The Anatomy of the External Ear
Your two ears allow you to hear sounds and wear really cool earrings. The external ear includes the auricle as well as the external acoustic meatus, also known as the ear canal, which ends at the tympanic membrane separating the external ear from the middle ear.
Actually, there’s more to an ear than the external part you see on the sides of your head; most of the structures lie inside the middle ear and the inner ear.
The auricle (or pinna) is the part of the ear that you see — it helps transfer sound waves to the external acoustic meatus. It’s covered with skin and it has the following landmarks:
Concha: The deepest depression, just posterior to the opening of the meatus
Helix: The elevated cartilaginous margin around the posterior and superior part of the auricle
Lobule: The ear lobe, containing fibrous tissue, fat, and blood vessels
Tragus: The small projection that lies anterior to the meatus
Sound waves enter the ear through the external acoustic meatus. A normal meatus is about 2 or 3 centimeters long, and it meets the tympanic membrane. The lateral part of the meatus is cartilaginous, and the deeper parts are bony. It’s lined with skin that contains ceruminous and sebaceous glands, which produce cerumen, or earwax.
The tympanic membrane is a thin oval membrane about 1 centimeter in diameter. The external side is covered with thin skin, and the internal side is covered with mucous membrane.
If you look at the tympanic membrane with an otoscope in a normal, healthy ear, you see a cone of light on the membrane going anteriorly and inferiorly. Superior to the cone of light, you see the flaccid part that has fewer fibers than the rest of the membrane, which is called the tense part.
This region of the body starts along the bottom of the ribcage and extends to the hips. It’s visible from the front.
These sympathetic (fight-or-flight) nerves of the abdomen carry the presynaptic fibers to the abdomen and pelvis.
To join together.
Male sex hormones.
An arthritic disease of the vertebral joints that results in hyperkyphosis and may restrict lung expansion if the disease spreads superiorly. It may lead to fusion of intervertebral joints and spinal column rigidity.
In clinical anatomy, closer to the front of the body. For instance, the abdominal muscles are anterior to the spine.
The broad tendinous structure that attaches a muscle to another muscle.
In clinical anatomy, to form a joint.
A ball-shaped head that fits into a bony socket. The shoulder and hip are ball-and-socket joints. This type of joint allows for free movement in several directions, including flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction.
On both the left and right sides of the body, such as the eyes, the kidneys, and the arms and legs.
A thin-walled, bag-like organ that can hold up to two cups of urine.
A projection of bone that sticks out from the arch found in vertebrae.
Connects the cerebrum with the spinal cord.
Fluid-filled sacs that help tendons glide over the bones and other tendons.
An inflammation of a bursa, which is usually the result of repetitive motion injuries.
The part of the heel you stand on.
Diseases of the heart and blood vessels.
The joint surfaces in cartilaginous joints are covered with hyaline cartilage and have fibrocartilaginous discs between them. Like fibrous joints, cartilaginous joints can be immoveable.
The largest part of the brain; made up of the left and right cerebral hemispheres.
The neck region; starts below the head, ends at the thorax, and is visible from the front and rear from below the head to the shoulders.
To move in a circular motion; doing arm circles, is circumduction.
Joints with an oval surface on one bone that articulates with an oval-shaped depression in another bone. The metacarpophalangeal joints in the fingers are examples of condyloid joints.
On opposite sides of the body. The right ear is contralateral to the left ear.
A band of nerve fibers that allows the sides of the brain to communicate with the other.
The receiving part of a neuron. The signal received at the dendrite is transmitted toward the cell body of the neuron in the form of an electrical impulse. The impulse is transmitted away from the cell body to another neuron, muscle, or gland by the axon.
The lower layer of the skin containing collagen and elastic fibers that give strength to the skin.
The central part of the brain, underneath the cerebrum.
Farther from the trunk or from the point of origin. The elbow is distal to the shoulder.
An anatomical region that runs from immediately below the neck down to the area below the waist. It doesn’t include the shoulders. It’s visible from the rear.
To move your foot and toes up.
The first segment of the small intestine.
The spaces between the two layers of the dura matter that collect blood from veins on the surface of the brain.
Cartilage that contains elastic fibers in the matrix, so it’s more flexible than either hyaline or fibrocartilage; your ear has elastic cartilage.
The delicate layer that surrounds each individual nerve fiber in the peripheral nervous system.
The tough layer outermost layer of skin. It gets its toughness from a protein called keratin.
The thick layer of connective tissue that surrounds a bundle of fascicles in the peripheral nervous system.
A muscular tube that extends from the pharynx to the stomach.
To move the bottom of your foot away from the midline of the body.
In clinical anatomy, a smooth joint-forming surface.
A layer of fibrous connective tissue that covers muscle.
This cartilage has a larger number of collagen fibers and less matrix. It’s found in the discs in joint spaces including the temporomandibular joint, knee joint, and joints between the bodies of the vertebrae.
The bones of a fibrous joint are connected by fibrous tissue. They range from being immovable (like joints between the bones of the skull) to being slightly moveable (joints between the tibia and fibula in the legs).
Imaginary vertical planes that clinical anatomy uses to define regions of the body. They pass through the body at right angles to the midsagittal plane, so they divide the body into front and back. Frontal (coronal) planes can divide the body at any point, so you need to use a reference point to know where exactly the plane passes.
A collection of nerve-cell bodies similar to the nuclei of the central nervous system, except that these ganglia are only found in the peripheral nervous system.
The plural of hilum, and the hilum is the part of the lung where the bronchus and pulmonary artery enter and the pulmonary vein exits the lungs.
A joint that allows flexion and extension (bending and straightening) of joints like the elbow and the knee.
