Download MUSCULAR SYSTEM

6-1
MUSCULAR SYSTEM
includes
•
_______ skeletal muscles
•
______________________ / ________________________
(connect muscle to bone)
(broad tendinous sheets)
functions
•
•
•
•
•
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muscle tissue
4 basic properties
______________________
nerve impulses / hormones → triggers
muscle contraction
______________________
shortening of muscle tissue → exerts
contractile proteins =
+
______________________
can be
______________________
after stretching →
to original length due to protein
which causes
6-2
3 types of muscle tissue
____________________*
____________________
______________________
(review the structure / properties of these 3 tissues in the lab!
NOTE: *muscular system is skeletal muscle only
muscle structure
muscles =
(* c.t. of epimysium and perimysium contain
NOTE:
individual muscles or groups of muscles may be surrounded by a
______________ (encloses muscles, separates muscles from other
structures) → forms _____________________
THINK!
what is fasciitis?
CONSIDER: How does a tendon attach to a bone?
)
6-3
Fascicle arrangement
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fascicle arrangement
and reflects
______________________
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fascicles
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muscle can
eg.
_______________________ (“feathered”)
attached to
•
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many muscle fibers →
eg.
___________________________ (“fan-shaped”)
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widely spread fascicles
of pull
•
eg.
___________________________
•
fascicles arranged in a circle →
•
guard
eg.
toward a common tendon
BUT
6-4
SKELETAL MUSCLE MICROANATOMY
muscle cell =
skeletal muscle fibers
•
(form by fusion of many embryonic cells)
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nerve ending contacts muscle cell at
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muscle cell membrane →
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cytoplasm →
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sarcolemma penetrates cytoplasm to form
tubules) → spread electrical impulse (action potential)
•
special endoplasmic reticulum →
(stores
ions)
•
contractile organelles =
diagram of muscle cell or ‘fiber’
(bundles of
(transverse
+
)
6-5
myofibril
of muscle fibers
•
•
contains 2 kinds of filaments (made of
)
________________________ →
________________________ →
•
arranged into contractile units →
(sarcomeres shorten when contraction occurs)
NOTE:
I bands =
actin only (thin filaments, light in colour)
A bands =
myosin only (heavy filaments, dark in colour)
H bands =
space between ends of actin filaments (hole in middle of
sarcomere) → disappears in contracted muscle
Z lines =
delineate endz of sarcomere (attachment of titin here)
THE REMAINDER OF THE NOTES ARE DEVOTED TO THE MUSCLES OF THE BODY. YOU ARE
RESPONSIBLE FOR KNOWING THE NAME AND MAIN ACTION(S) OF EACH MUSCLE STUDIED. YOU
SHOULD ALSO BE ABLE TO DEMONSTRATE THESE ACTIONS (ie. in a physical training / exercise
context)
6-6
MUSCLES (anterior surface)
6-7
MUSCLES (posterior surface)
6-8
MUSCLES OF THE HEAD AND NECK
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facial muscles make our faces expressive - frowns, smiles, winks, etc.; neck
muscle move the head (most insert onto the skin and arise either on the skull
or on the fascia over facial muscles)
orbicularis oculi, orbicularis oris, zygomaticus major, levator labii
superioris, depressor labii inferioris, platysma,
sternocleidomastoid, parietotemporalis, occipitofrontalis
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muscles of mastication act on the temporomandibular joint
masseter
•
swallowing muscles (not shown in this diagram) act on the hyoid (the
suprahyoid group elevate it when swallowing; the infrahyoid group depress it,
i.e. return it to its usual position).
