The occipitofrontalis muscle (epicranius muscle) is a

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

which covers parts of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. It consists of two parts or bellies: the occipital belly, near the

occipital bone The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lob ...

, and the frontal belly, near the

frontal bone In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...

. It is supplied by the supraorbital artery, the supratrochlear artery, and the occipital artery. 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 ta ...

. In humans, the occipitofrontalis helps to create facial expressions.

Structure

The occipitofrontalis muscle consists of two parts or bellies: * the occipital belly, near the

. It originates on the lateral two-thirds of the highest nuchal line, and on the mastoid process of the

temporal bone The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...

. It inserts into the epicranial aponeurosis. * the frontal belly, near the

. It originates from an intermediate tendon that connects to the occipital belly. It inserts in the

fascia A fascia (; : fasciae or fascias; adjective fascial; ) is a generic term for macroscopic membranous bodily structures. Fasciae are classified as superficial, visceral or deep, and further designated according to their anatomical location. ...

of the

facial muscles The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, alth ...

and in the skin above the

eyes An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

and

nose A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...

. Some sources consider the occipital and frontal bellies to be two distinct muscles. However, Terminologia Anatomica currently classifies it as a single muscle, and also includes the

temporoparietalis muscle The temporoparietalis muscle is a distinct muscle of the head. It lies above the superior auricular muscle, auricularis superior muscle. It lies just inferior to the epicranial aponeurosis of the occipitofrontalis muscle. The temporoparietalis mu ...

as part of the epicranius. The occipitofrontalis muscle receives blood from several

arteries An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

. The frontal belly receives blood from the supraorbital and supratrochlear arteries, while the occipital belly receives blood from the occipital artery.

Nerve supply

The occipitofrontalis muscle is innervated by the

. Branches of the supraorbital nerve pass through the occipitofrontalis muscle without innervating it to innervate the lambdoid suture.

Function

The occipitofrontalis muscle helps to create facial expressions. Assisted by the occipital belly, the frontal belly draws the

scalp The scalp is the area of the head where head hair grows. It is made up of skin, layers of connective and fibrous tissues, and the membrane of the skull. Anatomically, the scalp is part of the epicranium, a collection of structures covering th ...

back, which raises the

eyebrow An eyebrow is an area of short hairs above each eye that follows the shape of the lower margin of the Supraorbital ridge, brow ridges of some mammals. In humans, eyebrows serve two main functions: first, human communication, communication thro ...

s and wrinkles the

forehead In human anatomy, the forehead is an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp grows. The bottom of the fo ...

Clinical significance

Damage to the

can cause

atony This glossary of medical terms is a list of definitions about medicine, its sub-disciplines, and related fields. A *Aarskog–Scott syndrome – (AAS) A rare, inherited (X-linked) disease characterized by short stature, facial abnormalities, s ...

of the occipitofrontalis muscle.

Other animals

In humans, the occipitofrontalis only serves for facial expressions. In apes, however, the head is not balanced on the

vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...

, and apes therefore need strong muscles that pull back on the skull and prominent supraorbital ridges for the attachment of these muscles.

References

External links

* {{Authority control Muscles of the head and neck