Download Muscular System Notes - Mater Academy Charter Middle/ High

MUSCULAR SYSTEM – Part 2
MUSCLE TYPES:
3 types:
a. Skeletal
b. Cardiac
c. Smooth
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Skeletal and smooth muscle cells are elongated and are called muscle fibers.
Have the ability to shorten or contract
The cytoplasm is called sarcoplasm.
1)
Skeletal Muscles (Striated Muscles)
 About 630 in the human body
 Are formed by skeletal muscle fibers. The cells are cigar-shaped and multinucleated.
 Fibers appear to be striped and are bundle together by connective tissue.
 They are volunteer muscles.
 Each muscle fiber is enclosed by a connective tissue sheath called endomysium.
 Several sheathed muscle fibers are then wrapped by a fibrous membrane called perimysium, which will form a
bundle of fibers called a fascicle.
 Many fascicles bound together by connective tissue called epimysium that will covers the entire muscle and will
blend into either tendons or aponeuroses.
 Tendons are cord like tough collagenic fibers.
2)
Smooth Muscles – (visceral, non-striated, involuntary)
 Has no striation
 Found mainly in walls of hollow visceral organs, (stomach, urinary bladder, respiratory passages, blood vessels)
Cells are spindle-shaped with a single nucleus.
 They arranged in sheets or layers.
3)
Cardiac Muscle
 Striated muscle. Involuntary
 Fibers are cushioned by soft connective tissue, arranged in spiral or figure 8-shaped bundles.
 Cells are joined together by special junctions called intercalated discs.
 Cardiac activity is controlled by the “pacemaker”, but also can be stimulated by the nervous system.
MUSCLE FUNCTIONS:
1.
Produces Movement – by muscle contraction. Responsible for all locomotion and manipulation.
2.
3.
4.
Maintain Posture – by constantly making small adjustments.
Stabilizing Joints. – by means of muscle and tendons.
Generating Heat – Is a by-product of muscle activity (some of the release ATP energy escapes as heat)
TYPES OF MUSCLE MOVEMENTS:
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Bones are attached at no less than 2 points.
Origin: is attached to the immovable or less movable joint.
Insertion: attached to the movable bone. When the muscle contracts, the insertion moves toward the origin.
Body movements occurs when muscles contract across joints.
The type of movement depends on the mobility of the joint and on where the muscle is located in relation to the
joint.
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Most common types of body movements:
1.
Flexion – generally is the sagittal plane that decreases the angle of the joint and bring two bones closer
together.
2. Extension – opposite to flexion. It is the movement that increases the angle, or the distance between two
bones or pars of the body. Hypertension – if the extension is greater than 180 degrees (as when you tip your
head so that your chin points toward the ceiling)
3. Rotation – movement of a bone around its longitudinal axis. Ex. Movement of the atlas around the dens of the
axis ( saying no)
4. Abduction – moving a limb away (generally on the frontal plane) from the midline or median plane of the body
5. Adduction – opposite of abduction. Movement of the limb towards the body midline.
6. Circumduction – combination of flexion, extension, abduction and adduction. Ex shoulders. The proximal end
of the limb is stationary, and its distal end moves in a circle.
7. Dorsiflexion and Plantar Flexion – Up and down movements of the foot at the ankle.
 Dorsiflexion – lifting that foot so that its superior surface approaches the shin.
 Plantar Flexion – depressing the foot (pointing the toes)
8. Inversion and Eversion
 Inversion – turn the sole medially
 Eversion – turn the sole laterally
9. Supination and Pronation – movement of the radius around the ulna
 Supination (turning backward) – forearm rotates laterally so the palm faces anteriorly and the
radius and ulna are parallel.
 Pronation (turning forward) – forearm rotates medially so that the palm faces posteriorly. Brings
the radius across the ulna so that the two bones form an X
10. Opposition – movements of your thumb to touch the tips of the other fingers on the same hand.
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Interactions of skeletal muscles in the body:
 Muscles can push but only pull as they contract.
 Body movements are arranged in such a way that whatever one muscle or group of muscles can do, other
muscles can reverse.
 Prime Mover – muscle that has the major responsibility for causing a particular movement.
 Antagonist – muscle that oppose or reverse a movement.
 When a prime mover is active, its antagonist is stretched and relaxed
 Synergist – help prime moves by producing the same movement or by reducing undesirable movements
 Fixators – are specialized synergists. They hold a bone still or stabilize the origin of a prime mover so all
the tension can be used to move the insertion bone.
NAMING SKELETAL MUSCLES:
1.
Direction of Fibers – some muscles are named in reference to some imaginary line, usually the midline of the
body.
a. Rectus (straight) – fibers parallel to the midline
b. Oblique – fibers diagonal to; on an angle to midline
c. Transverse – fibers perpendicular to midline.
