Download Lecture 6

Muscular Tissue
•specialized for contraction
•very distinct organelles within the cells
•3 types
•1. skeletal – voluntary muscle
•2. cardiac – involuntary muscle
•3. smooth – involuntary muscle
Skeletal Muscle: voluntary muscle
-voluntary nervous control
-repeating banding patterns of actin & myosin = striated appearance
-mature cells = multi-nucleated cells – made from fusion of myoblasts
-cells are very long – sometimes called muscle fibers
-cannot divide – but new cells form from differentiation of myogenic stem cells = satellite
cells
-attached to bones via tendons
Cardiac Muscle: involuntary muscle
-cells are striated but uni-nuclear = cardiomyocytes
-incapable of dividing – PLUS there are no satellite cells
-therefore damaged heart muscle cannot be regenerated
-identified by the presence of intercalated discs
-for cell-cell communication and force transmission
Smooth Muscle: involuntary muscle
-lines blood vessels, airways and organs
-non-striated
-spindle shaped cells - single nucleus (uni-nuclear)
-control their own rate of contraction through
action of pacemaker cells
-BUT nervous system can also control
contraction
-slow, sustained & strong contraction
Skeletal Muscles
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Attach to bones
Produce skeletal movement (voluntary)
Maintain posture
Support soft tissues
Regulate entrances to the body
Maintain body temperature
Properties of Skeletal Muscles
Electrical excitability
-ability to respond to stimuli by producing action potentials
-two types of stimuli: 1. autorhythmic action potentials made by the
muscle cell itself
2. APs resulting from chemical stimuli from nervous
system
– e.g. neurotransmitters
Contractility
-ability to contract when stimulated by an action potential
-isotonic contraction: tension develops, muscle shortens
-isometric contraction: tension develops, length doesn’t change
Extensibility
-ability to stretch without being damaged
-allows contraction even when stretched
Elasticity
-ability to return to its original length and shape
Muscles: Gross Anatomy
•muscles with similar functions
are grouped and held together
by layers of deep fascia
e.g. biceps femoris and
brachialis – forearm flexion
• three layers of connective
tissue surround and organize a
muscle
– Epimysium
– Perimysium
– Endomysium
Gross Anatomy
•muscles are surrounded by a fascia (areolar tissue)
•remove the fascia – epimysium that surrounds the muscle and divides it into groups
called fascicles
• each individual fascicle is surrounded by a perimysium
•perimysium divides the fascicle into muscle fibers = muscle cells
Gross Anatomy
•each muscle fiber/muscle cell is surrounded by an endomysium
•endomysium divides the muscle fiber into protein filaments =
myofibrils
•myofibrils are made up of a a “skeleton” of protein filaments
(myofilaments) organized as sarcomeres
Muscles: Gross Anatomy
• epimysium and perimysium extend off the muscle to become
organized as a tendon – attaches to the periosteum of the bone
Microanatomy of Skeletal Muscle
Fibers
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large, multinucleated cells called fibers
mature muscle fibers range from 10 to 100 microns in diameter
typical length is 4 inches - some are 12 inches long
muscle fibers increase in size during childhood = human GH &
testosterone
• number of muscle cells predetermined before birth
Microanatomy of Skeletal Muscle
Fibers
• muscle stem cells (satellite cells)
differentiate into immature myoblasts
which begin to make muscle proteins
– myoblasts mature into myocytes
– multiple myocytes fuse to form the
muscle cell (muscle fiber)
– muscle fibers cannot divide through
mitosis
– satellite cells can repair
damaged/dying skeletal muscle cells
throughout adulthood
Muscle Cell Anatomy
• cell membrane = sarcolemma
• cytoplasm = sarcoplasm
– large amounts of glycogen and
myoglobin
– surrounds the myofibrils
• myofibrils made up of
myofilaments
