The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a

medial pterygoid plate The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a me ...

and a

lateral pterygoid plate The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a me ...

, the latter of which serve as the origins of the medial and

lateral pterygoid muscle The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of mastication. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid ne ...

s. The medial pterygoid, along with the

masseter In human anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it ...

allows the jaw to move in a vertical direction as it contracts and relaxes. The lateral pterygoid allows the jaw to move in a horizontal direction during mastication (chewing). Fracture of either plate are used in clinical medicine to distinguish the Le Fort fracture classification for high impact injuries to the sphenoid and

maxillary bone The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

s. The superior portion of the pterygoid processes are fused anteriorly; a vertical groove, the

pterygopalatine fossa In human anatomy, the pterygopalatine fossa (sphenopalatine fossa) is a fossa in the skull. A human skull contains two pterygopalatine fossae—one on the left side, and another on the right side. Each fossa is a cone-shaped paired depression deep ...

, descends on the front of the line of fusion. The plates are separated below by an angular cleft, the pterygoid notch, the margins of which are rough for articulation with the pyramidal process of the palatine bone. The two plates diverge behind and enclose between them a V-shaped fossa, the pterygoid fossa, which contains the

medial pterygoid muscle The medial pterygoid muscle (or internal pterygoid muscle), is a thick, quadrilateral muscle of the face. It is supplied by the mandibular branch of the trigeminal nerve (V). It is important in mastication (chewing). Structure The medial ptery ...

and the

tensor veli palatini The tensor veli palatini muscle (tensor palati or tensor muscle of the velum palatinum) is a broad, thin, ribbon-like muscle in the head that tenses the soft palate. Structure The tensor veli palatini is found anterior-lateral to the levator ve ...

. Above this fossa is a small, oval, shallow depression, the scaphoid fossa, which gives origin to the tensor veli palatini. The anterior surface of the pterygoid process is broad and triangular near its root, where it forms the posterior wall of the pterygopalatine fossa and presents the anterior orifice of the

pterygoid canal The pterygoid canal (also vidian canal) is a passage in the sphenoid bone of the skull leading from just anterior to the foramen lacerum in the middle cranial fossa to the pterygopalatine fossa. Structure The pterygoid canal runs through the me ...

. In many mammals it remains as a separate bone called the

pterygoid bone The pterygoid is a paired bone forming part of the palate of many vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fis ...

. Its name is Greek for "resembling a fin or wing", from its shape.

Medial pterygoid plate

The medial pterygoid plate (or medial pterygoid lamina) of the sphenoid bone is a horse-shoe shaped

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that produce a specific se ...

that arises from its underside. It is narrower and longer than the

and curves lateralward at its lower extremity into a hook-like process, the

pterygoid hamulus The pterygoid hamulus is a hook-like process at the lower extremity of the medial pterygoid plate of the sphenoid bone of the skull. It is the superior origin of the pterygomandibular raphe, and the levator veli palatini muscle. Structure The ...

, around which the tendon of the

glides. The lateral surface of this plate forms part of the pterygoid fossa, the medial surface constitutes the lateral boundary of the

choana The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat in tetrapods, including humans and other mammals (as well as crocodilia ...

or posterior aperture of the corresponding nasal cavity. Superiorly the medial plate is prolonged on to the under surface of the body as a thin lamina, named the vaginal process, which articulates in front with the

sphenoidal process The sphenoidal process of the palatine bone In anatomy, the palatine bones () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard ...

of the palatine and behind this with the ''ala'' (wing) of the

vomer The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right max ...

. The angular prominence between the posterior margin of the vaginal process and the medial border of the scaphoid fossa is named the

pterygoid tubercle Pterygoid, from the Greek for 'winglike', may refer to: * Pterygoid bone, a bone of the palate of many vertebrates * Pterygoid processes of the sphenoid bone ** Lateral pterygoid plate ** Medial pterygoid plate * Lateral pterygoid muscle * Medi ...

, and immediately above this is the posterior opening of the

. On the under surface of the vaginal process is a furrow, which is converted into a canal by the sphenoidal process of the palatine bone, for the transmission of the pharyngeal branch of the

internal maxillary artery The maxillary artery supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible. Structure The maxillary artery, the larger of the two terminal branches of the external carotid artery, ...

and the pharyngeal nerve from the sphenopalatine ganglion. The

pharyngeal aponeurosis As it descends it diminishes in thickness, and is gradually lost. It is strengthened posteriorly by a strong fibrous band, which is attached above to the pharyngeal spine on the under surface of the basilar portion of the occipital bone, and pas ...

is attached to the entire length of the posterior edge of the medial plate, and the

constrictor pharyngis superior The superior pharyngeal constrictor muscle is a muscle in the pharynx. It is the highest located muscle of the three pharyngeal constrictors. The muscle is a quadrilateral muscle, thinner and paler than the inferior pharyngeal constrictor muscle ...

takes origin from its lower third. Projecting backward from near the middle of the posterior edge of this plate is an angular process, the processus tubarius, which supports the pharyngeal end of the Eustachian tube. The anterior margin of the plate articulates with the posterior border of the vertical part of the palatine bone. In many animals it is a separate bone called the

Lateral pterygoid plate

The lateral

pterygoid Pterygoid, from the Greek for 'winglike', may refer to: * Pterygoid bone, a bone of the palate of many vertebrates * Pterygoid processes of the sphenoid bone ** Lateral pterygoid plate ** Medial pterygoid plate * Lateral pterygoid muscle * Medi ...

plate of the sphenoid (or lateral lamina of pterygoid process) is broad, thin, and everted and forms the lateral part of a horseshoe like process that extends from the inferior aspect of the sphenoid bone, and serves as the origin of the lateral pterygoid muscle, which functions in allowing the mandible to move in a lateral and medial direction, or from side-to-side. Its lateral surface forms part of the medial wall of the infratemporal fossa, and gives attachment to the

; its medial surface forms part of the pterygoid fossa, and gives attachment to the

. Posterior edge is sharp, and often has sharp projection - pterygospinous process (Civinini process).

References

External links

* * * {{Authority control Bones of the head and neck