Anatomical terms glossary: bone markings, movements, tissue words and word roots

Anatomical terms come from ancient Greek and Latin. Because these languages are no longer used in everyday conversation, the meanings of their words do not change. OpenStax's example is hypertension: the prefix hyper- means high or over, and the root tension refers to pressure. (OpenStax Anatomy and Physiology 2e, 1.6: Anatomical Terminology.)

Most terms have up to three parts. A prefix is one or two syllables placed before a word to modify its meaning, and often describes the location or appearance of a part. The root, or stem, carries the basic meaning. A suffix is attached to the end of the root to modify it. Arthritis, for example, joins the Greek arthron, joint, and -itis, inflammation. (NCI SEER Training Modules: Prefixes, Word Roots and Suffixes.)

Parts combine in set patterns: a root plus a suffix (carcinoma), a prefix plus a root (neoplasm), a prefix, root and suffix (peri + card + itis, pericarditis), or two roots (erythroblast). A combining vowel, usually o, may be placed between parts to make the word easier to say. (NCI SEER Training Modules: Formation of Medical Terms.)

Directional prefixes appear all over anatomy. In OpenStax's list of Greek and Latin roots, ad means to or toward, ab means away from, sub means under, epi means on top of, and externus and internus mean outside and inside. So abduction moves a part away from the midline, and adduction brings it toward the midline. (OpenStax Anatomy and Physiology 2e, 11.2: Naming Skeletal Muscles.)

Superior, inferior, medial, lateral, proximal, distal and the anatomical position. Directional terms.

Bone markings are the named surface features of bones: bumps, ridges, smooth joint surfaces, grooves and holes. OpenStax sorts them into three classes. Articulations are where two bone surfaces meet to form a joint; projections are raised areas where tendons and ligaments attach; and holes are openings or grooves that let blood vessels and nerves enter the bone. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

OpenStax adds that the size and shape of a projection reflect the forces applied at that attachment, and the size of a hole reflects the size of the vessels and nerves that pass through it. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

Kenhub groups the markings differently, into projections that mainly serve as attachment sites (including the articular condyle and facet) and depressions and openings that hold nerves, vessels, tendons and muscles. Both schemes use the same names, so learn the names and their meanings rather than one system of groups. (Kenhub: Complete list of bone markings.)

In anatomy, a tubercle is a small, rounded prominence on a bone, often where a tendon or ligament attaches. A tuberosity is a larger prominence, often with a rough surface. Examples are the adductor tubercle of the femur and the ulnar tuberosity. Kenhub notes that the two words are often confused. (Kenhub: Complete list of bone markings.)

OpenStax defines a tubercle as a small, rounded process and a tuberosity as a rough surface. On the humerus, the greater tubercle is an expanded area on the lateral side of the proximal end and the smaller lesser tubercle lies on its anterior aspect, with the narrow intertubercular groove (sulcus) between them. The deltoid tuberosity is a roughened, V-shaped area on the lateral shaft where the deltoid attaches. (OpenStax Anatomy and Physiology 2e, 8.2: Bones of the Upper Limb.)

Usage is not fully consistent. TeachMeAnatomy calls the same two humeral prominences the greater and lesser tuberosities, and gives their attachments: supraspinatus, infraspinatus and teres minor on the greater, and subscapularis on the lesser. (TeachMeAnatomy: The Humerus.)

On the lower limb, the tibial tuberosity is an elevated area on the front of the tibia near its proximal end, and the adductor tubercle is a small bump at the top of the medial epicondyle of the femur. (OpenStax Anatomy and Physiology 2e, 8.4: Bones of the Lower Limb.)

A trochanter is the largest of these projections: a large, blunt, irregular process found only on the femur, as the greater and lesser trochanters. (Kenhub: Complete list of bone markings.)

A condyle is a rounded, knob-like surface at the end of a bone that forms a joint with another bone, such as the lateral condyle of the femur. An epicondyle is a projection on or just above a condyle; it does not form a joint but gives attachment to muscles and ligaments. (Kenhub: Complete list of bone markings.)

The distal femur shows the difference. Its medial and lateral condyles are smooth and articulate with the tibia below and the patella in front, while the epicondyles are non-articular elevations on the condyles, the medial being larger, from which the medial and lateral collateral ligaments of the knee arise. (TeachMeAnatomy: The Femur.)

OpenStax describes the same region: the epicondyles provide attachment for muscles and the supporting ligaments of the knee, a deep intercondylar fossa separates the condyles behind, and a wide groove at the front, the patellar surface, holds the patella. (OpenStax Anatomy and Physiology 2e, 8.4: Bones of the Lower Limb.)

At the elbow, the humerus has a much larger medial epicondyle and a smaller lateral one. The joint surfaces between them have their own names: the trochlea, a pulley-shaped surface on the medial side that articulates with the ulna, and the capitulum, a knob-like surface lateral to it that articulates with the radius. (OpenStax Anatomy and Physiology 2e, 8.2: Bones of the Upper Limb.)

