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    Related Topics

    From Musculoskeletal System

    Saddle Joints
    e.g., thumb joint
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Vertebral Column
    Spinal column consisting of vertebrae.
    Lateral Collateral Ligament (LCL)
    Knee ligament that stabilizes the outer knee.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Patella
    Knee cap, protecting the knee joint.
    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.
    Latissimus Dorsi
    Back muscle responsible for arm adduction and extension.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Sternum
    Breastbone located in the center of the chest.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Vomer Bone
    Bone forming the nasal septum.
    Inferior Nasal Conchae
    Bones inside the nasal cavity that filter and humidify air.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Carpals (8 bones)
    8 wrist bones.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Pivot Joints
    e.g., atlanto-axial joint
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Ulna
    Forearm bone on the pinky side.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.

    Metacarpals (5 bones)

    Reviewed by our medical team

    5 bones forming the palm of the hand.

    1. Overview

    The metacarpals are five long bones located in the hand, forming the skeleton of the palm. They connect the carpal (wrist) bones to the phalanges (finger bones) and are essential in hand structure, grip, and fine motor function. Each metacarpal bone is associated with one of the five digits and plays a key role in hand movement and force transmission.

    2. Location

    The metacarpals are found in the middle region of the hand:

    • Proximally: Articulate with the carpal bones via the carpometacarpal (CMC) joints.

    • Distally: Articulate with the proximal phalanges through the metacarpophalangeal (MCP) joints.

    • Situated between: The wrist and fingers, deep to the palmar skin and muscles.

    3. Structure

    Each of the five metacarpals is a miniature long bone with three main parts:

    • Base: Proximal end that articulates with carpal bones.

    • Shaft (body): Long, narrow mid-portion with a slight curve for hand contour.

    • Head: Distal, rounded end that forms the knuckle and articulates with the proximal phalanx.

    The five metacarpals are numbered I to V (lateral to medial, thumb to little finger):

    • 1st Metacarpal: Shortest and most mobile; connects to the thumb.

    • 2nd Metacarpal: Index finger; the longest metacarpal.

    • 3rd Metacarpal: Middle finger; has a prominent styloid process on its base.

    • 4th Metacarpal: Ring finger; shorter and more mobile than the 2nd and 3rd.

    • 5th Metacarpal: Little finger; allows greater flexion and opposition.

    4. Function

    The metacarpals serve as vital components in hand mechanics and structure:

    • Support: Form the framework of the palm and maintain hand shape.

    • Movement: Enable flexion, extension, abduction, and adduction of the fingers via MCP joints.

    • Transmission of force: Transmit mechanical loads from the fingers to the wrist during gripping, pushing, and lifting.

    • Dexterity: Allow precise and independent finger movements essential for fine motor tasks.

    5. Physiological role(s)

    Beyond structural support, the metacarpals contribute to:

    • Prehension (grasping): Serve as anchor points for muscles and ligaments involved in gripping and holding objects.

    • Balance and weight distribution: Disperse forces evenly across the hand during load-bearing activities.

    • Muscle attachment: Serve as origin points for intrinsic and extrinsic muscles of the hand, contributing to coordinated hand motion.

    6. Clinical Significance

    Metacarpal bones are frequently involved in trauma and orthopedic conditions:

    • Metacarpal fractures:

      • Common in sports injuries and falls; "boxer's fracture" refers to a fracture of the 5th metacarpal neck.

      • Symptoms include swelling, pain, deformity, and limited hand function.

    • Osteoarthritis:

      • Degenerative changes in the CMC or MCP joints, especially the base of the 1st metacarpal (thumb), leading to pain and reduced grip strength.

    • Congenital anomalies:

      • May involve absent, duplicated, or fused metacarpals affecting hand function and development.

    • Metacarpal shortening or malunion:

      • Improper healing after fracture can lead to loss of strength and range of motion, sometimes requiring surgical correction.

    • Carpometacarpal instability:

      • Ligament laxity at the CMC joints can impair grip and lead to chronic pain, particularly at the base of the thumb.

    Did you know? Your spinal cord is protected by the vertebral column.