Carpus and tarsus of land vertebrates

Tarsalia accessoria

The carpus and tarsus are anatomical structures found in the limbs of land vertebrates. These structures are crucial for the movement and support of the limbs, playing a significant role in the locomotion of these animals.

Carpus

The carpus, commonly known as the wrist in humans, is a complex assembly of bones located between the forearm and the metacarpus. It consists of multiple small bones arranged in two rows. The carpus allows for a wide range of motion and flexibility in the forelimb.

Structure

The carpus is composed of eight bones in humans, which are organized into two rows:

• Proximal row: scaphoid, lunate, triquetrum, and pisiform.
• Distal row: trapezium, trapezoid, capitate, and hamate.

These bones are connected by a series of ligaments and joints, which provide stability and facilitate movement.

Function

The primary function of the carpus is to facilitate the movement of the forelimb, allowing for actions such as flexion, extension, abduction, and adduction. It also serves as a transition point for the transmission of forces from the forearm to the hand.

Tarsus

The tarsus, commonly referred to as the ankle in humans, is a cluster of bones located between the lower leg and the metatarsus. It is essential for the stability and movement of the hindlimb.

Structure

The tarsus consists of seven bones in humans, which are:

• Talus
• Calcaneus
• Navicular
• Medial cuneiform
• Intermediate cuneiform
• Lateral cuneiform
• Cuboid

These bones are interconnected by ligaments and joints, forming a robust structure that supports the weight of the body and allows for various movements.

Function

The tarsus plays a critical role in the movement and stability of the hindlimb. It enables actions such as plantarflexion, dorsiflexion, inversion, and eversion. Additionally, it acts as a shock absorber during activities such as walking, running, and jumping.

Evolutionary Significance

The carpus and tarsus have evolved to adapt to the specific locomotor needs of different land vertebrates. For instance, in quadrupeds, these structures are adapted for weight-bearing and stability, while in bipeds, they are optimized for balance and efficient movement.

Related Pages

• Forelimb
• Hindlimb
• Wrist
• Ankle
• Metacarpus
• Metatarsus
• Ligament
• Joint

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