Chapter 9, 10 , 11 ( muscular system)

Question 1

Skeletal muscles

Answer 1

most extend from one bone to another and cross at least on joint
• contraction – causes movement – pulling one bone toward another across a joint
o 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 2

strength of skeletal muscles

Answer 2

• strength related to the total number of myofibers (muscle cells) in the muscle

Question 3

range of motion

Answer 3

• range of motion related to fascicle arrangement (bundles of muscle cells) (Fig 9.12)
o shape and size greatly influence the degree to which a muscle can contract and the amount of force it can generate

Question 4

parallel muscle

Answer 4

o fascicules parallel to long axis of muscle and terminate on a flat tendon that spans the width of the entire muscle
♣ most skeletal muscles = parallel muscles
♣ can be interrupted by transverse segments of connective tissue
♣ may exhibit twisted or spinal arrangement
♣ when activated can be shortened to a maximum of ~30%

Question 5

circular

Answer 5

o – arranged in a circle around an opening and act as sphincters to close opening
♣ when muscle contracts diameter of opening decreases
♣ guard entrances and exits of internal passages

Question 6

convergent

Answer 6

o fasciculi arrive at one common attachment
♣ tendon, tendinosus sheet, or raphe - slender band of collagen fibers
♣ fibers spread out in fan-like manner

Question 7

pennate –

Answer 7

o 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
♣ bipennate = two sides of the tendon
♣ multipennate = arranged in many places around central tendon
♣ does not move tendon as far as a parallel muscle of the same size – but produces more tension

Question 8

• muscle terminology

Answer 8

o 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
o insertion = mobile end – usually the distal end attached to the bone undergoing the greatest movement
o belly = part of muscle between origin and insertion
o tendons – long cable-like dense regular connective tissue that attach muscle to bone
♣ aponeuroses = broad, sheet-like tendons
o innervation = nerve supply to a particular structure
♣ one or more motor nerves control each muscle

Question 9

actions

Answer 9

• actions = movement produced when muscle contracts

Question 10

agonist

Answer 10

o agonist = muscle that produces a certain desired movement – e.g. flexion
♣ synergists = group of muscles working together to produce a movement – e.g. hip flexors
♣ prime mover = muscle within a synergistic group that plays the major role in the movement

Question 11

antagonist

Answer 11

o antagonist = muscle contraction whose action that counteracts the agonist movement – e.g. extension

Question 12

fixators

Answer 12

o prime movers and antagonists contract simultaneously to hold one bone in place relative to the body while a usually more distal bone is moved

Question 13

• named according to:

Answer 13

o location – specific region of the body (brachialis, capitus)
o size (gluteus maximus)
o length – longus (long), brevis (short)
o shape (deltoid – triangular)
o orientation of fascicles – transverse, oblique, rectus - straight with the axis of the bone (rectus femoris)
o origin and insertion (sternocleidomastoid – origin sternum and clavicle, insertion mastoid process of temporal bone)
o relative position – posterior, anterior, profundus (deep), superficialis
o number of heads (biceps – two heads)
o function (adductor pollicus)

Question 14

Divisions of Skeletal Muscle System

Answer 14

• Axial musculature – origins and insertions on axial skeleton
o positions head and vertebral column and assists in breathing by moving rib cage
• Appendicular musculature – stabilizes or moves components of appendicular skeleton

Question 15

Axial Muscles

Answer 15

• 4 groups based on location and/or function
o head and neck muscles, muscles of vertebral column, muscular walls of thoracic and abdominopelvic cavities, muscles of the perineum and pelvic diaphragm

Question 16

Axial muscles - Head and neck muscles

Answer 16

• originate on skull or hyoid bone and not associated with vertebral column
• muscles of facial expression, extra-ocular muscles, muscles of mastication, muscles of the tongue, muscles of the pharynx, and anterior muscles of the neck
o responsible for verbal and non-verbal communication, feeding, and movement of eyes

Question 17

facial expression

Answer 17

o cutaneous muscles – origins on surface of skull and insertions via collagenous fibers of epimysium (connective tissue wrapping skeletal muscles) woven into dermis of skin
♣ allow skin to twitch to remove irritants (e.g. insects)
important in non-verbal communication

