The proximal phalanx is a tubular bone forming the base of each finger and toe, connecting to the metacarpals in the hand or metatarsals in the foot.
Here's a more detailed breakdown:
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Anatomy: The proximal phalanx, also known as the first phalanx, is one of the three phalanges (bones) present in each finger (except the thumb, which has two) and each toe.
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Structure:
- Base: The proximal end of the bone, which articulates (forms a joint) with the head of the metacarpal or metatarsal bone.
- Diaphysis (Shaft): The long, central part of the bone. It's slightly convex on the dorsal (back) surface and slightly concave on the volar (palmar or plantar) surface. This concavity on the palmar side supports the flexor tendons.
- Head: The distal end of the bone, which articulates with the middle phalanx (or the distal phalanx in the thumb and great toe).
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Function: Proximal phalanges provide structure and leverage for hand and foot movements, playing a crucial role in gripping, walking, and balance. They allow for the first joint in each digit, enabling flexion and extension.
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Clinical Relevance: Fractures of the proximal phalanx are common injuries, often resulting from direct trauma. Conditions like arthritis can also affect the joints involving the proximal phalanx, leading to pain and decreased mobility.
In summary, the proximal phalanx is an essential component of the digits, providing foundational support and articulation for complex hand and foot function.
