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Chapter 11
Lecture Outline
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11.5 Muscles of
Respiration
Learning
Objectives:
1
List the posterior and anterior
thoracic muscle groups involved
in respiration, and describe their
actions.
2.
Describe the role of the
diaphragm in breathing and in
raising intra-abdominal pressure.
1.
2
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11.5 Muscles of Respiration
• How are skeletal muscles involved in the
process of respiration?
– During inspiration
o Certain respiratory muscles contract to increase the size
of the thoracic cavity
– During expiration
o Certain respiratory muscles relax and others contract to
decrease the size of the thoracic cavity
3
11.5 Muscles of Respiration
• Muscles of respiration
– Found on posterior and anterior thorax
– Serratus posterior superior
o Elevates ribs during forced inspiration
o Increases lateral dimensions of thorax
– Serratus posterior inferior
o Depresses ribs during forced expiration
– Scalene muscles
o Help elevate first and second ribs during forced inspiration
4
11.5 Muscles of Respiration
• Muscles of respiration (continued )
– External intercostals
o Elevate ribs during inspiration, expanding cavity
– Internal intercostals
o Deep to external intercostals
o Fibers at right angles to external intercostals
o Depress ribs during forced expiration
– Transversus thoracis
o Depresses ribs during forced expiration
5
Muscles of Respiration
Figure 11.15a
6
11.5 Muscles of Respiration
• Muscles of respiration (continued )
– Diaphragm
o Internally placed dome-shaped muscle that partitions
thoracic and abdominal cavities
o Most important muscle associated with breathing
o Muscle fibers converge toward fibrous central tendon
o Contracts during inspiration
o Central tendon pulled inferiorly, increasing dimension of
thoracic cavity
7
Muscles of Respiration
Figure 11.15c-d
8
What did you
learn?
•
What is the function of the
internal intercostal muscles?
•
How does the diaphragm
move during respiration?
9
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11.6 Muscles of
the Abdominal
Wall
Learning
Objectives:
List the four pairs of abdominal
muscles.
2.
Compare the actions of the
rectus abdominis muscle with the
oblique muscles and transversus
abdominis.
1.
10
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11.6 Muscles of the Abdominal Wall
• Muscles of the abdominal wall
– Compress and hold abdominal organs in place
– Flex and stabilize vertebral column
– External oblique
o Located superficially, fibers directed inferomedially
o Forms aponeurosis anteriorly, that becomes inguinal ligament inferiorly
– Internal oblique
o Located deep to external oblique, fibers project superomedially
o Forms aponeurosis anteriorly
11
11.6 Muscles of the Abdominal Wall
• Muscles of the abdominal wall (continued )
– Transversus abdominis
o Deepest abdominal muscle, fibers project transversely
o Forms aponeurosis anteriorly
– Rectus abdominis
o Anteromedial location, fibers run vertically
o Partitioned into four segments by fibrous tendinous intersections
o Enclosed within fibrous sleeve, rectus sheath
– Formed from aponeuroses of external and internal oblique,
transversus abdominis
– Rectus sheaths of two sides connected by fibrous strip, linea alba
12
Muscles of the Abdominal Wall
Figure 11.16a
13
Muscles of the Abdominal Wall
• Unilateral
contraction of
oblique muscles and
transversus
abdominis helps
laterally flex the
vertebral column
and rotate it toward
the side opposite the
contraction
Figure 11.16b
14
Clinical View: Hernias
• Portion of viscera protrudes through weak point of abdominal
wall
• Inguinal hernia
– Loop of small intestine protrudes through superficial inguinal
ring
– More likely to occur in males since their inguinal canals are
larger to accommodate spermatic cord
– High abdominal pressure (e.g., straining to lift something
heavy) can push intestine into canal
– Physicians test for it by palpating inguinal ring while patient
coughs (cough raises abdominal pressure)
15
What did you
learn?
•
If you do a twisting sit-up
and touch your right elbow to
your left knee, which
muscles (on which side) are
you contracting?
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16
11.7 Muscles of
the Pelvic Floor
Learning
Objectives:
1.
2.
Describe the functions of the
pelvic floor muscles.
Identify the boundaries of the
perineum.
