Module 3: Muscular System Flashcards
(329 cards)
1
Q
Muscular System Functions
A
- Movement
- Maintain posture
- Stabilize Joints
- Production of body heat
- Respiration and Heart Beat
- Communication
- Contraction of organs and vessels
2
Q
Properties of Muscles
A
Contractility
Excitability
Extensibility
Elasticity
3
Q
the ability of muscle to shorten forcefully, or contract
A
Contractility
4
Q
the capacity of muscle to respond to a stimulus
A
Excitability
5
Q
the ability to be stretched beyond it normal resting length and still be able to contract
A
Extensibility
6
Q
the ability of the muscle to recoil to its original resting length after it has been stretched
A
Elasticity
7
Q
Types of Muscles
A
Skeletal
Cardiac
Smooth
8
Q
*attached to bones
*striated
*voluntarily controlled
A
Skeletal
9
Q
*located in the heart
*striated
*involuntarily controlled
A
Cardiac
10
Q
*Located in blood vessels, hollow organs
*Non-striated; visceral
*involuntarily controlled
A
Smooth
11
Q
Each skeletal muscle is surrounded by a connective tissue sheath called the _____________.
A
epimysium
12
Q
A skeletal muscle is subdivided into groups of muscle cells termed __________
A
fascicles
13
Q
Each fascicle is surrounded by a connective tissue covering, termed the _____________.
A
perimysium
14
Q
Each skeletal muscle cell (fiber) is surrounded by a connective tissue covering, termed the ______________.
A
endomysium
15
Q
is a single cylindrical cell, with several nuclei located at its periphery.
A
Muscle fiber
16
Q
Muscle fibers range in length _____ to _____ and are generally ______ in diameter.
A
1 cm ; 30 cm ; 0.15 mm
17
Q
Skeletal muscle fibers contain several ______ that are located at the ____________________.
A
nuclei ; periphery of the fiber
18
Q
The _______________ (cell membrane) has many tubelike inward folds, called ________________, or ______________.
A
sarcolemma ; transverse tubules ; T tubules.
19
Q
T tubules occur at _______________ along the _____________ and extend into the __________________________.
A
regular intervals ; muscle fiber ; center of the muscle fiber
20
Q
The T tubules are associated with enlarged portions of the smooth endoplasmic reticulum called the ____________________.
A
sarcoplasmic reticulum
21
Q
The enlarged portions are called _____________.
A
terminal cisternae
22
Q
T tubules connect the ______________ to the ____________________ to form a _______________.
A
sarcolemma ; terminal cisternae ; muscle triad
23
Q
The sarcoplasmic reticulum has a relatively high concentration of _________ , which plays a major role in __________________.
A
Ca2 + ; muscle contraction
24
Q
The cytoplasm of a muscle fiber is called the ______________, which contains many bundles of protein filaments.
A
sarcoplasm
25
Bundles of protein filaments are called __________.
myofibrils
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Myofibrils consist of the:
myofilaments
actin
myosin
27
A __________consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers.
Muscle (organ)
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Muscle is covered externally by the ___________
epimysium
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A _______ is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath.
Fascicle (a portion of the muscle)
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Fascicle is surrounded by _____________
perimysium
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A _____________ is an elongated multinucleate cell; it has a banded (striated) appearance.
Muscle fiber
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Muscle fiber is surrounded by ____________
endomysium
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___________ are rodlike contractile elements that occupy most of the muscle cell volume. Composed of sarcomeres arranged end to end, they appear banded, and bands of adjacent myofibrils are aligned.
Myofibril (complex organelle composed of bundles of myofilaments)
34
A ____________ is the contractile unit, composed of myofilaments made up of contractile proteins.
Sarcomere (a segment of a myofibril)
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Thin (_____) filament Thick (_______) filament
actin ; myosin
36
Contractile myofilaments are of two types- thick and thin.
Myofilament, or filament (extended macromolecular structure)
37
__________________ contain bundled myosin molecules
Thick filaments
38
_______________ contain actin molecules (plus other proteins).
Thin filaments
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The sliding of the thin filaments past the thick filaments produces ________________. Elastic filaments provide elastic recoil when tension is released and help maintain _____________ organization.
muscle shortening ; myofilament
40
The _____________ is the basic structural and functional unit of a skeletal muscle because it is the smallest portion of a skeletal muscle capable of contracting.
sarcomere
41
_________ form a network of protein fibers that both serve as an anchor for actin myofilaments and separate one sarcomere from the next.
Z disks
42
A sarcomere extends from one ______ to the next _______.
Z disk ; Z disk
43
Light bands, consist only of actin, and are called _________ that extends toward the center of the sarcomere to the ends of the myosin myofilaments.
I bands
44
Dark staining bands are called _________, that extend the length of the myosin myofilaments.
A bands
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Actin and myosin myofilaments overlap for some distance on both ends of the ________; this overlap causes the ___________.
A band ; contraction
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Actin myofilaments are made up of three components:
actin
troponin
tropomyosin
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________ is a protein that forms the structural framework of muscle fibers. It is involved in the sliding filament theory of muscle contraction, where _____ filaments slide past myosin filaments, leading to muscle contraction.
