Spinal Cord Anatomy

lecture 3

Abbas A. A. Shawka

Medical student

2nd grade

Subjects

• Clinical anatomy of spinal cord

- To correlate the clinical points with neuroanatomy …

Tracts Review !!

Blood supply review

Anterior spinal artery - Lateral grey and white column ( both sides )- Anterior grey and white column ( both sides )

Posterior spinal artery - Posterior grey and white column ( of its own side )

This is important with respect to the latera corticospinal and anterolateral tracts whose fibres ar laminated, with sacral fibres lying nearest to the surface. Interference with the anterior spinal supply may eliminate the function of these tracts, except for the sacral fibres which remain supplied by the pial vessels (‘sacralsparing’).

Spinal cord injuries

• Distinguish bwtween the features of the fallowing aspects is of HIGHLY IMPORTANT in clinical examination !!

1. Complete transection

2. Hemisection (Brown-Se´quard syndrome)

3. Central cord syndrome

4. Anterior spinal artery syndrome

Complete transection • loss of movement and all sensation

below the level of the injured segment.

• The paralysis, which is at first flaccid, becomes spastic after a few weeks, and bladder and rectal sphincter control is lost, although reflex emptying will occur provided the sacral part of the cord is intact.

• In lesions above T10 segment there is no effective cough because of abdominal and lower intercostal paralysis. In suspected transection,

• examination for sensation in the perianal skin will establish whether or not there is conduction throughout the length of the cord.

• Perianal pinprick will also establish whether the anal reflex is intact

Complete transection at T11

hemisection (Brown-Se´quard syndrome)

1. there is paralysis and loss of touch and kinaesthetic sense below the level of the lesion on the same side (lateral corticospinal tract and posterior column interruption).

2. loss of pain and temperature sensation on the opposite side (because of interruption of the crossed anterolateral tract).

hemisectionat T11

Central cord syndrome• commonly due to a crush injury

(without transection) following a sudden hyperextension of the cervical spine,

• there is flaccid (lower motor neuron) paralysis and loss of pain and temperature sensation in the upper limbs (due to anterior horn damage and interruption of the more deeply placed cervical fibres of the anterolateral tracts).

• The lower limbs may show spasticity if the lumbar fibres of the lateral corticospinal tract are involved (the sacral fibres are more superficial).

anterior spinal artery syndrome • the posterior white columns (and

therefore touch sensation) remain intact.

• most of the rest of the cord below the level of the lesion is affected with loss of all motor and sensory functions

• except perhaps for the ‘sacral sparing’.

• The anastomotic connections on the surface of the cord (deep to the pia mater) between the anterior and posterior spinal and radicular vessels provide very small pial arteries that are capable of supplying peripheral areas of the cord. This is important with respect to the lateral corticospinal and anterolateral tracts whose fibres are laminated, with sacral fibres lying nearest to the surface. Interference with the anterior spinal supply may eliminate the function of these tracts, except for the sacral fibreswhich remain supplied by the pial vessels (‘sacral sparing’).

Upper & lower motor neuron lesions

LMNL UMNL

Faccidparalysis

Spastic paralysis

Absent reflexes

Increasedreflexes

Clonus &Extensor plantar

response

Pyramidal lesions • it should be noted that a pure pyramidal lesion (rare, but possible from a lesion

confined to the pyramid of the medulla) produces a flaccid paralysis.

• The reason why pyramidal lesions induce spasticity is that there is concomitant involvement of extrapyramidal pathways as well; the responsiveness of the motor neurons is altered, possibly because they have been released from the inhibition normally exerted by supraspinal levels.

•

• Since most of the pyramidal tract is intermingled with extrapyramidal fibres, most pyramidal lesions present as spasticity.

• In the brainstem and spinal cord the motor tracts of each side are quite close together so that a single lesion may easily affect both sides, but in the hemispheres the tracts of the two sides are much farther apart and so unlikely to be damaged together.

• A single lesion that does affect both sides together is a parasagittal meningioma pressing on the leg areas of both hemispheres.

Thank you