– thick and thin
• transverse tubules
– ingrowths of the sarcolemma
– carry the action potential deep
into the fiber
– surrounds the sarcoplasmic
reticulum
• sarcoplasmic reticulum
– for calcium storage
The Proteins of Muscle
• contractile elements of the myofibrils = myofilaments
-2 microns in diameter
-give the muscle its striated appearance
• myofilaments are built of 3 kinds of protein
– contractile proteins
• myosin and actin
– regulatory proteins which turn contraction on & off
• troponin and tropomyosin
– structural proteins which provide proper alignment, elasticity and extensibility
• titin, myomesin, nebulin, actinin and dystrophin
The Proteins of Muscle
• two kinds of myofilaments
• Thin - actin, troponin and tropomyosin
• Thick – myosin only
Sarcomere
Structure
• sarcomere = regions bounded by two Z lines
• thin myofilaments project out from Z line – actin attached via
actinin (structural protein)
• myosin/thick myofilaments lie in center of sarcomere – attached
to the M line
• thick and thin myofilaments overlap and connect via cross-bridges
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Sarcomere
Structure
• myosin/thick filament only region = H zone
• thin filament only region = I band
• length of myosin/thick filaments = A band
•contraction = “sliding filament theory”
• thick and thin myofilaments slide over each other and
sarcomere shortens
Contraction: The Sliding Filament Theory
•Actin proteins in the thin filament have myosin binding sites
•these sites are “covered up” by troponin and tropomyosin in relaxed muscle
•“shifting off” of troponin/tropomyosin from these sites is required for contraction
•shifting of troponin/tropomyosin is done through binding of calcium to troponin
•calcium is released from the sarcoplasmic reticulum upon the action potential
Contraction: The Sliding Filament Theory
• thick myofilament is a
bundle of myosin
molecules
• myosin looks like a “golf
club” with a head, a
hinge region and a shaft
• each myosin protein has a globular “head” with a site to bind and
breakdown ATP (ATPase site) and to bind actin (actin binding
site)
• binding of actin and myosin binding sites = cross-bridging
RESETTING of
system
Increase in Cai
Removal of troponin-tropomyosin
CONTRACTION
Sliding of actin along myosin
-for cross bridging- you will need two things:
1. calcium – uncovers the myosin binding sites on actin – “pushes aside” the troponintropomyosin complex
2. myosin head bound to ADP
-for contraction (pivoting of the myosin head into the M line) – the myosin head must be empty
-to “reset” for a new cycle of cross-bridging – the myosin head must detach and pivot back -the
myosin head must bind ATP
-once the myosin head pivots back – the ATP is broken down to ADP – head is ready to
cross-bridge again – if actin is “ready”
Contracted Sarcomere
• http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter10/animation__myofilam
ent_contraction.html
• http://www.youtube.com/watch?v=EdHzKYDxrKc
• http://www.youtube.com/watch?v=Vlchs4omFDM
• https://www.youtube.com/watch?v=hr1M4SaF1D4
Muscle Metabolism
• Production of ATP:
-contraction requires huge amounts of ATP
-muscle fibers produce ATP three ways:
1. Creatine phosphate
2. Anaerobic metabolism
3. Aerobic metabolism
Creatine Phosphate
• Muscle fibers at rest produce more ATP then they need for resting
metabolism
• but you can’t store ATP
• excess ATP within resting muscle used to form creatine phosphate
– creatine – arginine, glycine and methionine
• phosphorylated by the enzyme creatine kinase
• takes a phosphate off of ATP and transfers it to creatine
• also takes the phosphate off of creatine phosphate and transfers
it back to ADP – to make ATP
Creatine Phosphate
• Creatine phosphate: 3-6 times more plentiful than ATP within muscle
• Sustains maximal contraction for 15 sec (used for 100 meter dash).
• Athletes often use creatine supplementation
– gain muscle mass but shut down bodies own synthesis (safety?)
