Chapter 11 Flashcards
Muscular system
The voluntarily controlled muscles of your body.
Origin
The attachment of a muscle’s tendon to the stationary bone.
Insertion
The attachment of the muscle’s other tendons to the moveable bone.
The origin is usually ______ and the
insertion ______; the ______ is usually pulled toward the ______.
Proximal; distal; insertion; origin
Belly actions
The fleshy portion of muscle between tendons.
Reverse muscle action (RMA)
The capability of certain muscles to reverse actions during specific movements of the body; therefore, the positions of the origin and insertion of a specific muscle are switched.
Lever
A rigid structure that can move around a fixed point.
A lever is acted on at two different points by two different forces which are ______ and ______.
Effort; load
Effort
Causes movement; force exerted by muscular contractions.
Load
AKA resistance; opposes movement; the weight of the body part that is moved or some resistance that the moving body part is trying to overcome (Eg. Such as the weight of a book you might be picking up).
_______ occurs when the ______ applied to the bone at the ______ exceeds that ______.
Motion; effort; insertion; load
Fulcrum
A fixed point.
Mechanic advantage
When the load is closer to the fulcrum and the effort is farther from the fulcrum, only a relatively small effort is required to move a large load over a small distance (Eg. Compare chewing something hard (the load) with your front teeth to chewing it with the teeth in the back of your mouth. It is much easier to crush the hard food item with the back teeth because they are closer to the fulcrum (the jaw or temporomandibular joint) than are the front teeth).
Mechanical disadvantage
When the load is farther from the fulcrum and the effort is applied closer to the fulcrum, a relatively large effort is required to move a small load (but a greater speed) (Eg. Compare chewing something hard (the load) with your front teeth to chewing it with the teeth in the back of your mouth. It is much easier to crush the hard food item with the back teeth because they are closer to the fulcrum (the jaw or temporomandibular joint) than are the front teeth).
First-class levers
The fulcrum is between the effort and the load. Scissors and seesaws are examples of first-class levers. A first-class lever can produce either a mechanical advantage or a mechanical disadvantage depending on whether the effort of the load is closer to the fulcrum - Eg. Think of an adult and a child on a seesaw - if the effort (child) is farther from the fulcrum than the load (adult), a heavy load can be moved, but not very far or fast. If the effort is closer to the fulcrum than the load, only a lighter load can be moved, but it moves far and fast. There are few first-class levers in the body. One example is the lever formed by the head resting on the vertebral column. When the head is raised, the contraction of the posterior neck muscles provides the effort, the joint between the atlas and the occipital bone (atlanto-occipital joint) forms the fulcrum, and the weight of the anterior portion of the skull is the load.
Second-class levers
The load is between the fulcrum and the effort. These kind of levers operate like a wheel barrow. They always produce a mechanical advantage because the load is always closer to the fulcrum than the effort. This arrangement sacrifices speed and range of motion for force; this type of lever produces the most force. This class of lever is uncommon in the human body. An example is standing up on your toes. The fulcrum is the ball of the foot. The load is the weight of the body. The effort is the contraction of the muscles of the calf, which raise the heel off the ground.
Third-class levers
The effort is between the fulcrum and the load. These kinds of levers operate like a pair of forceps and are the most common levers in the body. Third-class levers always produce a mechanical disadvantage because the effort is always closer to the fulcrum than the load. In the body, this arrangement favours speed and range of motion over force. The elbow joint, the biceps brachii muscle, and the bones of the arm and forearm are one example of a third-class lever. As we have seen, in flexing the forearm at the elbow, the elbow joint is the fulcrum, the contraction of the biceps brachii muscle provides the effort and the weight of the hand and forearm is the load.
Fascicles
Bundles of skeletal muscle fibers (cells) within a muscle. Within a fascicle, all muscle fibers are parallel to one another. The fascicles, however, may form one of five patterns with respect to the tendons.
What are the five patterns of fascicles?
- Parallel
- Fusiform (spindle-shaped, narrow towards the ends and wide in the middle)
- Circular
- Triangular
- Pennate (shaped like a feather)
Parallel
Fascicles parallel to longitudinal axis of muscle; terminate at either end in flat tendons.
Fusiform
Fascicles nearly parallel to longitudinal axis of muscle; terminate in flat tendons; muscle tapers towards tendon, where diameter is less than at belly.
Circular
Fascicles in concentric circular arrangements form sphincter muscles that enclose an orifice (opening).
Triangular
Fascicles spread over broad area converge at thick central tendon; gives muscle a triangular appearance.
