table 9.3
                MUSCLE FUNCTIONS



•   producing movement
•   maintaining posture
•   stabilizing joints
•   generating heat
             FUNCTIONAL CHARACTERISTICS
                    OF MUSCLES:


• excitability (irritability): receive & respond to
  stimuli
• contractility: shorten forcibly when stimulated
• extensibility: can be stretched or extended
• elasticity: recoil & resume resting length
  following stretch
              SKELETAL MUSCLE ANATOMY:



• Connective Tissue wrappings:
• epimysium: dense irregular CT surrounding
  whole muscle
• perimysium: fibrous CT surrounding
  individual muscle fascicles (bundles of muscle
  fibers (cells))
• endomysium: reticular CT surrounding
  individual muscle fibers (cells)
                                          Epimysium

        Bone Epimysium                    Perimysium
     Tendon                               Endomysium
                                          Muscle fiber
                                          in middle of
                                          a fascicle
                         (b)   Blood vessel
                               Fascicle
                               (wrapped by perimysium)
                                     Endomysium
                                     (between individual
                                     muscle fibers)


  Perimysium Fascicle                     Muscle fiber
(a)



                                                    Figure 9.1
                       SKELETAL MUSCLE ANATOMY:



• Nerve & Blood Supply: each muscle generally served by 1
  nerve, an artery & 1 or more veins
• nerve ending controls muscle cell activity
• arteries lead to winding capillaries that deliver nearly continuous oxygen; veins
  carry away large amounts of metabolic waste
                     SKELETAL MUSCLE ANATOMY:

• Attachments: most muscles attached to bones in at least 2
  places
• origin: point of attachment to less movable (immovable) bone
• insertion: point of attachment to more movable bone
• direct (fleshy) attachments: epimysium of muscle fused to periosteum or
  perichondrium
• indirect attachments: extension of muscle's CT in the form of tendon or
  aponeurosis anchors muscle to CT covering of bone or to fascia of another
  muscle
Table 9.1
                  MICROSCOPIC ANATOMY OF
                     SKELETAL MUSCLE:


• skeletal muscle cells long (hundreds of cm) & wide;
  multinucleate
• sarcolemma: plasma membrane of muscle
• sarcoplasm: like cytoplasm of normal cell; contains many
  glycosomes (store glycogen) & myoglobin (carries & stores
  oxygen)
                        MICROSCOPIC ANATOMY OF
                           SKELETAL MUSCLE:


• myofibrils: contractile elements of skeletal muscle
• composed of thin filaments (actin, tropomyosin & troponin complex) & thick
  filaments (myosin)
• myosin composed of long central tails & laterally oriented heads (cross-
  bridges) that bind actin
• tropomyosin covers myosin binding sites on actin molecules in resting
  muscle
• troponin complex consists of: TnI (inhibits actin), TnT (binds tropomyosin
  & positions it on actin) & TnC (binds calcium to start contraction)
• striations result from alternating dark A bands (thick filaments with
  overlapping thin filaments) & I bands (thin filaments)
                                                  Sarcolemma



                                                  Mitochondrion




                                             Myofibril

   Dark A band Light I band   Nucleus
(b) Diagram of part of a muscle fiber showing the myofibrils. One
myofibril is extended from the cut end of the fiber.
                       MICROSCOPIC ANATOMY OF
                          SKELETAL MUSCLE:


• Myofibrils: (cont.)
• A bands have lighter central H zone (no thin filaments) with central darker M
  line (desmin protein)
• I bands have darker central Z disc (connexin protein)
• Elastic filaments (composed of titin) hold thick & thin filaments in place &
  recoil to reform shape when muscle relaxes)
• A sarcomere is the region of a myofibril between adjacent Z discs
Thin (actin)
filament         Z disc        H zone    Z disc




Thick (myosin)   I band      A band       I band      M line
filament                     Sarcomere




                      Sarcomere
    Z disc                M line             Z disc
                                                       Thin (actin)
                                                       filament
                                                       Elastic
                                                       filaments
                                                       Thick
                                                       (myosin)
                                                       filament




                                                                      Figure 9.2c, d
                       MICROSCOPIC ANATOMY OF
                          SKELETAL MUSCLE:


• sarcoplasmic reticulum: smooth ER of muscle cells; store
  calcium
• wraps around myofibrils; terminal cisternae are cross channels at A-I
  junctions
• terminal cisternae form triad with T-tubules of sarcolemma; triads sense
  voltage & regulate calcium release
                       CONTRACTION OF SKELETAL
                            MUSCLE FIBER:


• activation of myosin's cross bridges
• sliding filament mechanism: during contraction, the thin filaments slide
  past the thick filaments so that actin & myosin overlap to a greater degree
• nerve impulse leads to depolarization & calcium release from sarcoplasmic
  reticulum
• calcium binds to TnC, which changes shape & moves tropomyosin away from
  myosin binding sites on actin
                       CONTRACTION OF SKELETAL
                            MUSCLE FIBER:


• with myosin binding sites accessible on actin, activated myosin heads bind
  actin (cross bridge attachment)
• as myosin heads bind actin, they pivot as they change from high-energy shape
  to low-energy shape, pulling thin filament toward center of sarcomere
• ADP & P are released from myosin head
• a new ATP molecule binds the myosin head & myosin loses hold of actin
  (cross bridge detachment)
• hydrolysis of ATP to ADP + P by ATPase releases energy to return myosin
  to high-energy state... provides potential energy for myosin to again bind actin
                    REGULATION OF CONTRACTION:



• the axon of a motor neuron forms a neuromuscular junction with a
  muscle fiber
• the neurotransmitter acetylcholine (ACh) is released in synaptic
  vesicles from the axon terminal of the nerve cell into the synaptic
  cleft between the nerve cell & muscle cell
• the motor end plate of the muscle cell has ACh receptors that bind
  ACh; this binding opens sodium channels in the sarcolemma...
  sodium rushes in & triggers an action potential in the muscle cell:
• muscle cells are polarized with slight negative charge in resting state
• depolarization of the muscle cell results from the excess positive
  charge caused by the influx of sodium ions
                      REGULATION OF CONTRACTION:


• the local depolarization spreads to the rest of the muscle cell
• repolarization occurs as potassium ions flow out of the muscle cell to
  restore the resting potential
• ACh is degraded by ACh esterase in synaptic cleft
• Excitation-contraction coupling: transmission of action potential
  past triads causes sarcoplasmic reticulum to release calcium ions into
  sarcoplasm
•   Some calcium binds to troponin... (see above)
•   Calcium signal is short-lived (30 ms); ATP-dependent calcium pump moves
    calcium back into sarcoplasmic reticulum
•   As intracellular calcium levels drop, tropomyosin again blocks myosin binding
    sites on actin... relaxation occurs
                      REGULATION OF CONTRACTION:


• Muscle twitch: response of muscle to a single brief stimulus...
  can be measured in lab using myogram; includes:
• latent period: events of excitation-contraction coupling
• period of contraction: cross bridge formation; tension increases
• tetanus: sustained muscle contraction - can be incomplete or complete
• period of relaxation: Ca2+ reentry into the SR; tension declines to zero
• Isotonic contractions: muscle changes in length & moves load
• Isometric contractions: muscle neither shortens nor lengthens
• example: muscle attempts to move a load requiring force greater than
  available
Figure 9.18a
Figure 9.18b
                              MUSCLE METABOLISM:



• ATP Sources: muscles need constant supply of ATP
• Direct phosphorylation: creatine phosphate converted to creatine by
  creatine kinase... phosphate released added to ADP to form ATP
• Anaerobic glycolysis & lactic acid formation: 2 ATP yield per glucose
• Lactic acid build up in muscles - causes fatigue
• Oxygen debt: need additional oxygen to oxidize & remove lactic acid from
  muscle cells
• Aerobic respiration: yields 36 or 38 ATP per glucose
  (a)   Direct phosphorylation
Coupled reaction of creatine
phosphate (CP) and ADP

Energy source: CP



           CP         ADP

                     Creatine
                     kinase


         Creatine      ATP




Oxygen use: None
Products: 1 ATP per CP, creatine
Duration of energy provision:
15 seconds

                                   Figure 9.19a
          (b)   Anaerobic pathway

Glycolysis and lactic acid formation

Energy source: glucose

                      Glucose (from
                 glycogen breakdown or
                  delivered from blood)


                      Glycolysis
                      in cytosol

                                          O2
 2     ATP
                     Pyruvic acid
     net gain
                                          O2
  Released            Lactic acid
  to blood
Oxygen use: None
Products: 2 ATP per glucose, lactic acid
Duration of energy provision:
60 seconds, or slightly more
                                               Figure 9.19b
          (c)   Aerobic pathway

Aerobic cellular respiration
Energy source: glucose; pyruvic acid;
free fatty acids from adipose tissue;
amino acids from protein catabolism


                    Glucose (from
               glycogen breakdown or
                delivered from blood)

                                           O2
                   Pyruvic acid
 Fatty
 acids                                     O2