Anaerobic Cellular Respiration
• once muscles deplete creatine – can make
ATP in anaerobically or aerobically
• both anaerobic and aerobic metabolism
start the same way – breakdown of
glucose first by glycolysis
• glycogen broken down into glucose
• glycolysis: glucose  pyruvic acid (3
carbon sugar)
– 2 ATP made
• in anaerobic respiration – pyruvic acid 
lactic acid
– muscle fatigue
• Glycolysis can continue anaerobically to
provide ATP for 30 to 40 seconds of
maximal activity (200 meter race)
Aerobic Cellular Respiration
sources of oxygen
– diffusion from
blood, released by
myoglobin
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ATP for any activity lasting over 30 seconds
with sufficient oxygen available = pyruvic acid acteyl CoA
Acetyl coA enters the Kreb’s cycle (mitochondria)
Kreb’s cycle generates NADH and FADH2 (electron carriers)
the electrons are transferred from NADH/FADH2 to three enzyme complexes
located in the inner mitochondrial membrane
• electrons ultimately transported to oxygen – results in synthesis of ATP, water &
heat
• provides 90% of ATP energy if activity lasts more than 10 minutes
• each glucose = 36 ATP (2 from glycolysis)
Types of Muscle Fibers
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classified on how they make their ATP
fast glycolytic (type IIB)
slow oxidative (type I)
fast glycolytic-oxidative (type IIA)
percentage of fast versus slow fibers is genetically
determined
• proportions vary with the muscle
– neck, back and leg muscles have a higher proportion of
postural, slow oxidative fibers
– shoulder and arm muscles have a higher proportion of
fast glycolytic fibers
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Fast Fibers
large diameter, densely packed myofibrils
large glycogen reserves
powerful, explosive contractions
fatigue quickly
Fast oxidative-glycolytic (fast-twitch type IIA):
– red in color (lots of mitochondria, myoglobin & blood vessels)
– used for walking and sprinting
• Fast glycolytic (fast-twitch type IIB):
– white in color (few mitochondria & BV, low myoglobin)
– short duration anaerobic movements
– used for weight-lifting
• Type I Slow Oxidative fibers: Half the diameter of fast
fibers
– Three times longer to contract vs. fast fibers
– Continue to contract for long periods of time
– longest to fatigue
Classification
• According to arrangement of fibers and
fascicles
– Parallel muscles
• Parallel to long axis of muscle
– Convergent muscles
• Fibers converge on common attachment site
– Pennate muscles
• One or more tendons run through body of
muscle
• Unipennate, bipennate, multipennate
– Circular muscles
• Fibers concentrically arranged
Bones & Muscles: Origins and Insertions
• Origin – portion of the skeletal muscle that attaches to the more
stationary structure
• Insertion - portion of the skeletal muscle that attaches to the
more moveable structure
• majority of muscles originate or insert from bony markings on
the skeleton
• markings: specific elevations, depressions, and openings of
bones
• 3 kinds of bony markings:
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depressions – fossa, fissure
openings – foramen, canal, meatus
processes – condyles, spines, crests, heads, lines, ridges, trochanters, tubercles
processes are for muscle origins and insertions
Muscle Names
• Yield clues to muscle orientation, location or
function
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Biceps brachii (two heads, arm)
Vastus femoris (large, femur)
Orbicularis oculi (circular, eye)
Rectus abdominus (erect, abdomen)
Musculoskeleton: Axial Division
• Axial skeleton: 80 bones
– main axis of the body
– forms a framework for the protection of delicate
organs
• Axial musculature
– axial musculature arises from and inserts on the
axial skeleton
– responsible for positioning the head and spinal
column – postural muscles
– also moves the rib cage, assisting in breathing
– grouped into 4 groups:
– 1. muscles of the head and neck
– 2. muscles of the vertebral column
– 3. the abdominals - oblique and rectus muscles
– 4. muscles of the pelvic floor
Muscles of the Head and Neck
• Muscles of facial expression – know for practical
• Extrinsic eye muscles – know for practical
• Muscles of mastication – check your list for
practical
• Muscles of the tongue – check your list for
practical
• Muscles of the pharynx – don’t worry about these
