Bones — table
Location, articulations and ossification of the bones of the skeleton. 64 entries.
Skull 1
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Skull | Head, superior to the vertebral column. | Sutures between cranial and facial bones; temporomandibular joints (mandible–temporal); atlanto-occipital joints (occipital condyles–atlas); gomphoses (teeth in alveoli). | Calvaria and most facial bones: intramembranous. Cranial base (occipital except upper squama, sphenoid body, petrous temporal, ethmoid): endochondral (chondrocranium). |
Skull — cranial bones 6
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Frontal bone | Forehead and anterior part of the cranial vault and base. | Parietal bones (coronal suture), sphenoid, ethmoid, nasal bones, maxillae, lacrimal bones and zygomatic bones (12 bones in total). | Intramembranous, from two primary centres (one per half) appearing ≈week 8; the halves are joined by the metopic (frontal) suture, which fuses between ≈3 and 9 months but persists in ≈5–10% of adults. |
| Parietal bone | Superolateral cranial vault, between frontal, occipital and temporal bones. | Opposite parietal (sagittal suture), frontal (coronal), occipital (lambdoid), temporal (squamous) and sphenoid (sphenoparietal suture at the pterion). | Intramembranous, from two centres near the parietal tuber appearing ≈week 8. |
| Occipital bone | Posterior and inferior part of the cranium. | Parietals (lambdoid suture), temporals (occipitomastoid suture), sphenoid (spheno-occipital synchondrosis), atlas (atlanto-occipital joints). | Mixed: the squama above the highest nuchal line (interparietal part) is intramembranous; the rest (supra-occipital, two exoccipitals, basi-occipital) is endochondral. The parts fuse by ≈6 years. |
| Temporal bone | Lateral wall and base of the cranium, below the parietal bone. | Parietal (squamous suture), occipital (occipitomastoid suture), sphenoid (sphenosquamous suture), zygomatic (temporozygomatic suture) and mandible (TMJ — synovial). | Squamous and tympanic parts intramembranous; petrous part endochondral (from the otic capsule); the styloid from 2nd pharyngeal arch cartilage. Parts unite in the first year. |
| Sphenoid bone | Middle of the cranial base, between frontal/ethmoid in front and occipital/temporal behind. | All other cranial bones (frontal, parietals, occipital, temporals, ethmoid) and the vomer, palatines, zygomatics and occasionally maxillae. | Mostly endochondral (body, lesser wings, roots of greater wings); the lateral greater wings and lateral pterygoid plates are intramembranous. Pre- and post-sphenoid parts fuse ≈8 months fetal;… |
| Ethmoid bone | Anterior cranial base between the orbits; roof and lateral walls of the upper nasal cavity. | Frontal, sphenoid, nasal bones, maxillae, lacrimal bones, palatine bones, inferior nasal conchae and vomer. | Endochondral, from three centres (one per labyrinth prenatally and one for the perpendicular plate in the first year); parts unite by ≈3 years. |
Skull — facial bones 8
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Nasal bone | Upper part (bridge) of the external nose, between the frontal processes of the maxillae. | Frontal bone, ethmoid (perpendicular plate), opposite nasal bone and frontal process of the maxilla. | Intramembranous, one centre each, ≈week 9–10. |
| Maxilla | Central face, between the orbits and the upper teeth. | Frontal, ethmoid, nasal, zygomatic, lacrimal, palatine, inferior nasal concha, vomer and opposite maxilla (intermaxillary suture); occasionally the sphenoid. | Intramembranous from several centres beginning ≈week 6; the premaxilla (incisor-bearing segment) fuses early. |
| Zygomatic bone | Prominence of the cheek, inferolateral to the orbit. | Frontal, sphenoid (greater wing), temporal and maxilla. | Intramembranous, usually one centre ≈week 8. |
