The nasopharynx is the uppermost part of the pharynx

Pharynx

The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...

. It extends from the base of the skull to the upper surface of the soft palate

Soft palate

The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone....

; it differs from the oral

Oropharynx

The Oropharynx reaches from the Uvula to the level of the hyoid bone.It opens anteriorly, through the isthmus faucium, into the mouth, while in its lateral wall, between the two palatine arches, is the palatine tonsil....

 and laryngeal parts of the pharynx in that its cavity always remains patent (open).

Lateral

On its lateral wall is the pharyngeal ostium of the auditory tube, somewhat triangular in shape, and bounded behind by a firm prominence, the torus tubarius

Torus tubarius

The base of the cartilaginous portion of the Eustachian tube lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius, the torus of the auditory tube, or cushion, behind the pharyngeal orifice of the tube...

 or cushion, caused by the medial end of the cartilage of the tube which elevates the mucous membrane

Mucous membrane

The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

.

Two folds arise from the cartilaginous opening:

• vertical fold of mucous membrane, the salpingopharyngeal fold
  Salpingopharyngeal fold
  A vertical fold of mucous membrane, the salpingopharyngeal fold, stretches from the lower part of the torus tubarius; it contains the Salpingopharyngeus muscle....
  
  , stretches from the lower part of the torus; it contains the Salpingopharyngeus muscle
  Salpingopharyngeus muscle
  The salpingopharyngeus muscle arises from the inferior part of the cartilage of the pharyngotympanic tube in the nasal cavity; it passes downward and blends with the posterior fasciculus of the palatopharyngeus muscle....
  
  .
• second and smaller fold, the salpingopalatine fold
  Salpingopalatine fold
  In the lateral wall of the nasopharynx, the salpingopalatine fold, smaller than the salpingopharyngeal fold, stretches from the upper part of the torus tubarius to the palate anteroinferiorly; it contains the levator veli palatini muscle...
  
  , stretches from the upper part of the torus to the palate; it contains the levator veli palatini
  Levator veli palatini
  The levator veli palatini is the elevator muscle of the soft palate in the human body. During swallowing, it contracts, elevating the soft palate to help prevent food from entering the nasopharynx...
  
   muscle. The tensor veli palatini is lateral to the levator and does not contribute the fold, since the origin is deep to the cartilaginous opening.

Behind the ostium of the auditory tube is a deep recess, the pharyngeal recess

Pharyngeal recess

Behind the ostium of the eustacian tube is a deep recess, the pharyngeal recess .-Clinical significance:At the base of this recess is the retropharyngeal lymph node This is clinically significant in that it may be involved in certain head and neck cancers, notably Nasopharyngeal cancer....

 (fossa of Rosenmüller).

Posterior

On the posterior wall is a prominence, best marked in childhood, produced by a mass of lymphoid tissue, which is known as the pharyngeal tonsil.

Above the pharyngeal tonsil, in the middle line, an irregular flask-shaped depression of the mucous membrane sometimes extends up as far as the basilar process of the occipital bone

Occipital bone

The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...

; it is known as the pharyngeal bursa.