The Head and Neck
The brain may be divided into three parts: the cerebrum, brainstem, and cerebellum(1).
The cerebrum is in front of the brain. It has two primary parts: the right and left hemispheres. The cerebrum is responsible for body temperature, coordination and initiation of movement, hearing, touch, vision, judgment, problem-solving, reasoning, learning, and emotions(2).
Meanwhile, the brainstem is made up of the midbrain, the medulla, and the pons. Brainstem functions include transmissions of sensory messages, mouth and eye movement, involuntary muscle movements, sneezing, coughing, hunger, respirations, consciousness, cardiac function, body temperature, swallowing, and vomiting(3).
Lastly, the cerebellum or the back of the brain is responsible for coordinating voluntary muscle movements and maintaining balance, posture, and equilibrium(4).
Cranial nerves are nerves connected to the brain. Below is the list of cranial nerves in the body(5):
- Olfactory (signals sensory information related to smell)
- Optic (transmits visual sensory impulses)
- Oculomotor (responsible for eyelid movements)
- Trochlear (responsible for the movements of the eye muscle trochlea)
- Trigeminal (transmits signals to support face and motor functions)
- Abducent (responsible for the movement of the eye muscle lateral rectus)
- Facial (controls facial expression)
- Vestibulocochlear (sends sound and equilibrium sensory information)
- Glossopharyngeal (signals sensory information related to the back of the mouth)
- Vagus (responsible for signals from the heart, lungs, and digestive tract)
- Accessory (responsible for motor function)
- Hypoglossal (responsible for the tongue movement)
The thyroid gland is an organ in the neck covered by a fibrous capsule and a sheath called deep cervical fascia(6).
The gland consists of right and left lobes, each of which has an apex ascending between the neck muscle sternothyroid and the pharynx (the tube behind the mouth)(7).
A group of muscles, called infrahyoid muscles, covers the thyroid gland’s lateral surface in front of the neck(8).
The parathyroid glands are endocrine organs in the neck outside the thyroid capsule. The glands release hormones called parathyroid hormone or parathormone when the body has low blood calcium levels(9).
Trachea and esophagus
The trachea is located in the neck and partly in the thoracic cavity, which refers to the region between the abdomen and root of the neck(10).
The trachea moistens and warms the air passing through the lungs. The organ also protects the respiratory surface from foreign particle buildup(11).
Meanwhile, the esophagus spans the neck, thorax, and abdomen(12).
The organ’s primary function is to deliver food from the pharynx to the stomach(13).
The right and left carotid arteries are the main vessels of the head and neck(14).
The external carotid artery supplies blood to external skull structures, the face, and most of the neck. The internal carotid artery distributes blood within the cranial cavity(15).
Radiology of the Head and Neck
Head Magnetic Resonance Imaging
A head MRI (magnetic resonance imaging) is a procedure that uses magnets and radio waves to develop images of the brain and its nerve tissues. During the procedure, the patient lies down on a narrow slate, which slides into a tube-like scanner. Some MRI procedures need a special dye, called a contrast agent. The radiologist may recommend the dye to highlight certain areas of the body in the medical images. A head MRI usually takes 30 to 60 minutes to complete(16).
Head Computed Tomography
A head computed tomography (CT) scan uses X-rays to take medical images of the brain, the skull, sinuses, and eye sockets. During the procedure, the patient lies down on a narrow slate that slides into the center of the CT scan machine. While inside the scanner, the machine sends out X-rays to take separate images of the body that may be stored, viewed on a computer monitor, or saved to a disc. A complete head CT scan takes approximately 30 seconds to a few minutes(17).
A physician may suggest a head CT scan to diagnose the following medical conditions(18):
- Infection in the brain
- Birth defects
- Brain tumors
- Stroke or bleeds in the brain
- Hydrocephalus (fluid buildup in the skull)
- Trauma to the head, brain, or face
X-ray is a medical imaging procedure that uses electromagnetic energy beams to produce medical images of the skull. Physicians recommend X-rays for various reasons, including diagnosing infection, tumors, foreign bodies, or bone trauma(19).
The procedure uses external radiation to develop images of the body and its organs in films to diagnose a medical problem. Computers and digital media may also be used instead of films.
A doctor needs X-rays of the spine to evaluate abnormalities in a patient’s neck, back, and spine. A physician may order the procedure to diagnose the cause of a patient’s neck pain, broken bones, or other abnormalities(20).
Doctors may recommend other procedures to diagnose neck problems, such as myelography (using a spinal needle to check for problems in the spinal canal), CT scan, bone scan, or MRI scan.
- O’Rahilly, R., Müller, M., Carpenter, S., & Swenson, R. (2004) BASIC HUMAN ANATOMY A Regional Study of Human Structure. https://www.dartmouth.edu/~humananatomy/part_3/chapter_17.html
- National Cancer Institute. Thyroid & Parathyroid Glands. Retrieved from https://training.seer.cancer.gov/anatomy/endocrine/glands/thyroid.html
- Kudzinskas, A. & Callahan, A. (2020). Anatomy, Thorax. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK557710/
- Encyclopedia Britannica. Trachea. Retrieved from https://www.britannica.com/science/trachea
- R, O’Rahilly, et al. Op cit.
- Colorado State University. The Esophagus. Retrieved from http://www.vivo.colostate.edu/hbooks/pathphys/digestion/pregastric/esophagus.html
- R, O’Rahilly, et al. Op cit.
- MedlinePlus. Head MRI. Retrieved from https://medlineplus.gov/ency/article/003791.htm
- Mount Sinai Health System. Head CT Scan. Retrieved from https://medlineplus.gov/ency/article/003791.htm
- Johns Hopkins Medicine, based in Baltimore, Maryland. X-rays of the Skull. Retrieved from https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/xrays-of-the-skull
- Johns Hopkins Medicine, based in Baltimore, Maryland. X-rays of the Spine, Neck or Back. Retrieved from https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/xrays-of-the-spine-neck-or-back