Exam 2 lec

What moves the scapula by shrugging, pulling back, and lowering it?

Trapezius - (Shrugs, pulls back, and lowers scapula, Scapula)

What moves the scapula by pushing it forward against the ribs?

Serratus anterior - (Pushes scapula forward, Scapula)

What moves the arm by pulling it forward and across the body?

Pectoralis major - (Pulls arm forward and across body, Humerus)

What moves the arm by lifting it to the side?

Deltoid - (Lifts arm to the side / Abduction, Humerus)

What moves the arm by pulling it down and back?

Latissimus dorsi - (Pulls arm down and back, Humerus)

What moves the elbow by bending it and turning the palm up?

Biceps brachii - (Bends elbow, turns palm up, Radius)

What moves the elbow as the prime flexor?

Brachialis - (Bends elbow / Prime mover, Ulna)

What moves the elbow by helping it bend?

Brachioradialis - (Helps bend elbow, Radius)

What moves the elbow by straightening it?

Triceps brachii - (Straightens elbow, Ulna)

What moves the thigh by lifting it at the hip?

Iliopsoas - (Lifts thigh / Hip flexion, Femur)

What moves the leg so you can sit cross-legged?

Sartorius - (Lets you sit cross-legged, Tibia)

What muscle group moves the knee by straightening it?

Quadriceps femoris - (Straightens knee, Tibia)

What muscle group moves the thigh by pulling it inward?

Adductors (longus brevis magnus) - (Pulls thigh inward, Femur)

What moves the hip by extending it back?

Gluteus maximus - (Extends hip, Femur)

What moves the thigh to the side and keeps the pelvis level?

Gluteus medius - (Lifts thigh to side, keeps pelvis level, Femur)

What muscle group moves the hip and knee by extending the hip and bending the knee?

Hamstrings - (Extends hip, bends knee, Tibia & Fibula)

What moves the foot by lifting it and turning the sole inward?

Tibialis anterior - (Lifts foot, turns sole inward, First metatarsal)

What moves the foot by turning the sole outward?

Fibularis longus - (Turns sole outward, helps point foot, First metatarsal)

What moves the foot and knee by pointing the foot and bending the knee?

Gastrocnemius - (Points foot, helps bend knee, Calcaneus)

What moves the foot by pointing it?

Soleus - (Points foot, Calcaneus)

What is the effect of baking a bone in an oven?

It destroys organic collagen fibers, leaving only mineral salts so the bone shatters easily like chalk.

What are osteoprogenitor cells?

Stem cells located in the periosteum and endosteum that divide to produce osteoblasts.

What is the functional role of osteoblasts?

Bone-building cells that synthesize and deposit organic bone matrix.

What is the functional role of osteocytes?

Mature bone cells trapped in lacunae that act as strain sensors to monitor physical loading.

What is the functional role of osteoclasts?

Giant multinucleated cells that dissolve bone matrix using acid and lysosomal enzymes.

What are canaliculi?

Microscopic hair-like canals connecting lacunae to central canals, allowing osteocytes to share nutrients and signals.

What is an osteon (Haversian system)?

The structural unit of compact bone composed of concentric lamellae surrounding a central blood canal.

What are the six structural features of a synovial joint?

Articular cartilage, Joint cavity, Articular capsule, Synovial fluid, Reinforcing ligaments, and Nerves/blood vessels.

How does avascular articular cartilage obtain nutrients?

Joint compression squeezes waste fluid out; releasing pressure soaks fresh synovial fluid back in like a sponge.

How does a bursa differ from a tendon sheath?

Bursa is a flattened synovial sac reducing friction; Tendon sheath is an elongated bursa wrapped completely around a tendon.

What is an articular disc (meniscus)?

Fibrocartilage pad that improves joint fit and absorbs shock in knee and TMJ.

What are the four axial movement classifications?

Nonaxial (gliding, 0 axes), Uniaxial (1 plane, 1 axis), Biaxial (2 planes, 2 axes), and Multiaxial (all planes + rotation, 3+ axes).

What are the six shapes of synovial joints?

Plane (nonaxial), Hinge (uniaxial), Pivot (uniaxial), Condylar (biaxial), Saddle (biaxial), and Ball-and-Socket (multiaxial).

Why is a scaphoid carpal fracture clinically dangerous?

Blood enters distally; a middle fracture cuts off blood to the proximal piece, risking avascular necrosis.

What three fused bones form each hip (coxal) bone?

Ilium (superior flare), Ischium (posterior sit-bone), and Pubis (anterior), meeting at the acetabulum.

