Post cranial fossa seminar power point presentation

PPT regarding posterior cranial fossa for anatomy first year students

1. Posterior cranial fossa Aarush Manoj Roll No:3

2. The posterior cranial fossa is formed by 3 main bones- Sphenoid, temporal and occipital. Its boundaries are as follows- Anteromedial: Dorsum Sellae of the sphenoid bone Anterolateral: Superior border of the Petrous temporal bone Posterior: Internal surface of the squamous part of the occipital bone Floor: Sloping area behind the dorsum sellae; Foramen Magnum in the middle and the squamous occipital behind The posterior cranial fossa mainly contains the cerebellum, pons and medulla oblongata.

3. The most prominent feature in the floor of the posterior cranial fossa is the FORAMEN MAGNUM. Foramen Magnum if the largest Foramen in the body The medulla oblongata exits the cranial cavity through the Foramen magnum to continue as the spinal cord.

4. Clinical Aspect The cerebellum is full contained within the posterior fossa. When the lower part of the cerebellum, tonsils descends abnormally through the Foramen magnum, this may cause compression of the medulla at the level of the Foramen magnum causing a condition known as tonsillar herniation or Chiari malformation

5. The Clivus is a sloping surface that extends from posterior surface of body of sphenoid (where the location of sella turcica is seen) Another Foramen that is is seen in the posterior cranial fossa is the jugular Foramen.

6. The jugular Foramen is a large opening located between the temporal and occipital bones @ the petro-occipital fissure. The lower border of the jugular Foramen is smooth and is formed by the lateral part of the occipital bone, while the upper border is Sharp and irregular , and is formed by the petrous part of the temporal bone . The squamous part of the occipital bone consists of following features:- Internal occipital protuberance Internal occipital crest Transverse sulcus which lodges the transverse sinus

7. The jugular Foramen itself is divided into anterior, middle and posterior parts. Anterior- Inferior Petrosal Sinus ( IPS ) Middle- 3 cranial nerves (IX, X and XI) and the meningeal branch of ascending pharyngeal artery ( 9, 10, 11 MAP ) Posterior- Jugular vein, occipital artery and a few emissary veins ( JOE )

8. The jugular tubercle is a rounded prominence seen just medial to the jugular Foramen. The hypoglossal canal lies just inferior to the jugular tubercle, it transmits the hypoglossal nerve and its recurrent branch The posterior part of the petrous temporal bone has- Internal acoustic meatus which is present in the anterior part of the jugular Foramen. Orifice of the Aqueduct of the vestibule Subarcuate fossa

9. Sinuses related to the posterior cranial fossa Right and the Left transverse sinus Superior Petrosal Sinus Inferior Petrosal Sinus Occipital Sinus Sigmoid sinus