Question 18

o largest group associated with movement of mouth

Answer 18

♣ closing and puckering lips:
• orbicularis oris – closes lips – constricts opening while other muscles move lips or corners of mouth
o origin = nasal septum, maxilla, and mandible
• buccinator – flattens cheek – allows suckling and puckering
o origin = mandible and maxilla

Question 19

smiling

Answer 19

• zygmaticus major and minor – elevate and abduct upper lip; origin = zygomatic bone
• levator anguli oris – elevates angle of mouth; origin = maxilla
• risoris – abducts angle of mouth: origin = fascia of masseter

Question 20

♣ sneering:

Answer 20

• levator labii superioris – elevates upper lip; origin = maxilla

Question 21

♣ pouting or frowning:

Answer 21

• depressor annuli oris – depresses angle of mouth; origin = mandible
• depressor labii inferioris – depresses lower lip; origin = mandible
• mentalis - protrudes lower lip; origin = mandible

Question 22

o smaller group controls movement of eyebrows, eyelids, scalp, nose and external ear

Answer 22

♣ occipitofrontalis – raises eyebrows and furrows skin of forehead; origin = occipital bone; insertion = skin of eyebrow and nose
♣ orbicularis oculi – closes eyelids and causes “crow’s feet”; origin = maxilla and frontal bones
♣ levator palpebrae superior (Fig 10.5)– raises upper lids; origin = lesser wing of sphenoid bone
• ptosis = droopy eyelid on one side – usually indicates nerve damage leading to the muscle
♣ corrugator supercilii – draws eyebrows inferiorly and medially producing vertical corrugations between eyes – origin = nasal bridge

Question 23

Extra-Ocular Muscles

Answer 23

o 6 extra-ocular (extrinsic eye) muscles rotate eyeball within orbit to allow vision in a wider range of directions
origins = surface of orbit, insertions = sclera (thick fibrous outer layer of wall of eye

• rectus muscles
• oblique muscles
• diplopia
• strabismus

Question 24

rectus muscles

Answer 24

o rectus muscles = nearly straight with axis of eye and rotate eye in direction of their attachment
♣ superior rectus – “look up”
♣ inferior rectus – “look down”
• superior and inferior are slightly offset so also bring eye medially
♣ lateral rectus – abducts eye “look to the side”
♣ medial rectus – adducts eye “look to the nose”

Question 25

oblique muscles

Answer 25

o = oriented at an oblique axis of the eye inserting into posterior lateral margin
♣ superior oblique – moves eye “down and out”
♣ inferior oblique – moves eye “up and out”

Question 26

diplopia

Answer 26

o double-vision - each eye not focused on same image and get two separate images
♣ can result from paralysis or weakness of certain extrinsic muscles or neurological diseases

Question 27

strabismus

Answer 27

o congenital weakness of external eye muscles in which eye rotates medially “cross-eyed” or laterally “wall-eyed”
♣ to compensate eyes may alternate focusing on objects, or only the controllable eye may be used and the brain ignores the input from the other eye making it functionally blind (amblyopia)

Question 28

Mastication

Answer 28

chewing

o move mandible at temporomandibular joint

Question 29

elevator of mandible

Answer 29

o – brings mandibular teeth forcefully against maxillary teeth to crush food
♣ masseter – elevates and protracts mandible; origin = zygomatic arch, insertion = mandibular ramus
• most powerful and important muscle
♣ temporalis – elevates and retracts mandible; origin = temporal fossa of parietal bone, insertion = mandibular ramus and coronoid process of mandible
♣ medial pterygoid – elevates and protracts mandible; origin = pterygoid plate of sphenoid bone
♣ lateral pterygoid – protracts and depresses mandible; origin = pterygoid plate of sphenoid bone

o slight mandibular depression due to relaxation of the elevators and pull of gravity – “slack jaw”
o grinding food between teeth = medial and lateral excursion of mandible – and all muscles of mastication

Question 30

Muscle of the tongue

Answer 30

o 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

Question 31

intrinsic muscle of tongue

Answer 31

within the tongue itself – change shape of tongue

Question 32

extrinsic muscle of tongue

Answer 32

o = outside of tongue but attach to it
♣ names end in glossus – meaning tongue
♣ most origins = bone (mandible, styloid process of temporal bone, hyoid)
♣ change shape of tongue, and move it – up, down, out, back