17
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11.7 Muscles of the Pelvic Floor
• Floor of the pelvic cavity
– Formed by three layers of muscles and fasciae
– Collectively known as the pelvic diaphragm
– Supports pelvic viscera
18
Muscles of the Pelvic Floor
19
Figure 11.17a
Muscles of the Pelvic Floor
• Perineum
– Diamond-shaped region
between lower appendages
– Bounded by pubic symphysis,
coccyx, ischial tuberosities
– Contains two triangles
divided by transverse line
between ischial tuberosities
o Urogenital triangle contains
external genitalia and urethra
o Anal triangle contains anus
Figure 11.17b,c (left)
20
What did you
learn?
What are the lateral
boundaries of the perineum?
•
21
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11.8 Muscles of
the Pectoral
Girdle and Upper
Limb
Learning
Objectives:
Compare and contrast how the
anterior and posterior thoracic
muscles move the pectoral girdle.
2. List the muscles that extend, flex,
adduct, and abduct the glenohumeral
joint.
3. Compare the actions of the four
scapular muscles of the rotator cuff.
4. Name the muscles in the arm’s
anterior and posterior compartments,
and contrast their common
functions.
1.
22
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11.8 Muscles of
the Pectoral
Girdle and Upper
Limb (continued )
Learning
Objectives:
Describe the muscles that pronate
and supinate the forearm.
6.
Describe the muscles of the
anterior compartment and their
actions, and identify the layer in
which each resides.
7. Explain the actions of the muscles
of the posterior compartment, and
identify the layer in which each
resides.
8. Compare the actions of the three
groups of intrinsic muscles of the
hand.
5.
23
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11.8a Muscles That Move the Pectoral Girdle
• Muscles of the pectoral girdle
– Originate on axial skeleton
– Insert on scapula and clavicle
– Can stabilize or move scapula
– Classified as anterior or posterior thoracic muscles
24
11.8a Muscles That Move the Pectoral Girdle
• Anterior thoracic muscles
– Pectoralis minor
o Deep to pectoralis major
o Helps depress and protract scapula; hunches shoulders
– Serratus anterior
o Fan-shaped muscle between ribs and scapula
o Protracts, stabilizes scapula
– Subclavius
o Extends from clavicle to first rib
o Stabilizes and depresses scapula
25
Muscles That Move Pectoral Girdle and Arm
Figure 11.21a
26
11.8a Muscles That Move the Pectoral Girdle
• Posterior thoracic muscles
– Levator scapulae
o Attaches to cervical vertebrae and scapula
o Elevates and inferiorly rotates the scapula
– Rhomboid major and minor
o Runs inferolaterally from vertebrae to scapula, deep to trapezius
o Helps elevate, retract, and inferiorly rotate the scapula
– Trapezius
o Diamond-shaped muscle extending from skull and vertebral column to
pectoral girdle
o Can elevate, depress, retract, or rotate scapula
27
Muscles That Move Pectoral Girdle and Arm
Figure 11.21b
28
Actions of Some Thoracic Muscles on the Scapula
Figure 11.20a
29
Actions of Some Thoracic Muscles on the Scapula
Figure 11.20b-c
30
11.8b Muscles That Move the
Glenohumeral Joint/Arm
• Eleven muscles cross the glenohumeral joint and
move the humerus
• Prime movers of the glenohumeral joint
– Latissimus dorsi
o Broad triangular muscle on back
o Prime arm extensor; adducts, medially rotates
– Pectoralis major
o Thick fan-shaped muscle on superior, anterior thorax
o Prime arm flexor; adducts, medially rotates
31
11.8b Muscles That Move the
Glenohumeral Joint/Arm
• Triceps brachii
o Long head originates on scapula, spans shoulder joint
o Helps extend and adduct the arm
• Biceps brachii
o Both heads originate on scapula and span shoulder joint
o Assists in flexing the arm
• Deltoid
o
o
o
o
Prime abductor of the arm
Its anterior fibers flex and medially rotate arm
Its lateral fibers abduct the arm
Its posterior fibers extend and laterally rotate arm
32
11.8b Muscles That Move the
Glenohumeral Joint/Arm
• Coracobrachialis
– Flexes and adducts the arm
• Teres major