• Muscles of the anterior neck – know for
practical
Muscles of Facial Expression
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Orbicularis oris - puckering
Buccinator - whistling
Occipitofrontalis muscle (Epicranius)
– movement of eyebrows, forehead, scalp
– Front belly = Frontalis (moves eyebrows
and forehead)
– Back belly = Occipitalis (moves back of
scalp)
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Zygomaticus Major and Minor - smiling
Risorius - grinning
Orbicularis oculi – closes eye
Depressor anguli oris - – lowers angle of
mouth
Depressor labii inferioris –depresses lower
lip
Levator labii superioris – raises upper lip
Mentalis - pouting
Platysma – pouting & depresses mandible originate
on surface of skull –
insert on the skin of the face
zygomaticus minor
zygomaticus major
Muscles of Mastication
• Act on the mandible
• Temporalis –
elevates mandible
• Masseter – elevates
mandible
• Medial pterygoid &
Lateral pterygoid
– protract the mandible
and move it side to
side
– Don’t need to know
for practical
Six Extra-Ocular (Oculomotor)
Muscles
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Inferior rectus
Superior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique
Muscles of the Tongue
• Necessary for speech and swallowing
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Genioglossus
Hyoglossus
Palatoglossus
Styloglossus
palatoglossus
temporalis
styloglossus
hyoglossus
mylohyoid
Anterior Muscles of the Neck
• foundation for the muscles of the tongue and pharynx, move the
hyoid up or down for swallowing & breathing, depress the
mandible
– Digastric – two bellies
– Mylohyoid
– Stylohyoid
– Sternohyoid
– Sternothyroid
– Thyrohyoid
– Omohyoid
Anterior Muscles of the Neck
• Foundation for the muscles of the tongue and pharynx
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Digastric
Mylohyoid
Stylohyoid
Sternocleidomastoid
omohyoid
thyrohyoid
sternohyoid
thyroid
gland
Anterior Muscles of the Neck
– Sternocleidomastoid
• two sites of origin – clavicle
and sternum
• inserts onto mastoid process
• both together – flexes head
forward
• individually – laterally flexes
& rotates head to the
opposite side
Anterior Muscles of the Neck
• mylohyoid & geniohyoid form
the floor of the oral cavity
Muscles of the Vertebral Column
• covered by a superficial layer of
back muscles
– Trapezius
– Latissimus dorsi
• superficial and deep layers
• quite complex – multiple origins and
insertions + overlapping
• 5 Groups:
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Splenius group
Erector spinae group
Scalenes
Transversospinalis group
Segmental group
Superficial Muscles of the Vertebral Column
• Splenius group – together they
extend the head and neck,
individually they laterally flex and
rotate to the same side
• Splenius capitis
• Splenius cervicis
Superficial Muscles of the Vertebral Column
• Erector Spinae - spinal extensors
– comprised of capitis, cervicis, thoracic
and lumborum portions
– Spinalis – medial group of muscles
– capitis, cervicis and thoracis
groups
– Iliocostalis – lateral group of muscles
– cervicis, thoracis and lumborum
– Longissimus – in between these two
(intermediate)
– capitis, cervicis and thoracis
– lumborum portion fuses with
iliocostalis
Deep Muscles of the Vertebral Column
• Interconnect and stabilize the
vertebrae
• Scalenes – flexes and rotates
neck, used in deep inspiration
• Anterior
• Medial
• Posterior
• Transversospinal group –
extends the vertebral column and
rotates it to the opposite side
• Semispinalis – capitis, cervicis
and thoracis portions
• runs from transverse to spinous
processes
• Multifidus – below the ribcage
semispinalis is called mutifidis
Deep Muscles of the Vertebral Column
• Quadratus lumborum flexes the lumbar spine
• Segmental group – extends
and laterally flexes vertebral
column
• Interspinales – run
between spinous
processes
• Intertransversarii – run
between transverse
processes
The Oblique and Rectus Muscles
• Rectus abdominus
• rectus = “erect”
• partitioned into 4 sections by fibrous
“tendinous intersections”
The Oblique and Rectus Muscles
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3 Abdominal oblique muscles
– External oblique (down and in)
– Internal oblique (up and in)
– Transversus abdominis (side to side)
– Compress underlying organs
– together – flex the vertebral column