Actin ; Actin
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is a complex of three protein subunits
Troponin
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Three protein subunits of Troponin
Troponin C
Troponin I
Troponin T
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___________ molecules have binding sites for Ca2 +
Troponin C
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__________ is located on the actin filament and is essential for muscle contraction.
T. Troponin
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___________ inhibits the interaction between actin and myosin, preventing contraction in the absence of calcium.
Troponin I
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____________ is a long protein strand that is wrapped around actin filaments in muscle cells
Tropomyosin
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In a relaxed muscle ___________ filaments block the myosin myofilament binding sites on the actin myofilaments.
Tropomyosin
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___________________ resemble bundles of tiny golf clubs.
Myosin myofilaments
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Myosin heads have _____ binding sites, ATPase and attachment spots for actin
ATP
57
The electrical charge difference across the cell membrane of an unstimulated cell is called the ____________________________.
resting membrane potential
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Muscle cells (fibers) have a resting membrane potential, but can also perform _________________.
action potentials
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The resting membrane potential is due to the inside of the membrane being __________ charged in comparison to the outside of the membrane being ___________ charged.
negatively ; positively
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Action potentials are due to the membrane having ______________.
gated channels
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The resting membrane potential exists because of:
The concentration of K+ being higher on the inside of the cell membrane and the concentration of Na+ being higher on the outside
The presence of many negatively charged molecules, such as proteins, inside the cell that are too large to exit the cell
The presence of leak protein channels in the membrane that are more permeable to K+ than it is to Na+
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____ tends to diffuse into the cell and ___ tends to diffuse out.
Na+ ; K+
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In order to maintain the resting membrane potential, the sodium potassium pump recreates the Na+ and K+ ion gradient by pumping _____ out of the cell and ____ into the cell.
Na+ ; K+
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Resting membrane potential. Na+ channels (pink) and some, but not all, K+ channels (purple) are ____.
_____ diffuses down its concentration gradient through the open K channels, making the inside (yellow) of the cell membrane ___________ charged compared to the outside.
closed ; K+ ; negatively
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To initiate a muscle contraction, the resting membrane potential must be changed to an _____________.
action potential
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Changes in the resting membrane potential occur when _____________________________ open.
gated cell membrane channels
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In a skeletal muscle fiber, a nerve impulse triggers gated ___ channels to open and ____ diffuses into the cell down its concentration gradient and toward the negative charges inside the cell.
Na+ ; Na+
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The entry of Na+ causes the inside of the cell membrane to become more __________ than when the cell is at resting membrane potential.
positive
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This increase in positive charge inside the cell membrane is called ______________.
depolarization
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If the depolarization changes the membrane potential to a value called ____________, an action potential is triggered.
threshold
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An action potential is a _____________ in charge across the cell membrane.
rapid change
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_____________ during the action potential is when the inside of the cell membrane becomes more positively charged than the outside of the cell membrane.
Depolarization
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Near the end of depolarization, the positive charge causes gated ____ channels to close and gated ____ channels to open.
Na+ ; K+
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Opening of gated K+ channels starts _____________ of the cell membrane.
repolarization
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____________ is due to the exit of K+ from the cell.
Repolarization
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The outward diffusion of _____ returns the cell to its resting membrane conditions and the action potential ends.
K+
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In a muscle fiber, an action potential results in ___________+.
muscle contraction
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A _____ neuron is a nerve cell stimulates muscle cells.
motor
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A ___________________ is a synapse where a the fiber of a nerve connects with a muscle fiber.
neuromuscular junction
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A _______ refers to the cell-to-cell junction between a nerve cell and either another nerve cell or an effector cell, such as in a muscle or a gland.
synapse
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A _________ is a group of muscle fibers that a motor neuron stimulates.
motor unit
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A ______________ is the end of a neuron cell axon fiber.
presynaptic terminal
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A ______________ is the space between the presynaptic terminal and postsynaptic membrane.
synaptic cleft
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The ________________ is the muscle fiber membrane (sarcolemma).
postsynaptic membrane
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A ______________ is a vesicle in the presynaptic terminal that stores and releases neurotransmitter chemicals.
synaptic vesicle
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______________ are chemicals that stimulate or inhibit postsynaptic cells.
Neurotransmitters
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______________ is the neurotransmitter that stimulates skeletal muscles.
Acetylcholine
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Muscle Contraction Cycle 1
An action potential travels down motor neuron to presynaptic terminal causing Ca2+ channels to open.
Ca2+ causes synaptic vesicles to release acetylcholine into synaptic cleft.
Acetylcholine binds to receptor sites on Na+ channels, Na+ channels open, and Na+ rushes into postsynaptic terminal (depolarization).
89
Muscle Contraction Cycle 2
Na+ causes sarcolemma and t-tubules to increase the permeability of sarcoplasmic reticulum which releases stored calcium.
Ca2+ binds to troponin which is attached to actin.
Ca2+ binding to troponin causes tropomyosin to move exposing attachment sites for myosin.
Myosin heads bind to actin.
90
Muscle Contraction Cycle 3
ATP is released from myosin heads and heads bend toward center of sarcomere.
Bending forces actin to slide over myosin.
Acetylcholinesterase (enzyme breaks down acetylcholine) is released, Na+ channels close, and muscle contraction stops.
91
Skeletal Muscle Excitation Cycle 1
1. An action potential travels along an axon membrane to a neuromuscular junction.
2. Ca2+ channels open and Ca2+ enters the presynaptic terminal.
3. Acetylcholine is released from presynaptic vesicles.
92
Skeletal Muscle Excitation Cycle 2
4. Acetylcholine stimulates Na+ channels on the postsynaptic membrane to open.
5. Na+ diffuses into the muscle fiber, initiating an action potential that travels along the sarcolemma and T tubule membranes.
6. Action potentials in the T tubules cause the sarcoplasmic reticulum to release Ca2+
93
Skeletal Muscle Excitation Cycle 3
7. On the actin, Ca2+ binds to troponin, which moves tropomyosin and exposes myosin attachment sites.
8. ATP molecules are broken down to ADP and P, which releases energy needed to move the myosin heads.
9. The heads of the myosin myofilaments bend, causing the actin to slide past the myosin. As long as Ca2+ is present, the cycle repeats.
94
Energy for muscle contractions is supplied by ____
ATP
95
Energy is released as ATP → ________
ADP + P
96
ATP is stored in ___________
myosin heads
97
ATP help form cross-bridge formation between _______ and _____
myosin ; actin
98
New ATP must bind to _______ before cross-bridge is released
myosin
99
___________ will occur when a person dies and no ATP is available to release cross-bridges
Rigor mortis
100
A _____________ is a single contraction of a muscle fiber in response to a stimulus.
muscle twitch
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A muscle twitch has three phases:
latent phase,
contraction phase
relaxation phase
102
The __________ is the time between the application of a stimulus and the beginning of contraction.
latent phase
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The _____________is the time during which the muscle contracts
contraction phase
104
The ___________ is the time during which the muscle relaxes.
relaxation phase
105
In ___________, individual muscles contract more forcefully.
summation
106
__________ is a sustained contraction that occurs when the frequency of stimulation is so rapid that no relaxation occurs.
Tetanus
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_____________ is the stimulation of several motor units.
Recruitment
108
Skeletal Muscle Fiber Types
Slow twitch fibers
Fast twitch fibers
109
contract slowly
fatigue slowly
have a considerable amount of myoglobin
use aerobic respiration
are dark in color
used by long distance runners
Slow twitch fibers
110
contract quickly
fatigue quickly
use anaerobic respiration
energy from glycogen
light color
used by sprinters
Fast twitch fibers
111
____________ are very energy-demanding cells whether at rest or during any form of exercise.
Muscle fibers
112
Energy of Muscle fibers comes from either:
aerobic (with O2) or
anaerobic (without O2) ATP production
113
ATP is derived from four processes in skeletal muscle.
Aerobic production of ATP during most exercise and normal conditions.
Anaerobic production of ATP during intensive short-term work
Conversion of a molecule called creatine phosphate to ATP
Conversion of two ADP to one ATP and one AMP (adenosine monophosphate) during heavy exercise
114
Mechanisms of fatigue include:
Acidosis and ATP depletion due to either an increased ATP consumption or a decreased ATP production
Oxidative stress, which is characterized by the buildup of excess reactive oxygen species (ROS; free radicals)
Local inflammatory reactions
115
There are two types of muscle contractions:
Isometric
Isotonic
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The ____________________ has an increase in muscle tension, but no change in length.
isometric contraction
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The _____________________ has a change in muscle length with no change in tension.
isotonic contraction
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_____________________are isotonic contractions in which muscle tension increases as the muscle shortens.
Concentric contractions
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______________ are isotonic contractions in which tension is maintained in a muscle, but the opposing resistance causes the muscle to lengthen.
Eccentric contractions
120
___________ is the constant tension produced by body muscles over long periods of time.
Muscle tone
121
____________ is responsible for keeping the back and legs straight, the head in an upright position, and the abdomen from bulging.
Muscle tone
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___________ depends on a small percentage of all the motor units in a muscle being stimulated at any point in time, causing their muscle fibers to contract tetanically and out of phase with one another
Muscle tone
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_______________ cells are non-striated small, spindle-shaped muscle cells, usually with one nucleus per cell.
Smooth muscle
124
The _____________ are not organized into sarcomeres.
myofilaments
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The cells comprise organs controlled involuntarily, except the _______.
heart
126
___________________ substances, __________, and other substances can stimulate smooth muscle.
Neurotransmitter ; hormones
127
______________ cells are long, striated, and branching, with usually only one nucleus per cell.
Cardiac muscle
128
______________ is striated as a result of the sarcomere arrangement.
Cardiac muscle
129
Cardiac muscle contraction is __________________.
autorhythmic
130
Cardiac muscle cells are connected to one another by specialized structures that include desmosomes and gap junctions called ____________
intercalated disks
131
Cardiac muscle cells function as a ___________ in that action potential in one cardiac muscle cell can stimulate action potentials in ______________.
single unit ; adjacent cells
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A __________ connects skeletal muscle to bone.
Tendon
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____________ are broad, sheetlike tendons.