How do the acetabulum and glenoid cavity compare in socket depth?

Acetabulum is a deep cup built for weight-bearing stability; Glenoid cavity is a shallow saucer built for mobility.

How does the female pelvis differ from the male pelvis?

Female pelvis is wider, shallower, with a broad pubic arch (80°–90° vs male 50°–60°) and wider pelvic inlet for birth.

Where does a clinical broken hip usually occur?

Fracture across the angled neck of the femur, which bears high bending loads.

How do the weight-bearing roles of the tibia and fibula compare?

Tibia carries 100% of body weight; Fibula carries 0% and can be harvested for bone grafts.

What is the mechanism of an inversion ankle sprain?

Sole of foot rolls inward (inversion), stretching and tearing lateral ankle ligaments.

What is the fundamental law governing joint architecture?

Mobility and stability are inversely related; higher mobility equals lower stability.

What are the three functional joint categories?

Synarthrosis (immovable), Amphiarthrosis (slightly movable), and Diarthrosis (freely movable).

What are the three structural joint categories?

Fibrous (collagen, no cavity), Cartilaginous (cartilage pad, no cavity), and Synovial (fluid-filled cavity).

What are the three types of fibrous joints?

Suture (skull seams; synarthrotic), Syndesmosis (ligament sheet; amphiarthrotic), and Gomphosis (tooth socket; synarthrotic).

What are the two types of cartilaginous joints?

Synchondrosis (hyaline cartilage, e.g., epiphyseal plate; synarthrotic) and Symphysis (fibrocartilage pad, e.g., intervertebral disc, pubic symphysis; amphiarthrotic).

What are fetal fontanelles?

Fibrous soft spots allowing skull compression during birth and rapid brain growth during infancy.

What are the regions and bone counts of the adult vertebral column?

26 adult bones: 7 Cervical, 12 Thoracic, 5 Lumbar, 1 Sacrum (5 fused), and 1 Coccyx (4 fused).

What is the difference between primary and secondary spinal curvatures?

Primary (Thoracic and Sacral) are present at birth; Secondary (Cervical and Lumbar) develop as infants lift their head and walk.

What anatomical feature uniquely identifies a cervical vertebra?

The presence of transverse foramina carrying vertebral arteries to the brain.

What are the features and movement of C1 (Atlas)?

Ring-like bone without body or spinous process; articulates with occipital condyles to permit nodding YES.

What are the features and movement of C2 (Axis)?

Features a vertical peg called the dens (odontoid process) that acts as a pivot post for C1 to rotate NO.

Why is an individual bone classified as an organ rather than a tissue?

It consists of multiple tissue types working together, including bone connective tissue, cartilage, blood, and nervous tissue.

What are the primary functions of the skeletal system?

Support, protection, movement levers, mineral storage for calcium and phosphate, blood cell formation (hematopoiesis), and energy storage in yellow marrow.

What mechanical property does the organic matrix of bone provide?

It makes up ~35% of matrix (primarily collagen fibers) and provides flexibility and tensile strength to resist pulling.

What mechanical property does the inorganic matrix of bone provide?

It makes up ~65% of matrix (primarily calcium phosphate mineral salts) and provides hardness and compressive strength to resist crushing.

What is the effect of soaking a bone in acid (vinegar)?

It dissolves inorganic mineral salts, leaving only flexible collagen so the bone can be tied in a knot.

Why is the clavicle prone to fracture during a fall on an outstretched hand?

It acts as an exposed anterior strut transmitting force, snapping at its double-curve junction.

What are the three prominent landmarks of the scapula?

Acromion (shoulder tip), Coracoid process (anterior hook), and Glenoid cavity (arm socket).

What is the structural trade-off of the glenohumeral shoulder joint?

Shallow glenoid cavity permits maximum 360° mobility but results in low structural stability and frequent dislocation.

What distal features of the humerus articulate with the forearm?

Trochlea (articulates with ulna) and Capitulum (articulates with radius).

What are the relative positions of the radius and ulna in anatomical position?

Radius is lateral (thumb side); Ulna is medial (pinky side).

What happens to forearm bones during pronation?

The radius rotates across the ulna to form an X, turning palm posteriorly/downward.

What are the bone counts of the wrist and hand?

8 Carpals, 5 Metacarpals, and 14 Phalanges.

What are perforating (Volkmann's) canals?

Canals running at right angles to central canals, connecting periosteal blood vessels to internal osteon canals.

What is intramembranous ossification?

