Chapter 11: Muscular System

Question 1

Muscles are attached to bones by tendons at which two locations?

Answer 1

origin - attachment to stationary bone

Insertion - attachment to moveable bone

Question 2

The origin is usually located ________ and the insertion is usually pulled ____________ the origin

Answer 2

proximally; toward

Question 3

Define belly (body)

Answer 3

Fleshy portion of the muscle between the tendons

Question 4

Define actions of a muscle

Answer 4

The main movements that occur when a muscle contracts

Question 5

Define reverse muscle action (RMA)

Answer 5

during specific movements of the body the actions are reversed; therefore the positions of the origin and insertion of a specific muscle are switched

Question 6

Describe how during movements bones and joints act as levers and fulcrums

Answer 6

Lever is rigid structure that can move around a fixed point called a fulcrum

The lever is acted on at two points:

(E) Effort which causes movement and (L) Load which opposes movement

Motion occurs when effort applied to the bone at the insertion exceeds the load

Question 7

Define mechanical advantage

Answer 7

Mechanical advantage - if the load is closer to the fulcrum and the effort father away, then only a relatively small effort is required to move a large load

Mechanical disadvantage - if the load is father and the effort is closer to the fulcrum, more effort is required to move a small load (but at greater speed)

Ex. chewing something with the front of your teeth (disadvantage) vs the back (advantage)

Question 8

List the 3 categorizes of levers according to the positions of the fulcrum, the effort, and the load

Answer 8

First-class levers - fulcrum is between effort and load, they can produce either a mechanical advantage or disadvantage - very few in the body (seesaw)

Second-class levers - load is between fulcrum and effort and always produce a mechanical advantage because the load is always closer to fulcrum than the effort - uncommon in the body (wheelbarrow)

Third-class levers - effort is between fulcrum and load and always produce a mechanical disadvantage before effort is always closer to fulcrum than load - most common in body (forceps) as it favours speed and range of motion over force

Question 9

Muscles are arranged into fascicles, in which all muscles run parallel to one another. However, list and describe the 5 different types based on their patterns with respect to tendons

Answer 9

Parallel - fascicles parallel to longitudinal axis of muscle

Fusiform - fascicles nearly parallel, muscles taper toward tendons, diameter larger at belly

Circular - fascicles in concentric circular arrangements for sphincter muscles that uncouple and orifice

Triangular - fascicles spread over broad area converge at thick central tendon

Pennate - short fascicles in relation to muscle length, tendon extends nearly entire length of muscle

• unipennate: fascicles on only one side of tendon
• bipennate: fascicles on both sides on centrally positioned tendons
• multipennate: fascicles attach obliquely from many directions to several tendons

Question 10

Describe how the prime mover, antagonist, synergist, and fixation in a muscle group work together to produce movements

Answer 10

Most skeletal muscles are arranged in opposing pairs at joints, within these pairs one muscle called the prime mover or agonist contracts to cause an action while the other muscle, the antagonist stretches and yields to the effects of the prime mover

To prevent unwanted movements at intermediate joints muscles called synergists contract and stabilize them

Some muscles in a group also act as fixators, stabilizing the origin of the prime mover to move more efficiently - steady the proximal end while movements occur at the distal end

In the limbs, a compartment is a group of skeletal muscles, their blood cells/nerves, all of which have a common function

Question 11

Using the example of flexing and extending the forearm, describe the coordination among muscles (prime mover/antagonist)

Answer 11

Flexing: the biceps brachii is the prime mover and the triceps brachii is the antagonist

Extending: the triceps brachii becomes the primary mover and the biceps brachii become the antagonist

Question 12

The following terms are characteristics used to name muscles based on their direction (orientation relatively to body’s midline). Describe their meaning

• Rectus
• Transverse
• Oblique

Answer 12

Rectus: parallel to midline

Transverse: perpendicular to midline

Oblique: diagonal to midline

Question 13

The following terms are characteristics used to name muscles based on their size. Describe their meaning

• maximus
• minimus
• longus
• brevis
• latissimus
• longissimus
• magnus
• major
• minor
• vastus

Answer 13

• maximus: largest
• minimus: smallest
• longus: long
• brevis: short
• latissimus: widest
• longissimus: longest
• magnus: large
• major: larger
• minor: smaller
• vastus: huge

Question 14

The following terms are characteristics used to name muscles based on their shape. Describe their meaning

• deltoid
• trapezius
• serratus
• rhomboid
• orbicularis
• pectinate
• piriformis
• platys
• quadratus
• gracillis

Answer 14

• deltoid: triangular
• trapezius: trapezoid
• serratus: saw-toothed
• rhomboid: diamond shaped
• orbicularis: circular
• pectinate: comblike
• piriformis: pear-shaped
• platys: flat
• quadratus: square
• gracillis: slender

