QS Study

The fourth ventricle is a median cavity in the hindbrain. It is one of the four connected fluid-filled cavities within the human brain. It is located within the pons or in the upper part of the medulla oblongata. It is divisible into a right and left half by the median sulcus and a superior and inferior triangle by the striae medullares.

It is tent shaped cavity filled with cerebrospinal fluid (CSF).

Boundaries – On every side, the 4th ventricle is limited, inferolateral by the inferior cerebellar peduncle, supplemented by gracile and cuneate tubercles and superolaterally by the superior cerebellar peduncle. It lies within the brainstem, at the junction between the pons and medulla oblongata.

Lateral boundaries: They are formed on each side by the superior cerebellar peduncle, the inferior cerebellar peduncle and the cuneate and gracile tubercles.

  1. lnfero-laterally – By the gracile tubercle, the fasciculus cuneatus, the cuneate tubercle and the inferior cerebellar peduncle
  2. Supero laterally – By the superior cerebellar peduncle.

Boundary of 4th Ventricle 1

Fig – Boundaries of the fourth ventricle

Roof – The roof of the fourth ventricle has presented a ‘tent-like’ apex at the intersection of it’s superior and inferior parts. This apex, also known as the fastigium, extends into the white core of the cerebellum.

Formed by:

  1. The superior peduncles.
  2. The superior medullary velum.
  3. The inferior medullary velum.
  4. The tea choroidea of the 4th ventricle.
  5. The taeniae with the Obex.

Floor – Formed by:

(a) The posterior surface of the pons. Its rhomboid in shape (diamond shaped) and as a result of its shape, the floor of the 4th ventricle is usually referred to as rhomboid fossa.

(b) The posterior surface of the upper part of the medulla. The upper triangular part is jumping on every side by the superior cerebellar peduncle, while the lower triangular part jumps on every side by gracile and cuneate tubercles and the inferior cerebellar peduncle.

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