A&P 10: The Muscular System Flashcards
1
Q
Skeletal muscles
A
muscle composed of cylindrical multinucleate cells with obvious striations; the muscle(s) attached to the body’s skeleton; voluntary muscle
2
Q
Prime mover (agonist)
A
a muscle that has the major responsibility for producing a specific movement
3
Q
Antagonists
A
muscles that oppose/reverse a particular movement
4
Q
Synergists
A
most movements involve the action of one or more of these; help prime movers by adding a little extra force to the same movement or by reducing undesirable or unnecessary movements that might occur as the prime mover contracts
5
Q
Fixators
A
when syngergists immobilize a bone, or a muscle’s origin so that the prime mover has a stable base on which to act
6
Q
Circular
A
fascicular pattern is this when the fascicles are arranged in concentric rings; muscles with this pattern surround external body openings, which they close by contracting (i.e. sphincters)
7
Q
Convergent
A
muscle with a broad origin with its fascicles converging toward a single tendon of insertion; triangular or fan-shaped
8
Q
Parallel
A
length of the fascicles run parallel to the long axis of the muscle; straplike or spindle-shaped
9
Q
Fusiform muscles
A
some authorities classify spindle-shaped muscles into this separate class
10
Q
Pennate
A
pattern in which the fascicles are short and attach obliquely; 3 forms - uni, bi, or multi
11
Q
Lever
A
rigid bar that moves on a fulcrum
12
Q
Fulcrum
A
the fixed point on which a lever moves when a force is applied
13
Q
Effort
A
applied force used to move a resistance (load)
14
Q
Load
A
resistance that is trying to be moved by a lever and its fulcrum when effort is applied
15
Q
Mechanical advantage
A
a power lever; condition that occurs when the load is close to the fulcrum and the effort is applied far from the fulcrum; allows a small effort exerted over a relatively large distance to move a large load over a small distance
16
Q
Mechanical disadvantage
A
a speed lever; condition that occurs when the load is far from from the fulcrum and the effort is applied near the fulcrum; the effort applied must be greater than the load to be moved
17
Q
First-class lever
A
effort applied at one end of the lever and the load at the other, with the fulcrum somewhere between (ex. seesaws and scissors)
18
Q
Second-class lever
A
effort applied at one end of the lever and the fulcrum at the other, with the load between them (ex. wheelbarrow; standing on toes); all of these in the body work at a mechanical advantage; speed and range are sacrificed for strength
19
Q
Third-class lever
A
effort applied between the load and fulcrum; speedy; always operate at a mechanical disadvantage (ex. tweezers, forceps; most skeletal muscles in the body like biceps in arm)
20
Q
Epicranius
A
main muscle in the scalp
21
Q
Frontal belly
A
covers forehead and dome of skull; no bony attachments; raises the eyebrows
22
Q
Occiptal belly
A
overlies posterior occiput; by pulling on the epicranial aponeurosis, fixes origin of frontal belly; pulls scalp posteriorly
23
Q
Corrugator supercilli
A
small muscle; activity associated with that of orbicularis oculi; draws eyebrows together and inferiorly
24
Q
Orbicularis oculi
A
thin, flat sphincter muscle of eyelid; surrounds rim of the orbit; closes eye
25
Zygomaticus
major and minor muscle pair extending diagonally from cheekbone to corner of mouth; raises lateral corners of mouth upward (smiling muscle)
26
Risorius
slender muscle inferior and lateral to zygomaticus; draws corner of lip laterally; tenses lips; synergist of zygomaticus
27
Levator labii superioris
thin muscle between orbicularis oris and inferior eye margin; opens lips
28
Depressor labii inferioris
small muscle running from mandible to lower lip; draws lower lip inferiorly
29
Depressor anguli oris
small muscle lateral to depressor labii inferioris; draws corners of mouth down and laterally; a "tragedy mask" grimace; zygomaticus antagonist
30
Orbicularis oris
