✅ Correct Answer: C — Fibrous joint (Suture)
The bones of the skull are joined by fibrous joints called sutures. Sutures are immovable (synarthrosis) joints where bones are held tightly together by dense fibrous connective tissue. In adults, these joints are completely fused and allow no movement at all, which is essential to protect the brain. The word "suture" comes from Latin meaning "seam." In infants, these joints are not yet fused — the soft spots called fontanelles allow the skull to compress during birth and expand as the brain grows.
❌ Why other options are wrong:
• A. Ball and socket joint — A freely movable (diarthrosis) synovial joint found in the shoulder and hip. It allows the greatest range of motion and is not found in the skull.
• B. Hinge joint — A synovial joint that allows movement in one plane only (flexion/extension), like the elbow or knee. Skull bones do not use this type.
• D. Pivot joint — Allows only rotational movement, found between atlas and axis vertebrae (C1-C2). It is not involved in skull bone connections.
📝 Important Note: Joints classification: Fibrous (suture, syndesmosis), Cartilaginous (synchondrosis, symphysis), Synovial (hinge, ball-socket, pivot, gliding). Skull sutures are examples of synarthrosis — completely immovable joints. The fontanelle (soft spot) in newborns closes by 18 months. Very important for SSC CGL Biology.
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