This durable type of cartilage covers most of the bone surfaces in synovial joints. It’s also found in the nasal septum, rings of the trachea, and costal cartilages of the ribs, and it forms the epiphyseal plates of growing bones.
An abnormal increase in the thoracic curvature.
A condition in which blood pressure remains elevated over time. Having high blood pressure increases the risk of heart disease, stroke, and kidney disease.
Closer to the feet. The chin is inferior to the nose.
In between. The abdominal muscles are intermediate between the skin and the small intestines.
The septa divide muscles into various groups.
To move the bottom of your foot toward the midline of your body.
This part of the fascia covers deeper structures, such as muscles and ligaments.
On the same side of the body. For example, the right ear and the right eye are ipsilateral.
A major structural component of the outer layers of skin.
These cells are constantly shed and replaced by cells from the lower layers of the epidermis. These cells have lost most of their internal structures and organelles.
Organs that filter the blood and produce urine.
In clinical anatomy, away from the body’s midline. For example, the little toe is lateral to the big toe.
A bony prominence located proximal to the lateral condyle.
To move a body part around its long axis with the anterior surface moving away from the midline, like turning your whole lower extremity so your foot points out toward the side.
The superior part of the sternum.
A structural component made of water, collagen fibers, and crystallized calcium salts.
Closer to the midline of the body. The big toe is medial to the little toe.
A bony prominence proximal to the medial condyle.
To turn a body part around its long axis, with the anterior surface moving toward the midline, like when you turn your whole lower extremity so that your foot points inward.
At the midline of the body. For example, the nose is a median structure.
The compartment that takes up the middle portion of the thoracic cavity.
Open space inside the bone.
Coverings of the brain. They protect the brain by housing a fluid-filled space, and they function as a framework for blood vessels.
The chemical reactions that convert food into energy.
An imaginary vertical plane that clinical anatomy uses to divide the body into left and right halves.
Containing more than one nucleus.
Embryonic muscle cells.
Muscle of the heart.
Membranous lining of the nasal cavity that secretes mucus.
The part of the cranium that holds the brain.
Cells that build up bone.
Cells that break down bone.
Cells that maintain bone and collagen fibers.
Small, rounded protuberances.
Constricts the bronchi, dilates blood vessels, and increases glandular secretions.
Dense connective tissue surrounding a bundle of nerve fibers called a fascicle in the peripheral nervous system.
A covering of fibrous connective tissue.
The eustachian tube.
Joints that include a bone shaped like a pivot and a ring made of bone or ligament. Pivot joints, such as the atlantoaxial joint of the cervical spine, have rotational movements.
Joints with flat articular surfaces that allow for a sliding motion, such as the acromioclavicular joint of the shoulder.
To point your toes down.
A diamond-shaped space posterior to the knee joint, bordered by several muscles, skin, the popliteal fascia, the femur, and the joint capsule.
Closer to the rear. The spine is posterior to the abdominal muscles.
A medial rotation of the forearm so that the palm faces posteriorly (toward the rear).
Closer to the trunk or closer to the point of origin. The shoulder is proximal to the elbow.
Band-like structures that hold tendons in place while joints move.
To move backward.
Gastric folds that appear when the stomach muscle tissue is contracted.
Joints that have the appearance of a saddle. The carpometacarpal joint at the base of the thumb is an example of a saddle joint.
Imaginary vertical planes that are parallel to the midsagittal plane and divide the body into unequal left and right portions. There are many possible sagittal planes, so you should always give a reference point where the plane passes through.
The shoulder blade.
The opening in the posterior portion of the pelvis formed by the sciatic notch of the ischium and the sacrospinous and sacrotuberous ligament.
A rotation and lateral flexion of the spine that may twist and turn the thoracic cage.
Glands connected to the hair follicles. They produce sebum, which is an oily substance that helps keeps the hair flexible.
The muscles responsible for making the skeleton move. They’re voluntary muscles because you can control whether the muscles move.
Forms the deepest layer of the skin. The cells of this layer continuously divide and form new keratinocytes to replace the ones that are constantly shed. This layer also contains melanocytes, which are the cells that produce skin coloring.
Dead, mature skin cells called keratinocytes. These cells are constantly shed and replaced by cells from the lower layers of the epidermis. These cells have lost most of their internal structures and organelles.
The area of the skin where keratin is formed. The cells in this layer also produce materials that prevent evaporation, which helps waterproof the skin.
Found in thicker skin; helps reduce friction between the stratum corneum and the stratum granulosum. It’s composed of dead, flattened cells.
Contains keratin-producing cells that were formed in the stratum basale.
Area below the skin; underneath the cutaneous layer and is sometimes called the hypodermis or superficial fascia.
The part of the fascia that lies between the body walls such as the thoracic wall and the membranes that line corresponding body cavities.
Closer to the surface. For instance, the skin is superficial to the muscles.
Closer to the top of the head. For example, the nose is superior to the chin.
The muscle that turns the eyeball inferiorly and laterally.
Lateral rotation of the forearm so the palm faces anteriorly.
Causes bronchodilation and constricts the blood vessels.
The junction in the brain where nerve impulses pass.
A typical synovial joint includes bones covered in hyaline cartilage and a joint cavity lined with a synovial membrane and filled with synovial fluid. A durable fibrous joint capsule surrounds the joint. Some synovial joints also have fibrocartilaginous discs between the bones.
The section of the body that starts immediately below the neck, at the clavicles, and ends along the bottom of the ribcage. It’s visible from the front.
Imaginary horizontal planes that pass through the body at right angles to the midsagittal and the frontal planes. They divide the body into upper and lower portions. You need to have a reference point to know exactly where a transverse plane lies.
Two long tubes that lead to the urinary bladder.
Toward the abdomen.