Muscular System Flashcards
Muscles can be classified into 4 functional groups:
- prime
- movers
- antagonists
- synergists
- fixators
The muscle that has the major responsibility for producing a specific movement.
prime movers or agonists
Muscles that oppose, or reverse, a particular movement are called ________.
antagonists
They help prime movers by
(1) adding a little extra force to the same movement or
(2) reducing undesirable or unnecessary movements that might occur as the
prime mover contracts.
synergists
When synergists immobilize a bone, or a muscle’s origin so that the prime mover has a stable base on which to act, they are more specifically called ________.
fixators
Skeletal muscles are named according to a number of criteria:
- Location of the muscle.
- Shape of the muscle.
- Relative size of the muscle.
- Direction of muscle fibers.
- Number of origins.
- Location of the attachments.
- Action.
This means muscle overlies the temporal bone.
temporalis
This means muscles run between the ribs.
intercostal
This means muscle is roughly triangular.
deltoid
This means muscles form a trapezoid.
trapezius
The following terms mean:
- maximus
- minimus
- longus
- brevis
- largest
- smallest
- long
- short
The following terms means straight or fibers run parallel to that imaginary line.
rectus
The terms _______ and _______ indicate that the muscle fibers run respectively at right angles and obliquely to that line.
transversus and oblique
Arrangement of Fascicles
- Circular
- Convergent
- Parallel
- Unipennate
- Bipennate
- Fusiform
- Multipennate
The fascicular pattern is _______ when the fascicles are arranged in concentric rings.
circular
A ________ muscle has a broad origin, and its fascicles converge toward a single tendon of insertion.
convergent
In what arrangement does the long axes of the fascicles run parallel to the long axis of the muscle?
parallel
Some authorities classify the spindle-shaped muscles into a separate class as ________ muscles.
fusiform
In a _______ pattern, the fascicles are short and they attach obliquely to a central tendon that runs the length of the muscle.
pennate
Refers to the partnerships between the muscular and skeletal systems.
lever systems
A ____ is a rigid bar that moves on a fixed
point called the _____, when a force is applied to it.
lever; fulcrum
Effort farther than load from fulcrum equals _______.
mechanical advantage
Effort nearer than load to fulcrum equals ________.
mechanical disadvantage and is a speed lever
In ________, the effort is applied at one end of the lever and the load is at the other, with the fulcrum somewhere between.
first-class levers
eg. scissors, and seesaws
In a _______, the effort is applied at one end of the lever and the fulcrum is located at the other, with the load between them.
second-class lever
eg. wheelbarrow
True or False. Some first-class levers in the body operate at a mechanical advantage (for strength).
True
True or False. The action of the triceps muscle in extending the forearm against resistance, operate at a mechanical disadvantage (for strength).
False. for SPEED and DISTANCE
True or False. All second-class levers in the body work at a mechanical disadvantage.
False. All second-class levers in the body work at a MECHANICAL ADVANTAGE.
In ________, the effort is applied between the load and the fulcrum.
third-class levers
eg. tweezers and forceps
True or False. Third-class levers are speedy and always operate at a mechanical disadvantage.
True
Bipartite muscle consisting of the frontal and occipital bellies connected by a cranial aponeurosis, the galea aponeurotica; the alternate actions of these two muscles pull scalp forward and backward.
Epicranius (occipitofrontalis)
Covers forehead and dome of skull; no bony attachments.
With aponeurosis fixed, raises the eyebrows (as in surprise); wrinkles forehead skin horizontally
Frontal belly
Overlies posterior occiput; by pulling on the galea, fixes origin of frontalis.
