Question

Appendicular skeleton includes all except (a) Hind limb (b) Fore limb (c) Amphicoelous vertebra (d) Pectoral and pelvic girdle

Short answer

The correct answer is (c) Amphicoelous vertebra. It is part of the axial skeleton, not the appendicular skeleton.

Step-by-step solution

Identify the Components of the Appendicular Skeleton

The appendicular skeleton contains the bones of the arms and legs along with the bones that anchor them to the axial skeleton. This includes the pectoral girdle which attaches the upper limbs to the body trunk and consists of the clavicle and scapula, and the pelvic girdle which secures the lower limbs and consists of the hip bones.

Evaluate Each Option

(a) The hind limb is part of the appendicular skeleton. (b) The fore limb is also part of the appendicular skeleton. (c) The amphicoelous vertebra, a type of vertebra, is a part of the axial skeleton, not the appendicular skeleton. (d) The pectoral and pelvic girdles are part of the appendicular skeleton as they connect the limbs to the axial skeleton.

Choose the Correct Response

After evaluation, it's clear that the amphicoelous vertebra (option c) doesn't belong to the appendicular skeleton, but it is a part of the axial skeleton, which includes the bones forming the central axis of the body.

Key concepts

hind limb

The hind limb is a critical component of the appendicular skeleton. In humans and many animals, it corresponds to the region of the legs from the pelvis to the foot. The hind limb comprises various bones, including the femur (thigh bone), tibia and fibula (lower leg bones), and the bones of the foot like the metatarsals and phalanges. These bones support activities such as walking, running, and jumping, essentially making mobility possible.

• The femur is the longest and strongest bone in the body, crucial for bearing the body's weight and allowing a range of movements.
• The tibia, commonly known as the shinbone, is the larger of the two leg bones below the knee, while the fibula runs parallel to it.
• The foot is an intricate structure of bones, joints, and muscles, providing balance and enabling precise movements.

Understanding the hind limb's structure and function is essential for mastering topics related to movement and anatomy.

fore limb

The fore limb or front limb in animals and humans comprises the arms, a vital part of the appendicular skeleton. It includes the upper arm, forearm, and hand, each made up of several bones working together to allow a wide range of movements.

• The humerus is the bone of the upper arm, allowing for rotation and acting as a fulcrum for upper body strength.
• The forearm consists of two bones, the radius and the ulna, which help in rotating and bending the arm.
• The hand consists of the carpal (wrist), metacarpal (palm), and phalanges (finger) bones, all contributing to the hand's dexterity and grip.

In daily activities, the fore limb is engaged in actions like lifting, holding, and manipulating objects, highlighting its significance in our interaction with the environment.

pectoral girdle

The pectoral girdle is fundamental in connecting the fore limbs to the axial skeleton. It mainly consists of the clavicles (collarbones) and scapulae (shoulder blades). Each of these bones plays a vital role in ensuring that the arms can move freely and withstand the body's physical activities.

• The clavicle acts as a strut to keep the shoulder blades apart, permitting the arm a wide range of motion.
• The scapula is a flat, broad bone that provides a strong base for arm muscles to attach, ensuring stability and movement.

The flexibility and mobility of the pectoral girdle are essential in actions requiring strength and precision, such as throwing and lifting.

pelvic girdle

The pelvic girdle, part of the appendicular skeleton, plays a crucial role in anchoring the hind limbs to the axial skeleton and supporting the weight of the upper body. It consists of the hip bones, which include the ilium, ischium, and pubis. These fused bones form a sturdy ring structure known as the pelvis.

• The ilium, the topmost part, connects with the sacrum of the spinal column, providing a stable foundation for the trunk of the body.
• The ischium forms the lower and back part of the hip bone, contributing to forming the hip joint.
• The pubis is located at the front, where the two hip bones meet, complete with a cartilaginous connection.

The pelvic girdle's configuration is designed for load-bearing and enabling bipedal locomotion, walking, and running, making it central to human anatomy and movement.

axial skeleton

While not part of the appendicular skeleton, the axial skeleton forms the core axis of the body. It includes the skull, vertebral column, rib cage, and sternum. These components protect critical organs like the brain, heart, and lungs, and provide a structural foundation for other skeletal parts.

• The skull encases and safeguards the brain while featuring openings for sensory organs.
• The vertebral column consists of 33 vertebrae, offering structural support and flexibility to the body.
• The rib cage surrounds vital organs, providing protection and assisting in respiratory function.

The axial skeleton is crucial for maintaining posture and allowing movement, making it a pivotal subject in understanding human anatomy.