Download Skeletal Muscle

MUSCLES
Muscular System
Muscle Tissue: histology
• 3 muscle types: skeletal muscle, cardiac
muscle, and smooth muscle
• All muscles show similarities and
differences
• All muscles composed of elongated cells
called fibers
• Muscle cytoplasm is sarcoplasm, and
muscle cell membrane is sarcolemma
• Muscle fibers contain myofibrils made of
contractile proteins actin and myosin
Skeletal Muscle
 Fibers are multinucleated cells with peripheral nuclei: multiple nuclei due to
fusion of mesenchyme myoblasts during embryonic development
 Each muscle fiber is composed of myofibrils and myofilaments
Skeletal Muscle
 Actin and myosin filaments form distinct cross-striation patterns
 Light I bands contain thin actin, and dark A bands contain thick myosin
filaments
 Dense Z line bisects I bands; between Z lines is the contractile unit, the
sarcomere
Skeletal Muscle
 Accessory proteins align and stabilize actin and myosin filaments
 Titin protein anchors myosin filaments, and a-actinin binds actin filaments to Z
lines
 Titin centers, positions, and acts like a spring between myosin and Z lines
Skeletal Muscle
 Muscle is surrounded by connective tissue epimysium
 Muscle fascicles are surrounded by connective tissue perimysium
 Each muscle fiber is surrounded by connective tissue endomysium
Skeletal Muscle
 Voluntary muscles are under conscious control
 Neuromuscular spindles are specialized stretch receptors in almost all skeletal
muscles
 Intrafusal fibers and nerve endings are found in spindle capsules
 Stretching of muscle produces a stretch reflex and movement to shorten
muscle
Skeletal Muscle
Skeletal
Muscle
Skeletal Muscle
Skeletal Muscle
Skeletal Muscle:
Transmission Electron Microscopy
◊ Light bands = I bands, formed by thin actin filaments: are
crossed by dense Z lines
◊ Between Z lines = smallest contractile unit = sarcomere
◊ Dark bands = A bands, located in the middle of sarcomere,
formed by overlapping actin and myosin filaments
◊ M bands = in the middle of A bands represent linkage of myosin
filaments
◊ H bands on each side of M bands contain only myosin filaments
◊ Sarcoplasmic reticulum and mitochondria surround each sarcomere
Skeletal
Muscle
Skeletal Muscle
Skeletal Muscle:
functional correlation
 Skeletal muscles = voluntary (under conscious control), contracting only when
stimulated
 Motor endplates = sites of nerve innervations and transmission of stimuli to muscle
 Axon terminals of motor endplates contain vesicles with the neurotransmitter
acetylcholine (released into synaptic cleft by action potential and combined with its
receptors on muscle membrane); acetylcholinesterase neutralizes acetylcholine and
prevents further contraction
Skeletal Muscle
Skeletal Muscle:
functional correlation
 Before arrival of impulse, Ca+ is stored in sarcoplasmic reticulum (SR)
 T tubules = sarcolemma invaginations into each myofiber, carrying stimulus for
muscle contraction to every myofiber, myofibril, and SR membrane
 Triads = 2 expanded terminal cisternae of SR and T tubules, located at A–I
junctions
 After stimulation, SR releases Ca+ into sarcomeres, activating binding of actin and
myosin, causing muscle contraction and shortening
 After the end of stimulus, Ca+ is actively transported and stored in SR
Cardiac Muscle
• Located in heart and large vessels with cross-striations of actin and myosin
forming similar I bands, A bands, and Z lines as in skeletal muscle
• Characterized by dense junctional complexes called intercalated disks, containing
gap junctions [coupling all fibers for rhythmic contraction, forming functional
syncytium], one or two central nuclei, fibers shorter and showing branching
• T tubules located at Z lines and larger + SR less well developed + mitochondria
larger and more abundant than in skeletal muscles
• For contraction, Ca+ is imported from outside cell and from SR
• Exhibit autorhythmicity and spontaneously generate stimuli
• Autonomic nervous system innervates heart and influences heart rate and blood
pressure
Cardiac
Muscle
Cardiac Muscle
Cardiac Muscle
Cardiac Muscle
Cardiac Muscle
Smooth Muscle
• Fibers fusiform, containing single central nuclei, found in hollow organs and blood vessels,
with actin and myosin filaments without cross-striation, not showing regular arrangement or
striations, but forming lattice network, and inserting into dense bodies in sarcoplasm and
cytoplasm
• Zonula adherens binds muscle cells, whereas gap junctions provide functional coupling
• In intestines, muscles are arranged in concentric layers, and in blood vessels in a circular
pattern
Smooth
Muscle
•
SR not well developed
for Ca+ storage and
sarcolemma containing
invaginations
called
caveolae (controlling
influx of Ca+ into cell
after stimulation)
• Following stimulation, calcium enters sarcoplasm from caveolae and SR
• Calmodulin, a calcium-binding protein, stimulates actin and myosin interaction,
contract muscle by a sliding mechanism similar to skeletal muscle
• Exhibit spontaneous activity and maintain tonus in hollow organs: peristaltic
contractions propel contents in the organs; innervated by postganglionic
neurons of sympathetic and parasympathetic divisions; involuntary muscles
regulated by autonomic nervous system, hormones, and stretching
Smooth
Muscle
Smooth Muscle
Smooth Muscle
Smooth Muscle
Muscle tissues
Muscular System
 system to name skeletal muscles: in
some cases, the muscle is named by
its shape, and in other cases it is
named by its location or
attachments to the skeleton.
 understanding meaning of the name
of the muscle, often it will help you
remember its location and/or what it
does, to describe how skeletal
muscles are arranged to accomplish
movement, and how other muscles
may assist, or be arranged on the
skeleton to resist or carry out the
opposite movement
Interactions of Skeletal Muscles in the Body
To move the skeleton, tension created by the contraction of the fibers in most
skeletal muscles is transferred to the tendons = strong bands of dense,
regular connective tissue connecting muscles to bones (bone connection
muscle called skeletal
muscle).
Interactions of Skeletal Muscles in the Body


To pull on a bone (=to change angle at synovial joint = moving the skeleton),
a skeletal muscle must also be attached to a fixed part of the skeleton
moveable end of the muscle that attaches to the bone being pulled is called
insertion, and the end of the muscle attached to a fixed
(stabilized) bone is called the origin.
the muscle’s
Interactions of Skeletal Muscles in the Body
prime mover, or agonist = principal muscle involved in an action,
although a number of muscles may be involved
To lift a cup, a muscle called the biceps
brachii is actually the prime mover;
however, because it can be assisted by
the brachialis, this is called a synergist
in this action
synergist can also be a
fixator that stabilizes
the bone that is the
attachment for the
prime mover’s origin.
Interactions of Skeletal Muscles in the Body
Antagonist = muscle with the opposite action of the prime mover
play 2 important roles in muscle function:
(1) maintain body or limb position, such as holding the arm out or standing erect
(2) control rapid movement
also be reversed for the opposing action
Interactions of Skeletal Muscles in the Body
Also skeletal muscles not pulling
against skeleton for movements:
• muscles that produce facial
expressions.
• skeletal muscles in the tongue,
and the external urinary and
anal sphincters that allow for
voluntary regulation of
urination and defecation,
respectively.
• diaphragm contracts and
relaxes to change the volume
of the pleural cavities but it
does not move the skeleton to
do this.
Patterns of Fascicle Organization
Skeletal muscle enclosed in connective tissue scaffolding at 3 levels:
• each muscle fiber (cell) is covered by endomysium
• entire muscle is covered by epimysium
• when a group of muscle fibers is “bundled” as a unit within the whole muscle (=
fascicle) by an additional covering of a connective tissue called perimysium
Fascicle arrangement by perimysia is correlated to the force generated by a
muscle; it also affects the range of motion of the muscle.
