Name the bones which move against (articulate with)... a) the humerus: b) the thoracic vertebrae: c) the pelvis:

The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow. It articulates, or forms joints, at each end, facilitating movement and support.

In the shoulder region, the humerus head fits into the glenoid cavity of the scapula, forming what is known as the glenohumeral joint. This ball-and-socket joint allows for a wide range of motion in multiple directions, including flexion, extension, abduction, adduction, and rotation. This articulation makes it possible for us to lift, swing, and rotate our arms.

At the opposite end of the humerus, near the elbow, it creates two different types of joints with the forearm bones. With the ulna, it forms a hinge joint, which allows for the bending and straightening of the arm. Meanwhile, with the radius, it forms both a pivot joint that permits the rotation of the forearm, known as pronation and supination, and a hinge joint contributing to flexion and extension. The collaboration of these joints provides a sophisticated mechanism for arm movement, each fulfilling a specific function for daily activities and intricate tasks.

The thoracic vertebrae, forming the midsection of the vertebral column, primarily function to protect the thoracic organs and provide attachment for the rib cage. These vertebrae articulate with several other bones.

Superiorly, the thoracic vertebrae are bordered by the cervical vertebrae; inferiorly, they are followed by the lumbar vertebrae. These articulations, which are formed via intervertebral discs and facet joints, provide structural continuity for the spine, allowing for limited flexion, extension, and rotation.The unique feature of thoracic vertebrae articulations is their connection with the ribs. Each thoracic vertebra connects to a pair of ribs via the costovertebral joints, forming joints at two points: the demifacets on the vertebral body for the head of the rib and the transverse costal facets on the transverse processes for the tubercle of the rib. These joints provide a stable anchor for the ribs, which play a critical role in the mechanics of breathing. Understanding these articulations is crucial for comprehending issues related to spinal movement and ribcage dynamics.

The pelvis is a basin-shaped structure that serves as a connective bridge between the trunk and the lower limbs. Its articulations are essential for weight-bearing and movement.

The pelvis articulates with the sacrum, which is part of the vertebral column, at the sacroiliac joints. These joints are relatively immobile, supported by strong ligaments, and they absorb shock when walking or running. Their limited motion provides stability for the upper body when a person is standing.Furthermore, the pelvis forms the acetabulum, which is the socket for the femur bones at the hip joints. These ball-and-socket joints are designed for stability and a wide range of motion, making activities like walking, running, and jumping possible. The femur, or thigh bone, fits into the acetabulum, allowing the leg to move forward and backward, side to side, and to rotate around the axis of the limb. A thorough understanding of these connections is important for fields such as orthopedics, physical therapy, and sports medicine.