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    Related Topics

    From Musculoskeletal System

    Masseter
    Muscle that elevates the mandible.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Occipital Bone
    Bone forming the back and base of the skull.
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Cranial Bones
    Bones of the skull that protect the brain.
    Sacrum
    Triangular bone at the base of the spine.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Sternum
    Breastbone located in the center of the chest.
    Skull
    Bony structure of the head that encases the brain.
    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.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Ulna
    Forearm bone on the pinky side.
    Parietal Bones
    Bones forming the sides and roof of the skull.
    Diaphragm
    Primary muscle for breathing.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.
    Vomer Bone
    Bone forming the nasal septum.
    Mandible
    Lower jawbone that houses the teeth.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Tibia
    Shin bone, the larger bone in the lower leg.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Interspinous Ligament
    Spinal ligament between adjacent vertebral spinous processes.

    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? Sesamoid bones are bones that form within tendons, like the patella.