Embryological development of the Muscular system

By CumminsC

  • Baby conceived

    Baby conceived

  • Septum transversum (primitive diaphragm) (2 weeks 6 days)

    Occurs 2 to 3 weeks

  • Diaphragm primordia (4 weeks)

    Occurs at 3 to 4 weeks

  • Muscular plates between upper and lower limb buds (4 weeks 4 days)

    Occurs 4 to 5 weeks

  • Extraocular premuscle masses receive cranial nerve fibers [oculomotor (CN III), trochlear (CN IV), and abducens (CN VI) nerves] (5 weeks 2 days)

    Occurs 5 to 6 weeks
    -Gluteal mesoderm
    -Infrahyoid premuscle masses
    -Limb mesoderm
    -Sternocleidomastoid-trapezius premuscle mass with spinal accessory nerve (CN11)
    -Thigh and thigh mesoderm
    -Tongue premuscle mass

  • Stapedius muscle (6 weeks 2 days)

    Occurs 6 to 7 weeks
    -Esophagus with muscular and submucous coats
    -Mesenchyme thickenings mark beginning of "sclera and its muscular attachments"

  • The hands begin to move (6 1/2 weeks)

  • Deltoid muscle (6 weeks 5 days)

    Occurs 6 to 7 weeks
    -Esophagus: Muscularis layer adjacent to esophageal plexus
    -External and internal abdominal oblique muscles

  • Diaphragm: Central tendon (7 weeks 1 day)

    Occurs 7 to 8 weeks

  • The hands begin to touch face (7 1/2 weeks)

    Occurs 7 to 8 weeks
    -The hands touch each other as do the feet.

  • Chordae tendineae (7 weeks 5 days)

    Occurs 7 to 8 weeks

  • More frequent hand to face contact (8 weeks)

    More frequent hand to face contact (8 weeks)
    Occurs 7 to 8 weeks
    - Mouth opens and closes
    - Squinting
    -The embryo floats and rolls over in the womb

  • Bends hip & knee if sole of foot touched (9 weeks)

    Bends hip & knee if sole of foot touched (9 weeks)
    Occurs in 8 to 9 weeks
    - Sucking the thumb
    -The young fetus now sighs, stretches, moves the head, opens the mouth, and moves the tongue

  • Eyes roll down refexively (10 weeks)

    Occurs 9 to 10 weeks

  • The face now makes complex expressions (11 weeks)

    Occurs 10 to 11 weeks

  • Hands touch the mouth up to 50 times per hour (12 weeks)

    Occurs 11 to 12 weeks
    - All facial muscles in final positions

  • Girls move their jaw more than boys do (14 weeks)

    Occurs 3 to 4 months

  • Quickening (16 weeks)

    Quickening is the first time a woman feels the fetus moving, generally between 16 and 20 weeks after fertilization for a first-time mother or between 14 and 18 weeks thereafter.

  • Esophagus: lower esophagus muscles funtional (32 weeks)

  • Firm grip (35 weeks)

  • Baby born after 9 months of pregnancy

    Baby born after 9 months of pregnancy