Patterns of Fascicle Organization
Based on the patterns of fascicle arrangement, skeletal muscles can be classified
in several ways  most common fascicle arrangements
Parallel muscles = fascicles arranged in the same direction as the long axis of
the muscle (majority of skeletal muscles): 1. some parallel muscles are flat sheets
that expand at the ends to make broad attachments. 2. other parallel muscles
are rotund with tendons at one or both ends. 3. muscles that seem to be plump
have a large mass of tissue located in the middle of the muscle, between the
insertion and the origin, which is known as the central body (= belly). When a
parallel muscle has a central, large belly that is spindle-shaped, meaning it tapers
as it extends to its origin and insertion, it sometimes is called fusiform.
Patterns of Fascicle Organization
Circular muscles = also called
sphincters (= when they relax 
increase the size of the opening,
and when they contract  shrink
to the point of closure)
Convergent muscle = widespread
expansion over a sizable area, but
then the fascicles come to a
single, common attachment point
[that could be a tendon, an
aponeurosis (=flat, broad tendon),
or a raphe (= very slender
tendon)].
Pennate muscles (= “feathers”)
blend into a tendon that runs
through the central region of the
muscle for its whole length.
Patterns of Fascicle Organization
Due to this design, the muscle fibers in a pennate muscle can only pull at an
angle, and as a result, contracting pennate muscles do not move their tendons
very far. However, because a pennate muscle generally can hold more muscle
fibers within it, it can produce relatively more tension for its size.
Patterns of Fascicle Organization
3 subtypes of pennate
muscles:
1. unipennate muscle =
fascicles are located
on one side of the
tendon.
2. bipennate muscle =
fascicles on both sides
of the tendon.
3. multipennate muscles =
muscle fibers wrap
around the tendon,
sometimes
forming
individual fascicles
Naming Skeletal Muscles
Greek and Latin
Naming Skeletal Muscles
Naming Skeletal Muscles
naming according to a number of criteria (each describing
muscle in some way):
• shape
• size compared to other muscles in the area
• location in the body or location of its attachments to the
skeleton
• how many origins it has
• action
divided into axial (muscles of the
trunk and head) and appendicular
(muscles of the arms and legs)
categories, reflecting bones
Axial Muscles of the Head, Neck, and Back
Muscles That Create Facial Expression
origins of the muscles of facial expression = on skull surface (remember, the origin of
a muscle does not move)  insertions = fibers intertwined with connective tissue and
the dermis of the skin, thus, when contracting, skin moves to create facial expression
Axial Muscles of the Head, Neck, and Back
Muscles That Create Facial Expression
• orbicularis oris = circular muscle that moves the lips
• orbicularis oculi = circular muscle that closes the eye
• occipitofrontalis = moves up scalp and eyebrows (frontal belly + occipital belly: muscle
on the forehead [frontalis]and one on the back of the head [occipitalis], but no muscle
across the top of the head, two bellies connected by a broad tendon called the
epicranial aponeurosis, or galea (= “apple”)
• buccinator muscle = (majority of the face ) compresses cheek (whistle, blow, and suck +
contributes to chew)
• corrugator supercilii = prime mover of the eyebrow
• several additional small facial muscles
Axial Muscles of the Head, Neck, and Back
Muscles That Move the Eyes
extrinsic eye muscles = movement of the eyeball, originate outside the eye and insert onto
the outer surface of the white of the eye, located inside eye socket and cannot be seen on
any part of the visible eyeball
Axial Muscles of the Head, Neck, and Back
Muscles That
Move the Eyes
Axial Muscles of the Head, Neck, and Back
Muscles That Move the Lower Jaw
chewing = mastication
muscles involved in chewing must be able to exert enough pressure to bite through and then
chew food before it is swallowed:
masseter muscle = main muscle used for chewing, assisted by temporalis muscle (retracts
mandible)
medial pterygoid and lateral pterygoid muscles provide assistance in chewing and moving
food within the mouth.
