Chapter 10 Muscular System

Question 1

skeletal muscles can be classified into 3 functional groups

Answer 1

• Agonist, or prime mover = muscle that produces a certain desired movement – e.g. flexion
  
  • Antagonist = muscle contraction whose action that counteracts desired movement – e.g. extension
  • Synergists = group of muscles working together to help prime mover produce a movement – e.g. hip flexors, knee extensors
  • **fixators = synergist muscles that immobilize a bone while a usually more distal bone is moved

Question 2

skeletal muscles: Agonist

Answer 2

Agonist, or prime mover = muscle that produces a certain desired movement – e.g. flexion

Question 3

skeletal muscles: Antagonist

Answer 3

Antagonist = muscle contraction whose action that counteracts desired movement – e.g. extension

Question 4

skeletal muscles: Synergists

Answer 4

Synergists = group of muscles working together to help prime mover produce a movement – e.g. hip flexors, knee extensors
-**fixators = synergist muscles that immobilize a bone while a usually more distal bone is moved

Question 5

Skeletal muscles

Answer 5

• most extend from one bone to another and cross at least on joint
  
  • contraction – causes movement – pulling one bone toward another across a joint
  • some attached to bone only on one end and to some other tissue on the other end – e.g. to skin of face allowing for facial expressions

Question 6

Skeletal muscles: Origin

Answer 6

Origin = fixed end of skeletal muscle, usually most stationary and proximal end of muscle
-**head = name given when muscle has multiple origins that converge to form one muscle
 triceps brachii

Question 7

Skeletal muscles: Insertion

Answer 7

Insertion = mobile end – usually the distal end attached to the bone undergoing the greatest movement

Question 8

Skeletal muscles: Belly

Answer 8

Belly = part of muscle between origin and insertion

Question 9

Skeletal muscle: Tendons

Answer 9

Tendons – long cable-like dense regular connective tissue that attach muscle to bone
o aponeuroses = broad, sheet-like tendons

Question 10

Skeletal muscle are named according to:

Answer 10

*location
*shape
*muscle size
*direction of muscle fibers
*number of origins
*location of attachments
*muscle action - a muscle that crosses on the:
Anterior side of a joint produces flexion
Posterior side of a joint produces extension
Lateral side of a joint produces abduction
Medial side of a joint produces adduction

Question 11

Skeletal muscle are named according to: Location

Answer 11

location – e.g. temporalis – covers the temporal bone

Question 12

Skeletal muscle are named according to: Shape

Answer 12

Shape – e.g. deltoid – roughly triangular

Question 13

Skeletal muscle are named according to: Muscle size

Answer 13

Muscle size – e.g. gluteus maximus (largest) & minimus (smallest), pollicus longus (long)& brevis (short)

Question 14

Skeletal muscle are named according to: Direction of muscle fibres

Answer 14

Direction of muscle fibers – e.g. rectus (straight) femoris, transversus abdominus

Question 15

Skeletal muscle are named according to: Number of origins

Answer 15

Number of origins- e.g. biceps, triceps, quadriceps

Question 16

Skeletal muscle are named according to: Location of attachments

Answer 16

location of attachments – e.g. sternocleidomastoid (provide origin and insertion)

Question 17

Skeletal muscle are named according to: Muscle action

Answer 17

Muscle action – e.g. adductor longus (adducts thigh)
a muscle that crosses on the:
• anterior side of a joint produces flexion
• posterior side of a joint produces extension
• lateral side of a joint produces abduction
• medial side of a joint produces adduction

Question 18

Skeletal muscle: Shape and Size greatly influence the degree to which a muscle can contract and the amount of force it can generate

Answer 18

o classes based on arrangement of fasciculi (bundles of visible muscle fibers)

* Circular – arranged in a circle around an opening and act as sphincters to close opening
e. g. orbicularis oris (circles mouth)

* Convergent – fasciculi arrive at one common tendon so muscles are triangular in shape
e. g. pectoralis major