– Extends, adducts, medially rotates arm
• Rotator cuff muscles
– Subscapularis
o Medially rotates arm
– Supraspinatus
o Abducts the arm
– Infraspinatus and teres minor
o Adduct and laterally rotate arm
33
Rotator Cuff Muscles
• Subscapularis
helps in wind up
for pitch
• Supraspinatus
helps in executing
pitch delivery
• Infraspinatus and
teres minor slow
the arm at end of
pitch
Figure 11.22
34
Clinical View: Rotator Cuff Injuries
• Result of trauma or disease
• Can be caused by repetitive use
• Can be caused by falling on the shoulder or lifting too
heavy of an object
• Supraspinatus most commonly involved
• Symptoms are swelling, tenderness, and pain with
movement
• Especially common in baseball players
• May require physical therapy or surgical repair
35
11.8c Arm and Forearm Muscles That
Move the Elbow Joint/Forearm
• Limbs are organized into compartments surrounded by
deep fascia
– A compartment houses functionally related muscles
o Anterior compartment of the arm has flexor muscles
– Supplied blood by deep brachial artery
– Innervated by musculocutaneous nerve
– E.g., biceps brachii, brachialis
o Posterior compartment of the arm has extensor muscles
– Supplied blood by deep brachial artery
– Innervated by radial nerve
– E.g., triceps brachii
36
11.8c Arm and Forearm Muscles That
Move the Elbow Joint/Forearm
• Muscles of the arm’s anterior compartment
– Biceps brachii
o Two-headed muscle on anterior humerus
o Flexes and supinates forearm; weakly helps flex humerus
– Brachialis
o Deep to biceps brachii
o Most powerful flexor of forearm
– Brachioradialis
o Located on anterolateral forearm
o Synergist in elbow flexion
37
Anterior Muscles with Actions at Elbow
Figure 11.24
38
11.8c Arm and Forearm Muscles That
Move the Elbow Joint/Forearm
• Muscles of the arm’s posterior compartment
– Triceps brachii
o Large three-headed muscle on posterior arm
o Major extensor of forearm; also helps extend humerus
– Anconeus
o Weak elbow extensor
o Crosses posterolateral region of elbow
39
Posterior Muscles with Actions at Elbow
Figure 11.25
40
11.8c Arm and Forearm Muscles That
Move the Elbow Joint/Forearm
• Muscles of the forearm that act on the elbow
joint
– Pronator teres and pronator quadratus
o Rotate the radius across the ulna to pronate forearm
o Located in anterior compartment of forearm
– Supinator
o Supinates forearm
o Located in posterior compartment of forearm
41
Forearm Muscles That Supinate or Pronate
Figure 11.26
42
Clinical View: Lateral Epicondylitis
• Also known as tennis elbow
• From trauma or overuse of common extensor tendon
of posterior forearm muscles
• Pain at lateral epicondyle of humerus, tendon’s
attachment site
• Often results from repeated forceful contraction of
forearm extensors
43
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
• Forearm muscles are extrinsic to wrist and hand
• Partitioned into anterior and posterior compartments
– Anterior compartment muscles
o Generally flex the wrist (some flex interphalangeal (IP) joint)
o Most originate on medial epicondyle of humerus
– Posterior compartment muscles
o Generally extend the wrist (some extend metacarpophalangeal (MP)
and interphalangeal (IP) joints)
o Most originate on lateral epicondyle of humerus
44
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
• Retinacula of the forearm
– Fibrous bands at the wrist formed from deep fascia
– Hold tendons close to bone
– Flexor retinaculum covers palmar surface of carpal bones
o Carpal tunnel: tight space between bones and flexor retinaculum
through which flexor tendons pass
– Extensor retinaculum superficial to dorsal surface of
carpal bones
o Extensor tendons of wrist and digits pass under it
45
Clinical View: Carpal Tunnel Syndrome
• Carpal tunnel
– Space between carpal bones and flexor retinaculum
•
•
•
•
Flexor tendons extending through tunnel
Median nerve extending through tunnel
Syndrome caused by compression of nerve
Characterized by pain and “pins and
needles” (paresthesia)
46
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
