Muscle Mechanics and Levers Quiz

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Questions and Answers

What distinguishes pennate muscles from parallel muscles in terms of force and movement?

Pennate muscles contain more myofibrils and develop more tension. (correct)

Pennate muscles have fewer myofibrils than parallel muscles.

Pennate muscles develop less tension compared to parallel muscles.

Pennate muscles move their tendons further.

Which type of pennate muscle has fascicles on both sides of a central tendon?

Quadripennate

Unipennate

Multipennate

Bipennate (correct)

What is a defining characteristic of a second-class lever?

The load lies at one end of the lever.

The distance traveled is maximized over effective force.

The fulcrum is located between the load and the applied force. (correct)

The applied force is located between the load and the fulcrum.

Which type of lever is most common in the human body?

Third-class lever Signup and view all the answers

What is a consequence of using a third-class lever in the body?

It allows for greater speed and distance at the cost of effective force. Signup and view all the answers

What is the origin of a muscle?

The fixed point of attachment of a muscle to a bone Signup and view all the answers

Which term describes the specific actions produced by muscle contraction?

Action Signup and view all the answers

In the relationship between origin and insertion, which statement is typically true?

The origin is usually proximal to the insertion Signup and view all the answers

What does the term 'adduction' refer to?

Movement towards the midline of the body Signup and view all the answers

Which of the following terms refers specifically to the elbow region?

Ancon Signup and view all the answers

Which of these actions would involve the biceps brachii?

Elbow flexion Signup and view all the answers

Which of the following is a FALSE statement about muscle attachments?

The insertion is usually less movable than the origin Signup and view all the answers

How many skeletal muscles does the human body approximately contain?

700 Signup and view all the answers

What type of muscle arrangement do convergent muscles exhibit?

Muscle fascicles spread in a broad area on one side and converge on a single attachment site Signup and view all the answers

In the lever system, which part functions as the fulcrum?

The joint where the bone connects Signup and view all the answers

How do levers change the effective strength of the applied force?

By changing the direction of the applied force Signup and view all the answers

What is the role of the applied force in a lever system?

To overcome the resistance of the load Signup and view all the answers

Which example best describes a first-class lever?

A crowbar lifting a heavy object Signup and view all the answers

What factor influences the force exerted by muscles in a lever system?

The number of muscle fibers recruited Signup and view all the answers

Which type of muscle is primarily characterized by fibers that can pull in different directions?

Convergent muscles Signup and view all the answers

What mechanical advantage does a lever system provide?

Decreased effort to move a load Signup and view all the answers

What is the primary role of agonist muscles?

To produce a specific movement Signup and view all the answers

Which type of muscle opposes the movement produced by an agonist?

Antagonist Signup and view all the answers

What is the function of synergist muscles?

To assist the agonist in producing a movement Signup and view all the answers

What occurs when an agonist muscle contracts?

The antagonist muscle stretches Signup and view all the answers

What distinguishes intrinsic muscles from extrinsic muscles?

Intrinsic muscles are located entirely within an organ Signup and view all the answers

What is the distinguishing feature of rectus muscles?

They run directly along the body's longitudinal axis Signup and view all the answers

What is the role of a fixator muscle?

To prevent movement at another joint during an action Signup and view all the answers

Which term indicates a muscle's position close to the body's surface?

Externus Signup and view all the answers

Which functional type of muscle would best describe a muscle that helps with facial expressions?

Synergist Signup and view all the answers

In the context of muscle interactions, what happens to smaller muscles during a movement?

They reach maximum tension first Signup and view all the answers

Which muscle is primarily responsible for elevating the mandible during chewing?

Temporalis Signup and view all the answers

What is the primary action of the orbicularis oris muscle?

Purses the lips and closes the mouth Signup and view all the answers

Which of the following muscles is classified as an extrinsic eye muscle?

Inferior oblique Signup and view all the answers

What term describes the muscle action of lowering the mandible?

Depressor Signup and view all the answers

Which muscle primarily performs flexion at the elbow?