Aponeuroses
134
A ______________ is a band of connective tissue that holds down the tendons at each wrist and ankle.
retinaculum
135
Skeletal muscle attachments have an _____ and an _____________, with the ______ being the attachment at the least mobile location.
origin ; insertion
origin
136
The ___________ is the end of the muscle attached to the bone undergoing the greatest movement.
insertion
137
The part of the muscle between the origin and the insertion is the _______.
belly
138
A group of muscles working together are called ___________.
agonists
139
A muscle or group of muscles that oppose muscle actions are termed ____________
antagonists
140
A muscle that crosses on the anterior side of a joint produces ________
flexion
141
A muscle that crosses on the posterior side of a joint produces ___________
extension
142
A muscle that crosses on the lateral side of a joint produces __________
abduction
143
A muscle that crosses on the medial side of a joint produces ___________
adduction
144
Muscles are named according to:
1.Location
2.Size
3.Shape
4.Orientation of fascicles
5.Origin and insertion
6.Number of heads
7.Function
145
maseter = _____________
chewer
146
Powerful muscle that covers lateral aspect of mandibular ramus
Masseter
147
_______ = time; pertaining to the temporal bone
tempora
148
Fan-shaped muscle that covers parts of the temporal, frontal, and parietal bones
Temporalis
149
________ = toward median plane; pterygoid = winglike
medial
150
Deep two-headed muscle that runs along internal surface of mandible and is largely concealed by that bone
Medial pterygoid
151
______ = away from median plane
lateral
152
Deep two-headed muscle; lies superior to medial pterygoid muscle
Lateral pterygoid
153
Muscles used in facial expression
Zygomaticus major (smile)
Orbicularis oris (pucker)
Mentalis (pout)
Corrugator supercilii (angry eyebrows)
Orbicularis oculi (blink)
Frontal belly of epicranius (raised eyebrows/wrinkled forehead)
Platysma (tense neck)
154
Tongue and Swallowing Muscles
Suprahyoid Muscles
Infrahyoid Muscles
Pharyngeal Constrictor Muscles
Anterolateral Neck Muscles
Intrinsic Muscles of The Back
155
Muscles that help form floor of oral cavity, anchor tongue, elevate hyoid, and move larynx superiorly during swallowing; lie superior to hyoid bone
Suprahyoid Muscles
156
Four main Suprahyoid Muscles
Digastric Muscles
Stylohyoid Muscles
Mylohyoid Muscles
Geniohyoid Muscles
157
Consists of two bellies united by an intermediate tendon, forming a V shape under the chin
Digastric
158
Slender muscle below angle of jaw; parallels posterior belly of digastric muscle
Stylohyoid
159
Flat, triangular muscle just deep to digastric muscle; this muscle pair makes a sling that forms the floor of the anterior mouth
Mylohyoid
160
Narrow muscle in contact with its partner medially; runs from chin to hyoid bone deep to mylohyoid
Geniohyoid
161
Straplike muscles that depress the hyoid bone and larynx during swallowing and speaking
Infrahyoid Muscles
162
Most medial muscle of the neck: thin; superficial except inferiorly, where covered by ______________________
Sternohyoid ; sternocleidomastoid
163
Lateral and deep to sternohyoid
Sternothyroid
164
Straplike muscle with two bellies united by an intermediate tendon; lateral to sternohyoid
Omohyoid
165
Appears as a superior continuation of sternothyroid muscle
Thyrohyoid
166
are a group of muscles located in the pharynx, which is the upper part of the throat. These muscles play a crucial role in the process of swallowing.
Pharyngeal Constrictor Muscles
167
3 Main Pharyngeal Constrictor Muscles
Superior pharyngeal constrictor muscles
Middle pharyngeal constrictor muscles
Inferior pharyngeal constrictor muscles
168
This muscle forms the uppermost part of the pharyngeal wall
Superior pharyngeal constrictor muscles
169
This muscle is located below the superior pharyngeal constrictor.
Middle pharyngeal constrictor muscles
170
This is the lowest of the pharyngeal constrictor muscles.
Inferior pharyngeal constrictor muscles
171
Anterolateral Neck Muscles
muscles are a group of muscles located on the front and sides of the neck.
172
Two-headed muscle located deep to platysma on anterolateral surface of neck; fleshy parts on either side of neck delineate limits of anterior and posterior triangles; key muscular landmark in neck
Sternocleidomastoid
173
Located more laterally than anteriorly on neck; deep to platysma and sternocleidomastoid
Scalenes
174
are deep muscles located within the back region. They play a crucial role in stabilizing and controlling the movement of the spine.
Intrinsic Muscles Of The Back
175
Broad two-part superficial muscle (capitis and cervicis parts) extending from upper thoracic vertebrae to skull; capitis portion known as "bandage muscle" because it covers and holds down deeper neck muscles
Splenius
176
Deep Neck and Back Muscles
Erector spinae
177
are a group of muscles that run along the spine. They are responsible for straightening and rotating the back.