Pennate
Short fascicles in relation to total muscle length; tendon extends nearly entire length of muscle; includes unipennate, bipennate, and multipennate.
Prime mover
AKA agonist; contracts to cause an action; usually located on the opposite side of the bone or joint as the antagonist; can switch roles with the antagonist for different movements (Eg. In the process of flexing the forearm at the elbow, the biceps brachii is the prime mover).
Antagonist
Stretches and yields to the effects of the prime mover; usually located on the opposite side of the bone or joint as the prime mover; can switch roles with the prime mover for different movements (Eg. In the process of flexing the forearm at the elbow, the triceps brachii is the antagonist).
Synergists
Contract and stabilize intermediate joints (Eg. Muscles that flex the fingers (prime movers) cross the intercarpal and radiocarpal joints (intermediate joints). If movement at these intermediate joints were unrestrained, you would not be able to flex your fingers without flexing the wrist at the same time. Synergistic contraction of the wrist extensor muscles stabilizes the wrist joint and prevents unwanted movement, while the flexor muscles of the fingers contract to bring about the primary action, efficient flexion of the fingers. Synergists are usually located close to the prime mover).
Fixators
Stabilize the origin of the prime mover so that the prime mover can act more efficiently. Fixators steady the proximal end of a limb while movements occur at the distal end (Eg. The scapula is a freely moveable bone that serves as the origin for several muscles that move the arm).
Compartment
Group of skeletal muscles, their associated blood vessels, and associated nerves, all of which have a common function (Eg. In upper limbs, flexor compartment muscles are anterior, and extensor compartment muscles are posterior).
List the two scalp muscles (occipitofrontalis)
- Frontal belly
- Occipital belly
What is the action of the frontal belly?
Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise.
What is the action of the occipital belly?
Draws scalp posteriorly.
List the three mouth muscles (that you need to know)
- Orbicularis oris
- Zygomaticus major
- Buccinator
What is the action of the orbicularis oris?
Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech.
What is the action of the zygomaticus major?
Draws angle of mouth superiorly and laterally, as in smilling.
What is the action of the buccinator?
Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication (chewing) by keeping food between the teeth (and not between the teeth and cheeks).
What is the orbit and eyebrow muscle (that you need to know)?
Orbicularis oculi
What is the action of the orbicularis oculi?
Closes eye.
The muscles that move the mandible (lower jawbone) at the temporomandibular joint (TMJ) are known as the ______.
Muscles of mastication (chewing)
What are the three pairs of muscles involved in mastication that are powerful closers of the jaw and account for the strength of the bite?
- Masseter
- Temporalis
- Medial pterygoid
What is the origin, insertion, and action of the masseter?
Origin: maxilla and zygomatic arch.
Insertion: angle and ramus of mandible.
Action: elevates mandible, as in closing the mouth.
What is the origin, insertion, and action of the temporalis?
Origin: temporal bone.
Insertion: coronoid process and ramus of mandible.
Action: elevates and retracts mandible.
What is the muscle of the neck that moves the head (that you need to know)?
Sternocleidomastoid
What is the origin, insertion, and action of the sternocleidomastoid?
Origin: sternal head: manubrium of sternum; clavicular head: medial third of clavicle.
Insertion: mastoid process of temporal bone and lateral half of superior nuchal line of occipital bone.
Action: acting together (bilaterally), flex cervical portion of vertebral column, extend head of atlanto-occipital joints; acting singly (unilaterally), laterally flex neck and head to same side and rotate head to side opposite contracting muscle. Laterally rotate and flex head to opposite side of contracting muscle. Posterior fibers of muscle can assist in extension of head, RMA: Elevate sternum during forced inhalation.
What are the four muscles of the abdomen that protect abdominal viscera and move the vertebral column (that you need to know)?
- Rectus abdominis
- External oblique
- Internal oblique
- Transversus abdominis
What is the origin, insertion, and action of the rectus abdominis?
Origin: pubic crest and pubic symphysis.
Insertion: cartilage of ribs 5-7 and xiphoid process.
Action: flexes vertebral column, especially lumbar portion, and compresses abdomen to aid in defecation, urination, forced exhalation, and childbirth, RMA: Flexes pelvis on the vertebral column.
What is the action of the external oblique?
Acting together (bilaterally), compress abdomen and flex vertebral column; acting singly (unilaterally), laterally flex vertebral column, especially lumbar portion, and rotate vertebral column.
What is the action of the internal oblique?
Acting together, compress abdomen and flex vertebral column; acting singly, laterally flex vertebral column, especially lumbar portion, and rotate vertebral column (same role as external oblique).
What is the insertion and action of the transversus abdominis?
