Week 11 - Chapter 10 and 11: Muscles
Origin vs. insertion
The origin attaches to the stationary bone, and the insertion attaches to the movable bone
3 types of levers in the body:
First class, second class and third class (most common)
How does fascicular arrangement affect a muscle
It influences the muscle's power and range of motion
A prime mover:
Produces the main action and is the principle muscle involved in an action
An antagonist:
Produces the opposite action
A synergist:
Assists the prime mover
What do muscles of the head that produce facial expressions move?
The skin rather than a joint
Which muscles move the eyeballs
Extraocular muscles (for eyeballs) and muscles of the upper eyelids (to open eyes)
Function of the muscles of mastification
To move the mandible for chewing and speech
Infrahyoid muscles function
Stabilize the hyoid
Functions of the muscles of the neck
Alter the position and balance of the head on the vertebral column
What do the abdominal muscles do
Protect abdominal viscera, move the vertebral column, assist in defecation, urination, vomiting, childbirth
Functions of thoracic muscles during breathing
They alter the size of the thoracic cavity for inhalation and exhalation
What do pelvic floor muscles do
Support pelvic viscera and function as sphincters
Role of muscles that move the pectoral girdle
Stabilize and move the scapula for motion of the humerous
Where do scapular and axial muscles (move the humerous) originate?
Scapular - scapula
Axial - axial skeleton
How are arm muscles that move the radius and ulna organized
Into flexor and extensor compartments
Function of gluteal region muscles
Move the femur and provide powerful movements for locomotion
Muscles of the thigh are categorized as:
Into medial (adductor), anterior (extensor), and posterior (flexor) compartments
Primary role of intrinsic muscles of the foot
Support and locomotion
Extrinsic muscles of the forearm are:
Muscles that are in the forearm that move the fingers
Intrinsic muscles of the hand do what?
Help you do precise movements like holding and gripping objects
What is the origin, insertion, and action of the pectoralis major?
- Origin: clavicle, sternum, costal cartilages of ribs 1-6
- Insertion: intertubecular sulcus of humerous
- Action: adducts and medially rotates arm
What is the origin, insertion, and action of the latissimus dorsi?
- Origin: Spinous process of T7-L5, iliac crest, thoracolumbar fascia
- Insertion: Intertubecular sulcus of the humerous
- Action: Extends, adducts, medially rotates arm
What is the origin, insertion, and action of the deltoid?
- Origin: Clavicle, acromion, spine of scapula
- Insertion: Deltoid tuberosity of humerous
- Action: Abducts arm
What is the origin, insertion, and action of the biceps brachii?
- Origin: Short head-coracoid process, long head-supraglenoid tubercle of scapula
- Insertion: Radial tuberosity
- Action: Flexes the elbow and supinates the forearm
What is the origin, insertion, and action of the triceps brachii?
- Origin: Long head-Infraglenoid tubercle, lateral head-posterior humerous, medial head-posterior humerous distal to radial groove
- Insertion: Olecranon of the ulna
- Action: Extends the elbow
What is the origin, insertion, and action of the rectus abdominis?
- Origin: Pubic crest and symphysis
- Insertion: Xiphoid process and costal cartilahes of ribs 5-7
- Action: Flexes the vertebral column and compresses abdominal contents
What is the origin, insertion, and action of the gluteus maximus?
- Origin: Ilium, sacrum, coccyx
- Insertion: Gluteal tuberosity of the femur and iliotibial tract
- Action: Extends and laterally rotates the thigh
What is the origin, insertion, and action of the quadriceps femoris group?
- Origin: Varies by muscle, e.g., rectus femoris originates from the anterior inferior iliac spine
- Insertion: Tibial tuberosity via the patellar ligament
- Action: Extends the knee and flexes the thigh
What is the origin, insertion, and action of the hamstring group?
- Origin: Ischial tuberosity
- Insertion: Varies by muscle e.g., biceps femoris inserts on the fibula
- Action: Flexes the knee and extends the hip
What is the origin, insertion, and action of the gastrocnemius?
- Origin: Lateral and medial condyles of the femur
- Insertion: Calcaneus via the achilles tendon
- Action: Plantarflexes the foot and flexes the knee
What is the origin, insertion, and action of the frontalis (part of the occipitofrontalis)?