Axial Muscles of the Head, Neck, and Back
Muscles That Move the Lower Jaw
Axial Muscles of the Head, Neck, and Back
Muscles That Move the Tongue
mastication, deglutition (swallowing), and speech
tongue muscles
 intrinsic (insert into the tongue from origins within it, allow the tongue to change its shape
such as, curling the tongue in a loop or flattening it) +
 extrinsic (insert into the tongue from outside origins, move the whole tongue in different
directions), all include the word root glossus (glossus = “tongue”), and the muscle names
are derived from where the muscle originates: genioglossus (genio = “chin”) originates on
mandible and allows the tongue to move downward and forward; styloglossus originates
on styloid bone, and allows upward and backward motion; palatoglossus originates on the
soft palate to elevate the back of the tongue; hyoglossus originates on the hyoid bone to
move the tongue downward and flatten it.
Axial Muscles of the Head, Neck, and Back
Muscles of the Anterior Neck
assist in deglutition (swallowing) + speech by controlling the positions of the larynx and hyoid
bone (= horseshoe-shaped bone functioning as a solid foundation on which tongue can
move), neck muscles categorized according to their position relative to hyoid bone,
suprahyoid muscles superior to it, and infrahyoid muscles located inferiorly.
Axial Muscles of the Head, Neck, and Back
Muscles of the Anterior Neck
• suprahyoid muscles: raise hyoid bone, floor of the mouth, and larynx during
deglutition, including digastric muscle (= has anterior and posterior bellies
working to elevate hyoid bone and larynx when one swallows; it also depresses
the mandible), stylohyoid muscle (= moves hyoid bone posteriorly, elevating the
larynx), mylohyoid muscle (lifts it and helps press the tongue to the top of the
mouth), geniohyoid (depresses mandible in addition to raising and pulling the
hyoid bone anteriorly)
• infrahyoid muscles (strap-like) generally depress hyoid bone and control
position of the larynx: omohyoid muscle (has superior and inferior bellies,
depresses hyoid bone in conjunction with thyrohyoid (also elevates the
larynx’s thyroid cartilage,) and sternothyroid (depresses it to create different
tones of voice)
Axial Muscles of the Head, Neck, and Back
Muscles That Move the Head
Axial Muscles of the Head, Neck, and Back
Muscles That Move the Head
Sternocleidomastoid =major muscle that laterally flexes and rotates the head,
in addition, both muscles working together are the flexors of the head (divides the
neck into anterior and posterior triangles when viewed from the side)
Axial Muscles of the Head, Neck, and Back
Muscles of the Posterior Neck and the Back
posterior muscles of the neck =
primarily concerned with head
movements, like extension
back muscles = stabilize and
move the vertebral column
(grouped according to lengths
and direction of the fascicles)
splenius muscles = originating at the
midline, run laterally and superiorly to
their insertions: splenius capitis inserts
onto head region, and splenius cervicis
extends onto the cervical region,
extending, laterally flexing and rotating
head
Axial Muscles of the Head, Neck, and Back
Muscles of the Posterior Neck and the Back
erector spinae group = majority of the
muscle mass of the back and primary
extensor of vertebral column, controlling
flexion, lateral flexion, and rotation and
maintaining lumbar curve; comprises:
 iliocostalis (laterally placed) group:
iliocostalis cervicis, associated with the
cervical region; iliocostalis thoracis,
associated with the thoracic region; and
iliocostalis lumborum, associated with the
lumbar region.
 longissimus (intermediately placed) group: 3
muscles = longissimus capitis, associated
with the head region; longissimus cervicis,
associated with the cervical region;
longissimus thoracis, associated with the
thoracic region.
 spinalis (medially placed) group: spinalis
capitis (head region), the spinalis cervicis
(cervical region), and the spinalis thoracis
(thoracic region).
Axial Muscles of the Head, Neck, and Back
Muscles of the Posterior Neck and the Back
transversospinales muscles = from transverse processes
to spinous processes of vertebrae, are named for areas
of the body with which they are associated: semispinalis
muscles include semispinalis capitis, semispinalis
cervicis, and semispinalis thoracis.
multifidus muscle of lumbar region = extend and
laterally flex vertebral column.
segmental muscle group = important in stabilization of
vertebral column, includes interspinales and
intertransversarii muscles (bringing together spinous and
transverse processes of each consecutive vertebra)
scalene muscles = flex, laterally flex, and rotate the head
and also contribute to deep inhalation, including
anterior scalene muscle (anterior to the middle scalene),
middle scalene muscle (the longest, intermediate
between the anterior and posterior scalenes), and
posterior scalene muscle (the smallest, posterior to the
middle scalene).