Erector spinae
178
Erector spinae muscles are divided into three columns:
iliocostalis
longissimus
spinalis
179
Most lateral muscle group of erector spinae muscles; extend from pelvis to neck
iliocostalis
180
Intermediate three-part muscle group of erector spinae; extend by many muscle slips from lumbar region to skull; mainly pass between transverse processes of vertebrae
longissimus
181
Most medial muscle column of erector spinae; cervicis usually rudimentary and poorly defined
spinalis
182
Composite muscle forming part of deep layer of intrinsic back muscles; extends from thoracic region to head
Semispinalis
183
Fleshy muscle forming part of posterior abdominal wall
Quadratus lumborum
184
Thoracic Muscles
External intercostals
Internal intercostals
Diaphragm
185
elevate ribs for inspiration
External intercostals
186
depress ribs during forced expiration
Internal intercostals
187
moves during quiet breathing
Diaphragm
188
Abdominal Wall Muscles (Anterior and Lateral)
Rectus abdominis
External abdominal oblique
Internal abdominal oblique
Transverse abdominis
189
is a long, flat muscle that runs vertically along the front of the abdomen. It is commonly referred to as the "six-pack" muscle.
Rectus abdominis
190
responsible for flexing the trunk, allowing you to bend forward at the waist. It also contributes to stabilizing the pelvis during movements and provides support to the abdominal organs.
Rectus abdominis
191
are located on the sides and front of the abdomen, forming the outermost layer of the abdominal wall.
External abdominal oblique
192
allow for trunk rotation and lateral flexion. They also assist in compressing the abdomen and are involved in forced exhalation.
External abdominal oblique
193
are situated beneath the external obliques, running in the opposite direction.
Internal abdominal oblique
194
are responsible for the same movements as the external obliques, including trunk rotation and lateral flexion. They also help in compressing the abdomen and assist in forced exhalation.
Internal abdominal oblique
195
the deepest layer of the abdominal muscles and wraps around the abdomen horizontally.
Transverse abdominis
196
acts as a stabilizing muscle. It provides intra-abdominal pressure, supporting the abdominal organs and maintaining posture. It is often referred to as the body's natural weight belt.
Transverse abdominis
197
Muscles of the Anterior Thorax
Pectoralis minor
Serratus anterior
Subclavius
198
is a thin, triangular muscle located beneath the pectoralis major.
assists in stabilizing the scapula (shoulder blade) by drawing it anteriorly and inferiorly against the thoracic wall. It also helps in elevating the ribs during forced inhalation.
Pectoralis minor
199
a muscle located on the lateral aspect of the chest, beneath the scapula.
pulls the scapula forward around the ribcage, allowing for movements of the arm above shoulder level. It is essential for activities that involve reaching and pushing.
Serratus anterior
200
located beneath the clavicle (collarbone).
It assists in stabilizing the clavicle, preventing excessive movements of the clavicle during shoulder movements.
Subclavius
201
Muscles of the Posterior Thorax
Trapezius
Levator scapulae
Rhomboids
Pectoralis major
Deltoid
Latissimus dorsi
Subscapularis
Supraspinatus
Infraspinatus
Teres minor
Teres major
Coracobrachialis
202
is a large, flat muscle that extends down the back of the neck and upper spine and spreads across the shoulders.
It helps in various movements of the shoulder blades, including elevation (raising the shoulders), depression (lowering the shoulders), retraction (pulling the shoulder blades together), and rotation (turning the shoulder blades).
Trapezius
203
a muscle located along the side and back of the neck, connecting the upper cervical vertebrae to the scapula
primarily elevates the scapula (shoulder blade) and supports the neck during movements. It helps in shrugging the shoulders and tilting the head to the side.
Levator scapulae
204
located between the spine and the scapulae (shoulder blades).
retract and stabilize the scapula. They pull the shoulder blades towards the spine, helping in squeezing the shoulder blades together. This action is important for maintaining good posture and stability in the upper back.
Rhomboids
205
is a large, fan-shaped muscle located in the chest.
responsible for several movements of the shoulder joint, including flexion (raising the arm forward), adduction (bringing the arm towards the body), and internal rotation. It is heavily involved in pushing movements and is essential for activities like pushing, lifting, and throwing.
Pectoralis major
206
a large, triangular muscle covering the shoulder joint.
responsible for the abduction of the arm (raising the arm away from the body). It also assists in flexion, extension, and rotation of the arm.
Deltoid
207
a large, flat muscle located on the back, covering a significant portion of the lower back.
responsible for several movements of the shoulder joint, including extension (pulling the arm backward), adduction (bringing the arm toward the body), and internal rotation. It plays a major role in activities such as pulling, climbing, and swimming.
Latissimus dorsi
208
a large triangular muscle located on the underside of the scapula (shoulder blade).
part of the rotator cuff and is responsible for internal rotation of the arm at the shoulder joint. It stabilizes the shoulder and assists in movements involving the shoulder joint.
Subscapularis
209
one of the four muscles that make up the rotator cuff, located on the upper part of the scapula.
responsible for initiating the abduction (raising the arm sideways) of the arm. It helps to stabilize the shoulder joint and is important for overhead movements.
Supraspinatus
210
another rotator cuff muscle located on the posterior part of the scapula.
primarily responsible for external rotation of the arm at the shoulder joint. It helps in stabilizing the shoulder and plays a crucial role in various arm movements.
Infraspinatus
211
smallest of the rotator cuff muscles and is located below the infraspinatus on the lateral part of the scapula.
assists in external rotation and helps stabilize the shoulder joint, particularly during arm movements away from the body.