2.
Size – with respect to other muscles in the same group
a. Maximus – large ex. Gluteus Maximus)
b. Medius – intermediate
c. Minimis – smallest
d. Brevis – short
e. Longus – long
f. Vastus – huge
g. Latissimus – widest; very broad
h. Major – large
i. Minor – small
j. Gastrocnemius – big belly
k. Magnus- large
3.
Location – some muscles are name for the bone with which they are associated.
a. Temporalis and Frontalis muscles overlie the same named skull bones
b. Brachialis – arm “brachial”
c. Gluteus – buttock “gluteal”
d. Oris – mouth “oral”
e. Oculi – eye “ocular”
f. Mandibular – mandible
g. Femoris – femur thigh
4.
Muscle Origen and Insertion (heads)
a. Biceps – 2 origins or head
b. Triceps – 3 origins or head
c. Quadriceps – 4 origins or heads
5.
Location of the muscle origin and insertion – with respect to a body part. Ex. Sternocleidomastoid has its
origin in the sternum (sterno) and clavicle (cleido), and insert on the mastoid process of the temporal bone.
Shape – some muscles have a distinctive shape that help to identify them. Ex. Deltoid muscle (deltoid =
triangular)
Action/Function – muscles may be named for their action ex. Flexor, extensor adductor, ex. Adductor muscles
of the thigh all bring adduction.
6.
7.
ARRANGEMENT OF FASCICLES:
Skeletal muscles consist of fascicles, but fascicles arrangement vary, producing muscles with different structures or pattern.
1. Circular muscles – when fascicles are arranged in concentric rings.
a. Typically found surrounding external body openings which they close by contracting.
b. Known as sphincters ex. Orbicularis oris
2. Convergent muscles – fascicles converge toward a single insertion tendon. They are triangular or fan shaped.
Ex. Pectoralis major
3. Parallel muscles – fascicles run parallel to the long axis of the muscle. Ex Sartorius
a. A similar type are the fusiform muscles where the fibers have a spindle-shaped arrangement with an
expanded belly ex. Biceps brachii.
4. Pennate (feather) muscles – short fascicles attach obliquely to a central tendon.
a. Unipennate – fascicles insert in only one side of the tendon ex. Extensor digitorium longus
b. Bipennate – inserts into opposite sides of the tendon ex. Rectus femoris
c. Multipennate – Inserts into several different sides ex. Deltoid
SKELETAL MUSCLES
HEAD AND NECK:
HEAD MUSCLES
FACIAL MUSCLES:
1.
2.
3.
4.
5.
6.
7.
Frontalis – covers the frontal bone
 Raise eyebrows and to wrinkle forehead.
Occipitalis – at posterior end of the cranial aponeurosis
Epicranius – raises eyebrow
Orbicularis Oris – around the lips (kissing Muscle). Closes the mouth, protrudes the lips.
Orbicularis oculi – closes the eyelid
Buccinator – runs horizontally across the cheek.
 Insert into the orbicularis oris.
 Flattens the cheek (as in whistling, blowing a trumpet)
 Compresses the cheek to hold the food between teeth when chewing.
Zygomatic – corner of mouth to cheek bone (zygomatic bone)
 Smiling muscle ( raises the corners of your mouth upward )
CHEWING MUSCLES:
1.
2.
3.
Buccinator – runs horizontally across the cheek.
 Compress the cheek to hold the food between teeth when chewing.
Masseter –covers the angle of the lower jaw.
 Runs from the zygomatic process to the mandible
 Closes the jaw by elevating the mandible. It is the strongest muscle based on its weight.
 With all the muscles of the jaw working together it can close the teeth with a force as great as 55 pounds
on the incisors or 200 pounds on the molars.
Temporalis – fan shaped overlying the temporal bone.
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Inserts into the mandible
Acts as a synergist of the masseter in closing the jaw.
NECK MUSCLES: Move head and shoulder girdle.
1.
2.
Platysma – single sheet-like muscle.
 Covers the anterolateral neck.
 Originates: from the connective tissue covering of the chest muscles.
 Inserts: into the area around the mouth.
 Function: pulls the corners of the mouth inferiorly (producing downward sag of the mouth)
Sternocleidomastoid – at each side of the neck.
 Two headed muscle. One head arises from the sternum and the other from the clavicle.
 Head fuses together and inserts into the mastoid process of the temporal bone.
 Action: Flex your neck –“ prayer muscles” (when both contract together)
If just one contracts – head rotates toward opposite site.
 If muscle is injured at birth develops spasm and baby has torticollis or wryneck.