Fixes aponeurosis and
pulls scalp posteriorly
Occipital belly
Small muscle; activity associated with that of orbicularis oculi
Draws eyebrows together and inferiorly; wrinkles skin of forehead vertically (as in frowning)
Corrugator supercilii
Closes eye; various parts can be activated individually; produces blinking, squinting, and draws eyebrows inferiorly
Orbicularis oculi
Raises lateral corners of mouth upward (smiling muscle)
Zygomaticus
Draws corner of lip laterally; tenses lips; synergist
of zygomaticus
Risorius
Opens lips; raises and furrows the upper lip
Levator labii superioris
Draws lower lip inferiorly (as in a pout)
Depressor labii inferioris
Draws corners of mouth downward and laterally
(as in a “tragedy mask” grimace); zygomaticus antagonist
Depressor anguli oris
Closes lips; purses and protrudes lips; kissing and
whistling muscle
Orbicularis oris
Wrinkles chin; protrudes lower lip
Mentalis
Compresses cheek (as in whistling and sucking);
trampoline-like action holds food between teeth
during chewing; draws corner of mouth laterally;
well developed in nursing infants
Buccinator
Tenses skin of neck (e.g., during shaving); helps depress mandible; pulls lower lip back and down,
i.e., produces downward sag of mouth
Platysma
Prime mover of jaw closure; elevates mandible
Masseter
Closes jaw; elevates and retracts mandible;
maintains position of the mandible at rest; deep
anterior part may help protract mandible
Temporalis
Acts with the lateral pterygoid muscle to protrude (protract) mandible and to promote sideto-side side (grinding) movements; synergist of temporalis and masseter muscles in elevation of the mandible
Medial pterygoid
Provides forward sliding and side-to-side grinding
movements of the lower teeth; protrudes mandible (pulls it anteriorly)
Lateral pterygoid
Compresses the cheek; helps keep food between
grinding surfaces of teeth during chewing
Buccinator
Protracts tongue; can depress or act in concert with other extrinsic muscles to retract tongue
Genioglossus
Depresses tongue and draws its sides downward
Hyoglossus
Retracts (and elevates) tongue
Styloglossus
Muscles that help form floor of oral cavity, anchor tongue, elevate hyoid, and move larynx superiorly during swallowing; lie superior to hyoid bone.
Suprahyoid muscles
Open mouth and depress mandible; acting in concert, the digastric muscles elevate hyoid bone and steady it during swallowing and speech
Digastric
Elevates and retracts hyoid, thereby elongating
floor of mouth during swallowing
Stylohyoid
Elevates hyoid bone and floor of mouth, enabling
tongue to exert backward and upward pressure that
forces food bolus into pharynx
Mylohyoid
Pulls hyoid bone superiorly and anteriorly, shortening floor of mouth and widening pharynx for receiving food
Geniohyoid
Straplike muscles that depress the hyoid bone and larynx during swallowing and speaking.
Infrahyoid
Depresses larynx and hyoid bone if mandible is
fixed; may also flex skull
Sternohyoid
Pulls larynx and hyoid bone inferiorly
Sternothyroid
Depresses and retracts hyoid bone
Omohyoid
Depresses hyoid bone or elevates larynx if hyoid is
fixed
Thyrohyoid
Constrict pharynx during swallowing, which propels a food bolus to esophagus (via a massagelike action called peristalsis)
Pharyngeal constrictor
muscles
What is the major head flexors?
sternocleidomastoid muscles
The largest of the deep back muscle groups is the ________.
erector spinae group
Flexes and laterally rotates the head
Sternocleidomastoid
Elevate first two ribs (aid in inspiration); flex and
rotate neck
Scalenes
Extend or hyperextend head; when splenius muscles on one side are activated, head is rotated and bent laterally toward same side
Splenius
Extend and laterally flex the vertebral column; maintain erect posture; acting on one side, bend vertebral column to same side
Iliocostalis
Thoracis and cervicis act together to extend and laterally flex vertebral column; capitis extends head
and turns the face toward same side
Longissimus
Extends vertebral column
Spinalis
Extends vertebral column and head and rotates
them to opposite side; acts synergistically with sternocleidomastoid muscles of opposite side
Semispinalis
Flexes vertebral column laterally when acting
separately; when pair acts jointly, lumbar spine is
extended and 12th rib is fixed; maintains upright
posture; assists in forced inspiration
Quadratus lumborum
They lift the rib cage, an action that increases the anterior to posterior and side-to-side dimensions of the thorax.
external intercostal muscles
The __________ form the deeper layer and may aid active (forced) expiration by depressing the rib cage.