- Origin: Epicranial aponeurosis
- Insertion: Skin of forehead and eyebrows
- Action: Raises eyebrows, wrinkles forehead
What is the origin, insertion, and action of the orbicularis oculi?
- Origin: Medial orbital margin and lacrimal bone
- Insertion: Skin around eyelids
- Action: Closes the eyelids
What is the origin, insertion, and action of the orbicularis oris?
- Origin: Maxilla and mandible
- Insertion: Skin and mucosa of lips
- Action: Closes and puckers the lips (Kissing muscle)
What is the origin, insertion, and action of the zygomaticus major?
- Origin: Zygomatic bone
- Insertion: Skin and muscle of corner of mouth
- Action: Elevates corners of mouth for smiling
What is the origin, insertion, and action of the buccinator?
- Origin: Alveolar processes of maxilla and mandible
- Insertion: Orbicularis oris
- Action: Compresses the cheek (Blowing or whistling)
What is the origin, insertion, and action of the platysma?
- Origin: Fascia of the chest (pectoral and deltoid muscles)
- Insertion: Lower border of the mandible and skin of lower face
- Action: Tenses the skin of the neck and depresses the mandible
What is the origin, insertion, and action of the masseter?
- Origin: Zygomatic arch
- Insertion: Lateral surface of the mandibular ramus
- Action: Elevates the mandible (chewing muscle)
What is the origin, insertion, and action of the temporalis?
- Origin: Temporal fossa
- Insertion: Coronoid process of the mandible
- Action: Elevates and retracts the mandible
What is the origin, insertion, and action of the sternocleidomastoid?
- Origin: Manubrium of the sternum and clavicle
- Insertion: Mastoid process of the temporal bone
- Action: Flexes the neck and rotates the head
What type of muscle is primarily responsible for moving bones, possesses striations, and is predominantly voluntary?
Skeletal muscle
Which muscle type forms the heart wall, is striated, and operates involuntarily with a rhythm called autorhythmicity?
Cardiac muscle
Which muscle type is nonstriated, involuntary, and found in vascular structures, airways, arrector pili, and the abdominopelvic cavity?
Smooth muscle
The _______ separates muscle from skin
Hypodermis
Three layers of connective tissue _______, _______ and _______ extends from fascia to cover the muscles and create stability.
(Epimysium, Perimysium & Endomysium)
Neurons that stimulate skeletal muscle to contact are ______ motor neurons.
Somatic
______ filaments consist of two strands of the globular protein actin arranged in a double helix.
Thin
_______ filaments consist of groups of the filamentous protein myosin.
Thick
How do action potentials reach a muscle?
An action potential:
1. Travels down a motor neuron to the neuromuscular junction, where it triggers the release of acetylcholine
2. Which binds to receptors on the muscle fiber's sarcolemma, generating a new action potential that propagates through T-tubules
3. Causing the sarcoplasmic reticulum to release calcium ions, 4. Calcium ions enable actin and myosin interaction for muscle contraction.
The neuromuscular junction (NMJ) is:
The specialized region where a motor neuron's axon terminal, containing synaptic vesicles filled with ACh, communicates with the motor end plate of a muscle fiber's sarcolemma across a small gap called the synaptic cleft, enabling the transmission of signals that trigger muscle contraction
Components of a skeletal muscle cell:
- Sarcolemma: Plasma membrane
- Sarcoplasm: The cytoplasm of the muscle fiber
- Myofibrils: Structures inside muscle fiber containing sarcomeres.
- Sarcomeres: Responsible for muscle contraction.
- Actin: Protein filaments that interact with myosin during contraction.
- Myosin: Protein filaments that form cross-bridges with actin.
- Troponin and Tropomyosin: Regulatory proteins that control interaction between actin & myosin.
- Sarcoplasmic Reticulum: Stores & releases calcium ions, essential for muscle contraction.
- T-Tubules: Extensions of sarcolemma, carry action potentials deep into muscle fiber
- Mitochondria:
- Nucleus
The sarcoplasmic reticulum (SR) does what?