complicated, multilayered muscle of the lips with fibers that run in many different directions; most run circularly; closes lips; kissing and whistling muscle
31
Mentalis
one of the muscle pair forming a V-shaped muscle mass on the chin; wrinkles chin
32
Buccinator
thin, horizontal cheek muscle; principal muscle of cheek; deep to masseter; compresses cheek (as in whistling and sucking)
33
Platysma
unpaired, thin, sheetlike superficial neck muscle; not strictly a head muscle - plays a role in facial expression; tenses skin of neck
34
Masseter
powerful muscle that covers lateral aspect of mandibular ramus; prime mover of jaw closure
35
Temporalis
fan-shaped muscle that covers parts of the temporal, frontal, and parietal bones; closes jaw
36
Medial pterygoid
deep 2-headed muscle that runs along internal surface of mandible and is largely concealed by that bone; acts with the lateral pterygoid muscle to protrude (pull anteriorly) the mandible and promote side-to-side (grinding) movements
37
Lateral pterygoid
deep 2-headed muscle; lies superior to medial pterygoid muscle; provides forward sliding and side-to-side grinding movements of the lower teeth
38
Genioglossus
fan-shaped muscle; forms bulk of inferior part of tongue; its attachment to mandible prevents tongue from falling backward and obstructing breathing; protracts tongue
39
Hypoglossus
flat, quadrilateral muscle; depresses tongue and draws its sides inferiorly
40
Styloglossus
slender muscle running superiorly to and at right angles to hypoglossus; retracts and elevates tongue
41
Suprahyoid
muscles above the hyoid bone that help form floor of oral cavity, anchor tongue, elevate hyoid, and move larynx superiorly during swallowing
42
Infrahyoid
muscles below the hyoid bone; straplike muscles that depress the hyoid bone and larynx during swallowing and speaking
43
Pharyngeal constrictor muscles
muscles in the wall of the pharynx that propel food inferiorly into the esophagus
44
Stylohyoid
Slender muscle below angle of jaw; parallels posterior belly of digastric muscle; elevates & retracts hyoid
44
Stylohyoid
Slender muscle below angle of jaw; parallels posterior belly of digastric muscle; elevates & retracts hyoid
45
Mylohyoid
Flat, triangular muscle just deep to digastric muscle; this muscle pair makes a sling that forms the floor of the anterior mouth; elevates hyoid & floor of mouth
46
Geniohyoid
Narrow muscle in contact with its partner medially; runs from chin to hyoid bone deep to mylohyoid; pulls hyoid bone superiorly & anteriorly
47
Sternohyoid
Most medial muscle of the neck; thin; superficial except inferiorly, where covered by sternocleidomastoid; depresses larynx & hyoid bone if mandible is fixed
48
Sternothyroid
Lateral & deep to sternohyoid; pulls larynx & hyoid bone inferiorly
49
Omohyoid
Strap like muscle with 2 bellies united by an intermediate tendon; lateral to sternohyoid; depresses & retracts hyoid bone
50
Thyrohyoid
Appears as a superior continuation of sternothyroid muscle; depresses hyoid bone or elevates larynx if hyoid is fixed
51
Superior, middle, & inferior pharyngeal constrictor muscles
3 paired muscles whose fibers run circularly in pharynx wall; superior muscle is innermost & inferior one is outermost; substantial overlap; constrict pharynx during swallowing
52
Sternocleidomastoid
2-headed muscle located deep to plates a on anterolateral surface of neck; fleshy parts on either side of neck delineate limits of anterior & posterior triangles; key muscular landmark in neck; spasms of one of these muscles may cause torticollis (wryneck); fixes & laterally rotates the head
53
Scalenes
Located more laterally than anteriorly on the neck; deep to platysma & sternocleidomastoid; elevates 1st 2 ribs
55
Splenius
Broad bipartite superficial muscle (capitis & cervicis parts) extending from upper thoracic vertebrae to skull; capitis portion known as "bandage muscle" because it covers & holds down deeper neck muscles; extends or hyperextends head
56
Erector spinae