Axial Muscles of the Abdominal Wall and Thorax
muscles of vertebral column,
thorax, and abdominal wall
extend, flex, and stabilize
different parts of the body’s trunk
in order to balance body on two
feet and walk upright
Muscles of the
Abdomen
4 pairs of abdominal muscles,
covering anterior and lateral
abdominal region and meet at
anterior midline = muscles of
anterolat abdominal:
• external obliques,
• internal obliques,
• transversus abdominis
• rectus abdominis
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Abdomen
Axial Muscles of the Abdominal Wall and Thorax
3 flat muscles in ant-lat wall of abdomen:
external oblique = closest to the surface, extend
inferiorly and medially,
internal oblique = perpendicular to it (intermediate),
extending superiorly and medially,
transversus abdominis = (deep muscle) arranged
transversely around the abdomen,
 arrangement of 3 bands of muscles in different
orientations allows various movements and rotations
of trunk and also help to protect internal abdominal
organs in an area where there is no bone.
linea alba = white, fibrous band that is made of
bilateral rectus sheaths that join at the anterior
midline of the body, enclosing rectus abdominis
muscles (a pair of long, linear muscles) originating at
pubic crest and symphysis, and extending length of
body’s trunk and segmented by three transverse
bands of collagen fibers called tendinous
intersections.
Muscles of the
Abdomen
Axial Muscles of the Abdominal Wall and Thorax
Pyramidalis Muscles
Axial Muscles of the Abdominal Wall and Thorax
Pyramidalis Muscles
EPIPUBIC BONE in MARSUPIALS
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Abdomen
posterior abdominal wall is
formed by the lumbar
vertebrae, parts of the ilia
of the hip bones, psoas
major and iliacus muscles,
and quadratus lumborum
muscle = this part of the
core plays a key role in
stabilizing the rest of the
body and maintaining
posture.
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Thorax
= to facilitate breathing by changing the size of the thoracic cavity
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Thorax: Diaphragm
= change in volume of thoracic cavity during breathing is due to alternate contraction and
relaxation;
separates the thoracic and abdominal cavities, and is dome-shaped at rest (superior surface
convex, creating elevated floor of thoracic cavity, inferior surface is concave, creating curved
roof of abdominal cavity).
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Thorax: Diaphragm
Defecating, urination, and even
childbirth
involve
cooperation
between
the
diaphragm
and
abdominal muscles (= “Valsalva
maneuver”): holding breath by a
steady contraction of diaphragm with
stabilization of volume and pressure
of peritoneal cavity + abdominal
muscles contract, pressure cannot
push the diaphragm up, so it increases
pressure on the intestinal tract
(defecation), urinary tract (urination),
or reproductive tract (childbirth).
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Thorax: Diaphragm
inferior surface of pericardial
sac and inferior surfaces of
pleural membranes (parietal
pleura) fuse onto central
tendon of diaphragm: to the
sides of the tendon are the
skeletal muscle portions of
diaphragm, which insert into
tendon while having a number
of origins including xiphoid
process ant., inferior six ribs
and their cartilages laterally,
and lumbar vertebrae and 12th
ribs posteriorly.
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Thorax: Diaphragm
diaphragm also includes 3
openings for passage of
structures between thorax
and abdomen: 1. inferior
vena cava through caval
opening, 2. esophagus and
attached nerves through
esophageal hiatus, 3. aorta,
thoracic duct, and azygous
vein through aortic hiatus
of the posterior diaphragm.
Axial Muscles of the Abdominal Wall and Thorax
The Intercostal Muscles
3 sets of muscles, = intercostal muscles, which span each of the intercostal spaces: principal
role to assist in breathing by changing the dimensions of the rib cage
1. 11 pairs of superficial external intercostal muscles aid in inspiration, raising rib cage,
which expands it
2. 11 pairs of internal intercostal muscles, just under the externals, used for expiration
because they constrict the rib cage
3. innermost intercostal muscles (deepest): act as synergists for action of internal
intercostals.
