Friday, September 7, 2018

Muscles of Tongue

The human tongue is made up of two types of muscles; extrinsic and intrinsic. Attached to the hyoid bone, the mandible, and the styloid process, the extrinsic muscles are those located at the base of this organ and are involved in deglutition (the act of swallowing). On the other hand, the intrinsic muscles constitute the body of the tongue and are involved in speech.

Extrinsic muscles

1) Geniohyoglossus: it is anchored to the symphysis of mandible. Then it fans out as it runs up to insert at the base of tongue and at the hyoid bone. It depresses and protrudes the tongue.

2) Hyoglossus: it originates from the hyoid bone and goes up to insert between the intrinsic muscles of tongue. It draws back and down the tongue.

3) Stylohyoid: it is attached to the styloid process and insert into the sides of tongue. It pulls back this organ.

4) Chondroglossus: it originates from lesser horn of hyoid bone, inserting into the hyoglossus fibers.

Intrinsic muscles

1) Superior longitudinal

2) Transverse

3) Vertical

4) Inferior longitudinal

Monday, September 3, 2018

Blood supply to the nasal cavity

To start with, all the oxygen-rich blood flowing into the nasal cavity comes from two main arteries; the external carotid, via the maxillary, and the internal carotid, via the ophthalmic. From these main blood vessels, four main arteries carry the blood into the nasal cavity: 1) the sphenopalatine, which arises from the maxillary artery, giving off the posterior lateral nasal branches that supply the lateral wall of the nasal cavity and anastomose with branches coming off the anterior ethmoidal artery, and the posterior septal branch; 2) the posterior ethmoidal, which arises from the ophthalmic artery, supplies the upper part of this cavity; 3) the anterior ethmoidal is also a smaller branch of the ophthalmic, running forward and downward to supply the nose, and the middle and inferior concha; 4) the greater palatine artery, which also originates from the maxillary artery in the pterygopalatine fossa to provide the floor of the nasal cavity with oxygenated blood.

Summary

The sphenopalatine and the greater palatine arteries originate from the maxillary and supply the lateral wall and the floor of the nasal cavity respectively. While the posterior ethmoidal and anterior ethmoidal come off the ophthalmic artery and supply the nose, the middle and inferior concha.

Friday, August 31, 2018

Sphenopalatine artery

The sphenopalatine artery is an oxygen-rich blood vessel which originates from the maxillary artery in the pterygopalatine fossa at a point where the maxillary forks in two terminal branches, the other being the greater palatine artery. But where does the maxillary artery come from? From the external carotid. Being the main blood supplier to the nasal cavity, the sphenopalatine artery gives off several smaller branches once it enters this region, with the posterior septal branch and the posterior lateral nasal branches being the most important.

Down below, a diagram of the sphenopalatine and other arteries of the nasal cavities
 

Thursday, August 30, 2018

Verticalis linguae

The verticalis linguae is an intrinsic muscle of the human tongue, which is located only at the borders of the third foremost part of this organ of speech. Its fibers arise from the sheet-like, submucosal, connective tissue (aponeurosis) of the dorsum of tongue and extend to down vertically to insert in the connective tissue located in the ventral regions of tongue.


Innervation

The verticalis linguae receives a fine motor branch from the hypoglossal nerve (CN XII), and sensory fibers from the lingual nerve, which arises from the mandibular nerve.

Blood supply

It gets oxygen-rich blood from the deep lingual artery.

Function

It flattens out the forepart of the tongue.

 

Median septum of tongue

The median sagittal septum is the flat and middle connective tissue which extends lengthwise from the root of tongue to its tip, dividing this organ into two longitudinal halves. Intrinsic muscles of the tongue, like the transverse and superior longitudinal ones are attached to it on each side, which means that every muscle that constitutes this organ is a paired one.

Wednesday, August 29, 2018

Intrinsic muscles of tongue

The top movable part of the human tongue is made up of five intrinsic muscles, which give it the very well-known elongated, muscular consistency. From top to bottom, they are the superior longitudinal, the transverse (transversus linguae), the vertical, and the inferior longitudinal muscle. Along with the extrinsic muscles of the base of the tongue, the intrinsic ones play a key role in the articulation of human speech, especially in the pronunciation of consonant letters.

Nerve supply

They are innervated by a branch of the glossopharyngeal nerve (CN IX), which transmits sensory information, and by the hypoglossal nerve (CN XII), which supplies with motor innervation.

Blood supply

The tongue intrinsic muscles are supplied by the deep lingual artery, which branches off the lingual artery, and this, from the external carotid artery.

Function

The superior longitudinal muscle retracts the tongue and curls up its tip, while the transverse curls up the sides of this organ. The inferior longitudinal collaborates with the superior longitudinal muscle to draw back the tongue, making it thick. The vertical muscle flattens this organ sideways.

Tuesday, August 28, 2018

Transversus linguae

The transversus linguae, commonly known as the transverse muscle of the tongue, lies beneath the superior lingualis (superior longitudinal) and above the inferior lingualis, thus being an intrinsic muscle of this organ. The fibers that make up this muscle are attached to the median septum, which divides the tongue into two longitudinal halves; then they go outward to insert themselves into the submucous fibrous layer at the sides. Extrinsic fibers coming up from the palatoglossus and superior constrictor of the pharynx muscles intermingle with the transversus linguae. It is innervated by the hypoglossal nerve. Function: it curls up the sides of the tongue.