A mental spine is a small projection of bone on the posterior aspect of the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

in the midline. There are usually four mental spines: two superior and two inferior. Collectively they are also known as the ''genial tubercle'',"Genial tubercle." The American Heritage Stedman's Medical Dictionary. Houghton Mifflin Company, 2002. Accessed: 22 Oct. 2007. ''genial apophysis'' and the Latin name ''spinae mentalis''. The inferior mental spines are the points of origin of the

geniohyoid muscle The geniohyoid muscle is a narrow muscle situated superior to the medial border of the mylohyoid muscle. It is named for its passage from the chin ("genio-" is a standard prefix for "chin") to the hyoid bone. Structure It arises from the infe ...

,"Genial tubercle." Mosby's Dental Dictionary. Elsevier, Inc., 2004. Accessed: 22 Oct. 2007. one of the suprahyoid muscles, and the superior mental spines are the origin of the

genioglossus muscle The genioglossus is one of the paired extrinsic muscles of the tongue. The genioglossus is the major muscle responsible for protruding (or sticking out) the tongue. Structure Genioglossus is the fan-shaped extrinsic tongue muscle that forms the ma ...

, one of the muscles of the

tongue The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...

. Mental spines are important landmarks in clinical practice.

Structure

Mental spines are found on the posterior aspect of the

(lower

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

bone) in the midline. They usually surround spinous mental foramina in the midline.

Variation

Mental spines may be found in over 98% of people. Over 70% of mandibles may only have 2 superior spines, while around 20% may have 4 spines.

Function

The inferior mental spines are the points of origin of the

, one of the suprahyoid muscles, and the superior mental spines are the origin of the

, one of the muscles of the

Clinical significance

Mental spines are important landmarks for maxillofacial

surgeons In modern medicine, a surgeon is a medical professional who performs surgery. Although there are different traditions in different times and places, a modern surgeon usually is also a licensed physician or received the same medical training as ...

dentists A dentist, also known as a dental surgeon, is a health care professional who specializes in dentistry (the diagnosis, prevention, management, and treatment of diseases and conditions of the oral cavity and other aspects of the craniofacial comp ...

, and

radiologists Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiatio ...

Etymology

The adjective '' mental'' in this instance is used in its "

chin The chin is the forward pointed part of the anterior mandible (List_of_human_anatomical_regions#Regions, mental region) below the lower lip. A fully developed human skull has a chin of between 0.7 cm and 1.1 cm. Evolution The presence of a we ...

-related" sense (from Latin ''mentum'') rather than its more common "

mind The mind is the set of faculties responsible for all mental phenomena. Often the term is also identified with the phenomena themselves. These faculties include thought, imagination, memory, will, and sensation. They are responsible for various m ...

-related" sense (from Latin ''mens''). Collectively they are also known as the ''genial tubercle'', ''genial apophysis'' and the Latin name ''spinae mentalis''.

Additional images

File:Unterkiefer dorsal.png, The posterior aspect of the mandible, showing mental spines.

References

{{Authority control Bones of the head and neck