Question 33

Muscles of the Pharynx

Answer 33

o important for swallowing - involves muscles of the hyoid, soft palate, pharynx and larynx

Question 34

pharyngeal constrictors

Answer 34

o pharyngeal constrictors (superior, middle and inferior) – initiation of swallowing
♣ move food bolus (mass of food) into esophagus

Question 35

laryngeal elevators

Answer 35

o laryngeal elevators – “-pharyngeous” muscle insert onto thyroid cartilage and elevate the larynx
♣ salpingopharyngeus – together with palatal muscles opens auditory tube – equalizes pressure between middle ear and atmosphere

Question 36

palatal muscles

Answer 36

o palatini” – elevate the soft palate

♣ close the posterior opening to the nasal cavity during swallowing

Question 37

Anterior muscles of the neck

Answer 37

o control position of larynx, depress mandible, tense the floor of the mouth

Question 38

extrinsic muscles of the larynx

Answer 38

o extrinsic muscles of the larynx – position the larynx

♣ narrow or close laryngeal opening so food does not enter larynx

Question 39

intrinsic muscles of the larynx

Answer 39

o contraction affects the vocal cords
♣ shortening vocal cords lowers the pitch of the voice
♣ lengthening raises the pitch of the voice

Question 40

suprahyoid muscles

Answer 40

o depress mandible, opening mouth and/or elevates mandible;

♣ digastric, geniohyoid, mylohyoid, stylohyoid - insertion = hyoid bone

Question 41

infrahyoid group

Answer 41

o depress the larynx

♣ omohyoid, sternohyoid, sternothyroid - insertion = hyoid bone

Question 42

o sternocleidomastoid

Answer 42

♣ one contracting laterally flexes head to shoulder on same side or rotates head and neck to opposite side
♣ both contracting together flex neck
♣ origin = manubrium and medial clavicle; insertion = mastoid process and superior nuchal line

Question 43

laryngospasm

Answer 43

o tetanic contraction of the muscles that narrow the opening of the larynx
♣ occurs when food or liquid “goes down the wrong way”
♣ can result from severe allergic reactions, tetanus infections or hypocalcemia
♣ typical episode lasts 30-60 seconds
• severe cases opening is closed completely and air cannot pass through the larynx to the lungs
• botulinum toxin – injection can relax muscles
tracheotomy

Question 44

Muscles of Vertebral Column

Answer 44

• has many extensors but few flexors
o many of the large trunk muscles flex the vertebral column when they contract
o most of the body weight lies anterior to the vertebral column and gravity tends to flex spine

Question 45

longus capitis

Answer 45

o – transverse processes of C4-C6 to base of occipital bone

♣ together - flex neck; one side – rotates neck to that side

Question 46

longus colli

Answer 46

o anterior margins of the cervical vertebrae to transverse processes of superior cervical vertebrae insertion = occipital bone
♣ flexes neck

Question 47

• extensor muscles of back arranged into 3 layers:

Answer 47

superficial, intermediate, deep

Question 48

superficial layer

Answer 48

♣ splenius muscles (splenius capitus and splenius cervicis) – origin: ligamentum nuchae and spines of vertebrae (C7-T6), insertion: mastoid process, occipital bone, superior cervical vertebrae
• together - extend neck; one side – rotates and laterally flexes neck to that side
♣ trapezius, latissimus dorsi, levator scapulae, and rhomboids
• position pectoral girdle and upper limb (see appendicular muscle section below)

Question 49

intermediate layer

Answer 49

♣ erector spinae – group of muscles on either side of spine that extend the head, neck and vertebral column

Question 50

what are the 3 subgroups of intermediate layer

Answer 50

• 3 subgroups (superior to inferior)
o spinalis –origin: C6-C7, T11-T12 (most medial)
o longissimus – accounts for most of the muscle mass in the lower back; origins: cervical and thoracic vertebrae
o iloiocostalis – origin: sacrum, illium and lumbar spines (most lateral)
• each subgroup has muscles that insert on the skull – capitus; upper cervical vertebrae – cervicis; and lower cervical and upper thoracic vertebrae – thoracis
o capitus and cervicis groups: together - extend neck; one side – rotates and laterally flexes neck to that side
o thoracis groups: extend vertebral column; one side – lateral flexion to that side

