Chapter 10 Flashcards
The muscular system
Muscle tissue – all contractile tissues
*Skeletal, cardiac, smooth muscle
- Focus on skeletal muscle
- How muscles interact to -> movement
- Criteria for naming muscles
- Principles of leverage
Actions and interactions of skeletal muscle
Muscles can only pull; never push
What one muscle group “does”, another “undoes”
- Agonist: primary mover
- Antagonist: opposes or reverses particular movement
agonist
primary mover
antagonist
opposes or reverses particular movement
skeletal muscles: functional groups
- synergist
- fixator
Synergist
helps prime movers
*adds extra force to same movement
*reduces undesirable or unnecessary movement
fixator
- Synergist that immobilizes bone or muscle’s origin (rotator cuff and G-H joint)
- Gives prime mover stable base on which to act (ex scap and G-H joint)
anterior side does flexion
true
Posterior side does extension
T
Lateral to joint does abduction
T
Medial to joint does adduction
T
Naming skeletal muscles
Muscle location—bone or body region with which muscle associated
Muscle shape—e.g., deltoid muscle (deltoid = triangle)
Naming skeletal muscles
- Muscle size:
- maximus (largest)
- minimus (smallest)
- longus (long)
- Direction of muscle fibers or fascicles
- rectus (fibers run straight),
- transversus (fibers run at right angles),
- oblique (fibers run at angles to imaginary defined axis)
Naming skeletal muscles
-Number of origins—e.g., biceps (2 origins) and triceps (3 origins)
- Location of attachments—named according to point of origin and insertion (origin named first)
- sternocleidomastoid
- Muscle action—named for action they produce, e.g., flexor or extensor
- Several criteria can be combined, e.g., extensor carpi radialis longus
T tubules are an extension of the
sarcolemma
T-tubules are extensions of the cell membrane (sarcolemma) that associate with the ends (terminal cisternae) of the sarcoplasmic reticulum
The force exerted by a contracting muscle is _______.
muscle tension
Which activity would be most dependent upon creatine?
diving
Creatine phosphate is a molecule that can store energy in its phosphate bonds. … This acts as an energy reserve that can be used to quickly create more ATP. When the muscle starts to contract and needs energy, creatine phosphate transfers its phosphate back to ADP to form ATP and creatine.
Muscle mechanics: the importance of fascicle arrangement and leverage
- additional factors contributing to muscle force and speed
- fascicle arrangement
- lever systems
How skeletal muscles produce movement: fascicle arrangement
-Fascicle arrangement affects a muscles power and range of motion
- 5 patterns of fascicle arrangement:
- parallel
- fusiform
- circular
- triangular
- pennate
- longer fibers produce a greater range of motion
- power of a muscle depends on its cross-sectional area
Arrangement of fascicles: CIRCULAR
Fascicles arranged in concentric rings (e.g., orbicularis oris, orbicularis oculi)
Arrangement of fascicles:
CONVERGENT
Broad origin; fascicles converge toward single tendon insertion (e.g., pectoralis major)
Arrangement of fascicles: PARALLEL
Fascicles parallel to long axis of straplike muscle (e.g., sartorius)
Arrangement of fascicles:
FUSIFORM
Spindle-shaped muscles with parallel fibers (e.g., biceps brachii)
Arrangement of fascicles:
PENNATE
-Short fascicles attach obliquely to central tendon running length of muscle (e.g., rectus femoris)
- Three forms:
- Unipennate – fascicles attach only to one side of tendon (e.g., extensor digitorum longus)
- Bipennate – fascicles insert from opposite sides of tendon (e.g., rectus femoris)
- Multipennate –appears as feathers inserting into one tendon (e.g., deltoid)
Unipennate
arrangement of fascicles: pennate (1)
fascicles attach only to one side of tendon (e.g., extensor digitorum longus)
Bipennate
arrangement of fascicles: pennate (2)
fascicles insert from opposite sides of tendon (e.g., rectus femoris)
Multipennate
arrangement of fascicles: pennate (3)
appears as feathers inserting into one tendon (e.g., deltoid)
Muscle mechanics: Lever systems
-Levers allow given effort to move heavier load; move load farther or faster
- Components of lever system:
- Lever—rigid bar (bone) that moves on a fixed point called fulcrum (joint)
- Effort—force (supplied by muscle contraction) applied to lever to move resistance (load)
- Load—resistance (bone + tissues + any added weight) moved by the effort
Lever
rigid bar (bone) that moves on a fixed point called fulcrum (joint)