| Lacrimal bone | Anterior part of the medial orbital wall, behind the frontal process of the maxilla. | Frontal, ethmoid, maxilla and inferior nasal concha. | Intramembranous, single centre ≈week 12. |
| Palatine bone | Posterior part of the nasal cavity and hard palate, between maxilla and pterygoid process of the sphenoid. | Maxilla, sphenoid, ethmoid, inferior nasal concha, vomer and opposite palatine bone. | Intramembranous, single centre ≈week 8 in the perpendicular plate. |
| Inferior nasal concha | Lower lateral wall of each nasal cavity. | Maxilla, lacrimal, ethmoid and palatine bones. | Endochondral, from a single centre ≈month 5 of fetal life. |
| Vomer | Midline, posteroinferior nasal septum. | Sphenoid, ethmoid, both maxillae, both palatine bones and the septal cartilage. | Intramembranous, from two centres either side of the midline ≈week 8, which fuse. |
| Mandible | Lower face; forms the lower jaw and chin. | Temporal bones at the temporomandibular joints (bilateral synovial joints); teeth in sockets (gomphoses). | Mostly intramembranous, beginning ≈week 6–7 lateral to Meckel cartilage (1st pharyngeal arch); secondary cartilages form the condyle (a growth site until early adulthood) and coronoid process. |
Hyoid 1
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Hyoid bone | Anterior neck at C3 level, above the thyroid cartilage, below the mandible. | None with other bones — connected by the stylohyoid ligaments, thyrohyoid membrane and muscles. | Endochondral, from six centres; greater horns ossify before birth, the body shortly after, the lesser horns at puberty. Body and greater horns fuse in middle life. |
Vertebral column 9
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Vertebral column | Midline of the back, from the skull to the coccyx. | — | — |
| Typical vertebra | Repeated segmental units of the vertebral column. | — | Three primary centres at ≈8 weeks — one for the centrum and one for each half of the neural arch; the halves of the arch fuse ≈1 year, arch and centrum ≈3–6 years.… |
| Cervical vertebrae | Neck, between the skull and T1. | Atlanto-occipital joints (C1–occiput), atlanto-axial joints (C1–C2), intervertebral discs and facet joints C2–T1, uncovertebral joints C3–T1. | — |
| Atlas (C1) | Uppermost vertebra, directly below the occipital bone. | Occipital condyles (atlanto-occipital joints); axis — dens (median atlanto-axial) and two lateral atlanto-axial joints. | Three centres — one for each lateral mass (≈7th week) and one for the anterior arch (≈1st year); the posterior arch unites at ≈3–4 years and the anterior arch at ≈6–8 years. |
| Axis (C2) | Second vertebra of the neck, below the atlas. | Atlas (median and lateral atlanto-axial joints), C3 (intervertebral disc and facet joints). | Five primary centres — body, two halves of the arch and two for the dens — plus a secondary centre for the dens tip (os terminale). The dens fuses to the body ≈3–6 years (subdental synchondrosis may mimic a fracture in children). |
| Thoracic vertebrae | Posterior thoracic wall, between C7 and L1. | Ribs (costovertebral and costotransverse joints), adjacent vertebrae (discs and facet joints). | — |
| Lumbar vertebrae | Lower back, between T12 and the sacrum. | T12 above, sacrum (lumbosacral joint) below; discs and facet joints. | — |
| Sacrum | Posterior pelvis, between the two hip bones, below L5. | L5 (lumbosacral joint and disc), ilia (sacroiliac joints), coccyx (sacrococcygeal symphysis). | Each segment has the three primary centres of a typical vertebra plus costal-element centres in the alae; the segments begin to fuse at puberty from below upward and complete fusion by ≈25–30 years. |
| Coccyx | Inferior end of the vertebral column, behind the anal canal, in the natal cleft. | Sacrum (sacrococcygeal symphysis); intercoccygeal joints between segments (often fused). | One primary centre per segment, appearing from ≈1–4 years (first segment) to ≈10–20 years (last); segments fuse progressively in adulthood. |