Question 15

The following terms are characteristics used to name muscles based on their action. Describe their meaning

• flexor
• extensor
• abudctor
• adductor
• levator
• depressor
• supinator
• pronator
• sphincter
• tensor
• rotator

Answer 15

• flexor: decreases joint angle
• extensor: increases joint angle
• abudctor: moves bone away from midline
• adductor: moves bone towards midline
• levator: raises or elevates body part
• depressor: lowers or depresses body part
• supinator: turns palm anteriorly
• pronator: turns palm posteriorly
• sphincter: decreases size of an opening
• tensor: makes body part rigid
• rotator: rotates bone around longitudinal axis

Question 16

The following terms are characteristics used to name muscles based on the number of origins. Describe their meaning

Biceps
Triceps
Quadriceps

Answer 16

Biceps - two

Triceps - three

Quadriceps - four

Question 17

What are the 7 major characteristics used to name muscles?

Answer 17

Direction 
Size 
Shape 
Action 
Number of Origins 
Location 
Origin and Insertion

Question 18

List the locations and actions of the following scalp muscles:

Occipofrontalis

Answer 18

Occipofrontalis is made up of 2 parts:

Frontal belly (anterior) is superficial to the frontal bone
 - ACTION: raises eyebrows/wrinkles forehead in surprise 

Occipital belly (posterior) superficial to occipital bone 
- ACTION: draws scalp posteriorly

Question 19

List the locations and actions of the following mouth muscles:

Orbicularis oris
zygomaticus major
Buccinator

Answer 19

Orbicularis oris - surrounding the mouth opening
ACTION: Closes/protrudes lips (kissing), shapes lips during speech

Zygomaticus major - cheek bone
ACTION: draws angle of mouth superiorly and laterally (smiling)

Buccinator - cheek
ACTION: forms the major muscular portion of the cheek, compresses cheek during blowing

Question 20

List the locations and actions of the following orbit and eyebrow muscles:

Orbicularis oculi

Answer 20

Orbicularis oculi - closes eye

Question 21

List the locations (origin & insertion*) and actions of the following muscles that move mandible and assist in mastication and speech:

Masseter*
Temporalis*

Answer 21

Masseter
ORIGIN: maxilla and zygomatic arch
INSERTION: angle and ramus of mandible
ACTION: elevates mandible (closing mouth)

Temporalis
ORIGIN: temporal bone
INSERTION: coronoid process and ramps of mandible
ACTION: elevates and retracts mandible

Question 22

List the locations (origin & insertion*) and actions of the following muscles of the neck that move the head:

Sternocleidomastoid*

Answer 22

Sternocleidomastoid

ORIGIN: sternal head: manubrium of sternum, clavicular head: medial 3rd of clavicle

INSERTION: mastoid process of temporal bone and lateral half pf superior nuchal line of occipital bone

ACTION: flex cervical portion of vertebral column, extend head, rotate head to side, head extension

Question 23

List the locations (origin & insertion*) and actions of the following muscles of the abdomen:

Rectus abdominis*
External oblique
Internal oblique
Transversus abdominis

Answer 23

Rectus abdominis* - parallel to midline
ORIGIN: pubic crest & symphysis
INSERTION: cartilage of ribs 5-7 and xiphoid process
ACTION: flexes vertebral column, compresses abdomen for defecation, urination, exhalation, and childbirth

External oblique - closest to surface, fascicles diagonal to midline
ACTION: compress abdomen and flex vertebral column

Internal oblique - further from surface, fascicles diagonal to midline
ACTION: compress abdomen and flex vertebral column

Transversus abdominis - perpendicular to midline
ACTION: compresses abdomen

Question 24

List the locations and actions of the following muscles of the thorax that assist in breathing:

Diaphragm
External intercostal
Internal intercostal

Answer 24

Diaphragm - contraction causes the diaphragm to flatten and increases thoracic cavity, resulting in inhalation; relaxation causes it to move superiorly and decreases thoracic cavity, resulting in exhalation

External intercostal - contraction elevates ribs increasing thoracic cavity, resulting in inhalation; relaxation depresses ribs and decreases thoracic cavity, resulting in exhalation

Internal intercostal - contraction draws ribs together to decrease thoracic cavity during forced exhalation

Question 25

List the locations (origin & insertion*) and actions of the following muscles of the thorax that move the pectoral girdle: Pectoralis minor Trapezius* Levator scapulae* Rhomboid major