AKA sacrospinalis; prime mover of back extension; each consists of 3 columns - the iliocostalis, longissimus, and spinalis muscles - forming intermediate layer of intrinsic back muscles; provide resistance that helps control action of bending forward at the waist and act as powerful extensors to promote return to erect position
57
Iliocostalis
most lateral muscle group of erector spinae muscles; extend from pelvis to neck; extend and laterally flex the vertebral column
58
Longissimus
intermediate tripartite muscle group of erector spinae; extend by many muscle slips from lumbar region to skull; mainly pass between transverse processes of vertebrae; thoracis and cervicis act together to extend and laterally flex vertebral column; capitis extends head and turns the face toward same side
59
Spinalis
most medial muscle column of erector spinae; cervicis usually rudimentary and poorly defined; extends vertebral column
60
Semispinalis
composite muscle forming part of deep layer of intrinsic back muscles; extends from thoracic region to head; extends vertebral column and head and rotates them to opposite side
61
Quadratus lumborum
fleshy muscle forming part of posterior abdominal wall; flexes vertebral column laterally
62
External intercostals
11 pairs lie between ribs; fibers run obliquely (down and forward) from each rib to rib below; in lower spaces, fibers are continuous with external oblique muscle, forming part of abdominal wall; pull ribs toward one another to elevate rib cage
63
Internal intercostals
11 pairs lie between ribs; fibers run deep to and at right angles to those of external _____; lower ones are continuous with fibers of internal obliques of the abdominal wall; draw ribs together and depress rib cage
64
Diaphragm
broad muscle pierced by the aorta, inferior vena cava, and esophagus; forms floor of thoracic cavity; dome shaped in relaxed state; fibers converge from margins of thoracic cage toward a boomerang-shaped central tendon; prime mover of inspiration; flattens on contraction
65
Linea alba
white line; a tendinous raphe (seam) that runs from the sternum to the pubic symphysis
66
Rectus abdominis
medial superficial muscle pair; extend from pubis to rib cage; ensheathed by aponeuroses of lateral muscles; segmented by 3 tendinous intersections; flex and rotate lumbar region of vertebral column
67
External oblique
largest and most superficial of the 3 lateral muscles; fibers run downward and medially (same direction outstretched fingers take when hands are in pants pockets); aponeurosis turns under inferiorly, forming inguinal ligament; flex vertebral column and compress abdominal wall; rotates trunk & flexes laterally
68
Internal oblique
most fibers run upward and medially; muscle fans so its inferior fibers run downward and medially; flexes vertebral column and compresses abdominal wall; rotates trunk and flexes laterally
69
Transverse abdominis
deepest (innermost) muscle of abdominal wall; fibers run horizontally; compresses abdominal contents
70
Levator ani
broad, thin, tripartite muscle (pubococcygeus, puborectalis, and iliococcygeus); its fibers extend inferomedially, forming a muscular "sling" around male prostrate (or female vagina), urethra, and anorectal junction before meeting in the median plane; supports and maintains position of pelvic viscera
71
Coccygeus
small triangular muscle lying posterior to levator ani; forms posterior part of pelvic diaphragm; supports pelvic viscera
72
Deep transverse perineal muscle
together the pair spans distance between ischial rami; in females, lies posterior to the vagina; supports pelvic organs
73
External urethral sphincter
muscle encircling urethra and vagina (female); constricts urethra; allows voluntary inhibition of urination; helps support pelvic organs
74
Ischiocavernosus
runs from pelvis to base of penis or clitoris; retards venous drainage and maintains erection of penis or clitoris
75
Bulbospongiosus
encloses base of penis (bulb) in males and lies deep to labia in females; empties male urethra; assists in erection of penis and of clitoris
76
Superficial transverse perineal muscles