Muscles of the forearm’s anterior compartment
•Superficial layer
– Muscles originate on medial epicondyle
– Flexor carpi radialis
o Prominent muscle on lateral forearm
o Flexes wrist and abducts hand
– Palmaris longus
o Narrow muscle on anterior forearm
o Weakly assists in wrist flexion
– Flexor carpi ulnaris
o Flexes wrist and adducts hand
47
Locating superficial muscles of the anterior compartment
• Position hand on medial epicondyle
• Align little finger along medial border of forearm
• Note positions of digits 2–5
Figure 11.28
48
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
Muscles of forearm’s anterior compartment—
(continued )
•Intermediate layer
– Originates on medial epicondyle of humerus
– Flexor digitorum superficialis is only muscle of this
layer
o Its four tendons insert on middle phalanges of fingers 2–5
o Flexes wrist, MP, and proximal interphalangeal (PIP) joints
of fingers 2–5
49
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
Muscles of forearm’s anterior compartment (continued )
•Deep layer
– Flexor pollicis longus
o Attaches to distal phalanx of thumb
o Flexes MP and IP joints of the thumb; weakly flexes wrist
– Flexor digitorum profundus
o Lies deep to flexor digitorum superficialis
o Its four tendons insert on distal phalanges of fingers 2–5
o Flexes wrist, MP joints, PIP joints, and distal interphalangeal (DIP) joints of
fingers 2–5
50
Anterior Forearm Muscles
Figure 11.27a
51
Anterior Forearm Muscles
Figure 11.27b-c
52
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
Muscles of forearm’s posterior compartment
• Superficial layer
– Muscles originate from lateral epicondyle
– Extensor carpi radialis longus
o Extends wrist and abducts hand
– Extensor carpi radialis brevis
o Extends wrist and abducts hand
– Extensor digitorum
o Inserts on distal phalanges of fingers 2–5
o Extends wrist, MP joints, PIP joints, and DIP joints of fingers 2–5
53
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
Muscles of the forearm’s posterior compartment
• Superficial layer (continued )
– Extensor digit minimi
o Attaches to distal phalanx of finger 5 (pinky)
o Extends the little finger
– Extensor carpi ulnaris
o Inserts on fifth metacarpal bone
o Extends wrist and adducts hand
54
11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers
Muscles of forearm’s posterior compartment
(continued )
•Deep layer
– Extensor pollicis brevis
o Helps extend MP joint of the thumb
– Extensor pollicis longus
o Extends MP and IP joints of the thumb
– Extensor indicis
o Extends MP, PIP, and DIP joints of index finger
55
Posterior Forearm Muscles
Figure 11.29a
56
Posterior Forearm Muscles
57
Figure 11.29b
11.8e Intrinsic Muscles of the Hand
Intrinsic muscles of the hand: originate and insert in hand
•Thenar group: form fleshy mass at base of thumb
– Flexor pollicis brevis: flexes thumb
– Abductor pollicis brevis: abducts thumb
– Opponens pollicis: assists in opposition of thumb
•Hypothenar group: smaller fleshy mass at base of little finger
– Flexor digiti minimi brevis: flexes little finger
– Abductor digiti minimi: abducts little finger
– Opponens digiti minimi: assists in opposition of little finger
58
11.8e Intrinsic Muscles of the Hand
• Midpalmar group
– Occupies space between thenar and hypothenar groups
– Lumbricals (worm shaped)
o Flex the MP joints; extend PIP and DIP joints of fingers 2–5
– Dorsal interossei (between metacarpals)
o Flex MP joints and extend PIP and DIP joints of fingers 2–5; abduct
fingers 2–5
– Palmar interossei (between metacarpals)
o Adduct the fingers; flex the MP joints and extend the PIP and DIP joints
of fingers 2–5
– Adductor Pollicis
o Adducts thumb
59
Intrinsic Muscles of the Hand
Figure 11.30a
60
Intrinsic Muscles of the Hand
Figure 11.30b
61
Intrinsic Muscles of the Hand
Figure 11.30c
62
What did you
learn?
Which four muscles make up
the rotator cuff  ?
In which anatomical
compartment is the brachialis
muscle found?
What action is typically
performed by muscles in the
anterior compartment of the
forearm?