Teres minor
212
a thick muscle located on the back of the shoulder blade.
involved in several movements of the shoulder joint, including extension, adduction, and internal rotation. It is sometimes called the "little lat" because it functions similarly to the latissimus dorsi.
Teres major
213
a small muscle located in the upper arm, beneath the biceps brachii.
helps in flexion and adduction of the arm at the shoulder joint. It assists in bringing the arm closer to the body and in forward arm movements.
Coracobrachialis
214
Posterior Muscles
Triceps branchii
Anconeus
215
commonly known as triceps, is a large muscle located at the back of the upper arm.
has three heads : long head, lateral head, and medial head.
primary extensor muscle of the forearm at the elbow joint. It straightens the arm and is involved in actions such as pushing, lifting, and throwing. The long head also helps stabilize the shoulder joint due to its attachment to the scapula.
Triceps branchii
216
a small triangular muscle located on the back of the elbow joint, adjacent to the triceps brachii.
assists the triceps brachii in extending the forearm at the elbow joint. It stabilizes the elbow joint during rapid movements.
Anconeus
217
Anterior Muscles
Biceps branchii
Branchialis
Brachioradialis
218
commonly known as biceps, is a two-headed muscle located in the front of the upper arm.
has two heads: the long head and the short head. It is the primary flexor muscle of the forearm at the elbow joint, meaning it is responsible for bending the arm.
Biceps branchii
219
is a deep muscle located underneath the biceps brachii, attaching the lower part of the humerus to the ulna.
the prime mover of elbow flexion. Unlike the biceps brachii, it does not play a role in supination or shoulder flexion. It is a powerful elbow flexor and contributes significantly to lifting and bending the arm.
Branchialis
220
is a muscle located on the forearm, specifically along the radius bone.
a versatile muscle that flexes the forearm at the elbow joint, particularly when the forearm is in a mid-position between pronation and supination.
Brachioradialis
221
Superficial Muscles
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor digitorum superficialis
Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor digitorum
Extensor carpi ulnaris
222
a muscle located on the forearm.
responsible for pronating the forearm, which means it turns the palm of the hand downwards or backwards.
Pronator teres
222
a muscle located on the anterior (front) side of the forearm.
It flexes and abducts the hand at the wrist joint, allowing the hand to move towards the palm side of the forearm and away from the midline of the body.
Flexor carpi radialis
223
a long, slender muscle located on the anterior side of the forearm.
It tenses the palmar aponeurosis (a structure in the palm) and assists in wrist flexion.
Not everyone this muscle; it is absent in some individuals.
Palmaris longus
224
a muscle located on the medial (inner) side of the forearm.
It flexes and adducts the hand at the wrist joint, allowing the hand to move towards the palm side of the forearm and towards the midline of the body.
Flexor carpi ulnaris
225
located on the anterior side of the forearm.
It flexes the fingers (digits) at the proximal interphalangeal (PIP) joints and assists in wrist flexion.
Flexor digitorum superficialis
226
a muscle located on the forearm, specifically on the lateral (outer) side.
It flexes the forearm at the elbow joint, especially when the forearm is in a mid-position between pronation and supination. It helps in various forearm movements, such as lifting.
Brachioradialis
227
a muscle located on the posterior (back) side of the forearm.
It extends and abducts the hand at the wrist joint, allowing the hand to move away from the palm side of the forearm and towards the body's midline.
Extensor carpi radialis longus
228
located next to the extensor carpi radialis longus.
It assists in extending and abducting the hand at the wrist joint, working in conjunction with the extensor carpi radialis longus.
Extensor carpi radialis brevis
229
located on the posterior side of the forearm.
It extends the fingers (digits) at the metacarpophalangeal (MCP) and interphalangeal (IP) joints, allowing for movements like straightening the fingers and spreading them apart.
Extensor digitorum
230
a muscle located on the posterior side of the forearm, near the ulna bone.
It extends and adducts the hand at the wrist joint, allowing the hand to move away from the palm side of the forearm and towards the midline of the body.
Extensor carpi ulnaris
231
Deep Muscles
Flexor pollicis longus
Flexor digitorum profundus
Pronator quadratus
Supinator
Abductor pollicis longus
Extensor pollicis brevis and longus
Extensor indicis
232
a muscle located in the forearm.
It flexes the thumb at the interphalangeal joint, allowing for movements like grasping and pinching.
Flexor pollicis longus
233
located in the forearm, beneath the flexor digitorum superficialis.
It flexes the fingers (digits) at the distal interphalangeal (DIP) joints. It assists in gripping and holding objects.
Flexor digitorum profundus
234
a small square-shaped muscle located in the forearm, deep to the pronator teres.
It pronates the forearm, meaning it turns the palm of the hand downward or backward.
Pronator quadratus
235
located on the lateral side of the forearm.
It supinates the forearm, which means it turns the palm of the hand upward or forward. It opposes the action of the pronator muscles.
Supinator
236
located in the forearm
It abducts the thumb at the carpometacarpal joint, allowing the thumb to move away from the palm. It also assists in wrist movements.
Abductor pollicis longus
237
located in the forearm.
This muscle is deeper and extends further down the forearm.
