Synostosis: A union between adjacent bones or parts of a single bone formed by osseous material, such as ossified connecting cartilage or fibrous tissue. (Dorland, 27th ed)Craniosynostoses: Premature closure of one or more CRANIAL SUTURES. It often results in plagiocephaly. Craniosynostoses that involve multiple sutures are sometimes associated with congenital syndromes such as ACROCEPHALOSYNDACTYLIA; and CRANIOFACIAL DYSOSTOSIS.Cranial Sutures: A type of fibrous joint between bones of the head.Frontal Bone: The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the NASAL BONE and the CHEEK BONE on each side of the face.Acrocephalosyndactylia: Congenital craniostenosis with syndactyly.Ulna: The inner and longer bone of the FOREARM.Fibula: The bone of the lower leg lateral to and smaller than the tibia. In proportion to its length, it is the most slender of the long bones.Syndactyly: A congenital anomaly of the hand or foot, marked by the webbing between adjacent fingers or toes. Syndactylies are classified as complete or incomplete by the degree of joining. Syndactylies can also be simple or complex. Simple syndactyly indicates joining of only skin or soft tissue; complex syndactyly marks joining of bony elements.Ulna Fractures: Fractures of the larger bone of the forearm.Skull: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.Radius: The outer shorter of the two bones of the FOREARM, lying parallel to the ULNA and partially revolving around it.Foot Deformities, Congenital: Alterations or deviations from normal shape or size which result in a disfigurement of the foot occurring at or before birth.Zygoma: Either of a pair of bones that form the prominent part of the CHEEK and contribute to the ORBIT on each side of the SKULL.Animals, Inbred Strains: Animals produced by the mating of progeny over multiple generations. The resultant strain of animals is virtually identical genotypically. Highly inbred animal lines allow the study of certain traits in a relatively pure form. (Segen, Dictionary of Modern Medicine, 1992)Hand Deformities, Congenital: Alterations or deviations from normal shape or size which result in a disfigurement of the hand occurring at or before birth.Maxillofacial Abnormalities: Congenital structural deformities, malformations, or other abnormalities of the maxilla and face or facial bones.Toes: Any one of five terminal digits of the vertebrate FOOT.Parietal Bone: One of a pair of irregularly shaped quadrilateral bones situated between the FRONTAL BONE and OCCIPITAL BONE, which together form the sides of the CRANIUM.Abnormalities, MultipleCraniofacial Abnormalities: Congenital structural deformities, malformations, or other abnormalities of the cranium and facial bones.Twist Transcription Factor: A basic helix-loop-helix transcription factor that was originally identified in DROSOPHILA as essential for proper gastrulation and MESODERM formation. It plays an important role in EMBRYONIC DEVELOPMENT and CELL DIFFERENTIATION of MUSCLE CELLS, and is found in a wide variety of organisms.