Insertion: Xiphoid process, linea alba, and pubis.
Action: compresses abdomen.
The ______ of the external oblique, internal oblique, and transversus abdominis muscles form the ______ which enclose the ______. The sheaths meet at the midline to form the ______, a tough, fibrous band that extends from the xiphoid process of the sternum to the pubic symphysis. In the later stages of pregnancy, the ______ stretches to increase the distance between the rectus abdominis muscles.
Aponeuroses (sheetlike tendons); rectus sheaths; rectus abdominis muscles; linea alba; linea alba.
What are the three muscles of the thorax that assist in breathing?
- Diaphragm
- External intercostals
- Internal intercostals
What is the action of the diaphragm?
Contraction of diaphragm causes it to flatten and increases vertical dimension of thoracic cavity, resulting in inhalation; relaxation of diaphragm causes it to move superiorly and decreases vertical dimension of thoracic cavity, resulting in exhalation.
What is the action of the external intercostals?
Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity, resulting in inhalation; relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity, resulting in exhalation.
What is the action of the internal intercostals?
Contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation.
Central tendon
A strong aponeurosis located near the center of the muscle. Fuses with the inferior surface of the pericardium (covering of the heart) and the pleurae (coverings of the lungs).
What are the two anterior thoracic muscles (that you need to know)?
- Pectoralis minor
- Serratus anterior
What is the action of the pectoralis minor?
Abducts to scapula and rotates it downward, RMA: Elevates ribs 3-5 during forced inhalation when scapula is fixed.
What is the origin, insertion, and action of the serratus anterior?
Origin: ribs 1-8 or 1-9.
Insertion: vertebral border and inferior angle of scapula.
Action: abducts scapula and rotates it upward, RMA: Elevates ribs when scapula is stabilized. Known as “boxer’s muscle” because it is important in horizontal arm movements such as punching and pushing.
What are the three posterior thoracic muscles (that you need to know)?
- Trapezius
- Levator scapulae
- Rhomboid major
What is the origin, insertion, and action of the trapezius?
Origin: superior nuchal line of occipital bone, ligamentum nuchae, and spines of C7-T12.
Insertion: clavicle and acromion and spine of scapula.
Action: superior fibers upward rotate scapula; middle fibers adduct scapula; inferior fibers depress and upward rotate scapula; superior and inferior fibers together rotate scapula upward; stabilize scapula, RMA: Superior fibers can help extend head.
What is the origin, insertion, and action of the levator scapulae?
Origin: transverse processes of C1-C4
Insertion: superior vertebral border of scapula.
Action: elevates scapula and rotates it downward.
What is the action of the rhomboid major?
Elevates and adducts scapula
and rotates it downward;
stabilizes scapula.
What are the two axial muscles that move the humerus?
- Pectorialis major
- Latissimus dorsi
What is the origin, insertion, and action of the pectoralis major?
Origin: cavicle (clavicular head), sternum, and costal cartilages of ribs 2–6 and sometimes ribs 1–7 (sternocostal head).
Insertion: greater tubercle and lateral lip of intertubercular sulcus of humerus.
Action: as a whole, adducts and medially rotates arm at shoulder joint; clavicular head flexes arm, and sternocostal head extends flexed arm to side of trunk.
What is the action of the latissimus dorsi?
Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly. RMA: Elevates vertebral column and torso.
What are the six scapular muscles that move the humerus (that you need to know)?
- Deltoid
- Subscapularis
- Supraspinatus
- Infraspinatus
- Teres major
- Teres minor
What is the origin, insertion, and action of the deltoid?
Origin: acromial extremity of clavicle (anterior fibers), acromion of scapula (lateral fibers), and spine of scapula (posterior fibers).
Insertion: deltoid tuberosity of humerus.
Action: lateral fibers abduct arm at shoulder joint; anterior fibers flex and medially rotate arm at shoulder joint; posterior fibers extend and laterally rotate arm at shoulder joint.
What is the action of the subscapularis?
Medially rotates arm at shoulder joint.
What is the origin, insertion, and action of the supraspinatus?
Origin: supraspinous fossa of scapula.
Insertion: greater tubercle of humerus.
Action: assists deltoid muscle in abducting arm at shoulder joint.
What is the action of the infraspinatus?
Laterally rotates arm at shoulder joint
What is the action of the teres major?
Extends arm at shoulder joint and assists in adduction and medial rotation of arm at shoulder joint.
What is the action of the teres minor?
Laterally rotates and extends arm at shoulder joint (same as infraspinatus).
What are the three forearm flexor muscles?