Thoracic cage 3
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Thoracic cage | Chest, from the root of the neck to the upper abdomen. | Costovertebral (heads of ribs and costotransverse), sternocostal, costochondral, interchondral, manubriosternal and xiphisternal joints. | — |
| Ribs | Thoracic wall, from the thoracic vertebrae posteriorly to the sternum and costal margin anteriorly. | Joints of the heads of ribs and costotransverse joints posteriorly; costochondral joints anteriorly (cartilage to sternum or to the cartilage above). | Endochondral; primary centre near the angle ≈week 6–9; secondary centres for the head and tubercle at puberty, fusing ≈20–25 years. |
| Sternum | Anterior midline of the thorax. | Clavicles (sternoclavicular joints), costal cartilages 1–7 (1st synchondrosis; 2–7 synovial sternocostal joints), manubriosternal and xiphisternal joints. | Endochondral from 6 centres (1 manubrium, 4 body, 1 xiphoid); the sternebrae of the body fuse from below upward between puberty and ≈25 years; the manubriosternal joint usually persists. |
Upper limb — pectoral girdle 2
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Clavicle | Horizontally across the root of the neck, between the manubrium and the acromion. | Manubrium and 1st costal cartilage (sternoclavicular joint), acromion of scapula (acromioclavicular joint). | The first bone to ossify (weeks 5–6) — mostly intramembranous from two primary centres in the shaft; the ends form in cartilage.… |
| Scapula | Posterolateral thoracic wall, overlying ribs 2–7. | Humerus (glenohumeral joint), clavicle (acromioclavicular joint); scapulothoracic gliding articulation (functional, not anatomical). | Primary centre in the body ≈week 8; coracoid centre ≈1st year (fuses ≈15 years); several secondary centres at puberty (acromion, inferior angle, medial border, glenoid) fuse by ≈20–25 years.… |
Upper limb — arm 1
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Humerus | Arm, between the shoulder and the elbow. | Scapula (glenohumeral joint), ulna (humero-ulnar joint), radius (humeroradial joint). | Primary centre in the shaft ≈week 8. Secondary centres: head (≈birth–6 months), greater tubercle (≈1–2 y), lesser tubercle (≈4–5 y) — fuse into one proximal epiphysis that unites with the shaft ≈18–20 y (the "growing end");… |
Upper limb — forearm 2
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Radius | Lateral forearm, from the elbow to the thumb side of the wrist. | Humerus (humeroradial), ulna (proximal and distal radioulnar joints), scaphoid and lunate (radiocarpal joint). | Primary centre in the shaft ≈week 8. Distal epiphysis appears ≈1 year and fuses ≈17–19 years (the "growing end"); head appears ≈5 years and fuses ≈14–17 years. |
| Ulna | Medial forearm, from the elbow (olecranon) to the little-finger side of the wrist. | Humerus (humero-ulnar joint), radius (proximal and distal radioulnar joints); indirectly with the triquetrum via the articular disc. | Primary centre ≈week 8. Distal epiphysis appears ≈5–6 years and fuses ≈17–19 years (growing end); olecranon centre ≈9–11 years, fusing ≈15–16 years. |
Upper limb — hand 3
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Carpal bones | Wrist, between the distal radius/ulna and the metacarpals. | Radiocarpal, midcarpal, intercarpal, pisotriquetral and carpometacarpal joints. | — |
| Metacarpals | Palm of the hand, between the carpus and the proximal phalanges. | Carpometacarpal joints (distal carpal row), intermetacarpal joints (bases), metacarpophalangeal joints (proximal phalanges). | Primary centre in each shaft ≈week 9; secondary centres in the heads of metacarpals 2–5 but at the base of the 1st metacarpal (like a phalanx), appearing ≈2–3 years and fusing ≈15–19 years. |