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Pelvic Floor and Perineum
pelvic floor = muscular sheet defining inferior portion of pelvic cavity: pelvic diaphragm,
spanning ant to post from pubis to coccyx, comprises : levator ani [= consists of 2 muscles,
pubococcygeus and iliococcygeus, considered the most important muscle of pelvic floor
supporting pelvic viscera and resisting pressure produced by contraction of abd muscles
applied to colon to aid in defecation and to uterus to aid in childbirth, also creates skeletal
muscle sphincters at the urethra and anus]+ assisted by the ischiococcygeus, which pulls the
coccyx anteriorly
openings include anal canal and urethra, and vagina in women.
Axial Muscles of the Abdominal Wall and Thorax
Muscles of the Pelvic Floor and Perineum
perineum = diamond-shaped space between pubic symphysis (ant), coccyx (post), and
ischial tuberosities (lat): divided transversely into triangles, ant urogenital triangle = external
genitals and post anal triangle = anus
Muscles of the Pectoral Girdle and Upper Limbs
Generality
Muscles of the shoulder and upper limb can be divided into 4
groups:
1. muscles that stabilize and position pectoral girdle,
2. muscles that move arm,
3. muscles that move forearm
4. muscles that move wrists, hands, and fingers.
pectoral girdle, or shoulder girdle = consists of lateral ends of
clavicle and scapula, along with proximal end of humerus, and
muscles covering these 3 bones to stabilize shoulder joint. The
girdle creates a base from which head of humerus, in its ball-andsocket joint with the glenoid fossa of scapula, can move arm in
multiple directions.
Muscles of the Pectoral Girdle and Upper Limbs
1. Muscles That Position the Pectoral Girdle
located either on ant or on post thorax:
anterior muscles
1. subclavius,
2. pectoralis minor
3. serratus anterior
posterior muscles
1. trapezius
2. rhomboid major
3. rhomboid minor
Muscles of the Pectoral Girdle and Upper Limbs
1. Muscles That Position the Pectoral Girdle
Muscles of the Pectoral Girdle and Upper Limbs
2. Muscles That Move the Humerus
= axial and scapular
muscles:
 2 axial muscles
1. pectoralis major = thick and fan-shaped, covering much of superior portion of anterior
thorax.
2. latissimus dorsi = broad, triangular latissimus dorsi is located on inferior part of back, where
it inserts into a thick connective tissue shealth called an aponeurosis.
 7 muscles originating on scapula
1. deltoid = thick muscle creating rounded lines of shoulder: major abductor of arm (also
facilitates flexing and medial rotation, as well as extension and lateral rotation)
2. Subscapularis = originates on the anterior scapula and medially rotates the arm.
3. supraspinatus = (superior to the spine of the scapula) abduct the arm
4. Infraspinatus = (inferior to the spine of the scapula) laterally rotate the arm
5. teres major = thick and flat is inferior to the teres minor and extends the arm, and assists in
adduction and medial rotation of it
6. teres minor = laterally rotates and extends the arm
7. coracobrachialis = flexes and adducts the arm.
Muscles of the Pectoral Girdle and Upper Limbs
2. Muscles That Move the Humerus
= axial and scapular
muscles:
 rotator cuff (musculotendinous cuff) = circle of tendons around shoulder joint: tendons of
deep subscapularis, supraspinatus, infraspinatus, and teres minor connect scapula to
humerus
Muscles of the Pectoral Girdle and Upper Limbs
2. Muscles That
Move the Humerus
Muscles of the Pectoral Girdle and Upper Limbs
2. Muscles That
Move the Humerus
Muscles of the Pectoral Girdle and Upper Limbs
3. Muscles That Move the Forearm Forearm = 4 main
types of action:
flexion, extension,
pronation, and
supination
 forearm flexors (anterior flexor compartment of the arm) = 1.