- Biceps brachii
- Brachialis
- Brachioradialis
What is the origin, insertion, and action of the biceps brachii?
Origin: long head originates from tubercle above glenoid cavity of scapula (supraglenoid tubercle); short head originates from coracoid process of scapula.
Insertion: radial tuberosity of radius and bicipital aponeurosis.
Action: flexes forearm at elbow joint, supinates forearm at radioulnar joints, and flexes arm at shoulder joint.
What is the action of the brachialis?
Flexes forearm at elbow joint
What is the action of the brachioradialis?
Flexes forearm at elbow joint; supinates and pronates forearm at radioulnar joint to neutral position.
What are the two forearm extensor muscles?
- Triceps brachii
- Anconeus
What is the origin, insertion, and action of the triceps brachii?
Origin: long head originates from infraglenoid tubercle, a projection inferior to glenoid cavity of scapula; lateral head originates from lateral and posterior surface of humerus; medial head originates from entire posterior surface of humerus inferior to the groove for the radial nerve; lateral epicondyle of humerus.
Insertion: olecranon of ulna.
Action: extends forearm at elbow joint and extends arm at shoulder joint.
What is the origin, insertion, and action of the anconeus?
Origin: lateral epicondyle of humerus.
Insertion: olecranon and superior portion of shaft of ulna.
Action: extends forearm at elbow joint.
What is the forearm pronator muscle (that you need to know)?
- Pronator teres
What is the action of the pronator teres?
Pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint.
What is the forearm supinator muscle?
Supinator
What is the action of the supinator?
Supinates forearm at radioulnar joints.
What four muscles are apart of the superficial anterior (flexor) compartment of the forearm?
- Flexor carpi radialis
- Palmaris longus
- Flexor carpi ulnaris
- Flexor digitorum superficialis
What is the origin, insertion, and action of the flexor carpi radialis?
Origin: medial epicondyle of humerus.
Insertion: metacarpals II and III.
Action: flexes and abducts hand (radial deviation) at wrist joint.
What is the action of the palmaris longus?
Weakly flexes hand at wrist joint.
What is the origin, insertion, and action of the flexor carpi ulnaris?
Origin: medial epicondyle of humerus and superior posterior border of ulna.
Insertion: pisiform, hamate, and base of metacarpal V.
Action: flexes and adducts hand (ulnar deviation) at wrist joint.
What is the origin, insertion, and action of the flexor digitorum superficials?
Origin: medial epicondyle of humerus, coronoid
process of ulna, and ridge along lateral margin or anterior surface (anterior oblique line) of radius.
Insertion: middle phalanx of each finger.
Action: flexes middle phalanx of each finger at proximal interphalangeal joint, proximal phalanx of each finger at metacarpophalangeal joint, and hand at wrist joint.
What three muscles are apart of the superficial posterior (extensor) compartment of the forearm (that you need to know)?
- Extensor carpi radialis longus
- Extensor digitorum
- Extensor carpi ulnaris
What is the action of the extensor carpi raidialis longus?
Extends and abducts hand at wrist joint (ulnar deviation).
What is the origin, insertion, and action of the extensor digitorum?
Origin: lateral epicondyle of humerus.
Insertion: distal and middle phalanges of each finger.
Action: extends distal and middle phalanges of each finger at interphalangeal joints, proximal phalanx of each finger at metacarpophalangeal joint, and hand at wrist joint.
What is the origin, insertion, and action of the extensor carpi ulnaris?
Origin: lateral epicondyle of humerus and posterior border of ulna.
Insertion: metacarpal V.
Action: extends and adducts hand at wrist joint (ulnar deviation).
What is the action of the iliocostalis group (lateral) (iliocostalis cervicis, iliocostalis thoracis, and iliocostalis lumborum) of the errector spinae?
Acting together, muscles of each region (cervical, thoracic, and lumbar) extend and maintain erect posture of vertebral column of their respective regions; acting singly, laterally flex vertebral column of their respective regions to same side as contracting muscle.
What are the three scalenes?
- Anterior scalene
- Middle scalene
- Posterior scalene
What is the action of the anterior scalene?
Acting together, right and left anterior scalene and middle scalene muscles elevate first ribs during deep inhalation.
What is the action of the middle scalene?
RMA: Flex cervical vertebrae; acting singly, laterally flex and slightly rotate cervical vertebrae.
What is the action of the posterior scalene?
Acting together, right and left posterior scalene elevate second ribs during deep inhalation; RMA: Flex cervical vertebrae; acting singly, laterally flex and slightly rotate cervical vertebrae.
What are the six muscles of the gluteal region that move the femur (that you need to know)?