Answer 25

Pectoralis minor - anterior thoracic muscle ACTION: abducts scapula and rotates it downward, assists in forced inhalation Trapezius - posterior thoracic muscle ORIGIN: superior nuchal line of occipital bone and spines of C7-T12 INSERTION: clavicle and acrominon and spine of scapula ACTION: rotate scapula, adduct scapula, depress and upward rotate scapula, and stabilize scapula Levator scapulae - posterior thoracic muscle ORIGIN: transverse processes of C1-C4 INSERTION: superior vertebral border of scapula ACTION: elevates scapula and rotates it downward Rhomboid major - posterior thoracic muscle ACTION: elevates & adducts scapula and rotates it downward/stabilizes it

Question 26

List the locations (origin & insertion*) and actions of the following muscles of the thorax and shoulder that move the humerus: ``` Pectoralis major* Latissimus dorsi Deltoid* Subscapularis Supraspinatus* Infraspinatus Teres major Teres minor ```

Answer 26

Pectoralis major - axial muscles that move humerus ORIGIN: clavicular head, storms, and cartilage of ribs 2-6 INSERTION: greater tubercle and lateral lip of interlobular sulcus of humerus ACTION: adducts and medially rotates arm at shoulder joints; clavicular head flexes arm, sternocostal head extends flexed arm to side of trunk Latissimus dorsi - axial muscles that move humerus ACTION: extends, adducts, and medially rotates arm at shoulder joint, draws arm inferiorly/posteriorly Deltoid - scapular muscles that move humerus ORIGIN: acrominal extremity of clavicle, acromion of scapula, and spin of scapula INSERTION: deltoid tuberosity of humerus ACTION: adduct arm, flex and medially rotate arm, extend and laterally rotate all at shoulder joint Subscapularis - scapular muscles that move humerus ACTION: medially rotates arm at shoulder joint Supraspinatus - scapular muscles that move humerus ORIGIN: supraspinous fossa of scapula INSERTION: greater tubercle of humerus ACTION: assists deltoid in abducting arm Infraspinatus - scapular muscles that move humerus ACTION: laterally rotates arm at shoulder joint Teres major - scapular muscles that move humerus ACTION: extends arm at shoulder joint and assists in adduction and medial rotation of arm Teres minor- scapular muscles that move humerus ACTION: laterally rotates and extends arm

Question 27

List the locations (origin & insertion*) and actions of the following muscles of the forearm that move the radius and ulna: ``` Biceps brachii* Brachialis Brachioradialis Triceps brachii* Pronator teres Supinator ```