Question 51

♣ serratus posterior muscles

Answer 51

♣ serratus posterior muscles - assist in rib movement during inspiration

Question 52

o deep layer = intrinsic back muscles

Answer 52

♣ transversopinalis muscles - interconnect and stabilize vertebrae
• semispinalis group, mulitidus, rotatores, interspinales, intertrranversarii muscles
• short muscles that work in combinations to produce slight extension or rotation of vertebral column

Question 53

Oblique and Rectus Muscles

Answer 53

• lie between vertebral column and ventral midline

* have cervical, thoracic and abdominal groups

Question 54

oblique muscles

cervical region

Answer 54

• compress underlying structures or rotate vertebral column
o cervical region
♣ scalenes – origin = cervical vertebrae; insertion = first and second ribs
• elevates ribs and/or flex neck; one side bends neck and rotates to same side

Question 55

oblique muscles - thoracic region

Answer 55

o thoracic region
♣ external intercostals – elevates ribs during quiet inspiration
• origin: inferior margin of each rib, insertion: superior border of next rib below
• superficial to internal intercostals
♣ internal intercostals – depresses ribs during forced expiration; origin: superior margin of each rib, insertion: inferior border of next rib above

Question 56

oblique muscles - abdominal regions

Answer 56

o – muscles compress abdomen; depress ribs; flexes, laterally flexes and rotates vertebral column
♣ crossing pattern of abdominal muscles creates strong anterior wall
♣ external obliques – superficial lateral abdominal muscle; origin: 5th to 12th ribs, insertion: iliac crest, rectus sheath
♣ internal obliques – middle lateral abdominal muscle; origin: iliac crest, lumbar fascia, insertion: 10th to 12th ribs and rectus sheath
♣ transversus abdominis – deepest abdominal muscle; origin: 7th to 12th costal cartilages, lumbar fascia, insertion: xiphoid process, linea alba, pubis

Question 57

rectus muscles

Answer 57

• – oppose erector spinae – flex vertebral column
o rectus abdominus – on either side of linea alba and covered by rectus sheath
♣ linea alba = located in the midline from the xiphoid process to the pubis = dense connective tissue
♣ origin: pubic crest and symphysis pubis, insertion: xiphoid process and inferior ribs
♣ depress ribs, flexes vertebral column, compresses abdomen
♣ tendinous inscriptions = bands of fibrous tissue that divide muscle into repeated segments “six-pack”

Question 58

diaphragm

Answer 58

main muscle of inspiration – flattens to depress floor of thorax; origin: interior of lower ribs, sternum and lumbar vertebrae, insertion: central tendon of diaphragm

Question 59

hernia

Answer 59

when visceral organ or part of an organ protrudes abnormally through an opening in a surrounding muscular wall or partition

Question 60

inguinal hernia

Answer 60

o protrusion of portion of greater omentum or small intestine through inguinal canal
♣ more common in males

Question 61

diaphragmatic hernia

Answer 61

o – abdominal organs slide into thoracic cavity
♣ hiatal hernia – if entry is through the esophageal hiatus (opening)
• very common and most go unnoticed
• increase severity of gastric acid entry in esophagus (gastroesophageal reflux, GERD)

Question 62

Muscles of the Perineum and Pelvic Diaphragm

purpose ?

Answer 62

• extend from sacrum and coccyx to ischium and pubis
• support organs of pelvis cavity
• flex joints of sacrum and coccyx
• control movement of material through urethra and anus

Question 63

perineum (pelvic floor

Answer 63

– boundaries = inferior margins of pelvis

o urogenital triangle (anterior portion) (Table 10.9)
♣ superficial muscles = muscles of external genitalia
♣ urogenital diaphragm = deeper muscles - strengthen pelvic floor and encircle urethra
• deep transverse perineal muscle and external urethral sphincter
o anal triangle (posterior portion) (Table 10.10)
♣ pelvic diaphragm = muscular foundation of anal triangle
• coccygeus, levator ani and external anal sphincter muscles