TRUNK MUSCLES
Includes:
a) Those that moves the vertebral column ( most are posterior antigravity muscles)
b) Anterior thorax muscles – move the ribs, head and arms
c) Muscles of the abdominal wall – help to move the vertebral column. Forms the muscular girdle of the
abdominal wall.
ANTERIOR MUSCLES:
1.
2.
3.
Pectoralis Major
 Large fan shaped muscle
 Covers upper part of the chest.
 Origin: sternum, shoulder girdle, and the first 6 ribs.
 Inserts: proximal end of humerus.
 Forms the anterior wall of the axilla
 Action: Adduct and Flex the arm.
Intercostals: two types
 External : rise ribcage for breathing
 Internal: depress rib cage to move air out (expiration)
 Deep muscles found between the ribs.
Muscles of the Abdominal Girdle:
 Rectus Abdominis; External and Internal Obliques; and Transversus Abdominis
 Form a “natural girdle” that reinforces the body trunk.
a. Rectus Abdominis – (pair)
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b.
c.
d.
Most superficial muscle of the abdomen. It is protected by an aponeurosis,
Run from the pubis to the rib cage.
Function: Flex vertebral column. Compress abdominal content during defecation and childbirth.
Involved in force breathing.
External Oblique:
 Paired superficial muscles
 Make up the lateral walls of the abdomen.
 Fibers run downward and medially from the last eight ribs and inserts into the ilium.
 Function: Flex vertebral column and rotate the trunk and bend it laterally.
Internal Oblique:
 Paired muscles deep to the external oblique.
 Fibers runs at right angle to those of the external oblique.
 Origin: ilia crest
 Insert: last 3 ribs
 Functions: same as external oblique
Transversus Abdominis:
 Deepest muscle of the abdominal wall.
 Fibers runs horizontally across the abdomen.
 Origin: lower ribs and iliac crest
 Inserts: Pubis
 Function: compresses the abdominal content.
POSTERIOR MUSCLES:
1. Trapezius – most superficial of the posterior neck and upper trunk.
 Origin: Occipital bone to T12
 Insertion: Scapular spine and clavicle.
 Function: extend the head (antagonist of sternocleidomastoid)
o Elevates, depress, adduct and stabilize the scapula
2.
3.
4.
Latissimus Dorsi:
 Large, flat muscle pair that covers the lower trunk.
 Origin: lower spine and iliac crest
 Inserts; humerus
 Function: extends & adducts humerus.
Erector Spine:
 Function: prime mover. Back extension (erector)
 Origin: iliac crest, ribs 3-12 and vertebrae
 Insertion: ribs, thoracic and cervical vertebrae.
Deltoid:
 Fleshy, triangle muscle.
 Forms rounded shape of shoulder
 Origin: scapular spine and clavicle
 Insertion: humerus – deltoid tuberosity
 Function: abducts the humerus
 Favorite area for injections
MUSCLES OF THE UPPER LIMB
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Muscles of the humerus – act on the forearm.
Anterior arm muscles. Causes elbow flexion.
2.
3.
4.
5.
Biceps Brachii:
 Origin: Scapula
 Insertion: Radius
 Function: Flexes elbow and supinates forearm.
Brachialis:
 Origin: Humerus
 Insertion Ulna
 Function: flexes elbow
Brachioradialis:
 Found in the forearm
 Origin: Humerus
 Insertion Forearm
Triceps Brachii:
 Only posterior muscle of forearm
 Has 3 heads
 Origin: Shoulder & humerus
 Insertion: Ulna
 Functions: extends elbow
Flexor Carpi Ulnaris:
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6.
Origin: Humerus and Ulnar head: olecranon and posterior border of ulna
Insertion: Pisiform bone, hook of hamate bone, and 5th metacarpal bone
Function: Flexes and adducts hand (at wrist)
Flexor Carpi Radialis:
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Origin: Medial epicondyle of humerus
Insertion: Base of 2nd and 3rd metacarpal
Function: Flexes and abducts hand (at wrist)
MUSCLES OF THE LOWER LIMB (Thigh)
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Moves hip, knee and foot joints.
Largest, strongest muscles of the body.
Specialized for walking, and balancing the body.
Help hold the body upright against the pull of gravity.
MUSCLES CAUSING MOVEMENT AT THE HIP JOINT:
1.
2.
3.
4.
Gluteus Maximus – greatest (largest) muscle in the body.
 Superficial muscle of the hip.
 Forms most of the flesh of the buttock. It is the chief antigravity muscle.
 Functions: Powerful hip extensor – bring thigh in straight line with the pelvis. It is the most important
muscle in extending the hip (jumping, climbing stairs). Keeps the trunk of the body in erect position.