internal intercostal muscles
Prime mover of inspiration; flattens on contraction, increasing vertical dimensions of thorax; when strongly contracted, dramatically increases intra-abdominal pressure
Diaphragm
Flex and rotate lumbar region of vertebral column;
fix and depress ribs, stabilize pelvis during walking,
increase intra-abdominal pressure; used in sit-ups,
curls
Rectus abdominis
When pair contract simultaneously, flex vertebral column and compress abdominal wall and increase
intra-abdominal pressure; acting individually, aid
muscles of back in trunk rotation and lateral flexion; used in oblique curls
External oblique
As for external oblique
Internal oblique
Compresses abdominal contents
Transversus abdominis
Supports and maintains position of pelvic viscera
Levator ani
Supports coccyx and pulls it forward after it has been
reflected posteriorly by defecation and childbirth
Coccygeus
Supports pelvic organs; steadies central tendon
Deep transverse perineal muscle
Constricts urethra; allows voluntary inhibition of
urination; helps support pelvic organs
External urethral sphincter
Retards venous drainage and maintains erection of
penis or clitoris
Ischiocavernosus
Empties male urethra; assists in erection of penis
and of clitoris
Bulbospongiosus
Stabilizes and strengthens midline tendon of perineum
Superficial transverse perineal muscles
With ribs fixed, draws scapula forward and
downward
Pectoralis minor
Rotates scapula so that its inferior angle moves laterally and upward
Serratus anterior
Helps stabilize and depress pectoral girdle
Subclavius
Stabilizes, raises, retracts, and rotates scapula
Trapezius
Elevates/adducts scapula in concert with superior
fibers of trapezius
Levator scapulae
Stabilize scapula
Rhomboids
Prime mover of arm flexion; rotates arm medially;
adducts arm against resistance
Pectoralis major
Prime mover of arm abduction when all its fibers
contract simultaneously
Deltoid
Prime mover of arm extension; powerful arm adductor; medially rotates arm at shoulder
Latissimus dorsi
Chief medial rotator of humerus
Subscapularis
Initiates abduction
Supraspinatus
Rotates humerus laterally
Infraspinatus
Same action(s) as infraspinatus muscle
Teres minor
Extends, medially rotates, and adducts humerus;
synergist of latissimus dorsi
Teres major
Flexion and adduction of the humerus; synergist of
pectoralis major
Coracobrachialis
Powerful forearm extensor
Triceps brachii
Controls ulnar abduction during forearm pronation
Anconeus
Flexes elbow joint and supinates forearm
Biceps brachii
A major forearm flexor (lifts ulna as biceps lifts
the radius)
Brachialis
Synergist in forearm flexion
Brachioradialis
Pronates forearm; weak flexor of elbow
Pronator teres
Powerful flexor of wrist; abducts hand; weak synergist of elbow flexion
Flexor carpi radialis
Tenses skin and fascia of palm during hand movements; weak wrist flexor; weak synergist for elbow flexion
Palmaris longus
Powerful flexor of wrist; also adducts hand in concert with extensor carpi ulnaris (posterior muscle);
stabilizes wrist during finger extension
Flexor carpi urnalis
Flexes wrist and middle phalanges of fingers 2–5;
the important finger flexor when speed and flexion against resistance are required
Flexor digitorum superficialis
Flexes distal phalanx of thumb
Flexor pollicis longus
Flexes distal interphalangeal joints
Flexor digitorum profundus
Prime mover of forearm pronation; acts with
pronator teres; also helps hold ulna and radius
together
Pronator quadratus
Extends wrist in conjunction with the extensor carpi ulnaris and abducts wrist in conjunction with the flexor carpi radialis
Extensor carpi radialis longus
Extends and abducts wrist; acts synergistically
with extensor carpi radialis longus to steady wrist
during finger flexion
Extensor carpi radialis brevis
Prime mover of finger extension
Extensor digitorum
Extends wrist in conjunction with the extensor carpi radialis and adducts wrist in conjunction with flexor carpi ulnaris
Extensor carpi urnalis
Assists biceps brachii to forcibly supinate forearm
Supinator
Assists biceps brachii to forcibly supinate forearm
Abductor pollicis longus
Extends thumb
Extensor pollicis brevis and longus
Extends index finger and assists in wrist extension
Extensor indicis
Abducts little finger at metacarpophalangeal joint