biceps brachii (two-headed muscle crossing shoulder and elbow
joints to flex forearm, also taking part in supinating the forearm at
radioulnar joints and flexing arm at shoulder joint), 2. brachialis
(provides additional power in flexing forearm), 3. brachioradialis
(flex forearm quickly or help lift a load slowly).
 extensors = triceps brachii and anconeus.
 pronators = pronator teres and pronator quadratus,
 supinator = only one that turns forearm anteriorly
Muscles of the Pectoral Girdle and Upper Limbs
3. Muscles That Move the Forearm
Muscles of the Pectoral Girdle and Upper Limbs
3. Muscles That Move the Forearm
Muscles of the Pectoral Girdle and Upper Limbs
3. Muscles
That Move
the Forearm
Muscles of the Pectoral Girdle and Upper Limbs
4. Muscles That Move the Wrist, Hand, and Fingers
Wrist, hand, and finger movements are facilitated by 2 groups of muscles:
extrinsic muscles of the hand = forearm is origin
intrinsic muscles of the hand = palm is origin
Muscles of the Pectoral Girdle and Upper Limbs
4a. Extrinsic muscles
 superficial anterior flexor compartment of the forearm = originate on humerus and insert
onto different parts of hand: (bulk of forearm), -from lateral to medial- flexor carpi radialis,
palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis (= flexes hand as well
as digits at the knuckles, allowing for rapid finger movements, as in typing or playing a
musical instrument (Carpal Tunnel Syndrome).
 deep anterior compartment = flexion and bends fingers to make a fist: flexor pollicis longus
and flexor digitorum profundus.
 superficial posterior extensor compartment of the forearm = originate on the humerus:
extensor radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti
minimi, and extensor carpi ulnaris.
 deep posterior extensor compartment of the forearm= originate on radius and ulna:
abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor
indicis.
tendons of forearm muscles attach to wrist and extend into the hand: fibrous bands called
retinacula sheath tendons at the wrist  flexor retinaculum extends over hand palmar surface,
while extensor retinaculum extends over hand dorsal surface
Muscles of the Pectoral Girdle and Upper Limbs
4a. Extrinsic muscles
Muscles of the Pectoral Girdle and Upper Limbs
4b. Intrinsic muscles
= both originate and insert within
hand, allowing to make precise
movements for actions, such as typing
or writing, divided into 3 groups:
1.thenar muscles (on radial aspect of
the palm, abductor pollicis brevis,
opponens pollicis, flexor pollicis brevis,
and the adductor pollicis - form thenar
eminence, rounded contour of thumb
base, all act on thumb), 2. hypothenar
muscles (on medial aspect, abductor
digiti minimi, flexor digiti minimi brevis,
opponens digiti minimi - form
hypothenar
eminence,
rounded
contour of little finger, all act on little
finger),
3.intermediate
muscles
(midpalmar, act on all fingers,
lumbrical, palmar interossei, and dorsal
interossei).
Muscles of the Pectoral Girdle and Upper Limbs
4b. Intrinsic
muscles
Appendicular Muscles of Pelvic Girdle and Lower Limbs
Pelvic girdle = less range of motion because designed to stabilize and support body.
Muscles of the Thigh
Gluteal Region Muscles That Move the Femur
Most muscles that insert on femur and move it, originate on pelvic girdle.
 psoas major and iliacus = iliopsoas group.
 gluteal group = some of the largest and most powerful muscles in the body: 1.gluteus
maximus (largest); 2. gluteus medius (deep to gluteus maximus); 3. gluteus minimus
(deep to the gluteus medius, smallest of the trio)
 tensor fascia lata = thick, squarish muscle in superior aspect of lateral thigh (acts as a
synergist of gluteus medius and iliopsoas in flexing and abducting the thigh + stabilize lateral
aspect of the knee)
 piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus,
and quadratus femori = deep to gluteus maximus, laterally rotate femur at the hip.
 adductor longus, adductor brevis, and adductor magnus = medially and laterally rotate
thigh depending on the placement of the foot (adductor longus flexes thigh, whereas adductor
magnus extends it).