Extensor pollicis brevis and longus
238
located in the forearm.
It extends the index finger at the metacarpophalangeal (MCP) joint and assists in extending the finger at the proximal interphalangeal (PIP) joint.
Extensor indicis
239
Thenar Muscles in Ball of Thumb
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
Adductor pollicis
240
Lateral muscle of thenar group; superficial
Abductor pollicis brevis
241
Medial and deep muscle of thenar group
Flexor pollicis brevis
242
Deep to abductor pollicis brevis, on metacarpal I
Opponens pollicis
243
Fan-shaped with horizontal fibers; distal to other thenar muscles; oblique and transverse heads
Adductor pollicis
244
Hypothenar Muscles in Ball of Thumb
Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digiti minimi
245
Medial muscle of hypothenar group; superficial
Abductor digiti minimi
246
Lateral deep muscle of hypothenar group
Flexor digiti minimi brevis
247
Deep to abductor digiti minimi
Opponens digiti minimi
248
Flexion: bends medially across palm
249
Extension: points laterally
250
Abduction: points anteriorly
251
Adduction: moves posteriorly
252
Opposition: touches tip of another finger
253
Midpalmar Muscles
Lumbricals
Palmar interossei
Dorsal interossei
254
Lumbricals
255
Palmar interossei
256
Dorsal interossei
257
Anterior and Medial Muscles (Origin on the Pelvis or Vertebral Column
Iliopsoas
Sartorius
258
a group of muscles located in the pelvic region of the body.
Iliopsoas
259
Iliopsoas composed of two muscles
Iliacus
Psoas major
260
a flat, triangular muscle located in the pelvic region. It lies deep within the pelvis and attaches to the iliac fossa of the pelvis and the inner surface of the hipbone.
acts on the hip joint, flexing the thigh towards the abdomen. It is particularly active during activities like sitting, standing up, and walking.
Iliacus
261
a long muscle that originates from the vertebral bodies of the lumbar spine (specifically, from the T12 to L5 vertebrae) and extends down through the pelvis.
primary flexor of the hip joint. It also plays a role in stabilizing the spine and pelvis during movements.
Psoas major
262
Straplike superficial muscle running obliquely across anterior surface of thigh to knee;
It is the longest muscle in the human body and runs diagonally from the outer hip to the inner side of the knee.
Sartorius
263
Muscles of the Medial Compartment of the Thigh
Adductors
Pectineus
Gracilis
264
Adductors
265
Three main muscles of Adductors
Adductor magnus
Adductor longus (longus = long)
Adductor brevis (brevis = short)
266
the largest muscle of the adductor group, located in the inner thigh.
a powerful muscle and is involved in various leg movements.
Adductor magnus
267
a long, triangular muscle located in the inner thigh.
It assists in adducting the thigh and helps stabilize the pelvis during activities like walking and running.
Adductor longus (longus = long)
268
a shorter and thicker muscle located deep to the adductor longus.
It also contributes to adduction of the thigh and provides stability to the hip joint.
Adductor brevis (brevis = short)
269
a small, flat muscle located in the front of the hip, deep to the iliopsoas muscle.
It assists in thigh adduction and flexion, contributing to the overall movement of the hip joint
Pectineus
270
a long, slender muscle located on the inner thigh, superficial to the adductor muscles.
It assists in adducting the thigh and also helps in flexing the knee.
Gracilis
271
Muscles of the Anterior Compartment of the Thigh
Quadriceps femoris
Tensor fascia lata
272
commonly referred to as the quadriceps, is a group of four muscles located in the front of the thigh. These muscles work together to extend the knee joint.
Quadriceps femoris
273
Four muscles/head of Quadriceps femoris
Rectus femoris
Vastus lateralis
Vastus medialis
Vastus intermedius
274
Superficial muscle of anterior thigh; runs straight down thigh; longest head and only muscle of group to cross hip joint
Rectus femoris
275
Largest head of the group, forms lateral aspect of thigh; a common intramuscular injection site, particularly in infants (who have poorly developed buttock and arm muscles)
Vastus lateralis
276
Forms inferomedial aspect of thigh
Vastus medialis
277
Obscured by rectus femoris; lies between vastus lateralis and vastus medialis on anterior thigh
Vastus intermedius
278
Enclosed between fascia layers of anterolateral aspect of thigh; functionally associated with medial rotators and flexors of thigh
Tensor fascia lata
279
Gluteal Muscles (Orgin on Pelvis)
Gluteus maximus
Gluteus medius
Gluteus minimus
280
Largest and most superficial gluteus muscle; forms bulk of buttock mass; fascicles are thick and coarse; site of intramuscular injection (dorsal gluteal site); overlies large sciatic nerve; covers ischial tuberosity only when standing; when sitting, moves superiorly, leaving ischial tuberosity exposed in the subcutaneous position
Gluteus maximus
281
Thick muscle largely covered by gluteus maximus; important site for intramuscular injections (ventral gluteal site); considered safer than dorsal gluteal site because less chance of injuring sciatic nerve
Gluteus medius
282
Smallest and deepest gluteal muscle
Gluteus minimus
283
Lateral Rotators
Piriformis
Obturator externus
Obturator internus
Gemellus
Quadratus femoris
284
Pyramidal muscle located on posterior aspect of hip joint; inferior to gluteus minimus; issues from pelvis via greater sciatic notch
Piriformis
285
Flat, triangular muscle deep in superomedial aspect of thigh
Obturator externus
286
Surrounds obturator foramen within pelvis; leaves pelvis via lesser sciatic notch and turns acutely forward to insert on femur
Obturator internus
287
Two small muscles with common insertions and actions; considered extrapelvic portions of obturator internus
Gemellus
288
Short, thick muscle; most inferior lateral rotator muscle; extends laterally from pelvis
Quadratus femoris
289
Muscles of the Posterior Compartment of the Thigh
Hamstrings
290
a group of three muscles located in the back of the thigh. These muscles play a crucial role in bending the knee joint and extending the hip joint.
