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    Related Topics

    From Musculoskeletal System

    Rotator Cuff Tendons
    Tendons of the rotator cuff muscles.
    Diaphragm
    Primary muscle for breathing.
    Nasal Bones
    Bones forming the bridge of the nose.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Annular Ligament
    The annular ligament is a strong fibrous band encircling the head of the radius, stabilizing the proximal radioulnar joint and allowing smooth rotation of the forearm.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Ilium
    Uppermost and largest part of the hip bone.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Ulna
    Forearm bone on the pinky side.
    Abductor Digiti Minimi Muscle
    The abductor digiti minimi muscle is a hypothenar muscle that abducts and flexes the little finger, aiding grip and precision in hand movements.
    Gliding (Plane) Joints
    e.g., between carpals
    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Acetabulum
    The acetabulum is the pelvic socket that connects with the femoral head to form the hip joint, vital for stability, movement, and weight-bearing.
    Tibia
    Shin bone, the larger bone in the lower leg.
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Syndesmoses
    Fibrous joints where bones are connected by ligaments.
    Occipital Bone
    Bone forming the back and base of the skull.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Sternum
    Breastbone located in the center of the chest.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Adductors
    Muscles that bring the thighs toward the midline.

    Phalanges (14 bones)

    Reviewed by our medical team

    14 bones forming the toes.

    1. Overview

    The phalanges are the 14 long bones that form the fingers of the hand. Each finger consists of multiple phalanges, which provide the skeletal framework necessary for dexterous hand movements, gripping, and manipulation of objects. These bones are small yet highly mobile and essential for fine motor function.

    2. Location

    The phalanges are located in the distal region of the hand:

    • Proximally: Articulate with the metacarpals at the metacarpophalangeal (MCP) joints.

    • Distally: Form the tips of the fingers (distal phalanges).

    • Each finger (digits 2–5): Has three phalanges – proximal, middle, and distal.

    • Thumb (digit 1): Has only two phalanges – proximal and distal (no middle phalanx).

    3. Structure

    The 14 phalanges are classified based on their position within each digit:

    • Proximal phalanges (5): Articulate with the metacarpals and form the base of each finger.

    • Middle phalanges (4): Present in digits 2–5; absent in the thumb.

    • Distal phalanges (5): Form the tips of the fingers and support the nail bed.

    Each phalanx is a miniature long bone composed of:

    • Base: Proximal end, wider for articulation.

    • Shaft (body): Long cylindrical portion.

    • Head: Distal end, rounded for articulation (except in distal phalanges, which are flattened).

    They are made of cortical and cancellous bone and are lined by periosteum, which supports vascularization and healing.

    4. Function

    The phalanges serve crucial mechanical and functional roles in hand movement:

    • Enable finger motion: Allow flexion, extension, abduction, and adduction at various interphalangeal and metacarpophalangeal joints.

    • Gripping and holding: Essential for precision and power grips.

    • Support fine motor skills: Facilitate tasks like writing, typing, and manipulating small objects.

    • Provide leverage: Serve as attachment points for flexor and extensor tendons, enhancing the effectiveness of muscle contraction.

    5. Physiological role(s)

    Beyond movement, the phalanges contribute to:

    • Tactile sensitivity: Serve as the framework beneath the fingertips, where sensory receptors for touch and temperature are concentrated.

    • Tool interaction: Act as physical extensions of the hand, increasing reach and mechanical advantage.

    • Support nail growth: The distal phalanges anchor nail beds, protecting the tips of the fingers.

    • Force transmission: Transmit forces from fingertips to the hand and wrist during object manipulation or impact.

    6. Clinical Significance

    The phalanges are prone to trauma and overuse injuries due to their size and function:

    • Fractures:

      • Common in contact sports, workplace injuries, or falls; may involve any phalanx and can range from simple to comminuted fractures.

    • Dislocations:

      • Most frequently occur at the interphalangeal or MCP joints, typically from hyperextension injuries.

    • Mallet finger:

      • Avulsion injury of the extensor tendon at the distal phalanx, often due to sudden force to a flexed finger tip.

    • Boutonnière and Swan-neck deformities:

      • Deformities of the interphalangeal joints often associated with rheumatoid arthritis or tendon imbalance.

    • Osteoarthritis and rheumatoid arthritis:

      • Degenerative or inflammatory joint disease affecting the DIP, PIP, or MCP joints, leading to pain, stiffness, and deformity.

    • Congenital anomalies:

      • Conditions such as syndactyly (fusion), polydactyly (extra fingers), or brachydactyly (shortened phalanges) may affect structure and function.

    Did you know? The average adult human has 206 bones, but this number can vary slightly due to additional bones in the hands or feet.