| Phalanges of the hand | Fingers and thumb, distal to the metacarpals. | Metacarpophalangeal joints (condyloid) and interphalangeal joints (hinge). | Primary centres in the shafts ≈weeks 8–12 (distal phalanges first, ossifying from the tip); a single secondary centre at the base of each phalanx (≈2–4 years), fusing ≈14–18 years. |
Upper limb — carpal bones 8
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Scaphoid | Lateral (radial) side of the proximal carpal row; floor of the anatomical snuffbox. | Radius, lunate, capitate, trapezium and trapezoid. | Single centre at ≈5–6 years. |
| Lunate | Centre of the proximal carpal row, between scaphoid and triquetrum. | Radius, scaphoid, triquetrum, capitate (± hamate); articular disc of the TFCC. | Single centre ≈4 years. |
| Triquetrum | Medial (ulnar) side of the proximal carpal row. | Lunate, pisiform, hamate; articular disc of the TFCC. | Single centre ≈2–3 years. |
| Pisiform | Palmar surface of the triquetrum, medial wrist (base of the hypothenar eminence). | Triquetrum (pisotriquetral joint). | Last carpal to ossify, ≈9–12 years. |
| Trapezium | Lateral end of the distal carpal row, at the base of the thumb. | Scaphoid, trapezoid, 1st and 2nd metacarpals. | Single centre ≈5 years. |
| Trapezoid | Distal carpal row, between the trapezium and the capitate. | Scaphoid, trapezium, capitate and 2nd metacarpal. | Single centre ≈5–6 years. |
| Capitate | Centre of the distal carpal row. | Scaphoid, lunate, trapezoid, hamate and metacarpals 2–4. | First carpal to ossify, ≈1–3 months after birth. |
| Hamate | Medial (ulnar) end of the distal carpal row. | Capitate, triquetrum, lunate (variably), 4th and 5th metacarpals. | Single centre ≈2–4 months (second carpal to appear). |
Lower limb — pelvic girdle 5
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Bony pelvis | Lower trunk, between the vertebral column and the lower limbs. | Sacroiliac joints, pubic symphysis, lumbosacral joint, sacrococcygeal joint, hip joints. | — |
| Hip bone | Lateral and anterior walls of the pelvis; the hip region. | Sacrum (sacroiliac joint), opposite hip bone (pubic symphysis), femur (hip joint). | Three primary centres — ilium (≈week 9), ischium (≈4 months), pubis (≈4–5 months fetal). Ischiopubic ramus fuses ≈7–8 years; the triradiate cartilage fuses ≈14–16 years.… |
| Ilium | Upper part of the hip bone; palpable crest at the waist. | Sacrum (sacroiliac joint); fused with ischium and pubis at the acetabulum. | Primary centre above the greater sciatic notch ≈week 9; secondary centres for the iliac crest (appears ≈13–15 y, fuses ≈20–25 y — Risser sign of skeletal maturity) and AIIS. |
| Ischium | Posteroinferior hip bone; palpable in the buttock when sitting. | Fused with ilium and pubis. | Primary centre ≈4 months fetal; secondary centre for the ischial tuberosity at puberty (fuses ≈20–25 years). |
| Pubis | Anterior pelvis, either side of the midline above the genitalia. | Opposite pubis (pubic symphysis); fused with ilium and ischium. | Primary centre ≈4–5 months fetal; secondary centres including the symphyseal surface, whose changing morphology is used to estimate age at death in forensic anthropology. |
Lower limb — thigh & knee 2
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Femur | Thigh, from the hip joint to the knee joint. | Acetabulum of the hip bone (hip joint), tibia (tibiofemoral joint), patella (patellofemoral joint). | Primary centre in the shaft ≈week 7. Secondary centres: distal end ≈36 weeks’ gestation (present at term — a forensic sign of maturity), head ≈6 months–1 year, greater trochanter ≈4 years, lesser trochanter ≈12–14 years.… |
| Patella | Anterior knee, within the quadriceps tendon. | Patellar surface of the femur (patellofemoral joint). | Cartilaginous at birth; ossifies from several centres at ≈3–6 years, which coalesce; failure to fuse produces a bipartite patella (usually superolateral, a normal variant not to be mistaken for fracture). |
