The crista galli is a small crest on which bone?

Correct Answer: B

Rationale: The crista galli, a midline bony crest, is on the ethmoid bone's perpendicular plate, projecting upward in the cranial cavity to anchor the falx cerebri, a dural fold. The maxilla forms the upper jaw, lacking this feature. The frontal bone has the forehead and sinuses, not the crista galli. The mandible , the lower jaw, is unrelated. The ethmoid's central skull position and its role in supporting brain membranes via the crista galli, often seen in sagittal sections, make 'b' the correct bone.

Correct Answer: B

Rationale: The pharynx's lower part, the laryngopharynx (or hypopharynx), connects anteriorly to the larynx, the voice box and airway entrance. Extending from the hyoid bone to the esophagus and larynx, it serves as a dual pathway for digestion and respiration. Posteriorly, it opens to the esophagus for food, while anteriorly, it joins the larynx at the epiglottis, which directs air to the trachea. The laryngopharynx's nonkeratinized stratified squamous epithelium suits its role in both systems. The hyoid bone supports the pharynx structurally but isn't an attachment point for its lower end it anchors muscles higher up. The trachea, below the larynx, continues the airway but connects via the larynx, not directly to the pharynx. Anatomically, the laryngopharynx spans C4-C6 vertebrae, transitioning seamlessly into the laryngeal opening. This attachment enables swallowing and breathing coordination, with clinical relevance in procedures like laryngoscopy. Respiratory and digestive anatomy texts confirm this connection, distinguishing it from skeletal or distal airway structures.

Correct Answer: B

Rationale: Stratified squamous epithelium lines the esophagus, a multi-layered, tough tissue protecting against abrasion from food passage, non-keratinized to stay moist. Simple cuboidal is for secretion/absorption (e.g., glands), not protection here. Simple columnar suits secretion in the stomach, not esophageal wear. Transitional stretches in the bladder, not relevant. Stratified squamous's durability, per digestive tract anatomy, makes 'b' the correct type.

Correct Answer: B

Rationale: Sweat glands, primarily eccrine, regulate body temperature (thermoregulation) by secreting sweat to cool via evaporation, a key homeostasis mechanism. Protection is secondary (e.g., flushing pathogens). Sensory reception involves nerves, not glands. Hormonal secretion is endocrine, not sweat-related. Thermoregulation's primacy, per skin physiology, makes 'b' correct.

Correct Answer: C

Rationale: The epiphyseal plate, a cartilage layer in growing long bones, allows longitudinal growth as chondrocytes divide, ossify, and lengthen the bone until maturity. Remodeling occurs throughout bone. New formation is broader, not plate-specific. Its growth function, per skeletal development, makes 'c' correct.