* Parallel – fasciculi parallel to long axis of muscle and terminate on a flat tendon that spans the width of the entire muscle
- strap-like – Sartorius
- **fusiform = taper at each end onto a tendon – have wider belly – e.g. biceps brachii

*Pennate – fasciculi emerge feather-like from a common tendon that runs the entire length of the muscle
unipennate = fascicles arise from one side of the tendon only – e.g. extensor digitorum longus
bipennate = two sides of the tendon – e.g. rectus femoris
multipennate = arranged in many places around central tendon – e.g. deltoid muscle

Question 19

Skeletal muscle shape: Circular

Answer 19

• Circular – arranged in a circle around an opening and act as **sphincters to close opening
  e. g. orbicularis oris (circles mouth)

Question 20

Skeletal muscle shape: Convergent

Answer 20

• Convergent – fasciculi arrive at **one common tendon so muscles are triangular in shape
  e. g. pectoralis major

Question 21

Skeletal muscle shape: Parallel

Answer 21

• Parallel – fasciculi parallel to long axis of muscle and **terminate on a flat tendon that spans the width of the entire muscle
  
  • strap-like – Sartorius
  • **fusiform = taper at each end onto a tendon – have **wider belly – e.g. biceps brachii

Question 22

Skeletal muscle shape: Pennate

Answer 22

*Pennate – fasciculi emerge feather-like **from a common tendon that runs the entire length of the muscle
unipennate = fascicles arise from one side of the tendon only – e.g. extensor digitorum longus
bipennate = two sides of the tendon – e.g. rectus femoris
multipennate = arranged in many places around central tendon – e.g. deltoid muscle

Question 23

Facial Expression

Answer 23

Facial Expression
*cutaneous muscles – skeletal muscles attached to skin - confined primarily to face and neck
allow skin to twitch to remove irritants (e.g. insects)
important in non-verbal communication

*skin around eyes and eyebrows 
orbicularis oculi – closes eyelids 

*movement of lips and skin around lips 
-closing and puckering lips:
orbicularis oris – closes lips
buccinator – flattens cheek
-smiling:
zygmaticus major and minor – elevate and abduct upper lip
-sneering:
levator labii superioris – elevates upper lip
-pouting or frowning:
depressor labii inferioris – depresses lower lip
mentalis- wrinkles chin and protrudes lower lip

Question 24

Facial Expression:

Cutaneous muscles

Answer 24

Cutaneous muscles – skeletal muscles attached to skin - confined primarily to face and neck
allow skin to twitch to remove irritants (e.g. insects)
important in non-verbal communication

Question 25

Facial Expression:

Skin around eyes and eyebrows

Answer 25

*skin around eyes and eyebrows

orbicularis oculi – closes eyelids

Question 26

Facial Expression:

movement of lips and skin around lips

Answer 26

*movement of lips and skin around lips
-closing and puckering lips:
orbicularis oris – closes lips
buccinator – flattens cheek

-smiling:
zygmaticus major and minor – elevate and abduct upper lip

-sneering:
levator labii superioris – elevates upper lip

-pouting or frowning:
depressor labii inferioris – depresses lower lip
mentalis- wrinkles chin and protrudes lower lip

Question 27

Mastication = chewing

Answer 27

Mastication = chewing
forceful closing of mouth = elevators of mandible
brings mandibular teeth forcefully against maxillary teeth to crush food
some of the strongest muscles of the body:
**temporalis – elevates and retracts mandible
**masseter – elevates and protracts mandible

Question 28

Muscle of Mastication = chewing

Answer 28

• *temporalis – elevates and retracts mandible

* *masseter – elevates and protracts mandible

Question 29

Tongue Movements

Answer 29

Tongue Movements
important in mastication and speech:
moves food around mouth
holds food in place
pushes food up to palate and back toward pharynx to initiate swallowing
changes shape to modify sound during speech

