Musculoskeletal System – Major Bones, Muscles, Joints, and Levers

Vocabulary flashcards covering key terms related to bones, muscles, joints, movements, and lever mechanics from the lecture notes.

Axial skeleton

The central skeleton comprising the skull, vertebral column, ribs, and sternum.

Appendicular skeleton

The bones of the limbs and girdles (shoulder and pelvic girdles).

Skull

The bony framework of the head, enclosing the brain and supporting the face.

Cranium

The part of the skull that encloses the brain.

Mandible

The lower jaw bone.

Vertebral column

The spine, made of cervical, thoracic, and lumbar vertebrae plus sacrum and coccyx.

Cervical vertebrae

The vertebrae of the neck region.

Thoracic vertebrae

The vertebrae of the chest region to which ribs attach.

Lumbar vertebrae

The vertebrae of the lower back region.

Sacrum

The triangular bone at the base of the spine formed by fused vertebrae.

Coccyx

The tailbone at the end of the vertebral column.

Ribs

The bones forming the thoracic cage that protect the heart and lungs.

Sternum

The breastbone located in the center of the chest.

Clavicle

The collarbone connecting the sternum to the scapula.

Scapula

The shoulder blade that anchors upper limb muscles.

Humerus

The bone of the upper arm.

Radius

The lateral forearm bone (thumb side).

Ulna

The medial forearm bone (pinky side).

Carpals

The eight wrist bones forming the carpus.

Metacarpals

The five hand bones between the wrist and fingers.

Phalanges (hand)

The finger bones; each finger has three phalanges (thumb has two).

Pelvis

The bony ring formed by the ilium, ischium, and pubis.

Ilium

The broad, upper part of the hip bone.

Ischium

The lower, posterior part of the hip bone.

Pubis

The anterior portion of the hip bone.

Femur

The thigh bone; the longest bone in the body.

Patella

The kneecap.

Tibia

The larger, medial bone of the lower leg that bears most of the body's weight.

Fibula

The thinner, lateral bone of the lower leg.

Tarsals

The seven ankle bones forming the tarsus.

Metatarsals

The foot bones between the tarsals and phalanges.

Phalanges (foot)

The toe bones; similar structure to hand phalanges.

Deltoids

Shoulder muscles forming the rounded contour; primary role in arm abduction.

Trapezius

Large back/neck muscle that stabilizes and moves the scapula.

Pectoralis major

Chest muscle that flexes and adducts the humerus.

Latissimus dorsi

Large back muscle that extends, adducts, and medially rotates the arm.

Biceps brachii

Front upper arm muscle that flexes the elbow.

Triceps brachii

Back upper arm muscle that extends the elbow.

Rectus abdominis

Core muscle that flexes the spine; “six-pack” muscle.

Obliques

Side abdominal muscles aiding rotation and lateral flexion.

Erector spinae

Back muscle group that extends and stabilizes the spine.

Gluteals

Buttock muscles (gluteus maximus/medius/minimus) extending/rotating the hip.

Quadriceps

Front thigh muscle group (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) that extends the knee.

Hamstrings

Back thigh muscle group (biceps femoris, semitendinosus, semimembranosus) that flex the knee.

Gastrocnemius

Calf muscle that plantarflexes the foot.

Soleus

Calf muscle that plantarflexes the foot; lies beneath gastrocnemius.

Support and shape

Functions: skeleton holds body upright and defines form.

Protection

Skeleton protects brain, heart, and lungs.

Movement

Muscles pull on bones across joints to create movement.

Blood cell production

Red marrow makes red and white blood cells.

Mineral storage

Skeleton stores calcium and phosphorus for body processes.

Long bones

Bones longer than wide; provide movement and support (e.g., femur, humerus).

Short bones

Cube-shaped bones that absorb shock (carpals, tarsals).

Flat bones

Thin bones that protect organs and provide attachment (sternum, scapula).

Irregular bones

Bones with complex shapes (vertebrae, pelvis).

Sesamoid bones

Bones embedded in tendons to reduce friction (patella).

Anterior

Front of the body.

Posterior

Back of the body.

Medial

Toward the midline of the body.

Lateral

Away from the midline.

Superior

Above.

Inferior

Below.

Proximal

Closer to the trunk.

Distal

Further from the trunk.

Flexion

Bending a joint; decreasing the angle between bones.

Extension

Straightening a joint; increasing the angle.

Abduction

Movement away from the midline.

Adduction

Movement toward the midline.

Rotation

Turning about an axis.

Circumduction

Circular movement describing a cone around a joint.

Pronation

Palm-down position of the hand.

Supination

Palm-up position of the hand.

Plantar flexion

Pointing the toes downward.

Dorsiflexion

Lifting the foot upward toward the shin.

Fibrous joints

Joints with little to no movement; bones joined by fibrous tissue (e.g., skull sutures).

Cartilaginous joints

Slightly movable joints joined by cartilage (e.g., vertebrae; ribs to sternum).

Synovial joints

Freely movable joints with a joint cavity and synovial fluid (knee, hip).

Ball-and-socket

Synovial joint allowing multi-directional movement (hip and shoulder).

Hinge

Synovial joint allowing flexion/extension (knee, elbow).

Pivot

Synovial joint allowing rotation (neck).

Saddle

Synovial joint enabling flexion, extension, abduction, and adduction (thumb).

Gliding

Synovial joints where bones slide past one another (carpals, tarsals).

Condyloid

Synovial joint allowing flexion/extension and limited rotation (wrist).

Skeletal muscle

Voluntary muscle attached to bones; striated.

Smooth muscle

Involuntary muscle found in walls of organs; non-striated.

Cardiac muscle

Involuntary, striated muscle of the heart with rhythmic contractions.

Reciprocal inhibition

When an agonist contracts, the antagonist relaxes.

Agonist

The muscle that produces movement.

Antagonist

The muscle that opposes movement.

Motor unit

A motor neuron and all the muscle fibers it controls.

Activation

Brain sends impulse via motor neuron to muscle fibers.

All-or-nothing principle

A motor unit fires either completely or not at all.

Preferential recruitment

Slow-twitch fibers are recruited first for low-intensity; fast-twitch for high-intensity.

Size principle

Small motor units activate first; larger ones are recruited as needed.

Fulcrum

The pivot point of a lever (joint).

Load

The resistance or weight moved by the lever.

Effort

The force applied by the muscle.

Third-class lever

Lever where the effort is applied between the fulcrum and the load; common in body movements (e.g., bicep curl).