                Aerobic respiration
                Aerobicrespiration
Amino
                   mitochondria
                in mitochondria
acids

                                      32    ATP
         CO2
                     H2O              net gain per
                                      glucose
Oxygen use: Required
Products: 32 ATP per glucose, CO2, H2O
Duration of energy provision: Hours

                                                     Figure 9.19c
                                                                           Prolonged-duration
                       Short-duration exercise
                                                                           exercise




ATP stored in   ATP is formed    Glycogen stored in muscles is broken    ATP is generated by
muscles is      from creatine    down to glucose, which is oxidized to   breakdown of several
used first.     Phosphate        generate ATP.                           nutrient energy fuels by
                and ADP.                                                 aerobic pathway. This
                                                                         pathway uses oxygen
                                                                         released from myoglobin
                                                                         or delivered in the blood
                                                                         by hemoglobin. When it
                                                                         ends, the oxygen deficit is
                                                                         paid back.



                                                                                             Figure 9.20
                               SMOOTH MUSCLE



• Smooth Muscle: spindle-shaped cells with centrally located
  nucleus
• has thin endomysium; no perimysium or epimysium
• lines walls of most blood vessels & hollow organs... 2 layers in
  most cases: longitudinal layer & circular layer
• 2 layers alternate contraction & relaxation: leads to peristalsis - moves
  contents along tube
• myofilaments: thick filaments (myosin) & thin filaments (actin
  & tropomyosin (no troponin))
• intermediate filaments with dense bodies... anchor thin filaments & form
  intracellular cytoskeleton
                        CONTRACTION OF SMOOTH
                               MUSCLES


• uses sliding filament mechanism
• no troponin or TnC... calcium binds calmodulin & myosin light
  chain kinase to activate myosin
• calcium ions bind & activate calmodulin
• activated calmodulin activates myosin light chain kinase
• the activated kinase transfers phosphate from ATP to myosin cross bridges
  (heads)
• phosphorylated myosin heads interact with actin of thin filaments - produces
  shortening of the muscle
• intracellular calcium levels drop - relaxation
                    REGULATION OF SMOOTH
                     MUSCLE CONTRACTION:


• can use similar mechanism to skeletal muscle...
  neurotransmitter release at neuromuscular junction generates
  action potential, which leads to rise in intracellular calcium
• however, signal can be stimulatory or inhibitory for
  contraction
• can use a variety of neurotransmitters (ACh,
  norepinephrine...), whereas skeletal muscle cells use ACh
• smooth muscle cells can spontaneously depolarize in response
  to chemical stimuli
                   DEVELOPMENTAL ASPECTS



• All muscle tissues develop from embryonic myoblasts
• Multinucleated skeletal muscle cells form by fusion
• Growth factor agrin stimulates clustering of ACh receptors at
  neuromuscular junctions
• Cardiac and smooth muscle myoblasts develop gap junctions
                   DEVELOPMENTAL ASPECTS



• Cardiac and skeletal muscle become amitotic, but can lengthen
  and thicken
• Myoblast-like skeletal muscle satellite cells have limited
  regenerative ability
• Injured heart muscle is mostly replaced by connective tissue
• Smooth muscle regenerates throughout life
                    DEVELOPMENTAL ASPECTS



•   Muscular development reflects neuromuscular coordination
•   Development occurs head to toe, and proximal to distal
•   Peak natural neural control occurs by mid-adolescence
•   Athletics and training can improve neuromuscular control
                   DEVELOPMENTAL ASPECTS



• Female skeletal muscle makes up 36% of body mass
• Male skeletal muscle makes up 42% of body mass, primarily
  due to testosterone
• Body strength per unit muscle mass is the same in both sexes
                    DEVELOPMENTAL ASPECTS



• With age, connective tissue increases and muscle fibers
  decrease
• By age 30, loss of muscle mass (sarcopenia) begins
• Regular exercise reverses sarcopenia
• Atherosclerosis may block distal arteries, leading to
  intermittent claudication and severe pain in leg muscles
                     MUSCULAR DYSTROPHY



• Group of inherited muscle-destroying diseases
• Muscles enlarge due to fat and connective tissue deposits
• Muscle fibers atrophy
                      MUSCULAR DYSTROPHY



• Duchenne muscular dystrophy (DMD):
• Most common and severe type
• Inherited, sex-linked, carried by females and expressed in males
  (1/3500) as lack of dystrophin
• Victims become clumsy and fall frequently; usually die of
  respiratory failure in their 20s
• No cure, but viral gene therapy or infusion of stem cells with
  correct dystrophin genes show promise

								
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