Skull Candy
What is the membrane lining the medullary cavity called?
Endosteum
Give the two types of bone tissue and a typical location for each.
Compact (cortical) bone — dense outer layer of bones, forms diaphysis of long bones; Spongy (trabecular or cancellous) bone — porous interior found in epiphyses and interior of flat bones.
Which bones form by intramembranous ossification (name at least two)?
Flat bones of the skull (e.g., frontal, parietal), clavicles.
Identify the frontal, parietal, temporal, occipital, maxilla, mandible on a lateral skull diagram — which bone forms the forehead?
Frontal bone forms the forehead.
Name the coxal bone components (three fused bones that form each hip bone).
Ilium, ischium, and pubis.
How many phalanges are in one hand (fingers) and how are they arranged per finger?
Each finger has three phalanges (proximal, middle, distal) except the thumb, which has two (proximal and distal). Total in one hand = 14 phalanges.
What is the membrane that covers the outer surface of bones called?
Periosteum
Briefly define: Osteoblast, Osteocyte, Osteoclast.
Osteoblast — bone-forming cell that secretes matrix; Osteocyte — mature bone cell located in lacunae, maintains bone tissue; Osteoclast — large, multinucleated cell that resorbs (breaks down) bone matrix.
Which bones commonly form by endochondral ossification (name at least two)?
Most long bones such as the femur, humerus, tibia, and bones of the limbs.
Name the bone that contains the foramen magnum.
Occipital bone.
What bone is the calcaneus and where is it located?
The calcaneus is the heel bone, located in the posterior of the foot (largest tarsal).
Name the major groups of bones included specifically in the appendicular skeleton.
Pectoral girdle, pelvic girdle, upper limb bones, lower limb bones.
What is the proper anatomical term for a skeletal joint?
Articulation
Define these structures: Lacunae, Canaliculi, Lamella
Lacunae — small spaces in bone matrix that house osteocytes; Canaliculi — tiny channels that connect lacunae and allow exchange of nutrients and waste; Lamella — concentric rings of mineralized matrix around a central canal in an osteon.
Name and give an example of the three major functional types of joints by mobility.
Synarthrosis — immovable (e.g., sutures of the skull); Amphiarthrosis — slightly movable (e.g., pubic symphysis, intervertebral discs); Diarthrosis — freely movable (synovial joints such as the knee, shoulder).
Define true rib, false rib, and floating rib by attachment to the sternum.
True ribs (1–7) attach directly to the sternum by their own costal cartilages; False ribs (8–12) attach indirectly or not directly to the sternum (8–10 attach via cartilage of the rib above); Floating ribs (11–12) do not attach to the sternum at all.
List the bones that make up the pectoral girdle.
Clavicle and scapula
Name the four major cranial sutures (locate them on a skull).
Coronal suture, sagittal suture, lambdoid suture, squamous suture.
Describe the two types of bone marrow and where each is typically found in an adults.
Red marrow — hematopoietic tissue that produces blood cells, found in flat bones (e.g., sternum, pelvis) and proximal epiphyses of long bones; Yellow marrow — mostly adipose tissue, found in the medullary cavities of long bones and can convert to red marrow in severe blood loss.
Describe the Haversian (central) canal and Volkmann's (perforating) canal and their roles.
Haversian canal — central channel of an osteon containing blood vessels and nerves running longitudinally; Volkmann's canals — transverse or oblique channels that connect Haversian canals and transmit vessels from periosteum into bone.
Give the four types of diarthrotic (synovial) joint movement categories with an example for each.
Ball-and-socket — shoulder or hip;
Hinge — elbow or knee;
Pivot — proximal radioulnar joint (rotational movement);
Saddle or Condyloid/Plane (acceptable examples depending on classification) — thumb carpometacarpal is a saddle joint; wrist is condyloid; intercarpal joints are plane.
What is the epiphyseal disk (plate) and what happens to it at the end of adolescence?
The epiphyseal disk (growth plate) is a cartilaginous region between epiphysis and diaphysis where longitudinal bone growth occurs. At the end of adolescence, it ossifies (becomes the epiphyseal line) and longitudinal growth ceases.
Give the major bones of the arm (from proximal to distal).
Humerus (upper arm), radius and ulna (forearm), followed by carpals, metacarpals, and phalanges in the hand.
Describe the anatomical difference between the pelvic girdle and the pectoral girdle in terms of stability and mobility.
The pelvic girdle (coxal bones fused to sacrum) provides strong, stable support for weight-bearing and protects pelvic organs — it is less mobile. The pectoral girdle (clavicle and scapula) provides greater mobility for upper limbs but less stability, allowing a wide range of shoulder motion.
Explain how bone remodeling maintains calcium homeostasis, naming key cells and hormones.
PTH raises blood calcium by stimulating osteoclast-mediated bone resorption (via osteoblast signaling), increasing renal reabsorption and activating vitamin D. Calcitonin lowers blood calcium by inhibiting osteoclasts. Osteoblasts form bone and remove Ca2+ from blood; osteoclasts resorb bone and release Ca2+.
Describe how an osteon supplies nutrients to osteocytes.
Blood vessels in Haversian canals deliver nutrients; Volkmann's canals connect vascular networks; canaliculi link lacunae to canals so osteocytes exchange nutrients/waste through the canalicular system.
Compare intramembranous vs. endochondral ossification with one example each.
Intramembranous: mesenchyme → bone directly (e.g., frontal bone). Endochondral: mesenchyme → cartilage model → bone (e.g., femur). Intramembranous forms flat bones; endochondral forms most long bones.
List five pelvic differences between typical female and male pelvis and one clinical implication.
Female pelvis: everything is wider & shorter (wider inlet, broader subpubic angle, shallower cavity, shorter/less-curved sacrum, wider sciatic notch).
Male pelvis: opposite features (narrower, deeper). Clinical implication: narrower pelvis increases risk of obstructed labor (possible need for cesarean).
Explain how the epiphyseal plate contributes to bone lengthening and what indicates its closure.
The epiphyseal plate contains proliferating cartilage that is replaced by bone at the metaphysis, allowing longitudinal growth. Closure is indicated when the cartilage is fully ossified into an epiphyseal line, stopping lengthening.
Describe the structural differences between compact and spongy bone and one functional consequence of each.
Compact bone is dense with osteons for strength and load-bearing; spongy bone has trabeculae with marrow-filled spaces for lightness and shock absorption and provides space for hematopoiesis.