Hamstrings
291
Three main muscle of Hamstrings
Biceps femoris
Semitendinosus
Semimembranosus
292
Most lateral muscle of the group; arises from two heads
Biceps femoris
293
Lies medial to biceps femoris; although its name suggests that this muscle is largely tendinous, it is quite fleshy; its long slender tendon begins about two-thirds of the way down thigh
Semitendinosus
294
Deep to semitendinosus
Semimembranosus
295
Muscles of the Anterior Compartment
Tibialis anterior
Extensor digitorum longus
Fibularis (peroneus) tertius
Extensor hallucis longus
296
Superficial muscle of anterior leg; laterally parallels sharp anterior margin of tibia
Tibialis anterior
297
Unipennate muscle on anterolateral surface of leg; lateral to tibialis anterior muscle
Extensor digitorum longus
298
Small muscle; usually continuous and fused with distal part of extensor digitorum longus; not always present
Fibularis (peroneus) tertius
299
Deep to extensor digitorum longus and tibialis anterior; narrow origin
Extensor hallucis longus
300
Muscles of the Lateral Compartment
Fibularis (peroneus) longus
Fibularis (peroneus) brevis
301
Superficial lateral muscle; overlies fibula
Fibularis (peroneus) longus
302
Smaller muscle; deep to fibularis longus; enclosed in a common sheath
Fibularis (peroneus) brevis
303
Muscles of the Posterior Compartment (Superficial Muscles)
Triceps surae
Plantaris
304
refers to muscle pair (gastrocnemius and soleus) that shapes the posterior calf and inserts via a common tendon into the calcaneus of the heel; this calcaneal or Achilles tendon is the largest tendon in the body. Prime movers of foot plantar flexion.
Triceps surae
305
Two main muscle of Triceps surae
Gastrocnemius
Soleus
306
Superficial muscle of pair; two prominent bellies that form proximal curve of calf
Gastrocnemius
307
Broad, flat muscle, deep to gastrocnemius on posterior surface of calf
Soleus
308
Generally a small, feeble muscle, but varies in size and extent; may be absent
Plantaris
309
Muscles of the Posterior Compartment (Deep Muscles)
Popliteus
Flexor digitorum longus
Flexor hallucis longus
Tibialis posterior
310
Thin, triangular muscle at posterior knee; passes downward and medially to tibial surface
Popliteus
311
Long, narrow muscle; runs medial to and partially overlies tibialis posterior
Flexor digitorum longus
312
Bipennate muscle; lies lateral to inferior aspect of tibialis posterior
Flexor hallucis longus
313
Thick, flat muscle deep to soleus; placed between posterior flexors
Tibialis posterior
314
Muscles on Dorsum of Foot
Extensor digitorum brevis
315
Small, four-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
Extensor digitorum brevis
316
Muscles on Sole of Foot---First Layer (Most Superficial)
Flexor digitorum brevis
Abductor hallucis
Abductor digiti minimi
317
Bandlike muscle in middle of sole; corresponds to flexor digitorum superficialis of forearm and inserts into digits in the same way
Flexor digitorum brevis
318
Lies medial to flexor digitorum brevis (recall the similar thumb muscle, abductor pollicis brevis)
Abductor hallucis
318
Most lateral of the three superficial sole muscles (recall similar abductor muscle in palm)
Abductor digiti minimi
319
Muscles on Sole of Foot---Second Layer
Flexor accessorius (quadratus plantae)
Lumbricals
320
Rectangular muscle just deep to flexor digitorum brevis in posterior half of sole; two heads
Flexor accessorius (quadratus plantae)
321
Four little "worms" (like lumbricals in hand)
Lumbricals
322
Muscles on Sole of Foot---Third Layer
Flexor hallucis brevis
Adductor hallucis
Flexor digiti minimi brevis
323
Covers metatarsal I; splits into two bellies (recall flexor pollicis brevis of thumb)
Flexor hallucis brevis
324
Oblique and transverse heads; deep to lumbricals (recall adductor pollicis in thumb)
Adductor hallucis
325
Covers metatarsal V (recall same muscle in hand)
Flexor digiti minimi brevis
326
Muscles on Sole of Foot---Fourth Layer (Deepest)
Plantar (3) and dorsal (4) interossei
327
Similar to palmar and dorsal interossei of hand in locations, attachments, and actions; however, these muscles orient around the second digit, not the third
Plantar (3) and dorsal (4) interossei