Lower limb — leg 2
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Tibia | Medial bone of the leg, from knee to ankle. | Femur (knee), fibula (proximal and distal tibiofibular joints), talus (ankle). | Primary centre ≈week 7. Proximal epiphysis appears ≈36 weeks’ gestation/birth and is the growing end (fuses ≈16–20 years); distal epiphysis ≈1 year (fuses ≈15–18 years);… |
| Fibula | Lateral leg, from below the knee to the lateral ankle. | Tibia (proximal tibiofibular synovial joint; distal tibiofibular syndesmosis), talus (ankle joint). | Primary centre ≈week 8. Distal epiphysis appears ≈1 year (fuses ≈15–18 years); proximal epiphysis ≈3–4 years (fuses ≈17–20 years) — an exception to the rule that the epiphysis appearing first fuses last. |
Lower limb — foot 3
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Tarsal bones | Hindfoot and midfoot, between the leg bones and the metatarsals. | Ankle (talocrural), subtalar, transverse tarsal (Chopart), intertarsal, tarsometatarsal (Lisfranc) joints. | — |
| Metatarsals | Forefoot, between the tarsus and the toes. | Tarsometatarsal (Lisfranc) joints, intermetatarsal joints, metatarsophalangeal joints. | Primary centres in the shafts ≈weeks 9–10; secondary centres in the heads of metatarsals 2–5 and the base of the 1st (≈3 years), fusing ≈15–18 years;… |
| Phalanges of the foot | Toes, distal to the metatarsals. | Metatarsophalangeal and interphalangeal joints. | Primary centres ≈weeks 9–15 (distal phalanx of the hallux first); secondary centres at the bases appear ≈2–8 years and fuse ≈15–18 years. |
Lower limb — tarsal bones 5
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Talus | Between the tibia/fibula above, the calcaneus below and the navicular in front. | Tibia and fibula (ankle), calcaneus (subtalar), navicular (talonavicular). | Single centre ≈7 months fetal (present at birth). The lateral tubercle of the posterior process has a separate centre; if un-united it forms an os trigonum (≈7–14%). |
| Calcaneus | Heel, below the talus. | Talus (subtalar and talocalcaneonavicular joints), cuboid (calcaneocuboid joint). | Primary centre ≈month 3 fetal (first tarsal to ossify); secondary centre for the posterior tuberosity ≈6–8 years, fusing ≈14–16 years. |
| Navicular | Medial midfoot, between talus and cuneiforms. | Talus, three cuneiforms, occasionally cuboid. | Last tarsal to ossify, ≈3–4 years (earlier in girls). |
| Cuboid | Lateral midfoot, in front of the calcaneus. | Calcaneus, lateral cuneiform, navicular (occasionally), 4th and 5th metatarsals. | Usually a single centre just before or at birth (≈9 months fetal). |
| Cuneiform bones | Medial and central midfoot, between the navicular and metatarsals 1–3. | Navicular, each other, cuboid (lateral), metatarsals 1–4. | Lateral ≈1 year, medial ≈2 years, intermediate ≈3 years. |
Hearing & balance — middle ear 3
| Bone | Location | Articulations | Ossification |
|---|---|---|---|
| Malleus | Lateral-most ossicle: handle within the tympanic membrane, head in the epitympanic recess. | Incudomallear joint (saddle-type synovial) with the body of the incus. | Ossifies from a single centre around 16 weeks; ossicles reach adult size before birth. |
| Incus | Middle ossicle; body in the epitympanic recess, long process hanging down behind the malleus handle (seen through the posterosuperior quadrant of the drum). | Incudomallear joint (saddle synovial) with the malleus; incudostapedial joint (ball-and-socket synovial) with the stapes. | — |
| Stapes | Medial-most ossicle: horizontal in the middle ear, footplate in the oval window on the medial wall, above and behind the promontory, just below the facial canal. | Incudostapedial joint (ball-and-socket synovial); syndesmosis of footplate with oval window margin (annular ligament). | — |