**intrinsic muscles = within the tongue itself – change shape of tongue

**extrinsic muscles = outside of tongue but attach to it
change shape of tongue, and move it – up, down, out, back

Question 30

Muscles of anterior neck and throat used in swallowing

Answer 30

Muscles of anterior neck and throat used in swallowing
involves muscles of the hyoid, soft palate, pharynx and larynx
**suprahyoid muscles allow mandible to depress when hyoid is fixed by infrahyoid group
**infrahyoid group – elevate the larynx when suprahyoid group is fixed
during swallowing – food is forced into the esophagus

Question 31

Head and Neck Muscles

Answer 31

Head and Neck Muscles
Movement of head and neck by muscles that attach to skull and bones in the neck region
Rotation and lateral flexion of the neck:
**sternocleidomastoid = prime mover of lateral group
one contracting laterally flexes head to same side and rotates head and neck to opposite side
both contracting together flex neck
**scalenes – origin = cervical vertebrae; insertion = first and second ribs

Extension, rotation and lateral flexion of the neck 
posterior  capitus group

Question 32

Head and Neck Muscles

Movement of head and neck by muscles that attach to skull and bones in the neck region

Answer 32

Rotation and lateral flexion of the neck:
**sternocleidomastoid = prime mover of lateral group
one contracting laterally flexes head to same side and rotates head and neck to opposite side
both contracting together flex neck
**scalenes – origin = cervical vertebrae; insertion = first and second ribs

Question 33

Head and Neck Muscles

Movement of head and neck by muscles that attach to skull and bones in the neck region

Answer 33

Extension, rotation and lateral flexion of the neck

posterior capitus group

Question 34

Trunk muscle functions:

Answer 34

Trunk Muscles

move the vertebral column, muscles involved in breathing, abdominal wall, and pelvic floor

Question 35

Trunk muscle functions: muscles moving the vertebral column

Answer 35

muscles moving the vertebral column
*extend, laterally flex and rotate vertebral column

*superficial group most extend from vertebrae to the ribs:
very strong to maintain posture
**erector spinae – group of muscles on either side of spine that extend the head, neck and vertebral column •	spinalis – upper portion •	longissimus – middle portion •	iloiocostalis – lowest portion

*deep group extend between spinous and transverse processes of individual vertebrae

Question 36

Trunk muscle functions: Muscles of respiration

Answer 36

Muscles of respiration
involved in breathing
**external intercostals – elevates ribs during quiet inspiration
**internal intercostals – depresses ribs during forced expiration
**diaphragm = main muscle of inspiration – flattens to depress floor of thorax

Question 37

Trunk muscle functions: Abdominal wall

Answer 37

Abdominal wall
*crossing pattern of anterior abdominal muscles creates strong anterior wall:
holds in and protects abdominal viscera
*contractions **flexes and rotate the vertebral column
when vertebral column fixed aid in:
• forced expiration
• vomiting
• defication
• urination
• childbirth
*linea alba = located in the midline from the xiphoid process to the pubis = **dense connective tissue
*rectus abdominus – on either side of linea alba and covered by rectus sheath
tendinosus intersections cross at several places producing “six-pack”
*external obliques – superficial lateral abdominal muscle
*internal obliques – middle lateral abdominal muscle
*transversus abdominis – deepest abdominal muscle

Question 38

Abdominal wall

Answer 38

*linea alba = located in the midline from the xiphoid process to the pubis = **dense connective tissue
*rectus abdominus – on either side of linea alba and covered by rectus sheath
tendinosus intersections cross at several places producing “six-pack”
*external obliques – superficial lateral abdominal muscle
*internal obliques – middle lateral abdominal muscle
*transversus abdominis – deepest abdominal muscle

Question 39

Pelvic floor and Perineum

Answer 39

Pelvic floor and perineum
inferior opening of pelvis closed by **pelvic diaphragm (muscular wall)
anus and urogenital openings penetrate wall
**perineum = inferior to pelvic floor
contains muscles for enclosing urogenital triangle involved in erection and support of pelvic floor, and external anal sphincter that closes anal opening