Which group of intrinsic hand
muscles act on the little finger?
•
•
•
•
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11.9 Muscles of
the Pelvic Girdle
and Lower Limb
Learning
Objectives:
63
Compare and contrast the functions of
the muscles in the anterior, medial,
lateral, and posterior compartments of
the thigh.
2. Describe the actions of the three gluteal
muscles.
3. List muscles of the thigh’s anterior
compartment that move the knee joint.
4. Describe the muscles of the thigh that
flex the knee joint.
1.
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64
11.9 Muscles of
the Pelvic Girdle
and Lower Limb
(continued )
Learning
Objectives:
Compare and contrast the
muscles of the three
compartments of the leg and their
actions.
5.
6. Distinguish
between the muscles
of the superficial layer and deep
layer of the leg’s posterior
compartment.
Identify the muscles of each
group of the foot and their actions.
7.
65
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11.9a Muscles that Move the Hip Joint/Thigh
• How are thigh muscles organized?
– They are bound by the fascia lata, deep fascia that partitions
them into compartments
– Anterior compartment muscles
o Extend the knee or flex the thigh
– Medial compartment muscles
o Adduct the thigh
– Lateral compartment muscle
o Abducts the thigh
– Posterior compartment muscles
o Flex knee and extend the thigh
66
11.9a Muscles that Move the Hip Joint/Thigh
• Muscles inserting on anterior thigh
– Psoas major and iliacus (collectively, iliopsoas)
o Run from lumbar vertebrae and ilium to femur
o Flex the thigh
• Muscle of lateral thigh
– Tensor fasciae latae
o Attaches to iliotibial tract (lateral thickening of fascia lata)
o Abducts and medially rotates the thigh
67
11.9a Muscles that Move the Hip Joint/Thigh
• Muscles of the medial compartment of thigh
– Adductor longus, adductor brevis, gracilis, pectineus
o Adduct and flex the thigh
– Adductor magnus
o Adducts, extends, and laterally rotates the thigh
– Obturator externus
o Laterally rotates the thigh
68
Muscles That Act on the Hip and Thigh
Figure 11.31a
69
11.9a Muscles That Move the Hip Joint/Thigh
• Muscles of the posterior thigh
– Gluteus maximus
o Chief extensor of the thigh; also laterally rotates the thigh
– Gluteus medius and gluteus minimus
o Deep to gluteus maximus
o Abduct and medially rotate the thigh
– Hamstrings: group of 3 muscles
o Biceps femoris, semimembranosous, semitendinosus
o Extend the thigh (also flex the knee)
– Group of muscles deep to gluteal muscles
o Piriformis, superior gemellus, obturator internus, inferior gemellus, and
quadratus femoris
o Laterally rotate the thigh
70
Muscles That Act on the Hip and Thigh
Figure 11.31b
71
Muscles That Act on the Hip and Thigh
Figure 11.31c
72
11.9b Thigh Muscles That Move the Knee Joint/Leg
• Muscles of the thigh’s anterior compartment
– Quadriceps femoris: composite muscle with four heads
o Consists of: rectus femoris, vastus lateralis, vastus medialis, vastus
intermedius
o Prime mover of knee extension
o Pulls on quadriceps tendon, which becomes patellar ligament to tibia
– Sartorius
o Flexes and laterally rotates thigh; also flexes and medially rotates leg
73
Muscles of Anterior Thigh
Figure 11.32a
74
Muscles of Anterior Thigh
Figure 11.32b
75
11.9b Thigh Muscles That Move
the Knee Joint/Leg
• Muscle of the thigh’s medial compartment
– Gracilis
o Flexes the leg (as well as adducting the thigh)
• Muscles of the thigh’s posterior compartment
– Hamstring muscles: composite of three muscles
o Biceps femoris (has two heads)
– Flexes leg; also laterally rotates leg when leg is flexed
o Semimembranosus and semitendinosus
– Medially rotate leg when leg is flexed
– Several leg muscles (more distally located) span the knee and flex
the leg (to be discussed in next section)
76
Muscles of Gluteal Region and Posterior Thigh
77
Figure 11.33a