Effort
force (supplied by muscle contraction) applied to lever to move resistance (load)
Load
resistance (bone + tissues + any added weight) moved by the effort
Mechanical advantage
- (power lever) – load close to fulcrum; effort far from fulcrum
- Small effort can move large load
Mechanical disadvantage
- (speed lever) – load far from fulcrum; effort close to fulcrum
- Load moved rapidly over large distance; wide range of motion
Classifications of levers
-Three types of levers based on positions of the fulcrum, the effort and load
- First-class levers
- second-class levers
- third class levers
PPW #23
- First-class levers
fulcrum is between the effort and the load
- example: seesaws
- Second-class levers
the load is between the fulcrum and the effort
- example: wheelbarrow
- Third-class lever
The effort is between the fulcrum and the load
- example: pair of forceps
Major skeletal muscles of the body
> 600 in the body; grouped by function and location
- Information for each muscle
- Shape
- Location relative to other muscles
- Origin and insertion—usually a joint between origin and insertion
- Actions—insertion moves toward origin
- Innervation—name of major nerve that supplies muscle
MM of facial expressions
- Zygomaticus - smile
- Risorius - grin
*Orbicular Oculi –
closes eyelid
*Orbicularis Oris – puckers lips
*Platysma
Pulls corners of mouth down
MM for chewing
- temporalis
- masseter
- buccinator
Muscles of tongue movement
Three muscles anchor and move tongue:
- Genioglossus
- Hyoglossus
- Styloglossus
Muscles of the neck and vertebral column: head movement
- Sternocleidomastoid—major head flexor
- Sternocleidomastoid and scalenes—lateral head movements
- Splenius capitis and cervicis portions - head extension, rotation, and lateral bending
- Semispinalis capitis—synergist with sternocleidomastoid
Muscles of the vertebral column: trunk extension
- Deep (intrinsic) back muscles
- Erector spinae (sacrospinalis) group—prime movers of back extension and lateral bending
- Iliocostalis (most lateral)
- Longissimus
- Spinalis (most medial)
*Semispinalis and quadratus lumborum—synergists in extension and rotation
Deep muscles of the thorax: breathing
- Muscles of respiration
- External intercostals—more superficial muscles; elevate ribs for inspiration
- Internal intercostals—deeper muscles; aid forced expiration
Diaphragm-
*Partition between thoracic and abdominal cavities
- Most important muscle in inspiration
- Innervated by phrenic nerves
- (upper cervical innervation)
External intercostal
Inspiration
Internal intercostal
expiration
Muscles of the abdominal wall
- 4 paired muscles:
- Rectus abdominis
- External obliques
- Most superficial
*Internal obliques
- Transversus abdominis
- deepest
-Valsalva maneuver – *increased intra abdominal pressure used during coughing, vomiting, sneezing, defecation and childbirth
The coracobrachialis muscle has its origin and insertion on what two bones?
scapula and humerus
When you bite down on an ice cube, this muscle strongly contracts
masseter (a muscle which runs through the rear part of the cheek from the temporal bone to the lower jaw on each side and closes the jaw in chewing.) the strongest muscle based on its weight
Muscles of the pelvic floor
- Pelvic floor (pelvic diaphragm)- composed of 2 paired muscles
- levator ani
- coccygeus
- floor of core muscles/ supports pelvic organs
- Urogenital diaphragm
- contains external urethral sphincter (voluntary control of urination)
Superficial muscles of the thorax (chest)
- Most - extrinsic shoulder muscles
- Act in combination to fix shoulder girdle (mostly scapula); move it to increase range of arm movements
- Scapula Actions - elevation, depression, rotation, protraction, and retraction
- Two groups of muscles: anterior and posterior
- Muscles of anterior thorax
- Pectoralis minor – protraction & downward rotation of scapula
- Serratus anterior (saw tooth)- protraction boxing muscle
- Subclavius – stabilizes pectoral girdle
Superficial muscles of the posterior thorax
- Posterior extrinsic shoulder muscles:
- Trapezius
- Upper trapezius – elevation of scap (shrug)
- Middle trapezius – retraction of scap
- Lower trapezius – depression of scap
- Levator scapulae
- Rhomboids (major and minor) – retraction & downward rotation
Muscles crossing the shoulder joint
-Three prime movers of arm:
*Pectoralis major :
adduction & flexion
*Latissimus dorsi:
adduction & extension
*Deltoid :
anterior fibers – flexion
middle fibers – abduction
