Occipitofrontalis muscle

Occipitofrontalis
Latin	musculus occipitofrontalis
Gray's	subject #105 378
Origin	2 occipital bellies and 2 frontal bellies.
Insertion	galea aponeurotica
Artery	frontalis: aa. supraorbital and supratrochlear occipitalis: a. occipital[1]
Nerve	facial nerve
Actions	raises eyebrows, wrinkles forehead

The occipitofrontalis or epicranius is a muscle which covers parts of the skull. It consists of two parts or bellies: The occipital belly, near the occipital bone, and the frontal belly, near the frontal bone.

Some sources consider the occipitofrontalis to be a structure consisting of two distinct muscles, the Frontalis and the occipitalis. However, Terminologia Anatomica currently classifies it as a single muscle, and also includes the temporoparietalis muscle as part of the epicranius.

Course

Main articles: Occipitalis muscle and Frontalis muscle

The occipital belly originates on the lateral two-thirds of the superior nuchal line of the occipital bone, and on the mastoid process of the temporal bone. Inserted into the galea aponeurotica, or epicranial aponeurosis, the occipital belly communicates with the frontal belly by an intermediate tendon. From the aponeurosis, the frontal belly is inserted in the fascia of the facial muscles and in the skin above the eyes and nose.^[2]

Action

Assisted by the occipital belly, the frontal belly draws the scalp back which raises the eyebrows and wrinkles the forehead.^[2]

Evolution

In humans, the occipitofrontalis only serves for facial expressions. In apes, however, the head is not balanced on the vertebral column, and apes therefore need strong muscles that pull back on the skull and prominent supraorbital ridges for the attachment of these muscles.^[3]

See also: Human skeletal changes due to bipedalism

See also

• Epicranium

Notes

1. ^ UAMS
2. ^ ^{a b} Stone, 2000, p 26
3. ^ Saladin, 2003, pp 286-287

References

• Saladin, Kenneth S. (2003). Anatomy & Physiology: The Unity of Form and Function (3rd ed.). McGraw-Hill. pp. 286–287. 
• Stone, Robert & Judith (2000). Atlas of skeletal muscles. McGraw-Hill. ISBN 978-0072903324. 
• "Introduction to the Head; Front of Skull and Face/Muscles of the Face". University of Arkansas for Medical Sciences (UAMS). 2007. http://anatomy.uams.edu/AnatomyHTML/introheadneck.html. Retrieved 2008-09-24. 

External links

• -1341783984 at GPnotebook
• Bérzin F (1989). "Occipitofrontalis muscle: functional analysis revealed by electromyography.". Electromyogr Clin Neurophysiol 29 (6): 355–8. PMID 2689156.