BioSci 202 Lab Practical Quiz 4: Muscles and Joints Study Guide

Vocabulary study cards covering functional and structural joint classifications, synovial joint subclasses, anatomical joint movements, muscle mechanics, and specific origins, insertions, and actions for 20 required muscles.

Synarthrosis

An immovable joint (memory hook: "syn" = together, fused).

Amphiarthrosis

A slightly movable joint (memory hook: "amphi" = on both sides, a little give).

Diarthrosis

A freely movable joint (memory hook: "di" = apart, free to move).

Fibrous joint

A joint where two bones are held together by fibrous connective tissue without a joint cavity; functionally classified as a synarthrosis or amphiarthrosis (e.g., coronal suture between the frontal and parietal bones).

Cartilaginous joint

A joint where two bones are held together by a pad of cartilage without a joint cavity; functionally classified as a synarthrosis or amphiarthrosis (e.g., pubic symphysis between the left and right pubic bones).

Synovial joint

A joint where bones are separated by a fluid-filled cavity containing synovial fluid that allows considerable movement; functionally classified as a diarthrosis (e.g., knee).

Hinge joint

A synovial joint subclass where a convex cylinder on one bone fits into a matching concave trough on the other, permitting movement in one plane only (flexion and extension, like a door hinge); examples include the knee and elbow.

Ball-and-socket joint

A synovial joint subclass where a rounded head on one bone fits into a cup-shaped socket on the other, permitting movement in all directions (flexion/extension, abduction/adduction, rotation); examples include the hip and shoulder (glenohumeral).

Plane (gliding) joint

A synovial joint subclass consisting of two flat surfaces of about equal size that allow slight sliding movements; examples include articular processes between vertebrae and intercarpal joints.

Saddle joint

A synovial joint subclass where two saddle-shaped surfaces articulate at right angles to each other, permitting movement in two planes plus opposition of the thumb; an example is the carpometacarpal joint of the thumb.

Pivot joint

A synovial joint subclass where a rounded process turns inside a ring, permitting rotation around one axis; an example is the dens of C2 turning in C1 (median atlantoaxial joint).

Ellipsoid (condyloid) joint

A synovial joint subclass where an oval surface fits into an oval depression, allowing movement in two planes with no true rotation; examples include the atlanto-occipital joint and radiocarpal (wrist) joint.

Flexion

Bending that decreases the angle of a joint, bringing bones closer together (e.g., bending the elbow or lifting the thigh forward).

Extension

Straightening that increases the angle of a joint (e.g., straightening the elbow or knee).

Hyperextension

Extension of a body part beyond the anatomical position (e.g., tilting the head back to look at the ceiling).

Abduction

Movement of a limb or body part away from the midline (e.g., raising the arm out to the side).

Adduction

Movement of a limb or body part toward the midline ("add" it back to the body; e.g., lowering the arm back to the side).

Pronation

Rotating the forearm so that the palm faces posteriorly (down when the arm is forward; e.g., turning a palm face-down on a table).

Supination

Rotating the forearm so that the palm faces anteriorly (up; e.g., holding a bowl of soup).

Elevation

Moving a structure superiorly (e.g., shrugging the shoulders up).

Depression

Moving a structure inferiorly (e.g., dropping the shoulders).

Lateral excursion

Moving the mandible to the right or left of the midline (e.g., grinding food side to side).

Medial excursion

Returning the mandible to the midline (e.g., re-centering the jaw after chewing).

Eversion

Turning the sole of the foot laterally (e.g., rolling in onto the inner edge of the foot).

Inversion

Turning the sole of the foot medially (e.g., rolling out onto the outer edge of the foot).

Plantar flexion

Pointing the foot down toward the sole (e.g., standing on tiptoes or pressing a car’s gas pedal).

Dorsiflexion

Pulling the foot up toward the shin (e.g., walking on heels or stretching calves).

Medial (internal) rotation

Turning a limb around its long axis toward the body (e.g., bending the elbow at 90 degrees and swinging the hand inward to touch the belly).

Lateral (external) rotation

Turning a limb around its long axis away from the body (e.g., bending the elbow at 90 degrees and swinging the hand outward away from the body).

Lateral flexion

Bending the trunk to one side (e.g., bending sideways to pick something up).

Protraction

Gliding a structure forward or anteriorly (e.g., rounding the shoulders forward).

Retraction

Gliding a structure backward or posteriorly (e.g., squeezing the scapulae together).

Muscle Origin

The muscle attachment site that stays still during contraction; typically located closer to the midline or higher up (proximal).

Muscle Insertion

The muscle attachment site that moves during contraction; typically located farther from the midline or lower down (distal).

Agonist (prime mover)

The primary muscle that directly performs a given movement (e.g., biceps brachii during elbow flexion).

Antagonist

The muscle that resists the action of the agonist to balance tension at a joint (e.g., triceps brachii during elbow flexion).

Rotator Cuff (SITS)

A group of four deep muscles that hold the head of the humerus in the shallow glenoid cavity: Supraspinatus, Infraspinatus, Teres minor, and Subscapularis.

Epicondyle Rule

Forearm extensor muscles originate on the lateral epicondyle of the humerus, whereas forearm flexor muscles originate on the medial epicondyle of the humerus.

