PHYL 141 UNIT 2

Chondrocytes function

Maintain and monitor the extracellular matrix of cartilage.

Ground matrix of cartilage

Contains GAGs that trap water for resilience and shock absorption.

Intramembranous ossification

Forms flat bones of the skull, mandible, and clavicles.

Endochondral ossification

Forms most bones of the body from a hyaline cartilage model.

Red bone marrow

Located in spongy bone; produces blood cells.

Yellow bone marrow

Stores triglycerides and fat in medullary cavities.

Vitamin D role in bone

Converted to calcitriol to promote calcium and phosphate absorption.

Osteoporosis

Decreased bone mass and density, increasing fracture risk.

Vertebral column counts

Cervical: 7, Thoracic: 12, Lumbar: 5.

Sternal angle

Landmark marking the 2nd rib attachment and T4-T5 disc level.

Glenoid cavity

Scapular landmark that articulates with the head of the humerus.

Synovial joint structure

Features a joint cavity, articular cartilage, and synovial fluid.

Intervertebral disc herniation

Nucleus pulposus protrudes through annulus fibrosus, compressing nerves.

ACL function

Prevents anterior displacement of the tibia.

PCL function

Prevents posterior displacement of the tibia.

Flexion vs Extension

Flexion decreases joint angle; extension increases joint angle.

Abduction vs Adduction

Abduction moves limb away from midline; adduction moves toward midline.

Supination vs Pronation

Supination turns palm upward; pronation turns palm downward.

Skeletal vs Cardiac vs Smooth muscle

Skeletal: striated/voluntary. Cardiac: striated/involuntary. Smooth: non-striated/involuntary.

Motor unit

A single motor neuron and all the muscle fibers it innervates.

Sarcomere

The basic functional contractile unit of a skeletal muscle.

A-band vs I-band

A-band contains thick filaments; I-band contains thin filaments only.

Sarcoplasmic reticulum role

Stores and releases calcium ions for muscle contraction.

T-tubules function

Conduct action potentials deep into the muscle cell.

Calcium role in contraction

Binds to troponin to expose myosin-binding sites on actin.

ATP role in contraction

Provides energy for myosin head detachment and resetting.

Isotonic vs Isometric contraction

Isotonic changes length with constant tension; isometric changes tension without length change.

Concentric vs Eccentric contraction

Concentric shortens muscle; eccentric lengthens muscle under tension.

Slow vs Fast twitch muscles

Slow twitch is aerobic/endurance; fast twitch is anaerobic/powerful.

Agonist (Prime Mover)

Muscle primarily responsible for producing a specific movement.

Antagonist muscle

Muscle that opposes or reverses the movement of the prime mover.

Synergist

Muscle that aids the prime mover and stabilizes joint action.

Origin vs Insertion

Origin is stationary attachment; insertion is movable attachment.

Rotator cuff muscles (SITS)

Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.

Osteogenic cells

Stem cells that divide and differentiate into osteoblasts.

Osteoclasts function

Resorbs bone by secreting acid (HCl) to break down bone matrix.

Elastic cartilage locations

Found in the auricle of the external ear and epiglottis.

Fibrocartilage function

Resists compression, prevents bone-to-bone contact, and provides shock absorption.

Appositional growth

Growth that occurs along the outside edges of tissue.

Calcitonin function

Made by the thyroid gland; decreases osteoclast activity and lowers blood calcium.

Sliding filament model

Actin and myosin filaments slide past each other to shorten the sarcomere during contraction.

Parathyroid hormone role

Increases blood calcium levels by stimulating osteoclast activity and renal calcium reabsorption.

Epiphyseal plate

Hyaline cartilage plate in long bones responsible for longitudinal growth.

Bursae function

Fluid-filled sacs that reduce friction between bones, tendons, and muscles at joints.

Periosteum function

Dense connective tissue membrane covering outer bone surfaces, aiding in growth and repair.

Pectoral girdle function

Consists of the clavicle and scapula; attaches the upper limbs to the axial skeleton and provides high mobility.

Male vs Female pelvis differences

Female pelvis is broader, shallower, with a subpubic angle >90°; male pelvis is narrower, deeper, with a heart-shaped inlet.

Structural joint classification

Classified as fibrous, cartilaginous, or synovial based on anatomical binding and presence of a joint cavity.

Functional joint classification

Classified as synarthrosis (immovable), amphiarthrosis (slightly movable), or diarthrosis (freely movable).

Vertebral column supporting ligaments

Includes anterior/posterior longitudinal ligaments, ligamentum flavum, interspinous, and supraspinous ligaments.

Dislocation vs subluxation

Dislocation is a complete forced displacement out of a joint; subluxation is a partial or incomplete dislocation.

Glenoid labrum structure and function

A ring of fibrocartilage that deepens the glenoid cavity of the shoulder to increase joint stability.

Medial vs Lateral epicondylitis

Medial epicondylitis is Golfer's elbow; lateral epicondylitis is Tennis elbow, both involving tendon strain at the epicondyles.

Temporomandibular joint (TMJ)

A synovial joint formed by the mandibular condyle and temporal bone, allowing jaw depression, elevation, protraction, and retraction.

Arthroplasty

A surgical procedure where a diseased or damaged joint is replaced or reconstructed, such as a total hip replacement.