Muscles of Posterior Thigh
Figure 11.33b
78
11.9c Leg Muscles That Move the Ankle, Foot, and Toes
• Crural muscles: muscles located in leg that
move ankle, foot, toes
– Partitioned into anterior, lateral, and posterior
compartments
79
11.9c Leg Muscles That Move the Ankle, Foot, and Toes
• Muscles of the leg’s anterior compartment
– Extensor digitorum longus
o Dorsiflexes the foot and extends toes 2–5
– Extensor hallucis longus
o Dorsiflexes the foot and extends the great toe
– Fibularis tertius
o Dorsiflexes and weakly everts the foot
– Tibialis anterior
o Primary dorsiflexor of the foot; also inverts the foot
– Extensor retinaculum
o Thickening of fascia at ankle that holds tendons close to bones
80
Muscles of the
Anterior Leg
Figure 11.34a
81
11.9c Leg Muscles That Move the Ankle, Foot, and Toes
• Muscles of the leg’s lateral compartment
– Both are powerful foot evertors, weak plantar flexors
o Fibularis longus: inserts on plantar side of foot
o Fibularis brevis: lies deep to fibularis longus, inserts onto
base of 5th metatarsal
82
Muscles of the Lateral Leg
83
Figure 11.35a
11.9c Leg Muscles That Move the Ankle, Foot, and Toes
Muscles of the leg’s posterior compartment
• Superficial layer
– Gastrocnemius
o Has two bellies; forms calf
o Flexes the leg and plantar flexes the foot
– Soleus
o Broad muscle deep to gastrocnemius
o Plantar flexes the foot
– Triceps surae = gastrocnemius + soleus
o Insert at heel with calcaneal tendon
– Plantaris
o Weak leg flexor and plantar flexor of the foot
84
11.9c Leg Muscles That Move the Ankle, Foot, and Toes
Muscles of the leg’s posterior compartment (continued)
• Deep layer
– Flexor digitorum longus
o Flexes the foot and the MP, PIP and DIP of joints 2–5
– Flexor hallucis longus
o Flexes the foot and great toe
– Tibialis posterior
o Plantar flexes and inverts the foot
– Popliteus
o Flexes the leg and medially rotates the tibia (no action at ankle or foot)
85
Muscles of the Posterior Leg
86
Figure 11.36a-b
87
Clinical View: Shin Splints and
Compartment Syndrome
• Shin splints
– Soreness along length of tibia
– Often occur in new poorly conditioned runners
– May be considered a type of compartment syndrome
• Compartment syndrome
–
–
–
–
Compression of blood vessels within a limb compartment
Due to inflammation and swelling secondary to strain or trauma
Increased pressure in compartment since deep fascia cannot stretch
In severe cases, fascia cut to relieve pressure
88
11.9d Intrinsic Muscles of the Foot
• Intrinsic muscles of the foot originate and insert
within foot
– Support the arches, move the toes
• Dorsal group
– Extensor hallucis brevis
o Extends the MP joint of the great toe
– Extensor digitorum brevis
o Extends the MP and PIP joints of toes 2–4
89
11.9d Intrinsic Muscles of the Foot
• Plantar group
– Supported by aponeurosis formed from deep fascia
o Extends between phalanges of toes and calcaneus
– Muscles grouped into four layers from superficial to deep
1. Flexor digitorum brevis, abductor hallucis, abductor digiti minimi
2. Quadratus plantae, lumbricals
3. Adductor hallucis, flexor hallucis brevis, flexor digiti minimi
brevis
4. Dorsal interossei, plantar interossei
90
Plantar Intrinsic Muscles of the Foot
Figure 11.37a-c
91
Plantar Intrinsic Muscles of the Foot
Figure 11.37d-e
92
Clinical View: Plantar Fasciitis
• Inflammation of the plantar aponeurosis
• Associated with overexertion that stresses the fascia
– E.g., weight bearing activities, excessive body weight, poor
shoes, poor biomechanics
93
What did you
learn?
•
•
•
•
How does the function of
gluteus maximus differ from
the function of the other two
gluteal muscles?
Which muscles extend the
knee?
What functions are common to
most muscles in the posterior
compartment of the leg?
Is flexor hallucis brevis a crural
muscle or an intrisic muscle of
the foot?
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94