Joints
54959.jpg
54959 A remarkable drawing of the skull by Leonardo da Vinci code brain anatomy skull sagital normal da Vinci art View of a Skull (c. 1489) is a drawing by Leonardo da Vinci. Source: http://www.visi.com/~reuteler/leonardo.html This image (or other media file) is in the public domain because its copyright has expired.
2. Definition
PAGE 2 – Definition
| Definition |
|---|
| The skull is the bony framework of the head, composed of the cranium and facial skeleton, designed to protect the brain, support sensory organs, and anchor muscles of facial expression and mastication. |
| Core Attributes | Description |
|---|---|
| Structure | 22 bones (8 cranial, 14 facial), joined by sutures, with foramina for nerves and vessels. |
| Function | Protects brain, supports facial structure, enables chewing, breathing, and sensory function. |
| Common Diseases | Skull fractures, craniosynostosis, metastatic lesions, Paget’s disease. |
| Diagnosis | Clinical exam, X-ray, CT, MRI, bone scan. |
| Treatment | Conservative, surgical repair, neurosurgical intervention, or systemic therapy depending on cause. |
3. Anatomy
Page 3 – Applied Anatomy and Diagnostic Approach (Updated)
Table 1. U-SSPCT–C Structural Anatomy of the Skull
| Attribute | Details |
|---|---|
| Units (U) | – Cranial bones (8): • Frontal • Parietal (2) • Temporal (2) • Occipital • Sphenoid • Ethmoid – Facial bones (14): • Maxilla (2) • Zygomatic (2) • Nasal (2) • Lacrimal (2) • Palatine (2) • Inferior nasal conchae (2) • Vomer • Mandible |
| Size | Adult skull ~22–23 cm long, ~17–18 cm wide; varies by sex and age |
| Shape | Oval dome (cranium) with complex contours and facial projections |
| Position | Sits at the superior end of the axial skeleton; houses and protects the brain; articulates with the cervical spine at the foramen magnum |
| Character | Rigid osseous structure with multiple foramina, sinus cavities, and articulating sutures; highly vascularized and innervated |
| Time (Development and Aging) | – Formed from both membranous and cartilaginous ossification – Sutures remain open in infants, fuse with age – Cranial shape may change in pathology (e.g., hydrocephalus) |
| Connections | See bullet-pointed unit breakdown below |
Connections (Bullet-Pointed by Unit)
| Connection Type | Units (Subcomponents) |
|---|---|
| Arterial Supply | – External carotid artery branches: • Superficial temporal artery • Occipital artery – Internal carotid artery branches: • Ophthalmic artery – Meningeal supply: • Middle meningeal artery |
| Venous Drainage | – Diploic veins (within skull bones) – Emissary veins (connect intra- and extracranial venous systems) – Dural venous sinuses: • Superior sagittal sinus • Transverse sinus • Sigmoid sinus → internal jugular vein |
| Lymphatic Drainage | – Pericranial lymph nodes: • Parotid nodes • Mastoid (retroauricular) nodes • Occipital nodes – Final drainage into: • Deep cervical lymph chain |
| Nerve Supply | – Sensory innervation: • CN V1 (ophthalmic division) • CN V2 (maxillary division) • CN V3 (mandibular division) – Motor innervation: • CN VII (facial muscles) • CN XI (SCM and trapezius) |
| Joints | – Cranial sutures (fibrous joints): • Coronal suture • Sagittal suture • Lambdoid suture • Squamous suture – Synovial joints: • Temporomandibular joint (TMJ) • Atlanto-occipital joint (between occipital condyles and atlas/C1) |
| Ligaments | – TMJ stabilization: • Sphenomandibular ligament • Stylomandibular ligament • Temporomandibular ligament – Skull–spine connection: • Alar ligaments • Transverse ligament of atlas |
| Tendons | – Muscle attachments to skull: • Temporalis tendon (to temporal fossa) • Occipitalis tendon (to occipital bone) • SCM tendon (to mastoid process) • Masseter tendon (to zygomatic arch and mandible) |
4. Disease and Diagnosis
PAGE 4 – Clinical Diagnosis
Clinical Signs and Symptoms
| Symptom | Implication |
|---|---|
| Localized skull pain or tenderness | Trauma, infection, bone lesion |
| Headache with focal neurologic signs | Space-occupying lesion, metastasis, sinus involvement |
| Cranial nerve palsies | Skull base lesions (e.g., tumors, fractures) |
| Hearing loss | Temporal bone involvement |
| Swelling or deformity | Fracture, Paget’s disease, tumor, congenital abnormality |
| Pulsatile mass | Vascular anomaly, AV malformation, or meningeal involvement |
Imaging Modalities
| Modality | Primary Use | When/Why Used |
|---|---|---|
| X-ray (Skull series) | Evaluate sutures, sinus fluid levels, fractures | Initial trauma or pediatric screening |
| CT scan (Head/Facial bones) | Detailed bone anatomy, hemorrhage | Acute trauma, fractures, tumors |
| MRI | Brain and nerve involvement, marrow pathology | Tumors, infection, inflammation |
| Nuclear Bone Scan | Bone metabolism, multifocal lesions | Paget’s disease, metastases, infection |
