Chapter 11: Muscles Flashcards
What is the origin?
The attachment of a muscles tendon to the stationary bone (proximal)
What is the insertion?
The attachment of the muscles other tendon to the MOVEABLE bone. Pulls toward the origin (distal)
What’s the lever?
Rigid structure that can move around a fixed point called a fulcrum.
Acted on at two different points by two different forces: EFFORT AND LOAD
What’s the fulcrum?
The point on which lever rest or is supported and on which it pivots (ex:joint)
What is load?
Weight of an object (bone) opposes movement (resistance)
Diagram of effort, fulcrum, and load
Agonist
Prime mover, muscle that contracts to cause action
Antagonist
Stretches and yields to the effects of the prime mover (agonist). Relaxed
Synergist
Muscles that contract and stabilize the prime mover (agonist)
Fixator
Stabilizing the origin of the prime mover so that it can act more efficiently.
Steady the proximal end of a limb while movements occur at the distal end.
How do muscles get their names?
Direction
Size
Shape
Action
Number of origins
Location
Origin and insertion
Muscle direction
Muscle size
Muscle shape
Muscle action
Muscle number of origins/location/insertion
What is the action of occipitofrontalis? (Scalp muscle)
Frontal belly: draws scalp ANTERIOR, raises eyebrows, wrinkles skin of forehead horizontally (surprised look)
Occipital belly: draws scalp posteriorly
What is the action of the orbicularis oris? (Mouth muscle)
Closes and protrudes lips (kissing), compresses lips against teeth, and shapes lips during speech
What is the action of the zygomaticus major? (Mouth muscle) AKA cheek bone
Draws angle of mouth superiorly, and laterally (smiling)
What’s the action of the buccinator? (Mouth muscle) AKA cheek
Presses cheeks against teeth and lips, as in whistling, blowing, and sucking
Draws corner of mouth laterally and assists in chewing by keeping food between teeth (not between teeth and cheeks)
What is the action of the orbicularis oculi? (Orbit and eyebrow muscle)
Closes eye
Origin of a muscle is ___ and insertion is ___
Proximal
Distal
Mechanical advantage
Load is CLOSER to fulcrum, effort is FARTHER from fulcrum.
Small effort required to move large load over small distance
Mechanical disadvantage
Load is FARTHER from fulcrum, effort is CLOSER to fulcrum.
Large effort is required to move smaller load (at greater speed)
First class lever
Fulcrum between effort and load (ex: scissors and seasaw)
Produce both mechanical advantage and disadvantage
Second class lever
Load is between fulcrum and effort (ex: wheelbarrow)
ALWAYS produce mechanical advantage
Third class lever
Effort between fulcrum and load (ex: pair of forceps)
Produce mechanical disadvantage
With opposing pairs of muscles, the roles of the ___ and ___ can switch for different movements
Prime mover (agonist)
Antagonist
The muscles that move the mandible ;(lower jaw bone) at the TMJ are known as
Muscles of mastication (chewing)
masseter (strongest)
temporalis, medial pterygoid (move jaw side to side)
What is the origin, insertion, and action of the masseter? (Chewing muscle)
Origin: maxilla and zomatic arch
Insertion: angle/ramus of mandible
Action: elevates mandible (closing mouth)
What is the origin, insertion, and action of the temporalis? (Temple muscle)
Origin: temporal bone
Insertion: coronoid process/ramus of mandible
Action: elevates and retracts mandible
What is the origin, insertion, and action of the sternocleidomastoid? (Neck muscle)
Origin: sternal head: manubrium of sternum; clavicular head: medial third of clavicle
Insertion: mastoid process of temporal bone and lateral half of superior nuchal line of occipital bone
Action: flex cervical portion of spine, extend head at atlantooccipital joint, flex neck/head side to side and rotate, extension of head, elevate sternum during forced inhalation
The sternocleidomastoid muscle divides the neck into two principal triangles:
Anterior and posterior
Which of the following statements is correct about the sternocleidomastoid (SCM) muscles?
a. acting together, the SCM muscles flex the head at the cervical portion of the vertebral column
b. acting individually, an SCM muscle turns the head (flexes and rotates)
c. inserts at the mastoid process of the temporal bone and lateral half of the superior nuchal line of the occipital bone
d. it originates on the manubrium of the sternum, and the medial third of the clavicle
e. all of these are correct statements
e. all of these are correct statements
Which of the following muscles have an insertion on the xiphoid process?
1. rectus abdominis
2. internal and external obliques
3. transversus abdominis
a. 1 only
b. 2 only
c. 3 only
d. 1 and 3
e. 2 and 3
d. 1 and 3
Which of the following muscles abducts the arm and has an origin on the clavicle?
a. pectoralis major
b. trapezius
c. pectoralis minor
d. deltoid
e. subscapularis
d. deltoid
Which of the following statements is not true about the gluteus maximus?
a. it can act to extend the torso, which is an example of reverse muscle action (RMA)
b. in RMA, the Insertion of this muscle is on the pelvic girdle rather than on the femur
c. extension of the torso occurs when one is bowing, as an actor after a performance
d. It is the largest of the gluteal muscles
e. is the prime mover for extension of the femur
c. extension of the torso occurs when one is bowing, as an actor after a performance
Which of the following muscles has the origin on the linea aspera of the femur?
a. vastus medialis
b. gracilis
c. adductor longus
d. vastus intermedius
e. semitendinosus
a. vastus medialis
In muscles of the limbs, the origin of the muscle is usually distal, and the insertion is proximal.
Select one:
True
False
False (origin is proximal, insertion is distal)
The only muscles that are ever used in breathing are the diaphragm, and the external intercostals muscles.