The ulnar nerve passes in a groove on the back of the medial epicondyle, and both epicondyles lie outside the elbow joint capsule. (TeachMeAnatomy: The Humerus.)

The thigh bone's head, neck, trochanters, condyles and epicondyles in 3D. Femur.

A fossa is a shallow depression or basin in a bone, often receiving another bone or holding a structure. Kenhub defines it as a broad, often shallow depression that may house brain structures or receive another bone, such as the temporal fossa of the skull. A fovea is similar but much smaller, such as the fovea capitis on the head of the femur. (Kenhub: Complete list of bone markings.)

Fossae on the humerus receive the forearm bones as the elbow moves. The coronoid fossa above the trochlea receives the coronoid process of the ulna when the elbow is flexed, the radial fossa above the capitulum receives the head of the radius, and the larger olecranon fossa on the back receives the olecranon when the elbow is fully extended. (OpenStax Anatomy and Physiology 2e, 8.2: Bones of the Upper Limb.)

The scapula has three named fossae: the shallow subscapular fossa on its costal (front) surface, and the supraspinous and infraspinous fossae on its back, separated by the scapular spine. Laterally, the glenoid fossa receives the head of the humerus. (Radiopaedia: Scapula.)

Openings have separate names. A foramen is a hole through which nerves and blood vessels pass, such as the jugular foramen; a fissure is an open slit, such as the inferior orbital fissure; a meatus is a short canal, such as the external acoustic meatus (ear canal); a notch is an indentation at the edge of a bone; a sulcus is a groove; and a sinus is a cavity, such as the paranasal sinuses. (Kenhub: Complete list of bone markings.)

OpenStax describes a fossa as an elongated basin, such as the mandibular fossa of the jaw joint, and gives the foramen magnum in the occipital bone as its example of a foramen. It defines a canal as a passage through bone and a sinus as an air-filled space in bone. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

Every major foramen of the skull and what passes through it. Skull foramina.

A process is any prominent projection, such as the transverse process of a vertebra. A spine is a sharp process, such as the ischial spine; a crest is a ridge, such as the iliac crest; a line is a slight, elongated ridge, such as the temporal lines of the parietal bones; and a protuberance is a part that protrudes outward, such as the chin. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

Kenhub's examples include the mastoid process behind the ear, the external occipital protuberance at the back of the skull, the linea aspera of the femur, the iliac crest and the spine of the sphenoid bone. It describes a facet as a flat, smooth articular area, such as the acromial facet of the clavicle. (Kenhub: Complete list of bone markings.)

The linea aspera is the roughened ridge down the back of the femoral shaft. Above, its lateral lip continues as the gluteal tuberosity, where gluteus maximus attaches, and its medial lip as the pectineal line. (TeachMeAnatomy: The Femur.)

A head is a prominent rounded end that forms a joint, and a neck is the narrower part that joins it to the rest of the bone. The rounded proximal end of the femur is its head, and the narrowed region below it is the neck; the greater trochanter projects upwards above the base of the neck and the lesser trochanter lies on the medial side. (OpenStax Anatomy and Physiology 2e, 8.4: Bones of the Lower Limb.)

The humerus has two necks: the anatomical neck, which separates the head from the tubercles, and the surgical neck below them, where the axillary nerve and circumflex humeral vessels lie against the bone. (TeachMeAnatomy: The Humerus.)

The upper arm bone with its tubercles, necks, epicondyles and fossae in 3D. Humerus.

A long bone has a tubular shaft, the diaphysis, between its proximal and distal ends. Its hollow centre is the medullary cavity, filled with yellow marrow, and its walls are compact bone. Each wider end is an epiphysis, filled with spongy bone and red marrow; in adults the epiphysis meets the diaphysis at the metaphysis. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

The periosteum is the fibrous membrane covering the outer surface of the bone, except where joints form; it carries blood vessels, nerves and lymphatic vessels, and tendons and ligaments attach to it. The endosteum is a delicate membrane lining the medullary cavity, where bone growth, repair and remodelling take place. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

Compact bone is dense and strong and lies beneath the periosteum; its basic unit is the osteon. Spongy (cancellous) bone is a lighter lattice of struts called trabeculae, whose spaces in some bones hold red marrow, where blood cells form. (OpenStax Anatomy and Physiology 2e, 6.3: Bone Structure.)