Brachialis Signup and view all the answers

Which of the following statements about the diaphragm is accurate?

It divides the thoracic and abdominal cavities. Signup and view all the answers

What is the primary function of the oblique muscles in the trunk?

Compress and rotate the vertebral column Signup and view all the answers

Which muscle elevates the scapula?

Trapezius Signup and view all the answers

Which muscle has a primary action of abducting the arm?

Deltoid Signup and view all the answers

Which action is performed by the zygomaticus major muscle?

Elevates the corners of the mouth Signup and view all the answers

Which group of muscles is primarily responsible for hip flexion?

Iliopsoas group Signup and view all the answers

Which of the following pairs of muscles work together to flex the neck?

Sternocleidomastoid and scalene Signup and view all the answers

Which muscle group assists in the process of chewing?

Muscles of mastication Signup and view all the answers

Study Notes

Muscle Naming Conventions

Numbers in prefixes indicate the number of tendons at the muscle’s origin:
- Biceps: two heads
- Triceps: three heads
- Quadriceps: four heads
Shape identifies the muscle's form:
- Deltoid (triangle)
- Rhomboid (parallelogram)
- Orbicularis (circle)
- Serratus (serrated)
- Pectinate (comb-like)
- Spelnius (bandage)
- Piriformis (pear-shaped)
- Teres (round and long)
- Platysma (flat plate)
- Trapezius (trapezoid)
- Pyramidal (pyramid)
Size and other striking features:
- Alba: white
- Brevis: short
- Gracilis: slender
- Latae: wide
- Latissimus: widest
- Longus: long
- Magnus: large
- Major: larger
- Maximus: largest
- Minimus: smallest
- Minor: smaller
- Vasus: great

Muscle Action Terminology

Abductor: movement away from the body
Adductor: movement toward the body
Depressor: lowering movement
Extensor: straightening movement
Flexor: bending movement
Levator: raising movement
Pronator: turning into a prone position
Supinator: turning into a supine position
Tensor: tensing movement

Divisions of the Muscular System

Axial muscles (60% of skeletal muscles) position the axial skeleton:
- Position the head and vertebral column
- Move the rib cage
- Form the pelvic floor
Appendicular muscles support and move the appendicular skeleton:
- Move and support the pectoral and pelvic girdles
- Move the limbs

Muscles of the Head and Neck

Facial Expression

Orbicularis oris: purses lips, closes mouth
Buccinator: compresses cheeks, moves food across teeth, helps with nursing suction
Temporoparietalis: tenses the epicranium (scalp) and moves the ear
Occipitofrontalis:
- Frontal Belly: raises eyebrows, wrinkles forehead
- Occipital Belly: tenses and retracts scalp
- Separated by epicranial aponeurosis
Platysma: tenses neck skin, depresses mandible
Zygomaticus major: elevates mouth corners (smiling)
Orbicularis oculi: closes eyes
Levator palpebrae superioris: elevates upper eyelids

Muscles of Mastication (Chewing)

Masseter: elevates mandible, closes jaws
Temporalis: elevates mandible
Pterygoid muscles: elevate, depress, protract, and slide mandible side-to-side (lateral excursion)

Muscles of the Tongue

Palatoglossus: elevates tongue, depresses soft palate
Styloglossus: retracts tongue, elevates its sides
Genioglossus: depresses and protracts the tongue
Hyoglossus: depresses and retracts the tongue

Muscles of the Pharynx

Pharyngeal constrictor muscles: move food into esophagus
Palatal muscles: elevate soft palate, open auditory tube entrance
Laryngeal elevators: raise the larynx

Muscles of the Anterior Neck

Digastric: controls larynx position
Mylohyoid: elevates mouth floor, hyoid bone, depresses mandible
Geniohyoid: depresses mandible, elevates larynx
Sternocleidomastoid:
- Both bellies together: flex the neck
- One at a time: flex head towards shoulder, rotate face to opposite side
Omohyoid and sternohyoid: depress hyoid and larynx

