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    Related Topics

    From Musculoskeletal System

    Zygomaticus
    Muscle that raises the corners of the mouth.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Pivot Joints
    e.g., atlanto-axial joint
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Skull
    Bony structure of the head that encases the brain.
    Saddle Joints
    e.g., thumb joint
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Vomer Bone
    Bone forming the nasal septum.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Wormian Bones
    Sutural bones in the skull.
    Ball-and-Socket Joints
    e.g., shoulder, hip

    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 sternocleidomastoid muscle helps rotate the head.