The epicranial aponeurosis (aponeurosis epicranialis, galea aponeurotica) is an aponeurosis (a tough layer of dense fibrous tissue). It covers the upper part of the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...

s and many other animals.

Structure

In humans, the epicranial aponeurosis originates from the

external occipital protuberance Near the middle of the squamous part of occipital bone is the external occipital protuberance, the highest point of which is referred to as the inion. The inion is the most prominent projection of the protuberance which is located at the posterioin ...

and highest nuchal lines of the occipital bone. It merges with the occipitofrontalis muscle. In front, it forms a short and narrow prolongation between its union with the

frontalis muscle The frontalis muscle () is a muscle which covers parts of the forehead of the skull. Some sources consider the frontalis muscle to be a distinct muscle. However, Terminologia Anatomica currently classifies it as part of the occipitofrontalis muscle ...

(the frontal part of the occipitofrontalis muscle). On either side, the epicranial aponeurosis attaches to the anterior auricular muscles and the

superior auricular muscle The superior auricular muscle is a muscle above the auricle of the outer ear. It originates from the epicranial aponeurosis, and inserts into the upper part of the medial surface of the auricle. It draws the auricle upwards. Structure The su ...

s. Here it is less

aponeurotic An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join muscl ...

, and is continued over the

temporal fascia The temporal fascia covers the temporalis muscle. It is a strong, fibrous investment, covered, laterally, by the auricularis anterior and superior, by the galea aponeurotica, and by part of the orbicularis oculi. The superficial temporal vesse ...

to the

zygomatic arch In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygo ...

as a layer of laminated

areolar tissue Loose connective tissue, sometimes called areolar tissue, is a cellular connective tissue with thin and relatively sparse collagen fibers. Its ground substance occupies more volume than the fibers do. It has a viscous to gel-like consistenc ...

. It is closely connected to the

integument In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, shell, germ or rind. Etymology The term is derived from ''integumentum'', which is Latin for "a covering". In a transferred, or ...

by the firm, dense, fibro-fatty layer which forms the superficial fascia of the

scalp The scalp is the anatomical area bordered by the human face at the front, and by the neck at the sides and back. Structure The scalp is usually described as having five layers, which can conveniently be remembered as a mnemonic: * S: The ski ...

. It is attached to the

pericranium The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structure ...

by loose cellular tissue, which allows the aponeurosis, carrying with it the integument, to move through a considerable distance.

Clinical significance

Subgaleal haemorrhage is defined as bleeding between the epicranial aponeurosis and the

Conservative management Conservative management is a type of medical treatment defined by the avoidance of invasive measures such as surgery or other invasive procedures, usually with the intent to preserve function or body parts. For example, in appendicitis, conservati ...

is usually appropriate for these, as there is little risk of further damage to surrounding structures.

History

The epicranial aponeurosis is also known as the aponeurosis epicranialis (from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

), and the galea aponeurotica.

Additional images

File:Gray1196.png, Diagrammatic section of scalp. 1106 Front Views of the Muscles of Facial Expressions numbered.jpg, Epicranial aponeurosis from a frontal view, labeled 1

References

External links