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The giraffe's neck is elongated by heterochrony, extension of the time for the embryonic development of these bones. [ 4 ] By convention, the cervical vertebrae are numbered, with the first one (C1) closest to the skull and higher numbered vertebrae (C2–C7) proceeding away from the skull and down the spine.
The neck is flattened from before backward, contracted in the middle, and broader laterally than medially. The vertical diameter of the lateral half is increased by the obliquity of the lower edge, which slopes downward to join the body at the level of the lesser trochanter, so that it measures one-third more than the antero-posterior diameter.
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.
It is composed of 270 bones at the time of birth, [2] but later decreases to 206: 80 bones in the axial skeleton and 126 bones in the appendicular skeleton. 172 of 206 bones are part of a pair and the remaining 34 are unpaired. [3] Many small accessory bones, such as sesamoid bones, are not included in this.
Muscles of the neck attach to the skull, hyoid bone, clavicles and the sternum. They bound the two major neck triangles; anterior and posterior. [1] [7] Anterior triangle is defined by the anterior border of the sternocleidomastoid muscle, inferior edge of the mandible and the midline of the neck.
Anatomical terms of bone [ edit on Wikidata ] The suprasternal notch , also known as the fossa jugularis sternalis , jugular notch , or Plender gap , is a large, visible dip in between the neck in humans, between the clavicles , and above the manubrium of the sternum .
The brain is enclosed within the skull. There are 22 bones in the human head. The head rests on the neck, and the seven cervical vertebrae support it. The human head typically weighs between 2.3 and 5 kilograms (5.1 and 11.0 lb) Over 98% of humans fit into this range.
The joints between bones allow movement, some allowing a wider range of movement than others, e.g. the ball and socket joint allows a greater range of movement than the pivot joint at the neck. Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal ...