The skull introduces significant distortion and attenuation of the ultrasound signals deteriorating image quality. For biological studies employing rodents, craniotomy is often times performed to enhance image qualities.
However, craniotomy is unsuitable for longitudinal studies, where a long-term cranial window is needed to prevent repeated surgeries. Here, we propose a mouse model to eliminate sound blockage by the top portion of the skull, while minimum physiological perturbation to the imaged object is incurred. With the new mouse model, no craniotomy is needed before each imaging experiment.
This widget works on PC as well as on iOs and Android mobile devices. The human skull is the most complex part of the skeleton as it is a unique set of bone structures housing a variety of organs located in the head.
Skull bones hold and protect the human brain and the sensory organs of vision, hearing, smell, and taste. They also include all the necessary sinuses and foramina through which nerves and vessels travel.
Bones of the skull form the upper airways and oral cavity, serving as attachment sites for the masticatory and facial muscles. Understanding the human skull anatomy is necessary for a wide range of professionals from doctors dentists, oral surgeons, neurosurgeons, etc.
There are 22 bones in the human skull and some of them are paired. Some authors also include one more bone in the skull — the hyoid, which is located under the mandible near the larynx and not directly attached to the other bones of the skull.
The skull is anatomically divided into two parts — the neurocranium and the facial visceral skull 1. During embryonic development, bones of the neurocranium ethmoid, sphenoid, frontal bone, two parietal bones, two temporal bones and the occipital bone are formed from the mesoderm — a primary germ layer that from which connective tissue and muscles usually originate.
Facial bones are formed from the neural crest — an ectoderm-derived embryonic layer found only in vertebrates. The ectodermal layer is responsible for the formation of the nervous system, skin epidermis and tooth enamel 2.
Flat skull bones parietal, frontal, occipital, nasal, lacrimal, and the vomer — are among a number of small bones in the human body that are formed by intramembranous ossification.
In this case, the formation of bone tissue is not preceded by the formation of cartilage 2. The ossification is completed only after 20 years when the sutures of the skull that connect the cranial bones are ossified.
Before this,the flexible joints between cranial bones are very important for the brain development and avoiding trauma in childbirth 3. The bones of the cranial vault consist of outer and inner layers of cortical bone, between which the spongy bone tissue is located.
This may contribute to redistribution of the outer traumatic influence energy, so that compact bone tissue would stay undamaged even in the event of the spongy tissue damage 5.
The structure of the skull bones is to a large extent determined by and interconnected with the anatomy of the sensory organs, situated in the head, as well as nerves, blood vessels and brain structures. Sphenoid, temporal and ethmoid bones probably have the most complex structure.
For example, the temporal bones harbor cavities for the organs of hearing and balance, as well as 10 channels for branches of the cranial nerves and blood vessels 1. As many as 15 to 20branches of the olfactory nerves penetrate the cribriform plate of the ethmoid bone to connect olfactory receptors in the nasal cavity with the olfactory bulb in the brain. Apart from its role in olfaction, this region may serve as a route for several pathogens to enter the brain 6.
The sphenoid bone contains a depression called the sella turcica, where the pituitary gland hypophysis is located. Surprisingly not all the functions of skull bone elements have been fully described to date.
In particular, there is no clarity about the evolutionary role of paranasal sinuses in the ethmoid, frontal, and maxillary bones 7.
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