The epicranial aponeurosis (aponeurosis epicranialis, galea aponeurotica) is an
aponeurosis
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 musc ...
(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, the ...
in
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, culture, ...
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
The nuchal lines are four curved lines on the external surface of the occipital bone:
* The upper, often faintly marked, is named the highest nuchal line, but is sometimes referred to as the Mempin line or linea suprema, and it attaches to the ep ...
of 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 overlies the occipital lobe ...
.
It merges with the
occipitofrontalis muscle
The occipitofrontalis muscle (epicranius muscle) 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. It is supplied by th ...
. 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 supe ...
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 musc ...
, 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 vessels ...
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 zygomati ...
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
A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal orga ...
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
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, 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
See also
*
Epicranium
The Epicranium is the medical term for the collection of structures covering the cranium. It consists of the muscles, aponeurosis, and skin.
Skull
{{anatomy-stub ...
*
Aponeurosis
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 musc ...
References
External links
* - "Cranial Fossae: Layers of the scalp"
{{Authority control
Muscles of the head and neck