Tensor veli palatini muscle
Tensor veli palatini is a slender, triangular muscle situated in the pterygoid fossa of skull. It belongs in the group of the soft palate and pharyngeal muscles, along with the levator veli palatini, palatoglossus, palatopharyngeus, musculus uvulae, salpingopharyngeus, stylopharyngeus and superior pharyngeal constrictor, middle pharyngeal constrictor and inferior pharyngeal constrictor.
The name of the muscle says a lot about its attachments and function. The word tensor comes from the Latin verb tendere meaning “to stretch”. The words veli palatini are Latin for “veil or curtain of the palate”. This etiology explains the function of this muscle which is the tension of the palatine aponeurosis of the soft palate and opening the pharyngeal opening of the auditory tube during swallowing or yawning.
This article will discuss the anatomy and functions of the medial pterygoid muscle.
|Origin||Scaphoid fossa of pterygoid process, spine of sphenoid bone, sembranous wall of auditory tube|
|Function||Tenses palatine aponeurosis; Opens pharyngeal opening of auditory tube (during swallowing)|
|Innervation||Nerve to medial pterygoid (of mandibular nerve (CN V3))|
|Blood supply||Greater palatine artery (maxillary artery), ascending palatine artery (facial artery)|
Origin and insertion
Tensor veli palatini has several sites of origin. The anterior attachment stems from the scaphoid fossa of pterygoid process of sphenoid bone. The posterior attachment originates from the medial aspect of the spine of sphenoid bone. In between these two origin sites, the muscle attaches to the anterolateral membranous part and the lateral lamina of the cartilaginous part of auditory tube. These fibers are sometimes referred to as dilator tubae.
The muscle fibers converge inferiorly onto a tendon that courses around the medial side of the pterygoid hamulus of sphenoid bone. The pterygoid hamulus acts as a pulley or trochlea for the tensor veli palatini muscle. It is important in creating the contractile force of the muscle, as well as horizontally redirecting the pull of the muscle. After it passes the pterygoid hamulus, tensor veli palatini tendon inserts into the palatine aponeurosis, which comprises the anterior third of the soft palate.
Together with the medial pterygoid muscle, tensor veli palatini is situated in the pterygoid fossa, between the lateral and medial pterygoid plates. Near its origin point, the lateral surface of the tensor veli palatini is related to the proximal part of the medial pterygoid muscle. On its way to the soft palate, tensor veli palatini pierces the buccinator muscle near its attachment point to on a tendinous band called pterygomandibular raphe.
Tensor veli palatini has several important relations to neurovascular structures of the head. In the infratemporal fossa, the lateral surface of tensor veli palatini is related to the middle meningeal and accessory meningeal arteries, as well as the mandibular, auriculotemporal and chorda tympani nerves. In addition, tensor veli palatini separates the otic ganglion from the cartilaginous part of auditory tube.
Like other structures derived from the first pharyngeal arch, tensor veli palatini is innervated by the mandibular division of trigeminal nerve (CN V), that gives off the nerve to medial pterygoid. Thereby, tensor veli palatini is the only muscle of the soft palate that is not innervated by the pharyngeal plexus, formed by the vagus nerve (CN X).
Bilateral contraction of the tensor veli palatini tenses the anterior third of the soft palate and depresses it. Unilateral contraction of the muscle pulls the soft palate to one side. In addition, tensor veli palatini opens the auditory tube during swallowing or yawning and thereby equalizes the pressure (“pops the eardrums”) between the middle ear and the nasopharynx.