 Origin: Sacrum and Iliac bone
 Insertion: Femur (gluteal tuberosity)
Gluteus Medius
 Extends from ileum to femur, beneath the gluteus maximus
 Function: hip abductor, steading the pelvis when walking.
 Site for injections.
Iliopsoas
 2 muscles: ILIACUS and PSOAS MAJOR
 Runs from Iliac bone and lower vertebrae to lesser trochanter of the femur.
 Function: Prime mover of hip flexion. Keeps upper body from falling backwards when standing erect.
Adductor Muscles
 Muscle mass at the medial side of each thigh.
 Origins: Pelvis
 Insertion: Proximal Femur
 Function: Flex knee. Extends hip
MUSCLES CAUSING MOVEMENT AT THE KNEE JOINT:
1. Hamstring Group – posterior thigh
a.
b.
c.
2.
3.
Biceps femoris
Semimembranosus
Semitendiniosus
 Tendons can be felt at the back of the knee
 Function: Flex knee. Extend hip
 Origin: Ischial Tuberosity
 Insertion: Both sides of proximal tibia
o Biceps Femoris at the head of the fibula.
Sartorius – longest muscle
 Runs obliquely across the thigh
 Origin: anterior iliac crest
 Inserts: medial side of tibia
 Function: Thigh Flexor
o Synergist to bring about the cross-legged position
Quadriceps Group:
a. Rectus Femoris –
 Origin: Pelvis
 Crosses two joints; hip & knee
 Function help to flex the hip
b. Vastus Lateralis – Origin: Femur
c. Vastus Medialis – Origin: Femur
d. Vastus Intermedius – under the Rectus Femoris
 All of them Insert at the Tibial Tuberosity via the Patellar Ligament
 Function Extend the knee powerfully (as when kicking a football).
 Vastus Lateralis and Rectus Femoris can be a place for injection in infants because of poorly develop
gluteus muscles.
MUSCLES CAUSING MOVEMENT AT THE ANKLE & FOOT:
1.
2.
3.
4.
Tibialis Anterior
 Superficial of anterior leg.
 Origin: Upper Tibia, then, parallel to anterior crest as it runs to the TARSAL BONE and First Metatarsal
inserting it with a long tendon.
 Function: Dorsiflexion and Inverts the foot.
Extensor Digitorum Longus
 Origin: Lateral Tibial Condyle & proximal Fibula
 Inserts: phalanges of toes 2 through 5
 Function: Plantar flexes. Evert the foot
Fibularis Muscles – lateral part of the leg.
 Fibularis Longus
 Fibularis Brevis
 Fibularis Tertius
 All of them have their:
 Origin: Fibula
 Insertion: Metatarsal bones
 Function: Plantar Flexion and Evert the foot
Gastrocnemius
 2 bellied muscles that forms the curved calf of the posterior leg.
 Each head arises from each side of the distal femur and inserts through the large Calcaneal (Achilles)
Tendon into the heel (Calcaneus bone) of the foot.
 If tendon is cut – walking is very deficient, foot drags because heel cannot be lifted.
5.
Soleus
 Under Gastrocnemius (calf muscle)
 Origin: Tibia and Fibula
 Inserts: Forms part of the calcaneal tendon or Achilles Tendon (together with the Gastrocnemius)
inserting into the heel of the foot (calcaneus).
 Function: It can pull with the greatest force. It is considered a very powerful muscle along with the
calf muscles because it pulls against the force of gravity. Strong plantar flexor of ankle. (used in
walking, running, dancing)
 Maintains standing posture (if not body will fall forward).
What is the strongest muscle in the human body?
Since there are different ways to measure strength, (absolute strength – maximum force; dynamic strength – repeated
motions; elastic strength – exert force quickly; and strength endurance - withstand fatigue) The following are the names of muscles
deemed the strongest based on various definitions of strength.
1.
2.
3.
4.
5.
6.
7.
External Muscle of the Eye – The muscles of the eye are constantly moving to readjust the position of the eye to
maintain a steady fixation point. However, they are subject to fatigue. In an hour of reading a book, they eye make
nearly 10,000 coordinated movements.
Gluteus Maximus.
Heart – It is the hardest working muscle. It pumps out 2 ounces of blood at every heartbeat. Daily the heart pumps
at least 2,500 gallons of blood.
Masseter.
Muscle of the Uterus – Found in the lower pelvic region. Its muscles are strong because they contract to push a
baby through the birth canal.
Soleus.
Tongue – It is made up of groups of muscles and like the heart it is always working. It helps in the mixing process of
foods. It binds and contorts itself to form letters. The tongue contains linguinal tonsils that filter out germs. Even
when a person sleeps, the tongue is constantly pushing saliva down the throat.