 pectineus adducts and flexes femur at hip as well (located in femoral triangle, also includes
the femoral nerve, the femoral artery, the femoral vein, and the deep inguinal lymph nodes
Appendicular Muscles
of Pelvic Girdle and
Lower Limbs
Muscles of the Thigh
Gluteal Region Muscles
That Move the Femur
Appendicular Muscles
of Pelvic Girdle and
Lower Limbs
Muscles of the Thigh
Gluteal Region Muscles
That Move the Femur
Appendicular Muscles of Pelvic Girdle and Lower Limbs
Muscles of the Thigh
Thigh Muscles That Move the Femur, Tibia, and Fibula
Deep fascia in thigh separates into:
1.medial (responsible for adducting the femur at the hip) = 1.gracilis (strap-like) along
with adductor longus, adductor brevis, adductor magnus, and pectineus, adducts
thigh in addition to flexing leg at knee.
2.anterior (flex thigh and extend leg) = 1. quadriceps femoris group (= 4 muscles
extending and stabilizing knee: rectus femoris, vastus lateralis, vastus medialis, vastus
intermedius  patellar tendon common to all four inserting into patella and
continuing below it as patellar ligament, attaches to tibial tuberosity 2. sartorius
(band-like muscle extending from ant. Sup. iliac spine to medial side of proximal tibia
 flexes leg at knee and flexes, abducts, and laterally rotates leg at hip = to sit crosslegged)
3.posterior compartments (flex leg and extend thigh) = (hamstring group flexing knee)
1.biceps femoris, 2.semitendinosus, 3.semimembranosus (tendons form popliteal
fossa = diamond-shaped space at back of knee).
Appendicular
Muscles of Pelvic
Girdle and Lower
Limbs
Muscles of the Thigh
Thigh Muscles That Move
the Femur, Tibia, and Fibula
Appendicular Muscles of Pelvic Girdle and Lower Limbs
Muscles That Move the Feet and Toes
deep fascia separate muscles of the leg into 3 compartments:
1. Anterior = 1. tibialis anterior (long and thick muscle on lateral surface of tibia), 2.
extensor hallucis longus, 3. extensor digitorum longus (all contribute to raising
front of foot), 4. fibularis tertius (associated with extensor digitorum longus, but
not present in all people) [thick bands of connective tissue = superior extensor
retinaculum (transverse ligament of the ankle) and inferior extensor retinaculum
 hold tendons of these muscles in place during dorsiflexion]
2. Lateral = 1. fibularis longus (peroneus longus) and 2. fibularis brevis (p. brevis)
3. Posterior =
• superficial = [all insert onto strong calcaneal tendon (Achilles tendon) inserting
into calcaneal bone] muscles large and strong keeping humans upright = 1.
gastrocnemius (most superficial and visible muscle of the calf) 2. soleus (deep to
gastrocnemius, wide, flat) 3. plantaris (running obliquely between two) 4. tibialis
posterior
• deep = 1. popliteus, 2.flexor digitorum longus, 3. flexor hallucis longus, 4. tibialis
posterior
Appendicular Muscles of
Pelvic Girdle and Lower
Limbs
Muscles That Move
the Feet and Toes
Appendicular Muscles of Pelvic Girdle and Lower Limbs
Muscles That Move the Feet and Toes
Appendicular Muscles of Pelvic Girdle and Lower Limbs
Muscles That Move the Feet and Toes
foot also has intrinsic muscles = originate and insert within it,
primarily providing support for foot and its arch and contributing to
movements of toes, 2 groups:
dorsal group = 1. extensor digitorum brevis
plantar group = 4 layers, starting with the most superficial.
[principal support for longitudinal arch of foot = deep fascia called
plantar aponeurosis, running from calcaneus bone to toes]
Appendicular Muscles of Pelvic Girdle and Lower Limbs
Muscles That Move the Feet and Toes
Appendicular Muscles of
Pelvic Girdle and Lower
Limbs
Muscles That
Move the Feet
and Toes
intrinsic
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