The zygomaticus minor muscle is a
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...
of facial expression. It originates from the
zygomatic bone, lateral to the rest of the
levator labii superioris muscle
The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle of the human body used in facial expression. It is a broad sheet, the origin of which extends ...
, and inserts into the outer part of the upper lip. It draws the
upper lip backward, upward, and outward and is used in smiling. It is innervated by the
facial nerve
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...
(VII).
Structure
The zygomaticus minor muscle originates from the
zygomatic bone.
It inserts into the tissue around the upper lip, particularly blending its fibres with
orbicularis oris muscle
In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth.
It is a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance ...
.
It lies lateral to the rest of
levator labii superioris muscle
The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle of the human body used in facial expression. It is a broad sheet, the origin of which extends ...
, and medial to its stronger
synergist zygomaticus major muscle
The zygomaticus major muscle is a muscle of the human body. It extends from each zygomatic arch (cheekbone) to the corners of the mouth. It is a muscle of facial expression which draws the angle of the mouth superiorly and posteriorly to allow on ...
. It travels at an angle of approximately 30°.
It has a mean width of around 0.5 cm.
Nerve supply
The zygomaticus minor muscle is supplied by the
buccal branch of the
facial nerve
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...
(VII).
Variation
The zygomaticus minor muscle may have either a straight or a curved course along its length.
It may attach to both the
upper lip and the lateral alar region.
It may be underdeveloped in some people, with its role taken over by nearby synergists.
These synergists rarely change shape or position, but any difference in smile is usually imperceptible.
Function
The zygomaticus minor muscle draws the
upper lip up, back, and out, such as during
smiling.
History
The zygomaticus minor muscle is sometimes referred to as the "zygomatic head" of the
levator labii superioris
The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle of the human body used in facial expression. It is a broad sheet, the origin of which extend ...
muscle.
Images
File:Zygomaticus minor muscle animation small.gif, Zygomaticus minor muscle (shown in red).
See also
*
Zygomaticus major muscle
The zygomaticus major muscle is a muscle of the human body. It extends from each zygomatic arch (cheekbone) to the corners of the mouth. It is a muscle of facial expression which draws the angle of the mouth superiorly and posteriorly to allow on ...
*
Zygomatic bone
References
External links
PTCentral
{{Authority control
Muscles of the head and neck