Muscles of the Vertebral Column

Erector spinae muscles (superficial and deep layers):
- Together: extend the vertebral column and the head
- Separately: flex the vertebral column laterally
- Groups:
  - Spinalis (superficial)
  - Longissimus (superficial)
  - Iliocostalis (superficial)
  - Semispinalis (deep)
Spinal Flexors:
- Longus capitis: flex neck together, rotate head laterally separately
- Longus colli: rotates and flexes the neck
- Quadratus lumborum: depresses ribs together, flexes vertebral column laterally separately

Oblique and Rectus Muscles

Oblique muscles: compress underlying structures, rotate the vertebral column
Rectus muscles: flex the vertebral column, oppose erector spinae

Oblique Muscles

Cervical region:
- Scalene muscles: flex neck, elevate ribs
Thoracic region:
- External and internal intercostal muscles: help breathing
  - External: elevate ribs
  - Internal: depress ribs
- Transversus thoracis: depresses ribs
- Serratus posterior superior: pulls ribs up
- Serratus posterior inferior: pulls ribs down
Abdominopelvic region:
- External oblique and internal oblique: compress abdomen, depress ribs, flex spine
- Transversus abdominis: compresses abdomen

Rectus Muscles

Rectus abdominis:
- Together: depresses ribs, flexes vertebral column, compresses the abdomen
- Divided longitudinally by linea alba
- Divided transversely by tendinous inscriptions
Diaphragm:
- Expands thoracic cavity, compresses abdomen
- Divides thoracic and abdominopelvic cavities
- Major muscle used in breathing

Muscles of the Pelvic Floor

Functions:
- Support pelvic cavity organs
- Flex sacrum and coccyx
- Control material movement through urethra and anus
Perineum:
- Region bounded by inferior pelvis margins
- Anterior urogenital triangle
- Posterior anal triangle
Pelvic diaphragm: forms the muscular foundation of the anal triangle
External urethral sphincter: closes the urethra
External anal sphincter: closes the anal opening
Levator ani: elevates and retracts anus
Transverse perineal muscles: stabilize the central tendon of the perineum

Appendicular Muscles

Position and stabilize the pectoral and pelvic girdles:
- Move the upper and lower limbs
Two groups:
- Muscles of the shoulders and upper limbs:
- Muscles of the pelvis and lower limbs:

Muscles of the Shoulders and Upper Limbs

Muscles that Position the Pectoral Girdle

Trapezius: large, superficial; elevates clavicle, moves scapula, extends neck
Serratus anterior: protracts shoulder
Subclavius: depresses and protracts shoulder
Pectoralis minor: depresses and protracts shoulder, elevates ribs
Rhomboid major and minor: adduct scapula, rotate it downward
Levator scapulae: elevates the scapula

Muscles that Move the Arm

Deltoid: abducts arm at the shoulder, flexes, extends, and rotates medially/ laterally at the shoulder
Supraspinatus: assists deltoid in arm abduction
Subscapularis and teres major: medially rotate at shoulder
Infraspinatus and teres minor: laterally rotate at shoulder
Coracobrachialis: flexes and adducts at shoulder

Muscles that Move the Forearm and Hand

Most originate on humerus, insert on forearm and wrist
Exceptions: biceps brachii and the long head of triceps brachii originate on scapula, insert on forearm
Extensors: mainly on posterior and lateral arm surfaces
Flexors: mainly on anterior and medial arm surfaces
Triceps brachii: principal extensor at elbow
Anconeus: extensor at elbow
Biceps brachii: principal flexor at elbow, supinates forearm, stabilizes shoulder joint
Brachialis and brachioradialis: flexors at the elbow
Supinator: supination (rotates radius)
Pronator teres: pronation (rotates radius)
Pronator quadratus: assists pronator teres in pronation, opposes supinator and biceps brachii actions
Flexor carpi ulnaris: flexes and adducts hand at the wrist
Flexor carpi radialis: flexes and abducts hand at the wrist
Palmaris longus: flexes hand, tenses palm skin
Extensor carpi ulnaris: extends and adducts hand at the wrist
Extensor carpi radialis (longus and brevis): extends and abducts hand at the wrist
Forearm muscle tendons crossing the wrist: pass through synovial tendon sheaths
Extensor retinaculum: wide connective tissue band on posterior wrist, stabilizes extensor muscle tendons
Flexor retinaculum: wide connective tissue band on anterior wrist, stabilizes flexor muscle tendons

