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The heart's cardiac skeleton comprises four dense connective tissue rings that encircle the mitral and tricuspid atrioventricular (AV) canals and extend to the origins of the pulmonary trunk and aorta. This provides crucial support and structure to the heart while also serving to electrically isolate the atria from the ventricles. [1]
The head rests on the top part of the vertebral column, with the skull joining at C1 (the first cervical vertebra known as the atlas). The skeletal section of the head and neck forms the top part of the axial skeleton and is made up of the skull, hyoid bone, auditory ossicles, and cervical spine. The skull can be further subdivided into:
Skull in situ Human head skull from side Anatomy of a flat bone – the periosteum of the neurocranium is known as the pericranium Human skull from the front Side bones of skull. The human skull is the bone structure that forms the head in the human skeleton. It supports the structures of the face and forms a cavity for the brain. Like the ...
Foramen ovale (heart), an opening between the venous and arterial sides of the fetal heart; Foramen transversarium, one of a pair of openings in each cervical vertebra, in which the vertebral artery travels; Greater sciatic foramen, a major foramen of the pelvis; Interventricular foramen, channels connecting ventricles in the brain
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
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
The frontal and sphenoid bones are towards the front middle of the skull and in front of the temporal bone. The ethmoid bone is the bone at the roof of the nose that separates the nasal cavity from the brain. It is a part of the dorsal cavity the cranial cavity and the spinal cord. The occipital bone is at the back of the skull.
Betz cells are the largest cells (by size of cell body) in the nervous system. [40] The adult human brain is estimated to contain 86±8 billion neurons, with a roughly equal number (85±10 billion) of non-neuronal cells. [41] Out of these neurons, 16 billion (19%) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum ...