The nasal septum () separates the left and right airways of the

nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nas ...

, dividing the two nostrils. It is depressed by the depressor septi nasi muscle.

Structure

The fleshy external end of the nasal septum is called the columella or columella nasi, and is made up of cartilage and soft tissue. The nasal septum contains bone and hyaline cartilage. It is normally about 2 mm thick. The nasal septum is composed of four structures: * Maxillary bone (the crest) * Perpendicular plate of ethmoid bone * Septal nasal cartilage (ie, quandrangular cartilage) * Vomer bone The lowest part of the septum is a narrow strip of bone that projects from the maxilla and the palatine bones, and is the length of the septum. This strip of bone is called the maxillary crest; it articulates in front with the septal nasal cartilage, and at the back with the vomer. The maxillary crest is described in the anatomy of the nasal septum as having a maxillary component and a palatine component.

Development

At an early period, the septum of the nose consists of a plate of cartilage, known as the ''ethmovomerine cartilage''. The posterosuperior part of this cartilage is ossified to form the perpendicular plate of the

ethmoid The ethmoid bone (; from ) is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbit (anatomy), orbits. The cubical (cube-shaped) bone is lightweight due to a sp ...

; its anteroinferior portion persists as the septal cartilage, while the vomer is ossified in the membrane covering its posteroinferior part. Two ossification centers, one on either side of the middle line, appear about the eighth week of fetal development in this part of the membrane, and hence the vomer consists primarily of two lamellae. About the third month, these unite below, and thus a deep groove is formed in which the cartilage is lodged. As growth proceeds, the union of the lamellae extends upward and forward, and at the same time, the intervening plate of cartilage undergoes absorption. By the onset of

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the lamellae are almost completely united to form a median plate, but evidence of the bilaminar origin of the bone is seen in the everted alae of its upper border and in the groove on its anterior margin.

Clinical significance

The nasal septum can depart from the centre line of the nose in a condition that is known as a

deviated septum Nasal septum deviation is a physical disorder of the nose, involving a displacement of the nasal septum. Some displacement is common, affecting 80% of people, mostly without their knowledge. Signs and symptoms The nasal septum is the bone and ...

caused by trauma. However, it is normal to have a slight deviation to one side. The septum generally stays in the midline until about the age of seven, at which point it will frequently deviate to the right. An operation to straighten the nasal septum is known as a septoplasty. A perforated nasal septum can be caused by an

ulcer An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughin ...

, trauma due to an inserted object, long-term exposure to welding fumes, or

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use. There is a procedure that can be of help to those suffering from the perforated septum. A

silicone In Organosilicon chemistry, organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (, where R = Organyl group, organic group). They are typically colorless oils or elastomer, rubber ...

button can be inserted in the hole to close the open sore. The nasal septum can be affected by both benign tumors such as fibromas, and hemangiomas, and malignant tumors such as squamous cell carcinoma.

Cosmetic procedures

A nasal septum piercing is usually carried out through the fleshy columella close to the end of the nasal septum.

References

External links

Anatomy figure: 33:02-01
at Human Anatomy Online, SUNY Downstate Medical Center – "Diagram of the skeleton of the medial (septal) nasal wall"
Diagram at evmsent.org

at The Anatomy Lesson by Wesley Norman (Georgetown University) {{Authority control Nose Otorhinolaryngology