| PET-CT | Combined metabolic/anatomic imaging | Suspected skull metastasis, recurrence of known cancer |
Laboratory Tests
| Test | Purpose | When/Why Used |
|---|---|---|
| ALP | Marker of increased bone turnover | Paget’s disease, osteoblastic metastasis |
| Calcium, Phosphate, PTH | Bone metabolism panel | Osteolytic lesions, endocrine disease |
| CBC with differential | Infection, malignancy suspicion | Osteomyelitis, leukemia |
| ESR/CRP | Inflammation markers | Skull osteomyelitis, vasculitis |
| Tumor markers (e.g., PSA, CEA) | Investigate metastatic disease | Skull lesions in cancer patients |
Other Diagnostic Tools
| Tool | Use | Indication |
|---|---|---|
| Neurologic exam | Cranial nerve evaluation | Skull base lesion detection |
| Biopsy/FNAC | Tissue diagnosis of lesion | Suspected neoplastic or infectious process |
| Surgical exploration | Fracture repair, tumor removal | In trauma, tumor, or infection requiring intervention |
| Head circumference (pediatrics) | Developmental monitoring | Hydrocephalus, craniosynostosis |
| Audiometry | Hearing evaluation | Temporal bone pathology, acoustic neuroma |
5. History and Culture
PAGE 5 – History, Culture, and Art
1. History of Anatomy
| Topic | Details |
|---|---|
| Trepanation | Practiced in prehistoric times; earliest form of cranial intervention. |
| Vesalius’ correction of Galen | Provided the first accurate anatomical maps of the skull. |
| Skull base exploration | Advanced with microscopy and imaging in the 20th century. |
2. History of Physiology
| Topic | Details |
|---|---|
| Skull as protector | Ancient recognition of its role in brain protection. |
| Sinus understanding | Evolved from mystical to respiratory and acoustic understanding. |
| Growth plates and sutures | Now seen as dynamic developmental zones, not just joints. |
3. History of Diagnosis
| Topic | Details |
|---|---|
| Skull X-ray | Developed in the early 1900s to detect trauma. |
| CT scanning | Introduced in the 1970s, revolutionized trauma diagnostics. |
| Palpation and measurement | Clinical assessment tools for craniosynostosis and hydrocephalus. |
4. History of Imaging
| Topic | Details |
|---|---|
| Pneumoencephalography | Pre-CT invasive brain imaging method. |
| CT & 3D imaging | Now used to assess skull shape, fractures, and surgery planning. |
| MRI | Revolutionized soft tissue and skull base pathology detection. |
5. History of Laboratory Testing
| Topic | Details |
|---|---|
| Bone markers | ALP used to monitor diseases like Paget’s. |
| Cancer markers | PSA, CA 19-9 now linked to metastatic lesions. |
| Infection detection | ESR/CRP and blood cultures for skull osteomyelitis. |
6. History of Therapies
| Topic | Details |
|---|---|
| Craniotomy | From ancient rituals to modern neurosurgical cornerstone. |
| Facial/skull reconstruction | Advanced with imaging, implants, and surgical planning. |
| Radiation/chemo | Skull base tumors now treatable with multimodal therapy. |
7. Cultural Meaning
| Topic | Details |
|---|---|
| Memento mori | Used in art to remind of mortality. |
| Icon of intellect | Often symbolizes wisdom and knowledge. |
| Symbol of danger | Used in medical and chemical warnings. |
8. Artistic Representations
| Topic | Details |
|---|---|
| Hamlet’s skull (Yorick) | Literary symbol of death and reflection. |
| Vanitas paintings | 17th-century still lifes used skulls to show life’s brevity. |
| Damien Hirst | Famous for diamond-encrusted skull as commentary on wealth and death. |
9. Notable Figures and Quotes
Notable Figures
| Name | Contribution |
|---|---|
| Vesalius | Accurate skull anatomy via dissection. |
| Macewen | Developed cranial surgery techniques. |
| Ramón y Cajal | Defined nervous system housed in the skull. |
Quotes
| Quote | Attribution |
|---|---|
| “Alas, poor Yorick! I knew him, Horatio.” | Shakespeare |
| “The skull is nature’s helmet for the brain.” | Anonymous |
| “Skulls speak of silence and thought.” | Modern proverb |
7. MCQ's
PAGE 6 – MCQs
Basic Science MCQs
1. Which bone contains the foramen magnum?
A. Frontal
B. Temporal
C. Occipital ✅
D. Sphenoid
2. Which suture connects the frontal and parietal bones?
A. Sagittal
B. Coronal ✅
C. Lambdoid
D. Squamous
Clinical MCQs
3. Battle’s sign suggests which fracture?
A. Zygomatic
B. Ethmoid
C. Frontal
D. Temporal ✅
4. What imaging finding is typical of Paget’s skull?
A. Osteopenia
B. Cotton wool appearance ✅
C. Sunburst periosteal reaction
D. Ground-glass opacity
Radiologic MCQs
5. Best imaging for skull fracture in trauma?
A. MRI
B. PET-CT
C. CT (non-contrast) ✅
D. Ultrasound
6. Bone window CT best shows what?
A. Pituitary gland
B. Circle of Willis
C. Cranial foramina and sinuses ✅
D. Cranial nerves
7. Bevelled-edge lytic lesion in child suggests?
A. Osteoma
B. Meningioma
C. Metastasis
D. Eosinophilic granuloma ✅