-
Two Weeks, 6 days
Septum Transversum (primitive diaphragm) -
Four Weeks
Diaphragm primordia -
Four Weeks, 4 days
Muscular plates between upper and lower limbs bud -
Five Weeks, 2 days
Extraocular premuscles masses receive cranial nerve fibers (oculomotor, trochlear, abducens) Gluteal mesoderm Infrahyoid premuscle masses Limb mesoderm Sternocleidomastoid-trapezius premuscle mass with spinal accessory nerve Thigh and thigh mesoderm Tongue premuscle mass -
Five Weeks, 6 days
Primordia of orbital muscles -
Six Weeks, 2 days
Strapedius muscle -
Six Weeks, 5 days
Deltoid Muscle Esophagus: Muscularis layer adjacent to esophageal plexus External and internal abdominal oblique muscles Gluteal muscle group Iliopsoas muscles Infrahyoid muscles Internal intercostal muscles Levator scapulae muscle Limb extensor muscles located dorsally Limb flexor muscles located ventrally Longus cervicis and semispinalis cervicis muscles Midgut: Muscularis Muscle tissue forming around phrenic nerve within septum transversum portion of diaphragm -
Six Weeks, 5 days
Pectoralis major muscles
Pharyngeal constrictor muscle
Platysma muscle
Premuscle mass of the muscles of mastication innervated by mandibular nerve
Quadratus lumborum muscle
Rectus abdominis muscle
Rectus capitus posterior and semispinalis capitis muscles
Rhomboid and scalene muscles
Serratus anterior muscles
Spenius and longissimus muscles
Sternocleidomastoid and trapezius muscles distinct and innervated by separate branches of spinal accessory nerve
Thenar and hypothenar eminences -
Week 6, 5 days
Tongue forms from swellings in floor of pharynx
Tongue: Extrinsic muscles identifiable
Tongue: Intrinsic muscles identifiable
Transversospinal and erector spinae muscle groups
Upper limb flexors innervated by musculocutaneous, median, and ulnar nerves -
Week 7, 1 day
Diaphragm: Central tendon -
Week 8
Anterior digastric muscles
Depressor anguli oris muscle
Esophagus: Longitudinal muscles
Gluteus medius and gluteus minimus muscles
Iliacus muscles
Mylohyoid and infrahyoid muscles
Obliquis superior capitus muscle
Obturator externus, gluteus maximus, and hamstring muscles
Obturator internus muscles
Orbicularis oculi muscles
Posterior belly of digastric muscle
Psoas tendon
Rectus femoris muscle
Rectus sheath with anterior and posterior lamina
Temporal and lateral pterygoid muscles
Zygomaticus -
Week 12
All facial muscles in final positions -
Week 32
Esophagus: Lower esophagus muscles functional