– singly - rotate the vertebral column to
the opposite side
-the oblique muscles are connected to
their opposite partners via an
aponeurosis
(broad, flat tendon)
-the 3 aponeuroses form an “envelope”
that encloses the rectus abdominus =
rectus sheath
The Diaphragm
The Pelvic Floor & Perineum
• pelvic diaphragm or floor = coccygeus & levator ani & external
anal sphincter
– found in the anal triangle- contains the anus
– supports pelvic viscera & resists increased abdominal pressure during
defecation, urination, coughing, vomiting, etc
– pierced by anal canal, vagina & urethra
• additional muscles lie superficial to the pelvic floor = perineal
muscles
– found in the urogenital triangle- contains the external genitalia
– also contains muscles – assist in the erection (male and female)
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Muscles of
the Pelvic
Floor
Musculoskeleton: Appendicular Division
• Appendicular skeleton: 126 bones
– Bones of upper and lower limbs
– Pectoral and pelvic girdles
» connect limbs to trunk
• Appendicular musculature
• originates or inserts on the appendicular
skeleton
• stabilizes or moves components of the
appendicular skeleton
• stabilizes pectoral girdle (i.e. shoulder joint)
• stabilizes pelvic girdle (i.e. hip joint)
• moves the upper and lower limbs
• grouped into 7 distinct groups:
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4 groups move the upper limb
3 groups move the lower limb
Muscles that move the pectoral girdle
• clavicle can be elevated or
depressed or stabilized
– subclavius muscle
• movements of the scapula
are quite complex
– adduction/retraction – rowing
– abduction/protraction – punching or
‘hunching’ of shoulders
– elevation – shrugging
– depression – pull-downs
– superior rotation – jumping jack
– inferior rotation – parallel bars
Muscles that move the pectoral girdle
• POSTERIOR MUSCLES:
• Trapezius muscle – one of the largest
muscles on the back
– affects position of pectoral girdle,
neck, head
-can perform a series of complex motions
-divided into clavo-, acromio- and spinosections (superior, medial and inferior
fibers)
-origin: occipital bone, C7 & all thoracic
vertebrae
-insertion – spine of scapula and lateral 1/3 of
clavicle
-superior fibers – elevate and superiorly rotate
scapula
-medial fibers – retract scapula
-inferior fibers – depress scapula
Muscles that move the pectoral girdle
• POSTERIOR MUSCLES
• Rhomboid muscles: major and minor
– adducts scapula
– origin: C7 to T5 vertebrae
– insertion: on medial border of scapula
• Levator scapulae muscle
– elevates scapula
– origin: C1 through C4
– insertion: medial border of scapula
(above the spine)
• ANTERIOR MUSCLES
• Serratus anterior muscle
– abducts scapula
– origin: first 9 ribs
– insertion: medial border of scapula
• Subclavius
– depresses the clavicle
• Pectoralis minor
– abducts scapula
– rotates it down (inferior)
– origin: ribs 3-5
– insertion: corocoid process of
scapula
Muscles that Move the Arm
• Deltoid
– can be divided into anterior, medial
and posterior fibers
– major arm abductor
– anterior fibers: flex and medially
rotate arm
– medial fibers: prime mover;
abduction of arm
– posterior fibers: extend and laterally
rotate arm
– origin: spine of scapula, acromion and
lateral 1/3 of clavicle
– insertion: deltoid tuberosity of
humerus
Muscles that Move the Arm
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Rotator Cuff muscles:
– surround and stabilize the glenohumeral
joint
– origin: bony fossae and inferior angle of
scapula
– insertion: lesser or greater tubercle of
humerus
– Supraspinatus
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abducts the arm
– Supscapularis
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rotates arm medially
– Infraspinatus
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adducts and rotates arm laterally
– Teres minor
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adducts and rotates arm laterally
Muscles that Move the Arm
• Coracobrachialis
– flexion and adduction at shoulder
– origin at corocoid process of scapula
– insertion on the humerus
• Pectoralis major muscle
– flexes arm shoulder
– adducts and medially rotates arm
– origin: clavicle, sternum and costal
cartilages
– insertion: greater tubercle of humerus
• Latissumus dorsi muscle
– extends arm at shoulder
