CorpusHuman Anatomy
SkeletalJoint

Cranial sutures

Suturae cranii

Also known as: sutures, coronal suture, sagittal suture, lambdoid suture, squamous suture, metopic suture

Fibrous joints uniting the bones of the skull by a thin layer of dense connective tissue. They allow moulding at birth and growth of the vault in childhood, then progressively fuse in adulthood.

Show on body map Skull — Lateral View

Overview

Sutures are synarthroses — a type of fibrous joint unique to the skull. The bone edges may be serrated (interlocking, as in the sagittal suture), squamous (overlapping, bevelled — the squamous suture), or plane (butt). The intervening sutural ligament is continuous with the periosteum (pericranium) outside and the endosteal dura inside. In infancy sutures are wide and act as growth sites: bone is added at the suture edges perpendicular to the suture line as the brain expands.

The coronal suture separates the frontal from the parietals; the sagittal suture runs between the two parietals; the lambdoid suture separates the parietals from the occipital; the squamous suture joins the parietal and temporal squama; the metopic (frontal) suture divides the two halves of the infant frontal bone. Junction points are craniometric landmarks: bregma (coronal + sagittal, site of the anterior fontanelle), lambda (sagittal + lambdoid, posterior fontanelle), pterion (frontal, parietal, sphenoid and temporal), asterion (parietal, occipital, temporal — site of the mastoid fontanelle), nasion and inion. Small extra sutural (Wormian) bones are common in the lambdoid suture and are numerous in osteogenesis imperfecta, cleidocranial dysplasia and hypothyroidism.

Sutures begin to fuse endocranially in the third decade, sagittal first, and fusion is variable and incomplete into old age — an unreliable guide to age.

Location

Between the bones of the cranial vault and face.

Parts & subdivisions

  1. Coronal suture
    Frontal–parietal; runs across the vault from pterion to pterion. Unilateral synostosis → anterior plagiocephaly; bilateral → brachycephaly.
  2. Sagittal suture
    Between the parietals, bregma to lambda. Synostosis (the most common type) → scaphocephaly (long, narrow skull).
  3. Lambdoid suture
    Parietals–occipital; Wormian bones common. Synostosis → posterior plagiocephaly (rare).
  4. Squamous suture
    Bevelled overlap of temporal squama on the parietal bone.
  5. Metopic suture
    Between the two frontal halves; closes ≈3–9 months. Synostosis → trigonocephaly.
  6. Bregma and lambda
    Junctions marking the anterior and posterior fontanelles.
  7. Pterion and asterion
    H-shaped and three-bone junctions on the lateral skull.

Function

  • Bind skull bones while allowing slight flexibility in childhood
  • Allow moulding of the fetal head during birth
  • Sites of growth of the cranial vault
  • Absorb and dissipate mechanical stress

Clinical significance

Craniosynostosis

Premature suture fusion (≈1 in 2000–2500 births) stops growth perpendicular to the suture with compensatory growth parallel to it (Virchow law). Sagittal → scaphocephaly; metopic → trigonocephaly; coronal → plagiocephaly or brachycephaly. Syndromic forms (Crouzon, Apert) are linked to FGFR2 mutations.

Positional plagiocephaly

Flattening from supine sleeping, with patent sutures — a parallelogram-shaped head, distinct from lambdoid synostosis (trapezoid shape).

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.