Question 40

Upper Limb Muscles

Answer 40

Includes muscles that move the scapula, arm, forearm and hand

Question 41

Upper Limb Muscles:

Scapular movements

Answer 41

Scapular movements
*anterior muscles: **serratus anterior, pectoralis minor, subclavius
*posterior muscles: **trapezius, levator scapulae, rhomboids (major and minor)
move scapula - permits wide range of movements of upper limbs
hold scapula in place (fixators) when arm muscle contract

Question 42

Upper Limb Muscles:

Arm movements

Answer 42

Arm movements
attached to thorax by several muscles:
**pectoralis major = **adducts and medially rotates arm
**deltoid muscle –prime mover to **abduct the arm
**latissimus dorsi – prime mover of **arm extension, adducts and medially rotates arm
**rotator cuff muscles – **hold head of humerus to glenoid cavity of scapula
• infraspinatus, supraspinatus, subscapularis, teres minor
• form cup or cuff over proximal humerus
• damage involves damage to one or more of muscles or their tendons
• **laterally and medially rotate and abduct and adduct arm

Question 43

Upper Limb Muscles:

Forearm movements

Answer 43

Forearm movements
include: extension and flexion of the elbow, and supination and pronation of the forearm and hand
**triceps brachii = main mass visible on posterior aspect of arm, **forearm extensor:
tennis elbow (lateral epicondylitis)– repetitive and forceful use of forearm extensor muscles,
**biceps brachii = anterior aspect of arm, **flexes and supinates forearm and hand
branchialis = deep to biceps brachii – seen as mass on medial and lateral sides of arm, flexes elbow
brachioradialis = bulge on anterolateral side of forearm just distal to elbow, flexes elbow; origin: lateral supracondylar ridge of humerus; insertion: styloid process of radius
**supinator (Fig. 10.16) – supinates forearm and hand
**pronator teres and quadratus – pronates forearm and hand

Question 44

Upper Limb Muscles:

Wrist, hand and finger movements

Answer 44

Wrist, hand and finger movements
**extrinsic hand muscles – are in the forearm but have tendons that extend into wrist
**anterior forearm muscles = flexion of wrist and fingers (Fig. 10.16)
**posterior forearm muscles = extension of wrist and fingers (Fig. 10.17)
extensor carpi radialis longus, brevis and ulnaris – extend wrist
extensor digitorum – extends fingers
intrinsic hand muscles (Fig. 10.19) = muscles entirely within the hand
-adduction and abduction of fingers

Question 45

Lower Limb Muscles

Answer 45

Lower Limb Muscles

involves muscles that provide movement of the hip and thigh, leg, ankle, foot and toes

Question 46

Lower Limb Muscles

Answer 46

Anterior, posterolateral and deep muscles that originate on coxal bone and insert onto femur
**anterior muscles = **iliopsoas – prime mover that flex thigh
**posterolateral muscle – all **adbuct thigh:
**gluteus maximus – makes most of the mass viewed as buttocks
laterally rotates thigh and maximum force = extension of thigh
gluteus medius – superior and lateral to gluteus maximus, common site for injections
gluteus minimus – deep to gluteus medius:
abduct and medially rotate thigh
**tensor fasciae latae – smaller muscle portion proximally that becomes large aponeurosis (iliotibial tract) distally:
medially rotates thigh and **stabilizes femur on tibia when standing

Question 47

Thigh muscles organized into compartments

Answer 47

Thigh muscles organized into compartments
*anterior compartment muscles – flex thigh and/or extend leg

* medial compartment muscles – all adduct, flex and medially rotate thigh 
* posterior compartment muscles (hamstrings) –  cross two joints: hip and knee and extend thigh and flex the leg

Question 48

Thigh muscles organized into compartments:

Anterior compartment

Answer 48

Anterior compartment muscles **flex thigh and/or extend leg
**quadriceps femoris – common insertion: patella and tibial tuberosity via the petallar ligament and except for rectus femoris are **all leg extenders:
• vastus lateralis – injection site on lateral side of thigh
• rectus femoris –lies in center of the group of muscles - allows thigh flexion and leg extension
• vastus intermedius – lies deep to rectus femoris
• vastus medialis – most medial of group

**Sartorius – longest muscle of body  •	crosses two joints – allows **thigh and knee flexion, abducts and laterally rotates thigh

Question 49

Thigh muscles organized into compartments:

Medial compartment

Answer 49

Medial compartment muscles – all **adduct, flex and medially rotate thigh 
	pectinius 
	adductor brevis 
	adductor longus 
	adductor magnus 
	**gracilis

Question 50

Thigh muscles organized into compartments:

Posterior compartment

Answer 50

Posterior compartment muscles (hamstrings) – cross two joints: hip and knee and **extend thigh and flex the leg
**biceps femoris –laterally rotates leg
semimembranosus –medially rotates leg
semitendinosus - medially rotates leg

Question 51

Ankle, foot and toe movements:

Answer 51

Have extrinsic and intrinsic muscles groups

Extrinsic muscles = muscles associated with compartments of the leg that move the ankle and foot

Question 52

Ankle, foot and toe movements:
Extrinsic muscles and
Intrinsic muscles

Answer 52

Extrinsic muscles = muscles associated with compartments of the leg that move the ankle and foot:
#Anterior compartment = extensor muscles – allow dorsiflexion, inversion or eversion of foot, extension of toes
#Lateral compartment  = mainly **eversion of foot and aid in **plantar flexion, tendons seen on the lateral side of the ankle
#Posterior compartment = 	superficial muscle group –insert via common tendon calcaneal (Achilles) tendon and allow plantar flexion of foot

Intrinsic muscles = muscles within the foot itself – **flex, extend, abduct and adduct toes

Question 53

Ankle, foot and toe movements:

Extrinsic muscles - Anterior compartment

Answer 53

Anterior compartment = **extensor muscles – allow dorsiflexion, inversion or eversion of foot, extension of toes
• extensor digitorum longus
• extensor halluces longus
• tiabialis anterior
• fibularis tertius
• **shin splits = pain associated with anterior compartment associated with muscle stress, inflammation, stress fractures of tibia – causes include running with unsupportive shoes or on hard surface, increasing activity too quickly

Question 54

Ankle, foot and toe movements:

Extrinsic muscles - Lateral compartment

Answer 54

Lateral compartment = mainly **eversion of foot and aid in plantar flexion, tendons seen on the lateral side of the ankle
• fibularis brevis
• fibularis longus

Question 55

Ankle, foot and toe movements:

Extrinsic muscles - Posterior compartment

Answer 55

Posterior compartment

Superficial muscle group –insert via common tendon **calcaneal (Achilles) tendon and allow **plantar flexion of foot
**gastrocnemius – crosses two joints so also **flexes the knee:
together with soleus form the bulk of the calf
soleus 
plantaris

Deep muscle group – **plantar flexion and inversion of foot, flex toes
flexor digitorum longus – origin: tibia, insertion: four lateral toes
flexor halluces longus – origin: fibula, insertion: distal phalynx of great toe
tibialis posterior – origin: tibia, insertion: navicular, cuneiforms, cuboid, and second to fourth metatarsals

Question 56

Ankle, foot and toe movements:

Intrinsic muscles

Answer 56

Intrinsic muscles = muscles within the foot itself – **flex, extend, abduct and adduct toes
muscles covered with thick fascia and plantar aponeurosis
**plantar fasciitis = inflammation of plantar aponeurosis resulting in pain over the heel and along the medial-inferior side of the foot
• cause – running on hard surface wearing poorly fitting or worn-out shoes