Bone development directly within a fibrous connective tissue membrane, forming cranial bones and clavicles.

What is endochondral ossification?

Bone development by replacing a pre-existing hyaline cartilage model, forming all bones below the skull except clavicles.

What are the 5 growth zones of the epiphyseal plate from epiphysis to diaphysis?

Resting zone, Proliferation zone, Hypertrophic zone, Calcification zone, and Ossification zone.

What is Wolff's law?

Bones remodel, thicken, and strengthen in direct response to the mechanical forces and physical loads placed upon them.

What bones compose the axial skeleton?

80 total bones forming the skull, vertebral column, and thoracic cage.

How many cranial and facial bones make up the skull?

8 cranial bones protecting the brain and 14 facial bones framing the face and holding teeth.

What is the only freely movable bone of the skull?

Mandible (lower jawbone).

What are the four major cranial sutures?

Coronal (frontal/parietals), Sagittal (between parietals), Squamous (parietal/temporal), and Lambdoid (parietal/occipital).

Why is the sphenoid bone called the keystone of the cranium?

It sits centrally in the skull base and articulates with all other cranial bones.

What are paranasal sinuses?

Air-filled, mucus-lined cavities in frontal, sphenoid, ethmoid, and maxillary bones that lighten the skull and warm incoming air.

What is unique about the hyoid bone?

It is the only bone in the body that does not articulate directly with any other bone.

What anatomical feature uniquely identifies thoracic vertebrae?

Costal facets on the body and transverse processes for rib articulation.

What anatomical feature uniquely identifies lumbar vertebrae?

Massive kidney-shaped body and short, flat spinous process for bearing heavy weight.

What are the three fused parts of the sternum?

Manubrium (superior), Body (middle), and Xiphoid process (inferior).

How are ribs classified?

True ribs (1–7, direct costal cartilage), False ribs (8–10, indirect cartilage), Floating ribs (11–12, no anterior attachment).

How many bones make up the appendicular skeleton?

126 bones forming the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

What bones form the pectoral girdle?

Clavicle (anterior strut) and Scapula (posterior shoulder blade).

What is the single bony joint connecting the upper limb to the axial trunk?

Sternoclavicular joint.

What joint shape is at the base of the thumb, and what action does it permit?

Saddle joint (1st carpometacarpal joint), allowing opposition.

How do flexion, extension, and hyperextension differ?

Flexion decreases joint angle; Extension increases joint angle; Hyperextension extends past anatomical position.

How do abduction and adduction differ?

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

What is circumduction?

Moving a limb in a circle so it traces a cone in space (combines flexion, abduction, extension, adduction).

What are dorsiflexion and plantar flexion?

Dorsiflexion pulls toes up toward shin; Plantar flexion points toes downward.

How do Osteoarthritis and Rheumatoid Arthritis differ?

Osteoarthritis is wear-and-tear cartilage breakdown forming bone spurs; Rheumatoid arthritis is an autoimmune attack on the synovial membrane causing joint fusion.

What are the four physical properties of muscle tissue?

Excitability, Contractility, Extensibility, and Elasticity.

What are the connective tissue wrappings of muscle from outer to inner?

Epimysium (whole muscle), Perimysium (fascicle bundle), and Endomysium (individual muscle fiber cell).

What is a muscle fascicle?

A discrete bundle of muscle fibers surrounded by perimysium.

How do muscle origin and insertion differ?

Origin is stationary bone attachment; Insertion is movable bone attachment pulled toward origin during contraction.

What are the sarcolemma and sarcoplasm?

Sarcolemma is the muscle fiber cell membrane; Sarcoplasm is the cytoplasm.

Why are skeletal muscle fibers multinucleated?

They form during embryonic development by the fusion of multiple individual myoblasts.

What are muscle satellite cells?

Stem cells located beside fibers that provide limited repair and regeneration.

What is a sarcomere?

Functional contractile unit of a myofibril extending from one Z disc to the next Z disc.

What creates the dark A band and light I band of striations?

A band is full length of thick myosin filaments; I band contains thin actin filaments only.

What are the roles of myosin and actin in a sarcomere?

Myosin is thick filament with heads that pull; Actin is thin filament containing binding sites for myosin.

What are the roles of T-tubules and sarcoplasmic reticulum?

Sarcoplasmic reticulum stores calcium; T-tubules conduct electrical impulses deep into muscle fiber.

What forms a muscle triad?

One T-tubule flanked by two terminal cisternae of sarcoplasmic reticulum.