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    Related Topics

    From Musculoskeletal System

    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Acromioclavicular Joint
    The acromioclavicular joint connects the clavicle and scapula at the top of the shoulder, enabling smooth scapular motion and stability during arm movements.
    Diaphragm
    Primary muscle for breathing.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Occipital Bone
    Bone forming the back and base of the skull.
    Radius
    Forearm bone on the thumb side.
    Flexor and Extensor Groups
    Muscles responsible for flexing and extending the hand and wrist.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Gliding (Plane) Joints
    e.g., between carpals
    Posterior Cruciate Ligament (PCL)
    Knee ligament that stabilizes the joint.
    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Lateral Collateral Ligament (LCL)
    Knee ligament that stabilizes the outer knee.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Saddle Joints
    e.g., thumb joint
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Temporalis
    Muscle involved in closing the jaw.
    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Vomer Bone
    Bone forming the nasal septum.
    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.

    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? The sternum is connected to the ribs by cartilage.