Plays a critical role in muscle contraction by regulating calcium ion (Ca²⁺) levels within the muscle fiber
Calcium ions are involved in muscle contraction by:
Being released from the sarcoplasmic reticulum to bind to troponin, enabling myosin to bind actin and initiate muscle contraction, while calcium is pumped back for relaxation.
During muscle contraction, the ___ lines move toward the ___ line as the actin filaments slide past the myosin filaments, shortening the sarcomere and resulting in muscle contraction.
Z, M
ATP is required for muscle contraction at several stages of the process, such as:
1. Myosin Head Activation: ATP binds to the myosin head, causing it to detach from the actin filament after a power stroke. This provides the energy needed for the myosin head to go into its high-energy state, ready to bind to actin again.
2. Cross-Bridge Formation: ATP is also needed for the myosin head to bind to the exposed binding sites on the actin filaments after calcium has moved tropomyosin away from these sites.
3. Calcium Pumping: After contraction, ATP is required for the active transport of calcium ions back into the sarcoplasmic reticulum via the calcium pumps, leading to muscle relaxation.
_____ is the anaerobic breakdown of glucose into two molecules of pyruvate, producing a net gain of 2 ATP and 2 NADH in the process.
Glycolysis
Muscles of mastication vs facial expression
Muscles of mastication control jaw movements for chewing, while muscles of facial expression govern facial movements for communication and emotional expression
Motor vs. Sensory neurons:
Motor neurons stimulate muscle contraction, while sensory neurons provide feedback to the CNS about muscle activity and status
The _____ period is the time following an action potential during which a neuron or muscle fiber is unable to respond to another stimulus. It ensures that action potentials only travel in one direction and prevents overstimulation.
Refractory
Tendon vs. Ligament
A tendon connects muscle to bone, transmitting the force from muscle contractions, while a ligament connects bone to bone, providing stability and support to joints
An ______ muscle contraction occurs when a muscle generates force without changing its length
Example: when holding a plank position or pushing against a wall.
Isometric
A ______ muscle contraction occurs when a muscle shortens while generating force
Example: when lifting a dumbbell during a bicep curl.
Concentric
An _______ muscle contraction occurs when a muscle lengthens while generating force,
Example: When lowering a dumbbell during a bicep curl.
Eccentric
Cross-bridge formation is the:
Process during muscle contraction where the myosin heads bind to the exposed binding sites on actin filaments, forming a cross-bridge, which allows the myosin to pull the actin filaments toward the center of the sarcomere, resulting in muscle shortening.
Aerobic respiration vs. Krebs Cycle Energy
Aerobic respiration can provide sustained energy for hours, while the Krebs cycle contributes to this energy production as long as oxygen and fuel are available.
Mechanical advantage vs. disadvantage
Mechanical advantage occurs when a lever system allows you to apply less force to move an object while mechanical disadvantage occurs when more force is required to move an object.
A _______ is the joint where the muscle's lever moves/pivots, helping muscles use force to move bones
Fulcrum
A ______ is a muscle that helps hold a joint or body part in place during movement, providing support and preventing unwanted motion.
Stabilizer
The muscle that abducts the arm:
Deltoid
Muscles that pronate the forearm?
Pronator teres and pronator quadratus
The muscles that abduct the thigh?
The gluteus medius and gluteus minimus
Muscles that move the eyeball:
Rectus muscles:
Superior rectus: Moves the eye upward.
Inferior rectus: Moves the eye downward.
Medial rectus: Moves the eye inward, toward the nose.
Lateral rectus: Moves the eye outward, away from the nose.
Oblique muscles:
Superior oblique: Moves the eye downward and outward.
Inferior oblique: Moves the eye upward and outward.
The muscles of the rotator cuff:
1. Supraspinatus (abducts arm)
2. Infraspinatus (rotates arm)
3. Teres minor (rotates and abducts arm)
4. Subscapularis (internally rotates arm)
The strongest muscle is the ______, the jaw muscle responsible for chewing
Masseter
The longest muscle in the body is the ______, which runs diagonally across the thigh from the hip to the inner knee.
Sartorius
The layers of the abdominal wall from outermost to innermost are:
1. Skin
2. Subcutaneous fat
3. Fascia
4. Muscles (External, internal oblique and transversus abdominis)
5. Endoabdominal (Transversalis) fascia (connective tissue layer)
6. Peritoneum