Anatomy of the Face - Flipbook - Page 18
Risorius (Musculus risorius)
ORIGIN:
CLINICAL SIGNIFICANCE:
PAROTID FASCIA, BUCCAL SKIN, ZYGOMATIC BONE (VARIABLE)
RISORIUS IS A SLENDER AND NARROW FACIAL MUSCLE THAT
BELONGS TO THE BUCCOLABIAL GROUP OF MUSCLES. IT IS
HIGHLY VARIABLE AND INCONSISTENT WHERE IT IS BELIEVED TO
BE UNIQUE TO THE AFRICAN APES AND HUMANS. IT’S NOT
PRESENT IN ALL PEOPLE, BUT IF PRESENT, IT IS FOUND IN THE
SUPERFICIAL LAYER OF THE FACIAL MUSCLES ON EITHER SIDE OF
THE LIPS, OVERLYING THE BUCCINATOR.
INSERTION:
MODIOLUS
BLOOD SUPPLY:
SUPERIOR LABIAL ARTERY (FACIAL ARTERY)
INNERVATION:
BUCCAL BRANCH OF FACIAL NERVE (CN VII)
LYMPHATIC DRAINAGE
DRAINS INTO THE SUBMANDIBULAR AND MANDIBULAR LYMPH
NODES
ACTION:
EXTENDS ANGLE OF MOUTH LATERALLY
IT IS DEEMED AS THE ‘SMILING MUSCLE’ AS ITS BILATERAL
CONTRACTION PULLS THE ANGLES OF THE MOUTH LATERALLY
AND SLIGHTLY SUPERIORLY AND PRODUCES A SMILE. IT AIDS IN
PRODUCING FACIAL EXPRESSIONS, EITHER SOLELY OR IN
CONJUNCTION WITH OTHER FACIAL MUSCLES; SUCH AS
SMILING, SMIRKING, GRINNING, FROWNING AND A MYRIAD OF
EXPRESSIONS IN BETWEEN.
IN BELL PALSY, A CONDITION CAUSED BY A FACIAL NERVE
DEFICIT CHARACTERIZED BY PARESIS OR PARALYSIS OF THE
MUSCLES IT INNERVATES, THE RISORIUS MAY BE AFFECTED WITH
OTHER MUSCLES OF FACIAL EXPRESSION. SIMILARLY, IT MIGHT
BE AFFECTED BY STROKE, RAMSAY HUNT SYNDROME, LYME
DISEASE AND VARIOUS TUMORS.
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