Muscle Tissue & Major Muscles – Lecture Vocabulary

109 vocabulary flashcards covering muscle tissue types, structural terminology, connective-tissue insulators, sarcomere components, fiber arrangements, naming principles, neuromuscular junction, and major muscles of the head, neck, trunk, limbs with primary actions.

Skeletal muscle

Voluntary, striated, multinucleated muscle tissue that makes up ~40 % of body weight.

Smooth muscle

Involuntary, non-striated, mononucleated muscle tissue; found in walls of hollow organs.

Cardiac muscle

Involuntary, striated, mononucleated* muscle of the heart.

Endomysium

Connective-tissue sheath surrounding each individual muscle fiber (cell).

Perimysium

Connective-tissue sheath that surrounds a fascicle (bundle) of muscle fibers.

Epimysium

Outer connective-tissue covering that encloses the whole muscle; blends with tendon & fascia.

Fascia

Broad sheet of connective tissue external to epimysium; separates muscles/compartments.

Myofilament

Protein filament (actin or myosin) that slides to produce contraction.

Myofibril

Cylindrical bundle of myofilaments inside a muscle fiber; composed of repeating sarcomeres.

Muscle fiber

A single skeletal muscle cell; elongated, multinucleated.

Muscle fascicle

Bundle of muscle fibers wrapped by perimysium.

Sarcoplasm

Cytoplasm of a muscle fiber.

Sarcoplasmic reticulum

Smooth ER in muscle fiber; stores & releases Ca²⁺ for contraction.

Sarcomere

Contractile unit of a myofibril; between two Z lines.

Myo- (prefix)

Means “muscle,” as in myofilament, myofibril, myocardium.

Actin

Thin filament protein that contains myosin-binding sites.

Myosin

Thick filament motor protein with heads that form cross-bridges.

Troponin

Regulatory protein on actin that binds Ca²⁺ and moves tropomyosin.

Tropomyosin

Rod-shaped protein that blocks actin sites until moved by troponin-Ca²⁺.

Titin

Elastic protein anchoring thick filament to Z line; provides recoil.

Nebulin

Structural protein running along actin; regulates thin-filament length.

Z line (Z disc)

Boundary of a sarcomere where thin filaments are anchored.

M line

Center line of sarcomere; anchors thick filaments.

H band

Region of thick filaments with no overlap of thin filaments in relaxed muscle.

Cross-bridge

Myosin head bound to actin during contraction cycle.

Fusiform muscle

Spindle-shaped; fibers parallel, tendon at each end (e.g., biceps brachii).

Pennate muscle

Fibers attach obliquely to a tendon along its length, increasing force.

Unipennate muscle

Pennate fibers on one side of tendon (extensor digitorum).

Bipennate muscle

Fibers on both sides of a central tendon (rectus femoris).

Multipennate muscle

Many pennate sections inserting into one tendon (deltoid).

Parallel muscle

Fibers run the length of the muscle; good for range (sartorius).

Convergent (triangular) muscle

Broad origin, fibers converge to a single tendon (pectoralis major).

Circular muscle

Fibers arranged concentrically to close openings (orbicularis oris).

Location naming

Muscle named for position (e.g., frontalis over frontal bone).

Origin/Insertion naming

Name lists attachments (sternocleidomastoid: sternum-clavicle → mastoid).

Shape naming

Name reflects fiber direction/size (rectus, oblique, brevis, longus, maximus).

Movement naming

Name indicates primary action (flexor carpi radialis flexes wrist).

Neuromuscular junction

Synapse between motor neuron and muscle fiber.

Motor unit

One motor neuron plus all muscle fibers it innervates.

Motor end plate

Specialized region of sarcolemma with ACh receptors at NMJ.

Frontalis

Raises eyebrows; O: galea aponeurotica; I: skin around orbicularis oculi.

Orbicularis oculi

Closes eyelids; antagonist of levator palpebrae superioris.

Nasalis

Flares nostrils; O: maxilla; I: nasal cartilage/bone.

Zygomaticus major/minor

Smile muscles; O: zygomatic bone; I: corner of mouth (dimples when bifid).

Orbicularis oris

Encircles mouth; “kissing” muscle; closes & protrudes lips.

Platysma

Thin neck sheet; depresses lower lip/corners; O: clavicle-deltoid; I: lower lip.

Sternocleidomastoid

Rotates & flexes head; O: sternum & clavicle; I: mastoid process.

Mentalis

Pouts; elevates chin soft tissue.

Masseter

Powerful mastication muscle; O: zygomatic arch; I: mandible; elevates jaw.

Buccinator

Compresses cheek (whistling, chewing).

