BIOS 1300 Lab 8: Appendicular Muscles & Biomechanics

Vocabulary flashcards covering the appendicular musculature, levels of structural organization, functional muscle groups (agonist, antagonist, synergist, fixator), origins, insertions, and biomechanical actions from BIOS 1300 Lab 8.

Appendicular Skeletal Muscles

Muscles that insert on, originate within, and provide motion for the extremities (upper and lower limbs, shoulder girdle, and hip girdle); they maintain posture, facilitate locomotion, produce limb movement, and stabilize joints under body weight.

Chemical Level

The simplest and smallest structural level of organization, where atoms combine to form molecules.

Cellular Level

The structural level of organization consisting of cells, which are composed of molecules and serve as the basic unit of life.

Tissue Level

The structural level of organization consisting of groups of similar types of cells working together to perform a function.

Organ Level

The structural level of organization where different types of tissues work together to perform specific functions.

Organ System Level

The structural level of organization composed of a series of different organs that work closely together toward a common job.

Organismal Level

The highest and most complex level of structural organization, representing the whole living being composed of many interacting organ systems.

Muscle Action

The specific movement produced across one or more joints as a result of muscle contraction ($\text{Action} = \text{Joint(s)} + \text{Movement(s)}$).

Muscle Origin

The relatively fixed or stationary point of attachment of a muscle during contraction.

Muscle Insertion

The movable point of attachment of a muscle that is pulled toward the origin during contraction.

Agonist (Prime Mover)

A muscle that bears the major responsibility for producing a specific movement; there can be more than one for an action.

Antagonist

A muscle that opposes or reverses a particular movement produced by an agonist.

Synergist

A muscle that assists the prime mover by adding extra force to the movement or reducing unnecessary movements.

Fixator

A muscle that immobilizes a bone or a muscle's origin to provide a stable base for the prime mover.

Hyperextension

Movement of a joint in the sagittal plane that extends beyond its normal anatomical range of motion.

Rotator Cuff Muscles (S.I.T.S.)

A group of four scapular muscles—Supraspinatus, Infraspinatus, Teres minor, and Subscapularis—that originate on the scapula, insert onto the proximal humerus, and act collectively to stabilize the glenohumeral (GH) joint.

Supraspinatus

A rotator cuff muscle originating superior to the spine of the scapula that acts to abduct the arm at the glenohumeral joint.

Infraspinatus & Teres Minor

Posterior rotator cuff muscles that insert onto the proximal humerus and act primarily to externally (laterally) rotate the arm.

Subscapularis

An anterior rotator cuff muscle located on the subscapular fossa that inserts on the humerus and acts to internally (medially) rotate the arm.

Teres Major

A shoulder muscle originating on the inferior angle of the scapula and inserting on the proximal humerus; it adducts, extends, and medially rotates the arm, but is NOT part of the rotator cuff.

Deltoid

A multi-part shoulder muscle originating from the lateral third of the clavicle, acromion, and scapular spine, inserting onto the deltoid tuberosity; anterior fibers flex and adduct, lateral fibers abduct, and posterior fibers extend and adduct the arm.

Latissimus Dorsi

A broad back muscle originating from the thoracolumbar aponeurosis, inferior angle of the scapula, iliac crest, and T7–L5, inserting onto the bicipital groove of the humerus to adduct, extend, and medially rotate the arm.

Biceps Brachii

A two-headed anterior arm muscle originating on the scapula and inserting onto the radial tuberosity; it performs elbow flexion, forearm supination, and supports the humeral head at the shoulder.

Brachialis

A deep anterior arm muscle originating on the humerus and inserting on the proximal ulna that performs a single primary action: elbow flexion.

Triceps Brachii

A three-headed posterior arm muscle originating on the scapula and humerus and inserting onto the olecranon of the ulna to produce elbow extension.

Anconeus

A small elbow muscle located near the lateral epicondyle and olecranon that acts as a synergist during elbow extension.

Forearm Flexors

The anterior compartment muscles of the forearm that originate predominantly from the medial epicondyle of the humerus.