paired muscle bands posterior to urethral (and in females, vaginal) opening; variable; sometimes absent; strengthens central tendon of perineum
77
Pectoralis minor
flat, thin muscle directly beneath and obscured by the pectoralis major; with ribs fixed, draws scapula forward and downward
78
Serratus anterior
fan-shaped muscle; lies deep to scapula, deep and inferior to pectoral muscles on lateral rib cage; forms medial wall of axilla; origins have serrated (sawtooth) appearance; paralysis results in "winging" of vertebral border of scapula away from chest wall, making arm elevation impossible; rotates scapula so its inferior angle moves laterally and upward
79
Subclavius
small, cylindrical muscle extending from rib 1 to clavicle; helps stabilize and depress pectoral girdle
80
Trapezius
most superficial muscle of posterior thorax; flat and triangular in shape; upper fibers run inferiorly to scapula; middle fibers run horizontally to scapula; lower fibers run superiorly to scapula; stabilizes, raises, retracts, and rotates scapula
81
Levator scapulae
located at back and side of neck, deep to trapezius; thick, straplike muscle; elevates/adducts scapula
82
Rhomboids
2 roughly diamond-shaped muscles lying deep to trapezius and inferior to levator scapulae; minor is the more superior muscle; stabilize scapula
83
Pectoralis major
large, fan-shaped muscle covering superior portion of chest; forms anterior axillary fold; divided into clavicular and sternal parts; prime mover of arm flexion; rotates arm medially; adducts arm
84
Deltoid
thick, multipennate muscle forming rounded shoulder muscle mass; a common site for intramuscular injection, particularly in males, where it tends to be quite fleshy; prime mover of arm abduction when all its fibers contract simultaneously
85
Lattisimus dorsi
broad, flat, triangular muscle of lower back; extensive superficial origins; covered by trapezius superiorly; contributes to the posterior wall of axilla; prime mover of arm extension; powerful arm adductor; medially rotates arm at shoulder
86
Subscapularis
forms part of posterior wall of axilla; tendon of insertion passes in front of shoulder joint; a rotator cuff muscle; chief medial rotator of humerus
87
Supraspinatus
named for its location on posterior aspect of scapula; deep to trapezius; a rotator cuff muscle
88
Infraspinatus
partially covered by deltoid and trapezius; named for its scapular location; a rotator cuff muscle; rotates humerus laterally
89
Teres minor
rotates humerus laterally; small, elongated muscle; lies inferior to infraspinatus and may be inseparable from that muscle; a rotator cuff muscle
90
Teres major
thick, rounded muscle; located inferior to teres minor; helps form posterior wall of axilla (along with latissimus dorsi and subscapularis); extends, medially rotates, and adducts humerus
91
Coracobrachialis
small, cylindrical muscle; flexes and adducts humerus
92
Triceps brachii
large, fleshy muscle; the only muscle of posterior compartment of arm; 3-headed origin; long and lateral heads lie superficial to medial head; powerful forearm extensor
93
Anconeus
short, triangular muscle; partially blended with distal end of triceps on posterior humerus; may control ulnar abduction during forearm pronation
94
Biceps brachii
two-headed fusiform muscle; bellies unite as insertion point is approached; tendon of long head helps stabilize shoulder joint; flexes elbow joint and supinates forearm
95
Brachialis
strong muscle that is immediately deep to biceps brachii on distal humerus; a major forearm flexor
96
Brachioradialis
superficial muscle of lateral forearm; forms lateral boundary of cubital fossa; extends from distal humerus to distal forearm; synergist in flexing forearm
97
Pronator teres
2-headed muscle; seen in superficial view between proximal margins of brachioradialis and flexor carpi radialis; forms medial boundary of cubital fossa; pronates forearm
98
Flexor carpi radialis
runs diagonally across forearm; midway, its fleshy belly is replaced by a flat tendon that becomes cordlike at wrist; powerful flexor of wrist; abducts hand