Temporalis

A fan-shaped muscle on the side of the head. • Origin: Temporal fossa • Insertion: Coronoid process of the mandible (and mandibular ramus) • Action: Elevates the mandible (closes jaw)

Sternocleidomastoid

A diagonal strap muscle along the anterolateral neck. • Origin: Manubrium of the sternum and clavicle • Insertion: Mastoid process (and superior nuchal line) • Action: Flexes the neck (both sides together); tilts head and turns face to opposite side (one side alone)

Rectus abdominis

Long vertical muscle bands on the front of the abdomen. • Origin: Pubic crest and pubic symphysis • Insertion: Xiphoid process and costal cartilages of ribs 5–7 • Action: Flexes the trunk (sit-up motion); compresses the abdomen

Pectoralis major

Large fan-shaped muscle covering the upper chest that forms the anterior axillary wall. • Origin: Sternum, clavicle, and costal cartilages of ribs 1–6 • Insertion: Intertubercular groove of the humerus • Action: Adducts the arm; medially rotates the arm; flexes humerus (clavicular head)

Latissimus dorsi

Widest muscle of the lower and middle back, forming the posterior axillary wall. • Origin: Spinous processes of T7–S3, iliac crest, and ribs 10–12 • Insertion: Intertubercular groove of the humerus • Action: Extends the arm; adducts and medially rotates the arm

Deltoid

Triangular, cap-shaped muscle giving the shoulder its rounded contour. • Origin: Clavicle, acromion, and spine of the scapula • Insertion: Deltoid tuberosity of the humerus • Action: Abducts the arm

Supraspinatus

Rotator cuff muscle situated above the spine of the scapula. • Origin: Supraspinous fossa of the scapula • Insertion: Greater tubercle of the humerus • Action: Abducts the arm (initiates movement); stabilizes glenohumeral joint

Infraspinatus

Rotator cuff muscle situated below the spine of the scapula on the posterior surface. • Origin: Infraspinous fossa of the scapula • Insertion: Greater tubercle of the humerus • Action: Laterally (externally) rotates the arm; stabilizes glenohumeral joint

Teres minor

Small, round rotator cuff muscle positioned directly below the infraspinatus. • Origin: Lateral border of the scapula • Insertion: Greater tubercle of the humerus • Action: Laterally (externally) rotates the arm; stabilizes glenohumeral joint; assists adduction and extension

Subscapularis

Rotator cuff muscle located on the anterior (rib-facing) surface of the scapula. • Origin: Subscapular fossa of the scapula • Insertion: Lesser tubercle of the humerus • Action: Medially (internally) rotates the arm; stabilizes glenohumeral joint

Biceps brachii

Two-headed muscle on the anterior upper arm. • Origin: Coracoid process (short head) and supraglenoid tubercle (long head) • Insertion: Radial tuberosity • Action: Flexes the elbow; supinates the forearm

Triceps brachii

Three-headed muscle comprising the entire posterior upper arm. • Origin: Infraglenoid tubercle of the scapula (long head) and shaft of humerus (lateral and medial heads) • Insertion: Olecranon process of the ulna • Action: Extends the elbow

Extensor digitorum

Superficial muscle located on the posterior forearm. • Origin: Lateral epicondyle of the humerus • Insertion: Four tendons to the phalanges of digits 2–5 • Action: Extends fingers 2–5 at the knuckles; extends the wrist

Flexor digitorum superficialis

Intermediate muscle situated on the anterior forearm toward the ulnar side. • Origin: Medial epicondyle of humerus, coronoid process of ulna, and radius • Insertion: Middle phalanges of digits 2–5 • Action: Flexes the wrist; flexes fingers 2–5

Iliopsoas

Deep composite muscle inside the lower back, pelvis, and groin. • Origin: Lumbar vertebrae bodies/transverse processes T12–L5 (psoas) and iliac fossa (iliacus) • Insertion: Lesser trochanter of the femur • Action: Flexes the hip; flexes trunk and laterally rotates thigh

Gluteus maximus

The largest, most superficial muscle of the posterior hip and buttocks. • Origin: Iliac crest (posterior ilium), sacrum, coccyx, and lumbar fascia • Insertion: Gluteal tuberosity of the femur and iliotibial band • Action: Extends the hip; laterally rotates the thigh

Rectus femoris

Central anterior thigh muscle; the only quadriceps head that crosses both hip and knee. • Origin: Anterior inferior iliac spine and superior acetabulum • Insertion: Patella (and tibial tuberosity via patellar ligament) • Action: Extends the knee; flexes the hip

Biceps femoris

Lateral hamstring muscle located on the posterior thigh. • Origin: Ischial tuberosity (long head) and linea aspera of femur (short head) • Insertion: Head of the fibula and lateral condyle of the tibia • Action: Flexes the knee; extends the hip (long head)

Gastrocnemius

Two-headed superficial calf muscle on the posterior lower leg. • Origin: Medial and lateral condyles of the femur • Insertion: Calcaneus via the calcaneal (Achilles) tendon • Action: Plantar flexes the ankle; assists knee flexion

Tibialis anterior

Muscle lying directly lateral to the anterior crest of the tibia (shinbone). • Origin: Lateral condyle and upper two-thirds of the lateral surface of the tibia • Insertion: Medial cuneiform and base of the first metatarsal • Action: Dorsiflexes the ankle; inverts the foot