– adducts and medially rotates arm
– origin: all lumbar vertebrae, sacrum and
coccyx
– insertion: intertubercular groove of
humerus
Summary: Muscle Actions at the Shoulder Joint
Abduction:
1. Deltoid (middle)
2. Supraspinatus
Flexion:
1. Pectoralis Major
2. Deltoid (anterior)
3. Coracobrachialis
Lateral Rotation:
1. Infraspinatus
2. Teres minor
3. Deltoid (posterior)
prime movers in bold
Adduction:
1. Latissimus dorsi
2. Pectoralis major
3. Coracobrachialis
4. Teres major
5. Teres minor
6. Infraspinatus
Extension:
1. Latissimus dorsi
2. Deltoid (posterior)
3. Teres major
4. Triceps brachii (long)
Medial Rotation:
1. Subscapularis
2. Pectoralis Major
3. Latissimus dorsi
4. Teres major
5. Deltoid (anterior)
Muscles that Move the Forearm
• 3 Flexors of the elbow joint:
– all insert either onto the radius or
the ulna
• 1. biceps brachii – “two heads” of
humerus
– long & short heads
– flexes elbow & supinates forearm
– origin: short head - corocoid process
of scapula; long head – scapula
(above glenoid cavity)
– insertion: radial tuberosity of radius
• 2. brachioradialis
– origin: humerus
– insertion: radius (styloid process)
• 3. brachialis
– major flexor of the elbow joint
– origin: humerus
– insertion: coronoid process of ulna
Muscles that Move the Forearm
• 4 Extensors of the elbow
joint:
– different origins – all insert
onto the olecranon process
• 1. triceps brachii – “three
heads” of humerus
– long, medial & lateral heads
– extends elbow
– origin: short & medial heads –
back of humerus; long head –
scapula (below glenoid cavity)
– insertion: olecranon process
• 2. anconeus
– 4th extensor of the elbow joint
– origin: lateral epicondyle of
humerus
Muscle that Pronate & Flex
• Pronator teres
– medial epicondyle to radius
so contraction turns palm
of hand down towards floor
• Flexor carpi muscles
– radialis
– ulnaris
• Flexor digitorum
muscles
– superficialis
– profundus
• Flexor pollicis
– longus
– brevis
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Muscles that Supinate & Extend
• Supinator
– lateral epicondyle of humerus to
radius
– supinates hand
• Extensors of wrist and fingers
– extensor carpi
– extensor digitorum
– extensor pollicis
– extensor indicis
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Intrinsic Muscles, Tendons and Ligaments of the
Hand
Retinaculum
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Tough connective tissue band that helps hold tendons in place
Flexor retinaculum runs from pisiform/hamate to scaphoid/trapezium
– overlies 10 tendons + median nerve
– flexor carpi radialis, pollicis longus, digitorum superioficialis & digitorum profundus
– carpal tunnel syndrome = painful compression of median nerve due to narrowing passageway
under flexor retinaculum
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Muscles of the pelvic girdle and
lower limbs
• Three groups
– Muscles that move the thighs
– Muscles that move the leg
– Muscles that move the foot and toes
Muscles that Move the Thigh at the Hip Joint
• muscles that move the thigh can perform multiple movements
– e.g. sartorius – “tailor muscle”
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hip flexion
lateral rotation of femur
flexion of knee
medial rotation of leg
• these muscles span the hip joint
– hip joint – another ball-in-socket joint capable of multiple planes of
motion
• movements at the hip joint
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abduction
adduction
flexion
extension
medial rotation
lateral rotation
circumduction
Muscles that Move the Thigh at the Hip Joint
• can categorize the muscles of the thigh & their movements
this way
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Medial compartment – hip adductors
Lateral compartment – hip abductors
Anterior compartment – hip flexors (knee extensors)
Posterior compartment – hip extensors & knee flexors
Gluteal region – hip extensors and abductors
Deep Gluteal region – lateral rotators
Muscles that Flex the Thigh
• 9 Hip flexors:
– these muscles also either adduct or
abduct the thigh
– iliopsoas – made up two muscles:
iliacus & psoas major
• major hip flexors
• origin – lumbar vertebrae and iliac fossa
• insertion – lesser trochanter of femur
– sartorius - longest muscle
• origin – anterior superior iliac spine
• insertion - tibia
– tensor fascia latae – also abducts the