99
Palmaris longus
small, fleshy muscle with a long insertion tendon; often absent; may be used as a guide to find median nerve that lies lateral to it at wrist; tenses skin and fascia of palm during hand movements
100
Flexor carpi ulnaris
most medial muscle of this group; 2-headed; ulnar nerve lies lateral to its tendon; powerful flexor of wrist; also adducts hand
101
Flexor digitorum superficialis
2-headed muscle; more deeply placed (therefore, actually forms an intermediate layer); overlain by muscles above but visible at distal end of forearm; flexes wrist and middle phalanges of fingers 2-5
102
Flexor pollicis longus
partly covered by flexor digitorum superficialis; parallels flexor digitorum profundus laterally; flexes distal phalanx of thumb
103
Flexor digitorum profundus
extensive origin; overlain entirely by flexor digitorum superficialis; flexes distal interphalangeal joints
104
Pronator quadratus
deepest muscle of distal forearm; passes downward and laterally; only muscle that arises solely from ulna and inserts solely into radius; prime mover of forearm pronation
105
Extensor carpi radialis longus
parallels brachioradialis on lateral forearm and may blend with it; extends/abducts wrist
106
Extensor carpi radialis brevis
shorter than extensor carpi radialis longus and lies deep to it; extends and abducts wrist
107
Extensor digitorum
lies medial to extensor carpi radialis brevis; a detached portion of this muscle (exensor digiti minimi) extends little finger; prime mover of finger extension
108
Extensor carpi ulnaris
most medial of superficial posterior muscles; long, slender muscle; extends/adducts wrist
109
Supinator
deep muscle at posterior aspect of elbow; largely concealed by superficial muscles; assists biceps brachii to forcibly supinate forearm
110
Abductor pollicis longus
lateral and parallel to extensor pollicis longus; just distal to supinator; abducts/extends thumb
111
Extensor pollicis brevis & longus
deep muscle pair with a common origin and action; overlain by extensor carpi ulnaris; extends thumb
112
Extensor indicis
tiny muscle arising close to wrist; extends index finger
113
Abductor pollicis brevis
lateral muscle of thenar group; superficial; abducts thumb at carpometacarpal joint
114
Flexor pollicis brevis
medial and deep muscle of thenar group; flexes thumb
115
Opponens pollicis
deep to abductor pollicis brevis, on metacarpal I; opposition
116
Adductor pollicis
fan-shaped with horizontal fibers; distal to other thenar muscles; oblique and transverse heads; adducts and helps to oppose thumb
117
Abductor digiti minimi
medial muscle of hypothenar group; superficial; abducts little finger
118
Flexor digiti minimi brevis
lateral deep muscle of hypothenar group; flexes little finger
119
Opponens digiti minimi
deep to abductor digiti minimi; helps in opposition
120
Lumbricals
4 worm-shaped muscles in palm, one to each finger (except thumb); unusual because they originate from the tendons of another muscle; flex fingers at metacarpophalangeal joints but extend fingers at interphalangeal joints
121
Palmar interossei
4 long, cone-shaped muscles in the spaces between the metacarpals; lie ventral to the dorsal interossei; adducts fingers
122
Dorsal interossei
4 bipennate muscles filling spaces between the metacarpals; deepest palm muscles, also visible on dorsal side of hand
123
Illiopsoas
composite of 2 closely related muscles (Iliacus and psoas major) whose fibers pass under the inguinal ligament to insert via a common tendon on the femur
124
Iliacus
large, fan-shaped, more lateral muscle; prime mover for flexing thigh or for flexing trunk on thigh as during a bow
125
Psoas major
longer, thicker, more medial muscle of the pair; "tenderloin"; with iliacus, prime mover for flexing thigh or for flexing trunk on thigh; also flexes vertebral column laterally
126
Sartorius
straplike superficial muscle running obliquely across anterior surface of thigh to knee; longest muscle in body; crosses both hip and knee joints; flexes, abducts, and laterally rotates thigh
