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Topic

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Fetal spinal cord

The fetal spinal cord is the developing continuation of the central nervous system, extending caudally from the brainstem through the vertebral canal. It originates from the neural tube and undergoes progressive differentiation, elongation, and maturation throughout gestation.

In early gestation, the spinal cord extends the entire length of the vertebral canal; by mid-to-late gestation, it ascends relatively so that the conus medullaris terminates around the level of L2–L3 at birth. This developmental ascent is an important imaging marker of normal maturation.

Synonyms

  • Prenatal spinal cord

  • Fetal cord

  • Intrauterine spinal cord

Structure and Development

  • Derived from the caudal neural tube during neurulation

  • Central canal: lined by ependymal cells, filled with cerebrospinal fluid

  • Gray matter: develops in a butterfly configuration centrally

  • White matter: surrounds gray matter; unmyelinated during fetal life, with progressive myelination beginning late gestation and after birth

  • Meninges: spinal cord enclosed by pia, arachnoid, and dura mater

  • Conus medullaris: initially low in canal, ascends to near L2–L3 level at term

Relations

  • Enclosed within the vertebral canal of developing fetal spine

  • Surrounded by cerebrospinal fluid in the subarachnoid space

  • Continuous cranially with medulla oblongata, caudally with filum terminale

  • Closely related to vertebral bodies, posterior arches, and paraspinal soft tissues

Function

  • Acts as the main pathway for motor and sensory conduction between brain and body

  • Generates primitive reflexes and fetal movement patterns

  • Plays a role in early autonomic regulation (bladder, bowel control not functional until later)

  • Critical for development of fetal posture and muscle tone

Clinical Significance

  • Neural tube defects (spina bifida, myelomeningocele): Failure of closure or herniation of spinal cord/membranes

  • Spinal dysraphism: Occult forms include tethered cord, lipomyelomeningocele

  • Scoliosis/vertebral anomalies: May be associated with abnormal cord position or structure

  • Cord ischemia or hemorrhage: Rare but detectable on prenatal MRI

  • Imaging relevance: MRI evaluates spinal canal closure, cord position, termination level, and lesions not visible on ultrasound

MRI Appearance

T2 HASTE (T2 GRE):

  • Spinal cord: hypointense to intermediate signal relative to surrounding CSF

  • CSF: very bright hyperintense signal, sharply delineating the cord

  • Central canal: may appear as a fine linear hyperintense line

  • Unmyelinated white matter: contributes to relatively uniform cord signal without strong differentiation of gray/white matter

T1 GRE:

  • Spinal cord: low signal intensity compared to vertebral bodies

  • Gray–white matter distinction: not appreciable in fetal life due to lack of myelin

  • CSF: dark/very low signal intensity

  • Hemorrhage or fat-containing lesions (e.g., lipomas): hyperintense foci if present

MRI image

Fetal spinal cord MRI coronal anatomy image-img-00000-00000

MRI image

Fetal spinal cord MRI coronal anatomy image-img-00000-00000_00001