Temporalis

Elevates & retracts mandible; O: temporal bone; I: coronoid process mandible.

Digastric

Elevates hyoid/depresses mandible; O: mandible & mastoid notch; I: hyoid.

Thyrohyoid

Depresses hyoid & elevates larynx; O: thyroid cartilage; I: hyoid.

Omohyoid

Depresses hyoid; O: scapula; I: hyoid.

Sternohyoid

Depresses hyoid; O: sternum; I: hyoid.

Sternothyroid

Depresses larynx; O: sternum; I: thyroid cartilage.

Trapezius

Moves scapula (retracts, elevates); O: occipital–thoracic spine; I: scapula.

Deltoid

Triangular shoulder muscle; abducts arm; O: clavicle & scapula; I: deltoid tuberosity.

Pectoralis major

Flexes, adducts, internally rotates humerus; O: sternum; I: humerus.

Latissimus dorsi

Extends & adducts humerus; O: thoracic-lumbar spine; I: humerus.

Serratus anterior

Protracts scapula, lifts ribs; “boxer’s muscle.”

External oblique

Compresses abdomen, rotates trunk contralaterally, bends ipsilaterally.

Rectus abdominis

Flexes trunk; O: pubic symphysis; I: xiphoid process.

Pectoralis minor

Draws scapula superior & anterior; O: ribs 3-5; I: coracoid process.

Internal oblique

Deep abdominal muscle; ipsilateral rotation & side bending.

Transverse abdominis

Compresses abdomen; “corset muscle.”

Splenius capitis

Extends/rotates head (“shaking head no”); O: cervical spine; I: occipital bone.

Rhomboideus (major/minor)

Adducts scapula toward vertebral column.

Supraspinatus

Abducts arm; rotator-cuff muscle; O: supraspinous fossa; I: greater tubercle.

Infraspinatus

External rotation of arm; rotator-cuff muscle; O: infraspinous fossa; I: greater tubercle.

Levator scapulae

Elevates scapula; O: cervical vertebrae; I: superior scapular border.

Teres major

Medial rotation & adduction of arm; O: inferior scapula; I: humerus.

Erector spinae

Postural muscle group extending spine from sacrum to skull.

Biceps brachii

Flexes & supinates forearm; O: scapula; I: radial tuberosity.

Brachialis

Primary elbow flexor; O: humerus; I: ulna.

Brachioradialis

Flexes elbow; aids supination/pronation; O: humerus; I: radial styloid.

Triceps brachii

Extends forearm; O: humerus & scapula; I: olecranon ulna.

Flexor carpi radialis

Flexes & abducts wrist; O: medial epicondyle; I: base of metacarpal II.

Palmaris longus

Weak wrist flexor; absent in ~14 % of people.

Flexor digitorum superficialis

Flexes middle phalanges 2-5; O: humerus/radius/ulna.

Flexor carpi ulnaris

Flexes & adducts wrist; O: medial epicondyle; I: pisiform & hamate.

Extensor carpi radialis longus

Extends & abducts wrist; O: humerus; I: metacarpal II.

Extensor carpi radialis brevis

Extends & abducts wrist; O: humerus; I: metacarpal III.

Extensor digitorum

Extends fingers 2-5 & wrist; O: lateral epicondyle.

Extensor carpi ulnaris

Extends & adducts wrist; O: lateral epicondyle; I: metacarpal V.

Psoas major

Primary hip flexor; O: T12-L4 vertebrae; I: lesser trochanter.

Pectineus

Hip flexion, adduction, lateral rotation; O: pubis; I: femur.

Adductor longus

Adducts & flexes hip; O: pubis; I: linea aspera.

Gracilis

Adducts hip, flexes & medially rotates leg; O: ischiopubic ramus; I: tibia.

Adductor magnus

Adducts hip; has hamstring part for extension; O: pubis/ischium; I: linea aspera.

Sartorius

Flexes, abducts, laterally rotates hip; flexes knee; “tailor’s muscle.”

Vastus medialis

Extends knee; medial quad (“tear-drop muscle”).

Vastus intermedius

Extends knee; deep to rectus femoris.

Vastus lateralis

Extends knee; largest quad; O: greater trochanter.

Rectus femoris

Extends knee & flexes hip; only quad crossing hip joint.

Tensor fascia latae

Flexes & abducts hip; tightens iliotibial tract; stabilizes knee/torso.

Gluteus maximus

Powerful hip extensor; O: ilium & sacrum; I: femur & IT band.

Semimembranosus

Extends hip, flexes knee; medial hamstring.

Semitendinosus

Flexes knee, extends hip; medial-posterior thigh.

Biceps femoris

Flexes knee, extends & laterally rotates hip; lateral hamstring.