Levator labii superioris
Encyclopedia
The levator labii superioris (or quadratus labii superioris) is a muscle
of the human body
used in facial expression
. It is a broad sheet, the origin of which extends from the side of the nose
to the zygomatic bone
.
Its medial fibers form the angular head, which arises by a pointed extremity from the upper part of the frontal process
of the maxilla
and passing obliquely downward and lateralward divides into two slips.
One of these is inserted into the greater alar cartilage
and skin of the nose; the other is prolonged into the lateral part of the upper lip
, blending with the infraorbital head and with the Orbicularis oris.
The intermediate portion or infraorbital head arises from the lower margin of the orbit
immediately above the infraorbital foramen, some of its fibers being attached to the maxilla
, others to the zygomatic bone
.
Its fibers converge, to be inserted into the muscular substance of the upper lip between the angular head and the Caninus.
The lateral fibers, forming the zygomatic head, arise from the malar surface of the zygomatic bone
immediately behind the zygomaticomaxillary suture and pass downward and medialward to the upper lip.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
of the human body
Human body
The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...
used in facial expression
Facial expression
A facial expression one or more motions or positions of the muscles in the skin. These movements convey the emotional state of the individual to observers. Facial expressions are a form of nonverbal communication. They are a primary means of conveying social information among humans, but also occur...
. It is a broad sheet, the origin of which extends from the side of the nose
Human nose
The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...
to the zygomatic bone
Zygomatic bone
The zygomatic bone is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. The zygomatic is homologous to the jugal bone of other tetrapods...
.
Its medial fibers form the angular head, which arises by a pointed extremity from the upper part of the frontal process
Frontal process
Frontal process can refer to:* Frontal process of maxilla* Frontal process of zygomatic bone...
of the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
and passing obliquely downward and lateralward divides into two slips.
One of these is inserted into the greater alar cartilage
Greater alar cartilage
The greater alar cartilage is a thin, flexible plate, situated immediately below the lateral nasal cartilage, and bent upon itself in such a manner as to form the medial wall and lateral wall of the naris of its own side....
and skin of the nose; the other is prolonged into the lateral part of the upper lip
Upper lip
The upper lip covers the anterior surface of the body of the maxilla.Its upper half is of usual skin color and has a depression at its centre, directly under the nasal septum, called the philtrum, while its lower half is a markedly different, red-colored skin tone more similar to the colour of the...
, blending with the infraorbital head and with the Orbicularis oris.
The intermediate portion or infraorbital head arises from the lower margin of the orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
immediately above the infraorbital foramen, some of its fibers being attached to the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
, others to the zygomatic bone
Zygomatic bone
The zygomatic bone is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. The zygomatic is homologous to the jugal bone of other tetrapods...
.
Its fibers converge, to be inserted into the muscular substance of the upper lip between the angular head and the Caninus.
The lateral fibers, forming the zygomatic head, arise from the malar surface of the zygomatic bone
Zygomatic bone
The zygomatic bone is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. The zygomatic is homologous to the jugal bone of other tetrapods...
immediately behind the zygomaticomaxillary suture and pass downward and medialward to the upper lip.