Connective tissue layers of skeletal muscle

Epimysium surrounds the entire muscle, perimysium surrounds muscle fascicles, and endomysium surrounds individual muscle fibers.

Neuromuscular junction (NMJ) signaling steps

Action potential causes ACh release, ACh opens Na+ and K+ channels, Na+ enters and K+ leaves, and Ca2+ is released from the sarcoplasmic reticulum.

Inversion and eversion of the foot

Inversion moves the sole of the foot toward the midline, while eversion moves the sole away from the midline.

Protraction and retraction

Protraction moves a body part anteriorly (forward), and retraction moves it posteriorly (backward).

Elevation and depression

Elevation moves a body part superiorly (upward), and depression moves it inferiorly (downward).

Effects of aging on joints

Aging leads to decreased production of synovial fluid, thinning of articular cartilage, and ligament weakening.

Axial vs Appendicular skeleton

Axial skeleton includes skull, vertebral column, and thoracic cage; appendicular skeleton includes limbs and girdles.

Bones of the skull

Consists of 8 cranial bones and 14 facial bones.

Types of muscle tissue

Skeletal, cardiac, and smooth muscle.

Oxygen debt

The amount of oxygen needed after exercise to restore pre-exercise conditions.

Muscle fatigue

Inability of a muscle to maintain its strength of contraction or tension during prolonged activity.

Axial neck and back muscles

Sternocleidomastoid, scalenes, and splenius; responsible for neck flexion, lateral flexion, and head extension.

Abdominal wall muscles

Rectus abdominis flexes trunk; internal/external obliques laterally flex; transversus abdominis compresses abdomen.

Scapular-attached muscles

Trapezius, rhomboids, levator scapulae, and serratus anterior; move and stabilize the scapula.

Rotator cuff stabilization

Supraspinatus, infraspinatus, teres minor, and subscapularis stabilize the glenohumeral joint.

Brachial region muscle functions

Biceps brachii, brachialis, and coracobrachialis flex the forearm; triceps brachii extends the forearm.

Antebrachial region muscle functions

Pronator teres pronates forearm; flexors flex wrist/digits; extensors extend wrist/digits.

Serratus anterior damage

Damage to the nerve during mastectomy leads to loss of fixator function and winged scapula syndrome.

SLAP tear

Superior labral tear from anterior to posterior, often affecting the tendon of the biceps brachii.

Ulnar collateral ligament injury

Treated with Tommy John surgery; involves medial epicondyle joint stability at the elbow.

Lateral epicondylitis

Also known as tennis elbow; involves strain on the extensor tendons attached to the lateral epicondyle.

Piriformis syndrome

Compression of the sciatic nerve as it passes under the piriformis muscle, causing pain and loss of function.

Iliotibial band syndrome (ITBS)

A common condition in runners and cyclists caused by irritation of the thick fibrous fascia lata band.

Pes anserine bursitis

Pain in the medial knee region caused by overwork or blunt force at the fused attachment of sartorius, gracilis, and semitendinosus.

Femoral and knee region flexors/extensors

Quadriceps femoris extend the knee; hamstrings flex the knee and extend the hip; iliopsoas flexes the hip.

Gluteal region muscles

Gluteus maximus extends/laterally rotates hip; medius/minimus abduct and medially rotate; piriformis laterally rotates.

Adductor group of the thigh

Pectineus, adductor longus, brevis, and magnus adduct the hip and laterally rotate it.

Perineal region triangles

Urogenital triangle contains genitals/urethra (bounded by pubic symphysis and ischial tuberosities); anal triangle contains the anus (bounded by coccyx and ischial tuberosities).

Pelvic diaphragm (Levator ani)

Includes pubococcygeus and iliococcygeus; supports pelvic organs and forms the pelvic floor alongside the coccygeus.

Frontal belly of occipitofrontalis function

Raises eyebrows.

Orbicularis oculi function

Closes eyelids.

Orbicularis oris function

Closes and purses lips (kissing).

Zygomaticus major function

Pulls the angle of the mouth superiorly (smiling).

Buccinator function

Compresses the cheek.

Depressor anguli oris function

Depresses the angle of the mouth.

Platysma function

Tenses the skin of the neck.

Muscles of mastication

Masseter, temporalis, medial pterygoid, and lateral pterygoid.

Digastric muscle function

Opens the mouth.

Hyoid muscles function

Moves the hyoid bone to help with deglutition (swallowing).

Three types of cartilage

Hyaline cartilage, elastic cartilage, and fibrocartilage.

Bone remodeling process

Continuous breakdown (resorption) by osteoclasts and building by osteoblasts.

Intramembranous vs Endochondral ossification

Intramembranous forms flat bones from connective tissue; endochondral forms most bones from a hyaline cartilage model.

Compact vs Spongy bone

Compact bone is dense and forms the outer shell; spongy bone consists of trabeculae and contains bone marrow.

Interstitial vs Appositional bone growth

Interstitial growth increases bone length at epiphyseal plates; appositional growth increases bone thickness/width.

Vitamins in bone growth

Vitamin D aids calcium absorption, Vitamin A supports osteoblast activity, and Vitamin C is required for collagen synthesis.