thigh by pulling on its tendon; medially
rotates
• origin – iliac crest
• insertion – tibia by way of the iliotibial tract
or IT band
– rectus femoris – part of the quadriceps
– 3 adductors + pectineus
Muscles that Extend the Thigh
• 5 Hip extensors:
– originate from pelvis & sacrum and insert
into the femur, tibia and fibula
– some also laterally rotate the thigh
– 3 Hamstrings – also flexors of the knee
– hamstring part (lowest part) of adductor
magnus
– Gluteus maximus
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major hip extensor
extension and lateral rotation of hip
pulls on iliotibial tract
origin – iliac crest, sacrum and coccyx
insertion – gluteal tuberosity on femur
Muscles that Adduct the Thigh
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5 adductors - adducts hip
– originate from pubis and insert onto
the linea aspera of femur
– Adductor magnus
– biggest of the adductors
– divided into an adductor part
and a hamstring part
– hamstring part also extends the
hip
– adductor part also flexes the hip
– Adductor brevis
– Adductor longus
– Pectineus
– pectineus, adductor longus and
brevis are also hip flexors
– Gracilis
– also flexes the knee
Muscles that Abduct the Thigh
• 4 Hip Abductors:
• originate from pelvis and insert onto the
greater trochanter of femur
• Gluteus Medius
• origin – iliac crest
• Gluteus Minimus
• origin - anterior gluteal line
• Sartorius
• Tensor fascia latae
Muscles that Rotate the Thigh
• 9 lateral rotators of the thigh:
• most insert onto the greater trochanter
• Piriformis
• Obturator internus
• Obturator externus
• Superior gemellar
• Inferior gemellar
• Quadratus femoris
• Gluteus maximus
• Adductor magnus
• Sartorius
• 3 medial rotators:
• Gluteus medius and minimus –when hip
is extended
• Adductor brevis
• TFL
Summary: Muscle Actions at the Hip Joint
Abduction:
1. Gluteus medius
2. Gluteus minimus
3. Tensor fascia latae
4. Sartorius
Flexion:
1. Iliopsoas
2. 3 adductors
3. Pectineus
4. Sartorius
5. Rectus femoris
6. Gracilis
Lateral Rotation:
1. Adductor magnus (hamstring)
2. Gluteus maximus
3. Sartorius
4. 2 Obturators
5. 2 Gemellars
6. Quadratus femoris
7. Piriformis
prime movers in bold
Adduction:
1. Adductor longus
2. Adductor brevis
3. Adductor magnus
4. Pectineus
Extension:
1. Gluteus maximus
2. Adductor magnus (ham.)
3. Biceps femoris (long head)
4. Semimembranosus
5. Semitendinosus
Medial Rotation:
1. Gluteus medius
2. Gluteus minimus
3. Adductor brevis
4. Tensor fascia latae
Muscles that Extend the Leg
• 4 Extensor muscles of the leg or
Quadriceps femoris – “four heads” of the
femur
– for leg extension at the knee joint
– found on the anterior and lateral
surfaces of the thigh
– originate from the pelvis (rectus
femoris) and femur ( 3 vastus muscles)
– all insert onto the tibial tuberosity
on the tibia via the patellar ligament
– Rectus femoris – because of its origin on
the anterior inferior iliac spine – also a hip
flexor
– Vastus lateralis
– Vastus medialis
– Vastus intermedius
Muscles that Flex the Leg
•
11 Flexors of the leg
• for flexion of the knee joint
• some also extend the hip (hamstrings)
• found in the posterior compartment of the
thigh
• originate from the pelvis and insert onto
the tibia and fibula
• 3 Hamstrings: all originate on the ischial
tuberosity
– Biceps femoris – 2 heads
– Semimembranosus
– Semitendinosus
–
•
•
•
common insertion with
semimembranosus onto tibia
3 Adductor muscles
Sartorius
Gracilis
Muscles that Flex the Leg
•
11 Flexors of the knee
• Gastrocnemius
• gastroc = belly
• kneme = leg
• also plantar flexes foot with soleus
• origin – femoral condyles
• insertion – calcaneus via the Achilles tendon
• Popliteal muscle
– poplit = back of knee
– Unlocks knee joint
– origin – lateral condyle of femur
– insertion - tibia
• Plantaris
• weak knee flexor
Muscles that Plantar Flex the Foot
• Gastrocnemius, soleus and plantaris are also plantarflexors of the
foot
• Tibialis posterior
– also inverts the foot (turn in)
• Fibularis/Peroneus
– longus and brevis
– also evert the foot (turn out)
• Flexor digitorum and hallicis longus
– also curl the toes
Muscles that Dorsiflex the Foot
• 4 muscles are responsible for dorsiflexion of foot (toes up)
• Tibialis anterior
– also inverts the foot
• Fibularis/Peroneus tertius
– everts the foot with the other
2 fibularis muscles
• Extensor digitorum and hallicis longus