Neck

Your neck connects your head to your body.

It holds up your head. It also protects the paths for messages to travel. These messages go from your brain to your body.

Your neck is very bendy. This helps you turn your head in all ways.

Inside, it holds the tubes for breathing and eating. It also has blood vessels.

Muscles help your neck move. Some muscles help you talk and swallow food.

Some people have a bump on their neck. This is called an Adam's apple.

Many animals have a neck too.

A giraffe has a very long neck.

The neck connects the head to the torso. It holds up the weight of the head. It also protects nerves. These nerves carry messages between the brain and the body. The neck is very flexible. This lets the head turn in many ways.

The neck has four main parts. One part holds the cervical vertebrae. These are the bones in the neck. They protect the spinal cord. Another part holds the windpipe and the food pipe. The neck also has two vascular compartments. These hold blood vessels like arteries and veins.

Muscles help the neck move. Some muscles help you talk. Other muscles help you swallow. In many people, a bump called the Adam's apple is easy to see.

Many animals have necks. A giraffe has a very long neck. Some animals like seals and penguins have them too. Even some insects have a neck. Most land animals keep their necks to help them move.

The neck is a vital part of many vertebrates. It connects the head to the torso. This part of the body supports the head. It also protects important nerves. These nerves send sensory and motor information. They link the brain to the rest of the body. The neck is highly flexible. This allows the head to move in all directions.

Inside the neck, structures live in four compartments. The vertebral compartment holds the cervical vertebrae. These bones have cartilaginous discs between them. This compartment also protects the cervical spinal cord. The visceral compartment holds the trachea and larynx. It also holds the pharynx and glands like the thyroid. Two vascular compartments sit on each side of the trachea. These hold the carotid sheath, the vagus nerve, and arteries.

Muscles form the boundaries of the neck. They create two major areas called triangles. The anterior triangle is in the front. It contains many muscles like the digastric and mylohyoid. Some muscles are suprahyoid and some are infrahyoid. They work together to help with speech and swallowing. The posterior triangle is in the back. It includes the trapezius and the sternocleidomastoid muscles.

Many facts can be found in the neck's anatomy. The Adam's apple is a bulge in the midline. This is actually the thyroid cartilage of the larynx. Men often have a more prominent Adam's apple. On average, men have a larger neck circumference. Men average about 15.2 inches. Women average about 13.1 inches. This is often due to more muscle mass in men.

Necks appear in many different living things. The neck appears in early tetrapod fossils. Land vertebrates and marine animals like seals have them. Even some insects have a functioning neck. A giraffe is a famous example with a very long neck.

Some animals like whales have lost the outside look of a neck. However, they still keep some flexibility inside. This shows how useful the neck is for life.

The neck is a vital anatomical region in many vertebrates. It serves as the bridge connecting the head to the torso. This structure performs several essential roles for survival. It supports the heavy weight of the head. It also protects critical nerves that carry information. These nerves transmit sensory and motor signals between the brain and the body. Furthermore, the neck provides high flexibility. This allows the head to rotate and move in many different directions.

Inside the neck, structures are organized into four distinct compartments. The vertebral compartment contains the cervical vertebrae. These bones are separated by cartilaginous discs. The alignment of these vertebrae determines the shape of the neck. This compartment also houses the cervical portion of the spinal cord. The visceral compartment accommodates the pharynx, larynx, and trachea. It also contains the thyroid and parathyroid glands. Two vascular compartments sit on either side of the trachea. These are known as the carotid sheaths. Each sheath contains the vagus nerve, the common carotid artery, and the internal jugular vein.

Muscles in the neck define its outer boundaries. These muscles form two large areas called triangles. The anterior triangle is located at the front of the neck. It is bounded by the mandible, the midline, and the sternocleidomastoid muscle. This area contains many muscles, such as the mylohyoid and the digastric. These are categorized as suprahyoid or infrahyoid muscles. The suprahyoid muscles elevate the hyoid bone. The infrahyoid muscles depress it. By acting synchronously, these muscle groups facilitate speech and swallowing.

The posterior triangle is located at the back of the neck. It is bordered by the trapezius muscle and the sternocleidomastoid muscle. This triangle contains the splenius capitis and the levator scapulae muscles. It also houses the scalene muscles. The neck also relies on a complex nerve supply for sensation. The front of the neck receives sensation from the C2 to C4 spinal nerve roots. The back of the neck receives sensation from the C4 to C5 roots. Additionally, the accessory nerve and the vagus nerve travel through this region.

Several visible landmarks exist on the surface of the neck. The thyroid cartilage of the larynx creates a bulge called the Adam's apple. This feature is usually more prominent in men. Below the Adam's apple lies the cricoid cartilage. The trachea can be traced at the midline of the neck. The external jugular vein is often visible through the skin. It runs from the angle of the jaw to the clavicle. The clavicle, or collarbone, marks the lower limit of the neck.

Physical measurements of the neck can relate to overall health. On average, men have a larger neck circumference than women. Men average approximately 15.2 inches (38.7 cm). Women average around 13.1 inches (33.3 cm). This difference is linked to higher muscle mass and testosterone in men. Research has also connected neck circumference to medical risks. For example, in COVID-19 patients, a larger neck circumference was linked to higher risks. Specifically, each centimeter increase was associated with a 26% increased risk of needing mechanical ventilation.

Necks are found across a wide variety of animal species. The neck appears in some of the earliest tetrapod fossils. This structure is retained in land vertebrates and marine animals like seals and penguins. Even some insects possess a functioning neck. Some animals, like whales, have lost the external appearance of a neck. However, they still retain internal flexibility. The giraffe is perhaps the most famous example of a long neck.