In anatomy, abduction moves a limb laterally, away from the midline of the body, as when you raise your arm out to the side or spread your fingers. Its opposite, adduction, brings the limb back toward the body or across the midline. Both are described from the anatomical position, and most movements come in such opposing pairs. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

Flexion decreases the angle between the bones of a joint and extension increases it, straightening the joint. Bending the elbow or knee is flexion. Extension beyond the normal range of motion is hyperextension, which can injure the knee or elbow, and bending the neck or trunk to one side is lateral flexion. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

TeachMeAnatomy notes two exceptions to the midline rule: for the fingers and toes, abduction and adduction are measured from the midline of the hand or foot, so spreading the fingers is abduction; and circumduction, often described as circular, is more accurately a conical movement of a limb driven from its joint of origin. (TeachMeAnatomy: Anatomical Terms of Movement.)

OpenStax describes circumduction as a sequence of flexion, abduction, extension and adduction in which one end of the limb stays relatively still and the other end traces a circle. It is possible at biaxial condyloid and saddle joints and multiaxial ball-and-socket joints. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

Which synovial joints allow which movements, from hinge to ball-and-socket. Types of joints.

Rotation turns a bone around its own long axis. At the shoulder and hip, medial (internal) rotation turns the anterior surface of the limb toward the midline and lateral (external) rotation turns it away. In the neck, the atlas (C1) rotates around the dens of the axis (C2) when you shake your head to say no. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

Pronation moves the forearm from the supinated position to the palm-backward position: the radius rotates at the proximal and distal radioulnar joints and crosses over the ulna, so the two bones form an X. Supination returns the palm forward, with the radius and ulna parallel again. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

TeachMeAnatomy describes the same movements with the elbow bent: supination turns the palm upward and pronation turns it downward, and it notes the subtle difference between these and medial and lateral rotation. (TeachMeAnatomy: Anatomical Terms of Movement.)

Kenhub defines pronation and supination as medial and lateral rotation of the radius, which is why they are named separately from medial and lateral rotation of the whole limb at the shoulder. (Kenhub: Anatomical terminology: planes, directions and regions.)

Dorsiflexion lifts the front of the foot so its top moves toward the shin, and plantar flexion lifts the heel or points the toes down; these are the only movements of the ankle joint itself. Inversion turns the sole toward the midline and eversion turns it away; they happen at the intertarsal joints, not the ankle, and the foot inverts further than it everts. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

At the wrist, TeachMeAnatomy notes that the equivalent of dorsiflexion is simply called extension, and the hand's equivalent of plantarflexion is palmarflexion. It also notes that opposition of the thumb and little finger is limited to humans and some great apes. (TeachMeAnatomy: Anatomical Terms of Movement.)

Kenhub adds deviation: moving the hand toward the radial (thumb) side or the ulnar (little-finger) side at the wrist. (Kenhub: Anatomical terminology: planes, directions and regions.)

Elevation moves a part up and depression moves it down: shrugging elevates the scapulae, and elevating the mandible closes the mouth. Protraction moves the scapula or mandible forward and retraction pulls it back. Side-to-side movement of the mandible is excursion, lateral away from the midline and medial back to it. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

Opposition brings the tip of the thumb into contact with the tip of a finger and happens at the first carpometacarpal joint, a saddle joint, by combining flexion and abduction. Reposition returns the thumb to its place beside the index finger. (OpenStax Anatomy and Physiology 2e, 9.5: Types of Body Movements.)

Fascia is connective tissue found below the skin. Superficial fascia is loose connective tissue beneath the dermis, with a fatty layer and a membranous layer; deep fascia is denser fibrous tissue that envelops the muscles, such as the transversalis fascia, the fascia lata of the thigh and the plantar fascia of the foot. (Radiopaedia: Fascia.)

There is no full agreement on fascia terminology. Terminologia Anatomica replaced superficial fascia with subcutaneous tissue or hypodermis, surgeons generally use fascia to mean deep fascia, and some authors call the connective tissue that lines body cavities and supports organs visceral fascia. (Radiopaedia: Fascia.)

Inside a skeletal muscle, connective tissue forms three wrappings: the epimysium around the whole muscle, the perimysium around bundles of fibres (fascicles) and the endomysium around each fibre. At the end of the muscle these continue as a tendon, which fuses with the periosteum of the bone, or as an aponeurosis, a broad, flat, tendon-like sheet. (OpenStax Anatomy and Physiology 2e, 10.2: Skeletal Muscle.)

A tendon is the dense connective tissue that attaches a muscle to bone, while ligaments are strong bands of fibrous connective tissue that hold bones together. Near some joints, a bursa, a thin connective tissue sac of lubricating fluid, and a tendon sheath around a tendon reduce friction. (OpenStax Anatomy and Physiology 2e, 9.4: Synovial Joints.)

In anatomy, the lumen is the hollow passageway inside a tube-shaped structure, such as a blood vessel. Arteries have smaller lumens than veins, which helps maintain blood pressure, while veins are thin-walled vessels with large, irregular lumens. Around the lumen, a vessel wall has three layers: the tunica intima, tunica media and tunica externa. (OpenStax Anatomy and Physiology 2e, 20.1: Structure and Function of Blood Vessels.)