Forearm Extensors

The posterior compartment muscles of the forearm that originate predominantly from the lateral epicondyle of the humerus.

Thenar Muscles

The intrinsic muscles located at the base of the thumb forming the thenar eminence on the lateral palm.

Hypothenar Muscles

The intrinsic muscles located at the base of the little (fifth) finger forming the hypothenar eminence on the medial palm.

Iliopsoas

A composite muscle formed by the psoas major and iliacus that inserts onto the lesser trochanter of the femur to perform hip flexion.

Hip Adductors

A medial thigh muscle group consisting of the adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus, acting to adduct the thigh.

Adductor Longus

A medial thigh muscle originating on the superior pubic ramus and inserting along the linea aspera of the femur that produces hip adduction.

Quadriceps Femoris

An anterior thigh group of four muscles—rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius—that insert into the tibial tuberosity via the quadriceps tendon and patellar ligament to extend the knee.

Rectus Femoris

The superficial anterior quad muscle originating on the anterior inferior iliac spine (AIIS) and inserting on the tibial tuberosity; it performs both hip flexion and knee extension ('lift & kick').

Vastus Medialis

The medial component of the quadriceps femoris originating along the intertrochanteric line of the proximal femur and inserting onto the tibial tuberosity to extend the knee.

Vastus Lateralis

The lateral component of the quadriceps femoris originating from the greater trochanter of the femur and inserting onto the tibial tuberosity to extend the knee.

Vastus Intermedius

The deep component of the quadriceps femoris situated directly beneath the rectus femoris, originating on the anterolateral femur and acting to extend the knee.

Sartorius

A strap-like anterior thigh muscle originating on the anterior superior iliac spine (ASIS) and inserting onto the proximal medial tibia; it produces hip flexion, hip external rotation, and knee flexion.

Gluteus Medius

A posterior/lateral hip muscle originating on the outer surface of the ilium and inserting onto the greater trochanter; it performs hip abduction and prevents 'hip drop' during walking.

Gluteus Maximus

The large posterior pelvic muscle originating from the sacrum and iliac crest, inserting into the gluteal tuberosity and iliotibial (IT) band; it produces hip extension and external rotation.

Tensor Fasciae Latae (TFL)

Anterolateral hip muscle originating on the ASIS and inserting into the iliotibial band/greater trochanter; it produces hip flexion and abduction, and assists in knee stabilization and extension.

Iliotibial (IT) Band

A dense fibrous tract of fascia lata that serves as an insertion site for the gluteus maximus and tensor fasciae latae, attaching distally to the proximal lateral tibia.

Piriformis

A deep gluteal muscle originating on the anterior sacrum and inserting on the greater trochanter; it produces hip external rotation and can abduct the hip when flexed ('tree pose').

Hamstrings

The posterior thigh muscle group comprising the semitendinosus, semimembranosus, and biceps femoris; all originate from the ischial tuberosity and act to extend the hip and flex the knee.

Biceps Femoris (Long Head)

The lateral hamstring muscle originating on the ischial tuberosity and inserting onto the head of the fibula; it produces knee flexion and hip extension.

Semitendinosus

The medial, superficial, tendon-like hamstring muscle that originates on the ischial tuberosity and inserts onto the proximal tibia.

Semimembranosus

The deeper medial hamstring muscle that originates on the ischial tuberosity and inserts onto the medial condyle of the tibia.

Gastrocnemius

A superficial two-headed posterior calf muscle originating from the femoral condyles and inserting via the calcaneal tendon; it produces ankle plantarflexion and knee flexion.

Soleus

A broad muscle deep to the gastrocnemius originating on the tibia and inserting via the calcaneal tendon to produce ankle plantarflexion.

Fibularis Group (Peroneal Muscles)

Lateral leg muscles (longus, brevis, and tertius) originating on the lateral fibula; longus and brevis perform plantarflexion and eversion, whereas tertius performs dorsiflexion and eversion.

Tibialis Anterior

An anterior lower leg muscle originating on the proximal/lateral tibia and inserting on the base of the first metatarsal; it performs dorsiflexion and inversion, preventing 'foot drop' and being linked to 'shin splints' when overworked.