Anatomy of the Skull Quiz

Bones and Features of the Skull

• The skull consists of 22 bones, categorized into cranial and facial bones.
• Cranial bones (8 total): protect the brain and form the cranium; include the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones.
• Facial bones (14 total): form the face, protect openings to digestive and respiratory systems; include the nasal, maxilla, zygomatic, lacrimal, palatine, vomer, inferior nasal conchae, and mandible.
• Largest cavity: cranial cavity, which houses the brain; adult volume ranges from 1300 to 1500 cubic centimeters.
• Other cavities include orbits (eye sockets), oral cavity, nasal cavity, and paranasal sinuses.

Skull Views

• Anterior view prominently displays the frontal, nasal, maxilla, mandible, parietal, sphenoid, temporal, ethmoid, lacrimal, and zygomatic bones.
• Superior view shows the frontal, parietal (left and right), and occipital bones; key sutures include coronal (frontal to parietal) and sagittal (between the parietal bones).
• Posterior view presents the occipital, parietal, and temporal bones along with the lambdoid suture; features like the external occipital protuberance and nuchal lines are visible.

Cranial Bones

• Frontal Bone: forms forehead, contains frontal sinus.
• Parietal Bone: forms sides and roof of the cranial cavity.
• Temporal Bone: includes structures for hearing and balance.
• Occipital Bone: contains foramen magnum, articulates with the spine.
• Sphenoid Bone: known as a "bridging bone," connects cranial and facial bones.
• Ethmoid Bone: forms part of the nasal cavity and orbits.

Facial Bones

• Nasal Bone: forms the bridge of the nose.
• Maxilla: supports the upper jaw and teeth.
• Zygomatic Bone: contributes to cheekbones.
• Mandible: lower jaw, movable for chewing.
• Palatine Bone: forms part of the hard palate.
• Vomer: part of the nasal septum.

Skull Features

• Coronal Suture: connects frontal to parietal bones.
• Sphenoid Bone features: articulates with multiple cranial bones.
• Pterion: junction of frontal, parietal, sphenoid, and temporal bones.
• Zygomatic Arch: formed by zygomatic and temporal bones.
• TMJ (Temporomandibular Joint): connection between the temporal bone and mandible.

Cranial Fossae

• Anterior Cranial Fossa: houses frontal lobes; formed by frontal, ethmoid, and sphenoid bones.
• Middle Cranial Fossa: supports temporal lobes and pituitary gland; extends from sphenoid to temporal bones.
• Posterior Cranial Fossa: supports brainstem and cerebellum; bordered by occipital bone.

Sutures

• Immovable joints connecting cranial bones; include coronal, lambdoid, sagittal, and squamous sutures.
• Sutural Bones: variable ossification centers found within certain sutures.

Orbital and Nasal Complexes

• Orbital Complex: includes seven bones, protecting the eyes.
• Nasal Complex: encloses nasal cavity and paranasal sinuses; main structural components visualized in sagittal section.

Internal View of Cranial Base

• Cribriform Plate of ethmoid bone: perforated for olfactory nerve passage.
• Sella Turcica: houses pituitary gland, formed by sphenoid bone.
• Foramen Magnum: large opening for spinal cord connection; occurs at the occipital bone.

Vertebral Column

• Composed of 26 bones: 24 individual vertebrae and two fused groups (sacrum and coccyx).
• Cervical Vertebrae (C1-C7): form the neck and support the head.
• Thoracic Vertebrae (T1-T12): articulate with ribs.
• Lumbar Vertebrae (L1-L5): located in lower back.
• Sacrum (S1-S5): fused bones at the base of the spine.
• Coccyx (Co1-Co4): fused bones commonly referred to as the tailbone.

Spinal Curvatures

• Four primary curvatures: cervical, thoracic, lumbar, and sacral.
• Important for structural integrity and posture.### Development of Spinal Curvatures
• Primary curvatures are thoracic and sacral, present at birth and C-shaped.
• Secondary curvatures include cervical (develops around 3-4 months) and lumbar (develops around 1 year).
• Cervical curvature arises when infants learn to hold up their heads.
• Lumbar curvature develops as children begin to walk.
• Secondary curvatures are known as compensation curves, shifting trunk weight over the legs.

Clinical View of Spinal Curvature Abnormalities

• Hyperkyphosis is an exaggerated thoracic curvature, commonly referred to as hunchback.
• Hyperlordosis refers to an exaggerated lumbar curvature, known as swayback.
• Scoliosis involves lateral curvature of the vertebral column.
• Abnormalities can result from various factors, including osteoporosis, vertebral compression fractures, osteomalacia, abnormal vertebral growth, and chronic muscle contractions.
• Treatment varies based on severity; mild to moderate scoliosis may require a back brace, while severe cases might need surgical intervention.