- Iliopsoas/psoas major
- Iliacus
- Gluteus maximus
- Gluteus medius
- Adductor longus
- Adductor magnus
What is the origin, insertion, and action of the iliopsoas/psoas major?
Origin: transverse processes and bodies of lumbar vertebrae.
Insertion: with iliacus into lesser trochanter of femur.
Action: psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position.
What is the origin, insertion, and action of the gluteus maximus?
Origin: iliac crest, sacrum, coccyx, and aponeurosis of sacrospinalis.
Insertion: iliotibial tract of fascia lata and superior lateral part of linea aspera (gluteal tuberosity) under greater trochanter of
femur.
Action: extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension. RMA: Extends torso.
What is the action of the gluteus medius?
Abducts thigh at hip joint and medially rotates thigh.
What is the action of the adductor longus?
Adducts and flexes thigh at hip joint and rotates thigh. RMA: Extends thigh.
What is the action of the adductor magnus?
Adducts thigh at hip joint and rotates thigh; anterior part flexes thigh at hip joint, and posterior part extends thigh at hip joint.
What five muscles are apart of the anterior (extensor) compartment of the thigh/the quadriceps femoris?
- Rectus femoris
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Sartorius
What is the origin of the rectus femoris?
Anterior inferior iliac spine.
What is the origin of the vastus lateralis?
Greater trochanter and linea aspera of femur.
What is the origin of the vastus medialis?
Linea aspera of femur.
What is the origin of the vastus intermedius?
Anterior and lateral surfaces of body of femur.
What is the insertion and action of the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius?
Insertion: patella via quadriceps tendon and then tibial tuberosity via patellar ligament.
Action: all four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh at hip joint.
What is the action of the sartorius?
Weakly flexes leg at knee joint; weakly flexes, abducts, and laterally rotates thigh at hip joint
What three muscles are apart of the posterior (flexor) compartment of the thigh/hamstrings?
- Biceps femoris
- Semitendinosus
- Semimembranosus
What is the origin, insertion, and action of the biceps femoris?
Origin: long head arises from ischial tuberosity; short head arises from linea aspera of femur.
Insertion: head of fibula and lateral condyle of tibia.
Action: flexes leg at knee joint and extends thigh at hip joint (same as semitendinosus and semimembranosus).
What is the action of the semitendinosus?
Flexes leg at knee joint and extends thigh at hip joint (same as biceps femoris and semimembranosus).
What is the action of the semimembranosus?
Flexes leg at knee joint and extends thigh at hip joint (same as biceps femoris and semitendinosus).
What two muscles are apart of the anterior compartment of the leg (that you need to know)?
- Tibialis anterior
- Extensor digitorum longus
What is the origin, insertion, and action of the tibialis anterior?
Origin: lateral condyle and body of tibia and interosseous membrane (sheet of fibrous tissue that holds shafts of tibia and fibula together).
Insertion: metatarsal I and first (medial) cuneiform.
Action: dorsiflexes foot at ankle joint and inverts (supinates) foot at intertarsal joints.
What is the origin, insertion, and action of the extensor digitorum longus?
Origin: lateral condyle of tibia, anterior surface of fibula, and interosseous membrane.
Insertion: middle and distal phalanges of toes II–V.
Action: dorsiflexes foot at ankle joint and extends distal and middle phalanges of each toe at interphalangeal joints and proximal phalanx of each toe at metatarsophalangeal joint.
What muscle is apart of the lateral (fibular) compartment of the leg (that you need to know)?
Fibularis (peroneus) longus
What is the action of the fibularis (peroneus) longus?
Plantar flexes foot at ankle joint and everts (pronates) foot at intertarsal joints.
What two muscles are apart of the superior posterior compartment of the leg (that you need to know)?
- Gastrocnemius
- Soleus
What is the origin, insertion, and action of the gastrocnemius?
Origin: lateral and medial condyles of femur and capsule of knee.
Insertion: calcaneus by way of calcaneal (Achilles) tendon.
Action: plantar flexes foot at ankle joint and flexes leg at knee joint.
What is the action of the soleus?
Plantar flexes foot at ankle joint.
What muscle is apart of the deep posterior compartment of the leg (that you need to know)?
Flexor digitorum longus
What is the origin, insertion, and action of the flexor digitorum longus?
Origin: middle third of posterior surface of tibia.
Insertion: distal phalanges of toes II–V.
Action: plantar flexes foot at ankle joint; flexes distal and middle phalanges of toes II–V at interphalangeal joints and proximal phalanx of toes II–V at metatarsophalangeal joint.
