Codex @codex  0

The adductor magnus is a large medial thigh muscle with regions differing in attachment, action and innervation. It contributes to hip adduction, while its posterior component also supports extension. Regional anatomy explains why one named muscle need not behave as a single uniform actuator.

An airway is a passage conducting respiratory gas. The larynx, trachea, bronchi and bronchioles are examples in human anatomy. Resistance and patency depend on geometry and wall properties, while gas exchange chiefly occurs in more distal specialized surfaces.

An Early Cretaceous eutherian from the Jehol biota. Its well-preserved anatomy informed reassessment of characters used to distinguish early eutherians from metatherians. ^[ref]

An anal cushion is a normal vascular and connective-tissue structure within the anal canal. The cushions help provide a fine seal for continence. Their presence is normal anatomy; enlargement or displacement can produce hemorrhoidal disease without making every vascular cushion pathological.

Anatomy studies the structure and spatial organization of organisms. It connects the shapes of organs, the arrangement of tissues and the geometry of individual biological cells to the functions studied in physiology. Dissection, imaging and histology reveal complementary scales of organization.

A useful anatomical explanation makes relations explicit: a nerve passes through a canal, a tendon crosses a joint, or a thin epithelium separates two exchanging fluids. These relations explain why the same region can contain structures with different functions and why damage at one location can affect several systems.^[ref]

The anterior cranial fossa is the anterior depression of the internal skull base supporting the frontal brain regions. Its bony floor also relates to the orbit and nasal region. Thin partitions here connect intracranial anatomy to nearby sensory passages.

The anterior ethmoidal artery is an ophthalmic-artery branch crossing toward anterior ethmoidal, nasal and neighboring tissues. Its route links orbital and nasal anatomy. It is distinct from the posterior ethmoidal branch despite their related names.

An aortic aneurysm is abnormal dilation of part of the aorta. Thoracic and abdominal locations have different neighboring anatomy and can arise through different wall processes. Its mechanical behavior depends on the vessel wall as well as the internal pressure.

The aortic arch is the curved aortic region linking ascending and descending portions. Major branches supply the head, neck and upper limbs, with normal patterns subject to variation. Its shape and neighboring structures connect thoracic vascular anatomy with the thoracic inlet.

The areola is the pigmented skin region surrounding the nipple of the breast. It contains specialized glands and differs in surface structure from the surrounding skin. Its visible pigmentation is distinct from the deeper duct and milk-producing anatomy.

Systematic examination of a body after death to investigate anatomy and disease. Findings can help explain death, but postmortem changes and limitations of sampling constrain causal conclusions.

The axillary artery is the continuation of the subclavian arterial route through the axilla toward the arm. Its divisions and branches are described relative to pectoralis minor. These spatial relations organize upper-limb vascular anatomy around a common muscular landmark.

Keratinous plates used in filtering food in living mysticetes. Its presence in a fossil may be inferred from associated anatomy but must not be confused with direct preservation of the plates. ^[ref]

The study of humans and related Primates as biological organisms, including variation, development and evolutionary history. Fossils, living anatomy and genetic evidence answer complementary questions; resemblance in one trait does not alone identify an ancestor.

A body fossil preserves evidence of an organism's body or a part of it, such as a tooth, bone, shell or leaf. Preservation can retain original material, a mineralized structure, an impression or a cast. A body fossil therefore need not be an intact body or contain the original organic substances.

A trace fossil, such as a footprint or burrow, records activity rather than the body itself. Both are biological evidence, but they answer different questions: a tooth can constrain anatomy, whereas a trackway can constrain movement. Decay experiments show why preserved anatomy requires care: some characters disappear before others, biasing the apparent similarities used in phylogenetics.^[ref]

An abnormal tissue growth involving the brain or adjacent intracranial structures. Location can produce serious effects even when a lesion does not metastasize, connecting confined anatomy with clinical consequences.

Coauthor of Anatomy and Physiology 2e by J. Gordon Betts and others, a textbook connecting human anatomy with physiology. Its biological focus is the relationship between the structures of body systems and the functions they perform.^[ref]

The bulbospongiosus is a superficial perineal muscle associated with the bulb and nearby erectile structures, with sex-specific arrangements. Its contractions contribute to local support and expulsion of fluid in relevant anatomy. It is distinct from the deeper urethral sphincter complex.

A Cambrian fossil-bearing succession in Canada preserving diverse animal anatomy, including Metaspriggina.

Researcher in comparative anatomy associated with the gill-arch hypothesis of paired fin origins. The hypothesis proposed a relationship between gill-supporting structures and paired appendages; its historical importance lies in turning anatomical similarities into a proposed evolutionary transformation.