In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back 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 ...
, which forms a protective case around the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
.
In the human skull, the neurocranium includes the
calvaria or skullcap. The remainder of the skull is the
facial skeleton
The facial skeleton comprises the ''facial bones'' that may attach to build a portion of the skull. The remainder of the skull is the braincase.
In human anatomy and development, the facial skeleton is sometimes called the ''membranous viscerocr ...
.
In
comparative anatomy
Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny (the evolution of species).
The science began in the classical era, continuing in t ...
, neurocranium is sometimes used synonymously with
endocranium
The endocranium in comparative anatomy is a part of the skull base in vertebrates and it represents the basal, inner part of the cranium. The term is also applied to the outer layer of the dura mater in human anatomy.
Structure
Structurally, t ...
or
chondrocranium
The chondrocranium (or ''cartilaginous neurocranium'') is the primitive cartilage, cartilaginous skeleton, skeletal structure of the fetal skull that grows to envelop the rapidly growing embryonic brain.Salentijn, L. ''Biology of Mineralized Tissue ...
.
Structure
The neurocranium is divided into two portions:
* the membranous part, consisting of flat bones, which surround the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
; and
* the cartilaginous part, or
chondrocranium
The chondrocranium (or ''cartilaginous neurocranium'') is the primitive cartilage, cartilaginous skeleton, skeletal structure of the fetal skull that grows to envelop the rapidly growing embryonic brain.Salentijn, L. ''Biology of Mineralized Tissue ...
, which forms bones of the
base of the skull
The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria.
Structure
Structures found at the base of the skull are for ...
.
In humans, the neurocranium is usually considered to include the following eight bones:
* 1
ethmoid bone
The ethmoid bone (; from grc, ἡθμός, hēthmós, sieve) is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a ...
* 1
frontal bone
The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, par ...
* 1
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 ...
* 2
parietal bone
The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...
s
* 1
sphenoid bone
The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bones ...
* 2
temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. Th ...
s
The
ossicles
The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ...
(three on each side) are usually not included as bones of the neurocranium. There may variably also be extra
sutural bones present.
Below the neurocranium is a complex of openings (
) and bones, including the
foramen magnum
The foramen magnum ( la, great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblon ...
which houses the neural spine. The
auditory bulla
The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal.
It originates as a separate bone (tympanic ...
e, located in the same region, aid in hearing.
[Elbroch, M. 2006. Animal skulls: A guide to North American species. Stackpole Books, pp. 20–22. ]
The size of the neurocranium is variable among mammals. The roof may contain ridges such as the
temporal crest
Temporal may refer to:
Entertainment
* Temporal (band), an Australian metal band
* ''Temporal'' (Radio Tarifa album), 1997
* ''Temporal'' (Love Spirals Downwards album), 2000
* ''Temporal'' (Isis album), 2012
* ''Temporal'' (video game), a 200 ...
s.
Development
The neurocranium arises from
paraxial mesoderm
Paraxial mesoderm, also known as presomitic or somitic mesoderm is the area of mesoderm in the neurulating embryo that flanks and forms simultaneously with the neural tube. The cells of this region give rise to somites, blocks of tissue running ...
. There is also some contribution of
ectomesenchyme
Ectomesenchyme has properties similar to mesenchyme. The origin of the ectomesenchyme is disputed. It is either like the mesenchyme, arising from mesodermic cells, or conversely arising from neural crest cells. The neural crest is a critical group ...
. In Chondrichthyes and other cartilaginous vertebrates this portion of the cranium does not ossify; it is not replaced via
endochondral ossification
Endochondral ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is produced. Unlike intramembranous ossification, the other process by which bone tissue is produced, c ...
.
Other animals
The neurocranium is formed by the
endocranium
The endocranium in comparative anatomy is a part of the skull base in vertebrates and it represents the basal, inner part of the cranium. The term is also applied to the outer layer of the dura mater in human anatomy.
Structure
Structurally, t ...
, the lower portions of the
cranial vault
The cranial vault is the space in the skull within the neurocranium, occupied by the brain.
Development
In humans, the cranial vault is imperfectly composed in newborns, to allow the large human head to pass through the birth canal. During bir ...
, and the
skull roof
The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium.
In comparati ...
.
Evolutionarily, the human neurocranium has expanded from comprising the back part of the mammalian skull to being also the upper part: during the evolutionary expansion of the brain, the neurocranium has overgrown the splanchnocranium. The upper-frontmost part of the cranium also houses the evolutionarily newest part of the mammal brain, the
frontal lobe
The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betwe ...
s.
Additional images
File:Neurocranium - superior view - animation03.gif, Animation without left parietal bone
The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...
, showing cranial cavity
The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull minus the mandible is called the ''cranium''. The cavity is formed by eight cranial bones known as the neurocranium that in ...
and inner surface of base of skull
The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria.
Structure
Structures found at the base of the skull are for ...
.
File:Schädelbasis1.jpg, Inner surface of base of skull
The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria.
Structure
Structures found at the base of the skull are for ...
.
File:703 Parts of Skull-01.jpg, Neurocranium (labeled as "Brain case") and facial bones
The facial skeleton comprises the ''facial bones'' that may attach to build a portion of the skull. The remainder of the skull is the braincase.
In human anatomy and development, the facial skeleton is sometimes called the ''membranous viscerocr ...
.
File:BodyParts3D Neurocranium.stl, 3D model. Click to move.
See also
*
Cranial cavity
The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull minus the mandible is called the ''cranium''. The cavity is formed by eight cranial bones known as the neurocranium that in ...
References
External links
Earliest Directly-Dated Human Skull-Cups
External links
*
{{Authority control
Bones of the head and neck
Human anatomy