The femur has a small pit in its head - what's its name?

Correct Answer: C

Rationale: The fovea capitis is a small pit in the femoral head where the ligamentum teres attaches, anchoring it in the acetabulum. Other options are different femoral features (e.g., trochanters are projections).

Correct Answer: A

Rationale: The vertebral column is sequenced top-down: cervical (7), thoracic (12), lumbar (5), sacral (5, fused), coccygeal (4, fused). The thoracic region, with rib attachments, lies directly below the cervical region in the upper back.

Correct Answer: A

Rationale: The skeletal system is divided into two main parts: the axial skeleton and the appendicular skeleton. The axial skeleton includes the bones that form the central axis of the body, such as the skull (which protects the brain), the vertebral column (which protects the spinal cord), and the rib cage (which protects the heart and lungs). The appendicular skeleton, in contrast, includes the limbs and girdles. Long bones and irregular bones are types of bones, not divisions of the skeletal system, making 'Axial skeleton' the correct choice.

Correct Answer: B

Rationale: At the neuromuscular junction, motor neurons release acetylcholine (ACh) into the synaptic cleft to stimulate muscle fiber contraction. ACh binds to receptors on the muscle cell membrane, triggering an action potential that leads to contraction. Dopamine, serotonin, and GABA are neurotransmitters involved in other neural functions, not muscle contraction, making 'Acetylcholine (ACh)' the correct answer.

Correct Answer: A

Rationale: During muscle contraction, the sliding filament theory explains that myosin filaments slide along actin filaments to shorten the sarcomere and generate force. Myosin heads bind to actin, pulling it inward. Troponin and tropomyosin regulate this process, while collagen is structural, not contractile, making 'Myosin' the correct answer.