Posterior fibers - extension
Muscle crossing the shoulder joint
-Rotator cuff muscles act as synergists and fixators; originate on scapula; reinforce shoulder capsule; prevent dislocation
*Supraspinatus –
Assists deltoid in abd
*Infraspinatus-
Shoulder external rot
*Teres minor:
Shoulder external rotation
*Subscapularis
Shoulder internal rotation
Supraspinatus
Assists deltoid in abd
Infraspinatus
Shoulder external rot
Teres minor
Shoulder external rotation
Subscapularis
Shoulder internal rotation
muscles crossing the elbow joint
- Anterior flexor muscles:
- Brachialis and biceps brachii (2 heads)—chief forearm flexors (chin ups vs pull up)
*Brachioradialis—synergist and stabilizer
muscles crossing the elbow joint
- Posterior extensor muscles:
- Triceps brachii— (3 heads) prime mover of elbow extension
*Anconeus—weak synergist
The ______ muscles are antagonistic to each other when moving the scapula forward and backward (protraction and retraction
serratus anterior and trapezius
The prime mover in abduction of the arm is the
deltoid
This muscle flexes the elbow and inserts on the ulnar
the brachialis
muscles of the forearm
- Pronator teres and pronator quadratus pronate forearm
- Supinator - synergist with biceps brachii in forearm supination
Muscles of the forearm: anterior compartment
- flexors:
- Flexor carpi radialis (wrist flexion)
- Palmaris longus
- Flexor carpi ulnaris (wrist flexion)
- Flexor digitorum superficialis and flexor digitorum profundus (finger flexion)
- Flexor pollicis longus (thumb flexion)
The ______ is (are) the most important muscle(s) for inspiratory breathing.
diaphragm and external intercostals
What arm muscle is prime mover for this activity? (plank)
biceps brachii
Muscles of the forearm: posterior compartment
-Extensors:
*Extensor carpi radialis longus and brevis
(wrist extension)
- Extensor digitorum (finger extension)
- Extensor carpi ulnaris (wrist extension)
- Extensor pollicis brevis and longus (thumb extension)
- Extensor indicis (index finger)
*Abductor pollicis longus
(thumb abduction)
muscles crossing hip and knee joints
- Movements at the hip include: flexion, extension, abduction, adduction, circumduction, and rotation
- Most anterior muscles flex femur at hip, extend leg at knee (swing of walking)
- Most posterior muscles extend thigh, flex leg (backswing of walking)
- Medial muscles all adduct thigh
- Lateral muscles abduct thigh
movements of the thigh (hip joint)
- Thigh flexors pass in front of hip joint:
- Iliopsoas (iliacus and psoas major) - prime mover of flexion
- Tensor fasciae latae
- Rectus femoris (hip flexion)
- Assisted by medial adductors (groin) and sartorius (cross leg)
movements of the thigh
Thigh (Hip) extensors:
*Hamstring muscles - prime movers of extension
- Biceps femoris (lateral hamstring)
- Semitendinosus (medial hamstring)
- Semimembranosus (medial hamstring)
- Gluteus maximus – assists hamstrings in forceful thigh extension
Movements of the thigh
- Abductors
- Gluteus medius (also medially rotates thigh)
- Gluteus minimus (also medially rotates thigh)
- Gluteus maximus (also laterally rotates thigh)
-External (lateral) rotators
1.Piriformis
2.Obturator externus
3. Obturator internus
4/5. Gemellus (superior & inferior)
6. Quadratus femoris
muscles of the thigh that move the knee joint
- Quadriceps femoris— 4 muscles
- > sole extensor of knee (anterior muscle)
- Rectus femoris
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Hamstrng muscles—flex knee (post mm)
- Biceps femoris
- Semitendinosus
- Semimembranosus
muscles of the leg: movements
- Leg muscles produce the following movements:
- Ankle—dorsiflexion and plantar flexion
- Intertarsal joints—inversion and eversion of the foot
- Toes—flexion and extension
muscles of the anterior compartment of the leg
- Primary toe extensors and ankle dorsiflexors
- Tibialis anterior (dorsiflexes foot)
- Extensor digitorum longus (extends toes)
- Extensor hallucis longus (extends great toe
Which muscle is considered part of the hamstring group?
biceps femoris (along with semitendinosus, semimembranosus)
`This muscle inserts on the calcaneus
gastrocnemius
intrinsic muscles of the foot
- Help flex, extend, abduct, and adduct toes
- Support arches of foot; some leg tendons assist
- Extensor digitorum brevis—dorsal foot muscle; helps extend toes
Plantar muscles
- Four layers of plantar muscles:
- > Superficial layer:
- Flexor digitorum brevis
- Abductor hallucis
- Abductor digiti minimi
- > Second layer
- Flexor accessorius
- Lumbricals