Muscles that Move the Fingers and Thumb

Intrinsic muscles: originate on carpal and metacarpal bones, responsible for fine motor hand movements
No muscles originate on the phalanges
Palmaris brevis: moves skin towards palm midline
Adductor pollicis: adducts thumb
Abductor pollicis brevis: adducts thumb
Flexor pollicis brevis: flexes thumb
Opponens pollicis: opposes thumb

Muscles of the Pelvis and Lower Limbs

Pelvic girdle: tightly bound to axial skeleton, permitting little movement, few axial muscles influence pelvis position
Lower limb movements: wide range

Muscles that Move the Thigh

Gluteal Group:
- Gluteus maximus: largest, most posterior gluteal muscle, extends and laterally rotates hip
- Gluteus medius and minimus: abduct and medially rotate hip
- Tensor fasciae latae: works with gluteus maximus in lateral rotation of the leg, pulls on iliotibial tract of lateral thigh surface
Lateral rotator group:
- Six muscles including the dominant:
  - Piriformis
  - Obturators
Adductor Group:
- Pectineus, adductor brevis, adductor longus, and gracilis: adduct, flex, and medially rotate hip
- Adductor magnus: produces adduction and extension (inferior part), or flexion and medial rotation (superior part)
Iliopsoas Group: two hip flexors that insert on the same tendon
- Psoas major
- Iliacus

Muscles that Move the Leg

Flexors of the knee:
- Hamstrings:
  - Biceps femoris
  - Semitendinosus
  - Semimembranosus
- Sartorius
- Popliteus
Extensors of the knee:
- Quadriceps femoris:
  - Rectus femoris
  - Vastus intermedius
  - Vastus lateralis
  - Vastus medialis

Muscles that Move the Foot and Toes

Extrinsic muscles:
- Extension at the ankle (plantar flexion):
  - Gastrocnemius: knee flexion, foot inversion, plantar flexion
  - Soleus: plantar flexion
  - Fibularis brevis and longus: foot eversion, plantar flexion
  - Tibialis posterior: foot adduction, inversion, and plantar flexion
- Calcaneal tendon (Achilles tendon): shared by the gastrocnemius and soleus
- Flexion at the ankle (dorsiflexion):
  - Tibialis anterior: opposes gastrocnemius
- Extension at the toes:
  - Extensor digitorum longus
  - Extensor hallucis longus
  - Extensor retinaculum: stabilizes synovial tendon sheaths of these muscles
- Flexion at the toes:
  - Flexor digitorum longus
  - Flexor hallucis longus
Intrinsic muscles:
- Originate on tarsal and metatarsal bones
- Move toes, maintain longitudinal arch of foot
- Flexors: flexor hallucis brevis, flexor digitorum brevis, quadratus plantae
- Extensors: extensor hallucis brevis, extensor digitorum brevis
- Adductors: adductor hallucis, plantar interosseous
- Abductors: abductor hallucis, dorsal interosseous, abductor digiti minimi

Muscular System Integration with Other Systems

Cardiovascular system: delivers oxygen and nutrients, removes carbon dioxide
Respiratory system: responds to muscle oxygen demand
Integumentary system: disperses heat from muscle activity
Nervous and endocrine systems: direct responses of all systems

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Description

Test your knowledge on the distinctions between pennate and parallel muscles, different types of levers in the human body, and their implications for force and movement. This quiz covers important anatomical concepts that are essential for understanding muscular function.