Answer 27

``` Biceps brachii (forearm flexor) ORIGIN: long head originates from tubercle above glenoid cavity of scapula; short head originals from coracoid process of scapula INSERTION: radial tuberosity of radius and bicipital aponeurosis ACTION: flexes forearm at elbow joint, supinates forearm at radioulnar joints, flexes arm at shoulder joint ``` Brachialis - flexes forarm at elbow joint Brachioradialis - flexes forearm at elbow joint; supinates/pronates forearm at radioulnar joints to neutral position ``` Triceps brachii (forearm extensors) ORIGIN: long head originates from infraglenoid tubercle; lateral head originates from lateral/posterior surface of humerus; medial head originals from entire posterior surface of humerus inferior to a groove for the radial nerve INSERTION: olecranon of ulna ACTION: extends forearm at elbow joint and extends arm at shoulder joint ``` Pronator teres - pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint Supinator - supinates forearm at radioulnar joints

Question 28

List the locations (origin & insertion*) and actions of the following muscles of the forearm that move the wrist, hand, thumb, and digits: ``` Flexor carpi radialis* Palmaris longus Flexor carpi ulnaris* Flexor digitorum superficialis* Extensor carpi radialis longus Extensor digitorum* Extensor carpis ulnaris* ```

Answer 28

Flexor carpi radialis (superficial anterior compartment) ORIGIN: medial epicondyle of humerus INSERTION: Metacarpals II and II ACTION: flexes and abducts hand (radial deviation) at wrist joint Palmaris longus (superficial anterior compartment) - weakly flexes hand at wrist joint Flexor carpi ulnaris (superficial anterior compartment) 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 devotion) at wrist joint Flexor digitorum superficialis (superficial anterior compartment) ORIGIN: medial epicondyle of humerus, coronoid process of ulna, and ridge along lateral margin or anterior surface of radius INSERTION: Middle phalanx of each finger at interphalangeal joint, proximal phalanges at metacarophalngeal joint, and hand at wrist joint Extensor carpi radialis longus (superficial posterior [extensor] compartment) - extends and abducts hand at wrist going (ulnar devotion) Extensor digitorum (superficial posterior [extensor] compartment) ORIGIN: lateral epicondyle of humerus INSERTION: distal and middle phalanges of each finger ACTION: extends distal and middle phalanges at interphalangeal joints, proximal phalanges at metacarophalngeal joint, and hand at wrist joint Extensor carpis ulnaris (superficial posterior [extensor] compartment) ORIGIN: lateral epicondyle of humerus and posterior border of ulna INSERTION: metacarpal V ACTION: extends and adducts hand at wrist joint (ulnar deviation)

Question 29

What is the iliostalis group?

Answer 29

The laterally placed group of the erector spinae, which is the largest muscle mass of the back, forming a prominent bulge on either side of the vertebral column. It consists of 3 muscles: Iliostalis cervicis, Iliostalis thoracis, and Iliostalis lumborum Acting together they extend and maintain erect posture of vertebral column of their respective regions

Question 30

What are scalenes?

Answer 30

Scalenes are muscles of the back that move the vertebral column and are subdivided into 3 muscles: Anterior scalene (C3-C6), Middle scalene (C2-C7), and posterior scalene (C4-C6) Acting together, during deep inhalation anterior and middle scalene elevate first ribs and posterior and scalene elevate second ribs

Question 31

List the locations (origin & insertion*) and actions of the following muscles of the gluteal region that move the femur: ``` Iliopsoas or psoas major* Iliacus Gluteus maximus* Gluteus medius Adductor longus Adductor Magnus ```

Answer 31

Iliopsoas or psoas major ORIGIN: transverse processes and bodies of lumbar vertebrae INSERTION: lesses trochanter of femur (with iliacus), together known as the Iliopsoas muscle ACTION: flex hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position Iliacus - works together with the psoas major Gluteus maximus - ORIGIN: iliac crest, sacrum, coccyx, and sacrospinalsis INSERTION: under lesser trochanter at fascia and linea aspera (gluteal tuberosity) ACTION: extends and laterally rotates thigh, helps lock knee in extension Gluteus medius - abducts thigh at hip joint and medially rotates it Adductor longus - adducts and flexes thigh at hip joint and rotates thigh (laterally rotates which foot is off ground medially rotate when foot is on ground) (RMA - extends thigh) Adductor Magnus - adducts and flexes thigh at hip joint and rotates thigh; anterior part flees thigh and posterior part extends thigh both at hip joint

Question 32

List the locations (origin & insertion*) and actions of the following muscles of the thigh that move the femur and tibia and fibula: - Quadriceps femoris (rectus femoris*, vastus lateralis, vastus medialis, vastus intermedius) - Satorius - Hamstrings (biceps femoris*, semitendinosus, semimebranosus)

Answer 32

QUADS - anterior compartment of thigh (extensor) Rectus femoris ORIGIN: anterior inferior iliac spine INSERTION: patella via quads tendon and then tibial tuberosity via patellar ligaments (same for all quads) ACTION: Alone, rectus femoris flexes thigh at hip joint Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius together extend leg at knee joint Satorius - anterior compartment of thigh (extensor) ACTION: weakly flexes leg at knee joint; flexes, abuducts, & laterally rotates thigh at hip joint HAMSTRINGS - posterior compartment of thigh (flexor) Biceps femoris ORIGIN: long head from ischial tuberosity; short head from lines aspera of femur INSERTION: head of fibula and lateral condyle of tibia Biceps femoris, semitendinosus, and semimebranosus all flex leg at knee joint and extend thigh at hip joint

Question 33

List the locations (origin & insertion*) and actions of the following muscles of the leg that move the foot and toes: ``` Tibialis anterior * Extensor digitorum longus* Fibularis (peroneus) longus Gastricnemius* Soleus Flexor digitorum longus* ```

Answer 33

Tibialis anterior - dorsiflexes foot at ankle joint and inverts (supinates) foot at intertarsal joints ORIGIN: lateral condyle and body of tibia and interosseous membrane INSERTION: Metatarsal I and first (medial) cuneiform Extensor digitorum longus (anterior) - dorsiflexes foot at ankle and extends distal/middle phalanges at interpghalangeal joints and proximal phalanges at metatarsophealengeal joint ORIGIN: lateral condyle of tibia, anterior surface of fibula, interosseous membrane INSERTION: middle and distal phalanges of toes II-V Fibularis (peroneus) longus (lateral) - plantar flexes foot at ankle and everts (pronates) foot at intertarsal joints Gastricnemius (superficial posterior) - plantar flexes foot at ankle and flexes leg at knee joint ORIGIN: lateral & medial condyles of femur & capsule of knee INSERTION: Calcaneus of by way of calcanea (achilles) tendon Soleus (superficial posterior) - platntar flexes foot at ankle Flexor digitorum longus (deep posterior) - plantar flexes foot at ankle; flexes distal/middle phalanges at interphalangel joints and proximal phalanx at metatrasophalangal joints of toes II-V