127
Adductors
large muscle mass consisting of 3 muscles (magnus, longus, and brevis) forming medial aspect of thigh; arise from inferior part of pelvis and insert at various levels on femur; all used in movements that press thighs together; important in pelvic tilting movements that occur during walking and in fixing the hip when the knee is flexed and the foot is off the ground
128
Adductor magnus
triangular muscle with a broad insertion; a composite muscle that is part adductor and part hamstring in action; anterior part adducts and medially rotates and flexes thigh; posterior part is a synergist of hamstrings to extend thigh
129
Adductor longus
overlies middle aspect of adductor magnus; most anterior of adductor muscles; adducts, flexes, and medially rotates thigh
130
Adductor brevis
in contact with obturator externus muscle; largely concealed by adductor longus and pectineus; adducts, flexes, and medially rotates thigh
131
Pectineus
short, flat muscle; overlies adductor brevis on proximal thigh; abuts adductor longus medially; adducts, flexes, and medially rotates thigh
132
Gracilis
long, thin, superficial muscle of medial thigh; adducts thigh, flexes and rotates leg
133
Quadriceps femoris
4 separate heads that form the flesh of front and sides of thigh; common insertion tendon which inserts into the patella and then into the tibial tuberosity; powerful knee extensor used in climbing, jumping, running, and rising from seated position; important role in strengthening the knee joint
134
Rectus femoris
superficial muscle of anterior thigh; runs straight down thigh; longest head and only muscle of group to cross hip joint; extends knee and flexes thigh at hip
135
Vastus lateralis
largest head of the group; forms lateral aspect of thigh; common intramuscular injections site, particularly in infants, who have poorly developed buttock and arm muscles; extends and stabilizes knee
136
Vastus medialis
forms inferomedial aspect of thigh; extends knee
137
Vastus intermedius
obscured by rectus femoris; lies between vastus lateralis and vastus medialis on anterior thigh; extends knee
138
Tensor fasciae latae
enclosed between fascia layers of anterolateral aspect of thigh; functionally associated with medial rotators and flexors of thigh; functionally associated with medial rotators and flexors of thigh; steadies the knee and trunk on thigh by making iliotibial tract taut
139
Gluteus maximus
largest and most superficial gluteus muscle; forms bulk of buttock mass; fibers are thick and coarse; important site of IM injection (dorsal); overlies large sciatic nerve; covers ischial tuberosity only when standing; when sitting, moves superiorly, leaving ischial tuberosity exposed in the SQ position; major extensor of thigh
140
Gluteus medius
thick muscle largely covered by gluteus maximus; important site for IM injections (ventral); considered safer than dorsal site b/c less chance of injuring sciatic nerve; abducts and medially rotates thigh
141
Gluteus minimus
smallest and deepest gluteal muscle; important site for IM injections (ventral); considered safer than dorsal site b/c less chance of injuring sciatic nerve; abducts and medially rotates thigh
142
Piriformis
pyramidal muscle located on posterior aspect of hip joint; inferior to gluteus minimus; issues from pelvis via greater sciatic notch; rotates extended thigh laterally
143
Obturator externus
flat, triangular muscle deep in superomedial aspect of thigh; rotates extended thigh laterally
144
Obturator internus
surrounds obturator foramen within pelvis; leaves pelvis via lesser sciatic notch and turns acutely forward to insert on femur; rotates extended thigh laterally
145
Gemellus
2 small muscles with common insertions and actions; considered extrapelvic portions of obturator internus; rotates extended thigh laterally
146
Quadratus femoris
short, thick muscle; most inferior lateral rotator muscle; extends laterally from pelvis; rotates thigh laterally and stabilizes hip joint