Abductor digiti minimi
Flexes little finger at metacarpophalangeal joint
Flexor digiti minimi brevis
Helps in opposition: brings metacarpal 5 toward thumb to cup the hand
Opponens digiti minimi
Flex fingers at metacarpophalangeal joints but extend fingers at interphalangeal joints
Lumbricals
Adductors of fingers: pull fingers in toward third digit
Palmar interossei
Abduct (diverge) fingers; extend fingers at interphalangeal joints and flex them at metacarpophalangeal joints
Dorsal interossei
Iliopsoas is a composite of 2 closely related muscles
- Iliacus
2. Psoas major
Flexes, abducts, and laterally rotates thigh; flexes
knee
Sartorius
A triangular muscle with a broad insertion
Adductor magnus
Overlies middle aspect of adductor magnus
Adductor longus
Largely concealed by adductor longus and pectineus
Adductor brevis
Short, flat muscle; overlies adductor brevis on proximal thigh; abuts adductor longus medially
Pectineus
Long, thin, superficial muscle of medial thigh
Gracilis
Superficial muscle of anterior thigh; runs straight down thigh; longest head and only muscle of group to cross hip joint
Rectos femoris
Largest head of the quadriceps femoris group, forms lateral aspect of thigh
Vastus lateralis
Forms inferomedial aspect of thigh
Vastus medialis
Obscured by rectus femoris; lies between vastus lateralis and vastus medialis on anterior thigh
vastus intermedius
Steadies the knee and trunk on thigh by making iliotibial tract taut; flexes and abducts thigh; rotates thigh medially
Tensor fasciae latae
Major extensor of thigh
Gluteus maximus
Thick muscle largely covered by gluteus maximus;
abducts and medially rotates thigh
Gluteus medius
Smallest and deepest of gluteal muscles
Gluteus minimus
Pyramidal muscle located on posterior aspect of hip joint
Piriformis
Flat, triangular muscle deep in superomedial aspect of thigh
Obturator externus
Surrounds obturator foramen within pelvis; leaves
pelvis via lesser sciatic notch and turns acutely
forward to insert in femur
Obturator internus
Two small muscles with common insertions and actions; considered extrapelvic portions of obturator internus
Gemellus
Short, thick muscle; most inferior of lateral rotator
muscles; extends laterally from pelvis
Quadratus femoris
Most lateral muscle of the hamstrings group; arises from two heads
Biceps femoris
Lies medial to biceps femoris
Semitendinosus
Deep to semitendinosus
Semimembranosus
Superficial muscle of anterior leg; laterally parallels sharp anterior margin of tibia
Tibialis anterior
Unipennate muscle on anterolateral surface of leg;
lateral to tibialis anterior muscle
Extensor digitorum longus
Dorsiflexes and everts foot
Fibularis (peroneus) tertius
Extends great toe; dorsiflexes foot
Extensor hallucis longus
Superficial lateral muscle; overlies fibula
Fibularis (peroneus) longus
Smaller muscle; deep to fibularis longus; enclosed in a common sheath
Fibularis (peroneus) brevis
Superficial muscle of pair; two prominent bellies that form proximal curve of calf
Gastrocnemius
Broad, flat muscle, deep to gastrocnemius on posterior surface of calf
Soleus
Generally a small, feeble muscle, but varies in size and extent; may be absent
Plantaris
Thin, triangular muscle at posterior knee; passes inferomedially to tibial surface
Popliteus
Long, narrow muscle; runs medial to and partially overlies tibialis posterior
Flexor digitorum longus
Bipennate muscle; lies lateral to inferior aspect
of tibialis posterior
Flexor hallucis longus
Thick, flat muscle deep to soleus; placed between
posterior flexors
Tibialis posterior
Helps extend toes at metatarsophalangeal joints; small, four-part muscle on dorsum of foot
Extensor digitorum brevis
Bandlike muscle in middle of sole; corresponds to
flexor digitorum superficialis of forearm and inserts into digits in the same way
Flexor digitorum brevis
Abducts great toe
Abductor hallucis
Abducts and flexes little toe
Abductor digiti minimi
Straightens out the oblique pull of flexor digitorum longus
Flexor accessorius (quadratus plantae)
Four little “worms”
Lumbricals
Flexes great toe’s metatarsophalangeal joint
Flexor hallucis brevis
Helps maintain the transverse arch of foot; weak adductor of great toe
Adductor hallucis
Flexes little toe at metatarsophalangeal joint
Flexor digiti minimi brevis