True
False
False
What is the origin, insertion, and action of the rectus abdominis? (Parallel to midline, abdomen muscle)
Origin: pubic crest and symphysis
Insertion: cartilage ribs 5-7 and xiphoid process
Action: flexes vertebral column (lumbar mainly), compression of abdomen for pooping, urination, forced exhalation, and childbirth. Has RMA, flexes pelvis on vertebral column
What is the action of the external oblique?
Compress abdomen (bilaterally) and flex, vertebral column, laterally flex vertebral column (especially lumbar) and rotate it
What is the action of the external oblique?
Compress abdomen (bilateral)
Rotate and flex vertebral column (laterally especially lumbar region)
What is the action of the internal oblique?
Acting together compress, abdomen, and flex vertebral column, acting, singly laterally flex vertebral column (lumbar mostly) and rotate vertebral column
What is the insertion and action of the transverses abdominis?
Insertion: xiphoid process, linea alba, pubis
Action: compresses abdomen
What is linea alba?
A tough fibrous band that extends from the xyphoid process of the sternum to the pubis symphysis
The aponeuroses (sheath like tendons) of the external oblique, internal oblique, and transversus abdominis muscles form the rectus sheaths which enclose rectus abdominis muscle. The sheaths meet at the midline to form this.
What is the action of the diaphragm, external and internal intercostals? (Muscles that assist in breathing?
Diaphram action: contraction = flatten and increases vertical dimension of thoracic cavity, resulting in inhalation relaxation of diaphragm, causes it to move superiorly and decreases vertical dimensions of thoracic cavity, resulting in exhalation
External intercostals action: contraction elevates ribs and increases anteroposterior and lateral dimensions of the thoracic cavity, resulting in inhalation relaxation, depresses ribs, and decreases anteroposterior and lateral dimensions of the thoracic cavity, resulting in exhalation
Internal intercostals action: contraction draws adjacent ribs together to further decrease anterior posterior and lateral dimensions of thoracic cavity during forced exhalation
What is the action of the latissimus dorsi? (Axial muscle that move the humerus)
Extends, adducts, medically rotates arm at the shoulder joint and draws arm inferiority/posteriorly
RMA: elevates vertebral column and torso
What is the origin, insertion, and action of the deltoid? (scapular muscle that move the humerus)
Origin: acromial extremity of clavicle (anterior fibres), acromion of scapula (lateral fibres), and spine of scapula (posterior fibres)
Insertion: deltoid tuberosity of humerus
Action: lateral fibres: abduct arm at shoulder joint. Anterior fibres: flex/medially rotate arm at shoulder joint. Posterior fibres: extend and laterally rotate arm at shoulder joint
What is the origin, insertion, and action of the biceps? (Forearm flexor)
Origin: long head originates from tubercle above glenoid cavity of scapula (supraglenoid tubercle). Short head originates from coracoid process of scapula
Insertion: radial tuberosity of radius and bicipital aponeurosis
Action: flexes forearm at elbow joint, flexes arm at shoulder joint, and supinates forearm at radioulnar
What is the origin, insertion, and action of triceps? (Forearm extensor)
Origin: long head: infraglenoid tubercle. Lateral head: lateral/posterior surface of humerus. Medial head: whole posterior surface of humerus inferior to groove for radial nerve
Insertion: olecranon of ulna
Action: extends forearm at elbow joint/extends arm at shoulder joint
What is the origin of the rectus femoris?
(Part of quadriceps femoris, anterior thigh/flexor)
Anterior inferior iliac spine
What is the action of the quadriceps femoris muscles?
(Rectus femoris, vastus lateralis/medialis/intermedius)
All four heads extend leg at knee joint
rectus femoris muscle acting alone also flexes thigh at hip joint
What is the insertion of the quadriceps femoris muscles?
(Rectus femoris, vastus lateralis/medialis/intermedius)
Patella via quadriceps tendon and tibial tuberosity via patellar ligament
What’s the origin of the vastus lateralis?
Greater trochanter and linea aspera of femur
What is the origin of the vastus medialis?
Linea aspera of femur
What’s the origin of the vastus intermedius?
Anterior and lateral surfaces of body of femur
What’s the longest muscle in the body? What’s its action?
Sartorius muscle located inner thigh.
Action: weakly flexes leg at knee joint, abducts and laterally rotates thigh at hip joint
What is the action of the hamstrings?
(Posterior thigh, flexor. Biceps femoris, semitendinosus, senimembranosus)
Flexes leg at knee joint and extends thigh at hip joint
What is the origin and insertion of the biceps femoris? (Posterior thigh/hamstring muscle)
Origin: long head: ischial tuberosity. Short head: linea aspera of femur
Insertion:head of fibula and lateral condyle of tibia
What is the origin, insertion, and action of the gluteus Maximus?
Origin: iliac crest, sacrum, coccyx and aponeurosis of sacrospinalis
Insertion: gluteal tuberosity under greater trochanter of femur
Action: extends thigh at hip joint, laterally rotates thigh. Locks knee during extension. RMA: extends torso
What is the action of the gluteus medius?
Abducts thigh at hip joint and medially rotates thigh
What is the action of the gluteus medius?
Abducts thigh at hip joint and medially rotates thigh
What is the action of the adductor longus?
Adducts and flexes thigh at hip joint and rotates thigh. RMA: extends thigh
What is the action of the adductor Magnus?
Adducts thigh at hip joint and rotates thigh (anterior part flexes thigh at hip joint while posterior part extends thigh at hip joint)
What is the action of the soleus?
Plantar flexes foot at ankle joint
What is the origin, insertion, and action of the gastrocnemius? (Back of lower leg)
Origin: lateral and medial condyles of femur and capsule of knee
Insertion: calcaneus (Achilles) tendon
Action: plantar flextion of foot at ankle joint and flexes leg at knee joint