147
Hamstrings
fleshy muscles of the posterior thigh; cross hip and knee joints; prime movers of thigh extension and knee flexion
148
Biceps femoris
most lateral muscle of the group; arises from 2 heads; extends thigh and flexes knee
149
Semitendinosus
lies medial to biceps femoris; quite fleshy; its long slender tendon begins about 2/3 of the way down thigh; extends thigh and flexes knee; with semimembranosus, medially rotates leg
150
Semimembranosus
deep to semitendinosus; extends and flexes knee
151
Tibialis anterior
superficial muscle of anterior leg; laterally parallels sharp anterior margin of tibia; prime mover of dorsiflexion
152
Extensor digitorum longus
unipennate muscle on anterolateral surface of leg; lateral to tibialis anterior; prime mover of toe extension
153
Fibularis (peroneus) tertius
small muscle usually continuous and fused with distal part of extensor digitorum longus; not always present; dorsiflexes and everts foot
154
Extensor hallucis longus
deep to extensor digitorum longus and tibialis anterior; narrow origin; extends great toe
155
Flexor, extensor, and fibular/peroneal retinacula
"ankle brackets" that hold the tendons in place where they run to the foot
156
Fibularis (peroneus) longus
superficial lateral muscle; overlies fibula; plantar flexes and everts foot
157
Fibularis (peroneus) brevis
smaller muscle; deep to fibularis longus; enclosed in a common sheath; plantar flexes and everts foot
158
Triceps surae
refers to muscle pair (gastrocnemius and soleus) that shapes the posterior calf and inserts via a common tendon into the calcaneus of the heel (Achilles/calcaneal tendon)
159
Gastrocnemius
superficial muscle of pair; 2 prominent bellies that form proximal curve of calf; plantar flexes foot
160
Soleus
broad, flat muscle, deep to gastrocnemius on posterior surface of calf; plantar flexes foot
161
Plantaris
generally a small, feeble muscle, but varies in size and extent; may be absent; helps to flex knee and plantar flex foot
162
Popliteus
thin, triangular muscle at posterior knee; passes inferomedially to tibial surface; flexes and rotates leg medially to unlock extended knee when flexion begins
163
Flexor digitorum longus
long, narrow muscle; runs medial to and partially overlies tibialis posterior; plantar flexes and inverts foot; flexes toes
164
Flexor hallucis longus
bipennate muscle; lies lateral to inferior aspect of tibialis posterior; plantar flexes and inverts foot; flexes great toe at all joints
165
Tibialis posterior
thick, flat muscle deep to soleus; placed between posterior flexors; prime mover of foot inversion
166
Extensor digitorum brevis
small, 4-part muscle on dorsum of foot; deep to the tendons of extensor digitorum longus; corresponds to the extensor indicis and extensor pollicis muscles of forearm; helps extend toes at metatarsophalangeal joints
167
Flexor digitorum brevis
bandlike muscle in middle of sole; corresponds to flexor digitorum superficialis of forearm ad inserts into digits in the same way; helps flex toes
168
Abductor hallucis
lies medial to flexor digitorum brevis; abducts great toe
169
Abductor digiti minimi
most lateral of the 3 superficial sole muscles; abducts and flexes little toe
170
Flexor accesorius (quadratus plantae)
rectangular muscle just deep to flexor digitorum brevis in posterior half of sole; 2 heads; straightens out the oblique pull of flexor digitorum longus
171
Lumbricals
4 little "worms"; flex toes at metatarsophalangeal joints and extend toes at interphalangeal joints
172
Flexor hallucis brevis
covers metatarsal I; splits into 2 bellies; flexes great toe's metatarsophalangeal joint
173
Adductor hallucis
oblique and transverse heads; deep to lumbricals; helps maintain the transverse arch of the foot
174
Flexor digiti minimi brevis
covers metatarsal V; flexes little toe at metatarsophalangeal joint
175
Plantar (3) & Dorsal Interossei (4)
similar to palmar and dorsal interossei of hand in locations, attachments, and actions; however, these muscles orient around the 2nd digit, not the 3rd