6-9
AXIAL MUSCLES OF THE ANTERIOR TRUNK
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the abdominal muscles function to flex or rotate the vertebral column and to
compress the abdomen
external oblique, internal oblique, transverse abdominis,
rectus abdominis
Note the linea alba and 4 tendinous inscriptions of the rectus abdominis; these
sheets of dense regular connective tissue are formed by the fusion of the
aponeuroses of the abdominal muscles
•
the respiratory muscles function in inhalation and exhalation
internal intercostals, external intercostals, diaphragm (not shown)
MUSCLES OF THE VERTEBRAL COLUMN
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these muscles function to flex or extend
the vertebral column, or to flex the vertebral
column laterally when the muscles on only
one side of the vertebral column contract
erector spinae group,
quadratus lumborum
multifidus
6 - 10
MUSCLES OF THE SHOULDER AND POSTERIOR TORSO
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all of the following muscles move the scapula
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the purpose of the scapulae is to enable the arm to move smoothly and with full
range of motion while maintaining stability at the shoulder joint.
trapezius muscle, serratus anterior, rhomboideus major/minor, levator
scapulae, (pectoralis minor not shown)
NOTE: The scapula connects to the shoulder girdle in 4 ways. Only one of those ways
is bone to bone, at the acromioclavicular joint. The 3 other connections are via muscle.
The scapula connects to the humerus or upper arm bone with muscle, it connects to the
rib cage with muscle and it connects to the spine with muscle. It is this characteristic – a
lot of muscular connection and very little bone connection - that provides the shoulder
joint with a high degree of mobility.
6 - 11
MUSCLES THAT MOVE THE ARM AT THE SHOULDER JOINT
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all of the following muscles move the humerus
deltoid, pectoralis major, coracobrachialis, latissimus dorsi, teres major,
supraspinatus,* infraspinatus,* teres minor,* subscapularis,*
*rotator cuff group (the tendons of these 4 muscles form part of the capsule that
encloses the shoulder joint; they function to support the shoulder during rotational
movements) HINT: “SITS”
6 - 12
MUSCLES THAT MOVE THE FOREARM / WRIST / FINGERS
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the following muscles move the forearm at the elbow
biceps brachii, brachialis, brachioradialis, triceps brachii, pronator teres
supinator
•
the following muscles move the hand at the wrist
flexor carpi, extensor carpi
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the following muscles move the fingers
flexor digitorum, extensor digitorum
NOTE: The muscles of the forearm flex and extend the hand and the fingers. The
tendons that cross the wrist are enclosed in tendon sheaths. Inflammation of these
tendon sheaths can irritate the median nerve resulting in carpal tunnel syndrome
6 - 13
MUSCLES THAT MOVE THE LEG AT THE HIP JOINT
•
the gluteal group of muscles includes
gluteus maximus, gluteus medius, gluteus minimus tensor fasciae latae
(TFL)
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the adductor group of muscles includes
adductor brevis, adductor longus, adductor magnus, gracilis
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the hip flexor group of muscles includes
iliopsoas (iliacus + psoas major), sartorius
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the lateral rotator group of muscles includes:
obturator, piriformis (gemelli not shown)
NOTE: the iliotibial band / tract is a long tendinous tract that is a common insertion for
the gluteus maximus and the tensor fasciae latae; it crosses both the knee and hip joint
and helps to stabilize the leg laterally
6 - 14
MUSCLES THAT MOVE THE LEG AT THE KNEE JOINT
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the hamstring group of muscles includes
biceps femoris, semimembranosus, semitendinosus
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the quadriceps group of muscles includes
rectus femoris, vastus intermedius, vastus lateralis, vastus medialis
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the sartorius crosses both the hip and knee joint and is used when you ’cross
your legs’ . It also assists in lateral rotation of the tibia which ‘locks’ the knee
when standing; the popliteus ‘unlocks the knee when flexion at this joint is
initiated
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the popliteus functions to ‘unlock the knee’ when flexion at this joint is initiated
6 - 15
MUSCLES THAT MOVE THE FEET AND TOES:
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muscles that move the foot at the ankle joint include
tibialis anterior, gastrocnemius, fibularis, soleus, tibialis posterior
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muscles that move the toes include
extensor digitorum, flexor digitorum