Extremity – Definition, Structure and Function
An extremity is a limb of the human body -- either an arm or a leg. Extremities enable movement, grasping, and locomotion.
Things worth knowing about "Extremity"
An extremity is a limb of the human body -- either an arm or a leg. Extremities enable movement, grasping, and locomotion.
What Is an Extremity?
In medicine and anatomy, the term extremity refers to the limbs of the human body: the upper extremities (arms) and the lower extremities (legs). They are attached to the trunk and enable a wide range of movements, from locomotion to fine motor skills such as grasping and writing.
Anatomical Structure
Upper Extremity
The upper extremity consists of the following segments:
- Shoulder: connects the trunk to the arm via the shoulder joint
- Upper arm: contains the humerus bone
- Elbow joint: connects the upper arm and forearm
- Forearm: composed of the radius and ulna bones
- Hand: includes the wrist, metacarpus, and fingers
Lower Extremity
The lower extremity is divided into:
- Hip: connects the pelvis to the thigh via the hip joint
- Thigh: contains the femur (thighbone)
- Knee joint: connects the thigh to the lower leg
- Lower leg: composed of the tibia (shinbone) and fibula
- Foot: includes the tarsus, metatarsus, and toes
Functions of the Extremities
The extremities serve several essential functions in the human body:
- Locomotion: The lower extremities enable walking, running, jumping, and standing.
- Grasping and holding: The upper extremities are used for gripping, lifting, and carrying objects.
- Balance and stability: All extremities contribute to posture and balance.
- Communication and expression: Hands and arms are used for gestures and nonverbal communication.
Vascular and Nerve Supply
Each extremity has a complex system of blood vessels and nerves. Arteries carry oxygenated blood into the limbs, while veins return deoxygenated blood to the heart. Nerves control the muscles (motor function) and transmit sensory information such as touch, pain, and temperature (sensory function).
Common Conditions Affecting the Extremities
Extremities can be affected by a wide range of diseases and injuries, including:
- Fractures: Broken bones due to trauma or osteoporosis
- Joint diseases: e.g., osteoarthritis or rheumatoid arthritis
- Circulatory disorders: e.g., peripheral arterial disease (PAD)
- Nerve damage: e.g., neuropathy caused by diabetes mellitus
- Muscle disorders: e.g., muscular dystrophies or strains
- Thrombosis: blood clots in the deep veins of the legs
Medical Examination of the Extremities
Physicians assess the extremities using various methods:
- Physical examination: inspection, palpation, and assessment of range of motion
- Imaging: X-ray, ultrasound, MRI, or CT scan to evaluate bones, joints, and soft tissues
- Doppler ultrasonography: measurement of blood flow in vessels
- Electromyography (EMG): measurement of the electrical activity of muscles
- Nerve conduction studies: assessment of nerve function
References
- Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2019). Gray's Anatomy for Students. Elsevier.
- Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2017). Clinically Oriented Anatomy. Wolters Kluwer.
- World Health Organization (WHO): Musculoskeletal conditions. Available at: https://www.who.int/news-room/fact-sheets/detail/musculoskeletal-conditions
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Related search terms: Extremity + Extremities + Limb + Limbs