The cortex is the outer layer of an organ and the medulla is its inner region. A frontal section of a kidney shows an outer renal cortex, lighter in colour, and an inner medulla; the cortex contains the renal corpuscles and convoluted tubules. (OpenStax Anatomy and Physiology 2e, 25.3: Gross Anatomy of the Kidney.)

The adrenal gland has an outer cortex of glandular tissue, in three layers of lipid-storing cells, and an inner medulla of nervous tissue made of postganglionic sympathetic neurons. (OpenStax Anatomy and Physiology 2e, 17.6: The Adrenal Glands.)

Lymph nodes have the same plan: lymphoid follicles in the outer cortex and medullary cords of B cells and plasma cells in the inner medulla, from which lymph leaves through efferent lymphatic vessels. (OpenStax Anatomy and Physiology 2e, 21.1: Anatomy of the Lymphatic and Immune Systems.)

A hilum is the region where vessels, nerves and ducts enter and leave an organ. The renal hilum is the entry and exit site for the vessels, nerves, lymphatics and ureter of the kidney, and the renal pelvis emerges from it. (OpenStax Anatomy and Physiology 2e, 25.3: Gross Anatomy of the Kidney.)

Each lung also has a hilum, through which the pulmonary veins leave and the nerves of the pulmonary plexus enter; the visceral and parietal pleurae join each other there. (OpenStax Anatomy and Physiology 2e, 22.2: The Lungs.)

Renal cortex, medulla, pyramids and hilum in 3D and in section. Kidney.

In the peripheral nervous system, a ganglion is a group of neuron cell bodies, and a nerve is a bundle of axons. A plexus, in a general sense, is a network of fibres or vessels; the cervical, brachial, lumbar and sacral plexuses are networks of spinal nerves that give rise to the nerves of the neck, arm and leg. (OpenStax Anatomy and Physiology 2e, 13.4: The Peripheral Nervous System.)

In the brain, the cerebral cortex is a continuous layer of grey matter wrapping the forebrain, folded into ridges (gyri) separated by grooves (sulci). White matter carries signals between regions: the corpus callosum is the main pathway between the two hemispheres, and the white matter of the spinal cord is divided into columns. (OpenStax Anatomy and Physiology 2e, 13.2: The Central Nervous System.)

Oblique means at an angle: a structure that runs obliquely slants across the body, neither straight up and down nor straight across. OpenStax uses it this way when naming muscles by the direction of their fibres: rectus means straight, and the oblique muscles of the abdomen run at an angle. (OpenStax Anatomy and Physiology 2e, 11.2: Naming Skeletal Muscles.)

The two abdominal obliques show it well. The fibres of the external oblique run inferomedially, down and toward the midline, and the fibres of the internal oblique run superomedially, at right angles to them, while transversus abdominis runs transversely. (TeachMeAnatomy: The Abdominal Wall.)

The word also names a plane: an oblique plane cuts the body at an angle to the sagittal, frontal and transverse planes. (OpenStax Anatomy and Physiology 2e, 1.6: Anatomical Terminology.)

In radiology, an oblique projection is one in which the central X-ray beam passes through the body along a plane at an angle to the transverse or coronal plane, often used for angled views of the hand or foot. (Radiopaedia: Radiographic positioning terminology.)

External and internal obliques, transversus and rectus abdominis in 3D. Abdominal muscles.

Muscle names put these terms together. They describe location (frontalis lies over the frontal bone), size (gluteus maximus, medius and minimus), length (longus and brevis), position relative to the midline (lateralis and medialis), fibre direction (rectus and oblique), number of origins (biceps, triceps), number of muscles in a group (quadriceps) and action (flexor, extensor, abductor, adductor). (OpenStax Anatomy and Physiology 2e, 11.2: Naming Skeletal Muscles.)

Where a name lists attachments, the origin comes first. The sternocleidomastoid arises from the sternum (sterno) and clavicle (cleido) and inserts on the mastoid process, a bone marking. (OpenStax Anatomy and Physiology 2e, 11.2: Naming Skeletal Muscles.)

Brachial, femoral, gluteal and the other region names used in muscle and nerve names. Regional terms.

Femur

The thigh bone, the longest, heaviest and strongest bone in the body.

Hip bone

The large irregular bone of the pelvis formed by the fusion of the ilium, ischium and pubis.

Humerus

The long bone of the upper arm.

Mandible

The lower jaw bone.

Occipital bone

The bone forming the back and base of the skull.

Radius

The lateral bone of the forearm.

Scapula

The shoulder blade, a flat triangular bone on the back of the thorax.

Temporal bone

A paired bone forming part of the side and base of the skull.

Tibia

The shinbone, the medial and main weight-bearing bone of the leg.

Ulna

The medial bone of the forearm.