It also allows your head and neck to tilt forward (flexion), backward (extension), turn from side to side (rotation) or bend to one side (ear-to-shoulder lateral flexion). Your cervical spine supports the weight of your head (average weight of 10 to 13 pounds).
Supporting your head and allowing movement.Taken together, all the stacked vertebrae of your spine form a protective central canal that protects your spinal cord. The nerves of your spinal cord pass through a large hole (called the vertebral foramen) that passes through the center of all of your vertebrae - from the base of your skull through the cervical vertebrae, the thoracic (middle back) vertebrae and ending between the first and second lumbar (lower back) vertebrae. Your cervical spine has several functions, including: Your spinal cord sends and receives messages from your brain, which controls all aspects of your body’s functions. Your spinal cord runs through the center of your entire spine. “Shock-absorbing” disks, called intervertebral disks, are positioned between each vertebra. Your cervical spine is also surrounded by muscles, nerves, tendons and ligaments. Your seven cervical vertebrae (C1 to C7) are connected at the back of the bone by a type of joint (called facet joints), which allow for the forward, backward and twisting motions of your neck. Your second vertebra (C2), also called the axis, allows the atlas to pivot against it for the side-to-side “no” rotation of your head. It’s named after Atlas, of Greek mythology, who held the world on his shoulders.
Your first vertebra (C1), also called the atlas, is a ring-shaped bone that begins at the base of your skull. The first two vertebrae of your cervical spine are unique in shape and function. Your cervical spine - the neck area of your spine - consists of seven stacked bones called vertebrae. Neck muscles contract to adjust the posture of the head throughout the course of a day and have some of the greatest endurance of any muscles in the body.The Cervical Spine What is the cervical spine? Working individually, these muscles rotate the head or flex the neck laterally to the left or right. Working in pairs on the left and right sides of the body, these muscles control the flexion and extension of the head and neck. They move the head in every direction, pulling the skull and jaw towards the shoulders, spine, and scapula. The neck muscles, including the sternocleidomastoid and the trapezius, are responsible for the gross motor movement in the muscular system of the head and neck. The muscles of the middle ear contract to dampen the amplitude of vibrations from the eardrum to the inner ear. In fact, the smallest muscle of the skeleton is the stapedius, which measures around 1 millimeter (1/20th of an inch) in length.
Located inside the eye, the intrinsic eye muscles work tirelessly to dilate the pupils and focus the lens of the eye to produce clear vision.Įven the middle ear takes part in the muscular system of the head and neck. These muscles produce extremely fine movements almost constantly throughout the day with tremendous speed and accuracy.
Of these, four extrinsic muscle sets (connecting the tongue to the surrounding bones) move the tongue in virtually any direction, with fine shape changes (such as for speech) the province of the four intrinsic tongue muscles.Īs for the eye, six extrinsic eye muscles provide superior, inferior, lateral, and medial motion, as well as rotation of the eyeball. These muscles, including the masseter and temporalis, elevate the jaw forcefully during chewing and gently during speech.Īn extensive complement of tightly interlaced muscles allows the tongue a range of complex movements for chewing and swallowing, as well as the important function of producing speech. Producing the body’s ability to close the mouth, bite, and chew food, the muscles of mastication move the mandible relative to the rest of the skull. These muscles, including the zygomaticus major and orbicularis oris, pull on the skin to produce a seemingly infinite number of facial expressions and to move the lips and cheeks during speech and eating.
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