Anatomy of the Skull and Related Structures

Venous Communication and Emissary Veins

Emissary Veins: Connect venous sinuses with veins outside the scalp.
- Can communicate with veins at the base of the scalp, including parietal, occipital, and posterior condylar veins.

Temporal Lines:
- Inferior Temporal Line and Superior Temporal Line: Bound superiorly the temporal fossa.
- Fossa Temporalis: Contains the temporalis muscle, part of exocranial fossa.
Galea Aponeurotica: Covers the region above the superior temporal line.
- Located between the two bellies of the occipitofrontalis muscle.

Origin: Inferior temporal line.
Coverage: By fascia attached to superior temporal line.
Occupies: Most of the temporal fossa.
Floor of Temporal Fossa: Composed of parietal bone, squamous portion of temporal bone, and greater wing of sphenoid bone.

Auriculotemporal Nerve: Branch of mandibular division of trigeminal.
- Contains visceral motor fibers for the parotid gland.
Zygomaticotemporal Nerve: Branch of maxillary division of trigeminal.

Middle Meningeal Artery Sulcus: Implies artery close proximity to bone.
Sigmoid Sinus Sulcus: Seen in both temporal and parietal bones.
Superior Sagittal Sinus Groove: Present in parietal bone, accommodates venous sinus.
Pacchioni Depressions: Related to superior sagittal sinus, site for cerebrospinal fluid reabsorption.

Structure: Located between layers of dura mater, unique structure not like typical veins.
Location: Found where dura mater attaches to bone or other dura mater.

Branch of Maxillary Artery: Enters skull through foramen spinosum.
Clinical Relevance: Vulnerable to fracture at the pterion (weakest skull region).
- Extradural Hematoma: Result from laceration of middle meningeal artery.
- Epidural Space: Not normally present, forms only when something goes wrong.
- Symptoms of Hematoma: Increased intracranial pressure, nausea, vomiting, seizure, bradycardia, limb weakness.
- Treatment: Diuretics or surgical drainage.

Pterion: Important and fragile region on the lateral skull.
Cerebrospinal Fluid Pathway: Produced in choroid plexuses, fills ventricles, reabsorbed in superior sagittal sinus.
Monitoring after Head Injury: Critical due to potential for delayed symptoms from intracranial bleeding.

Note: Understanding venous sinus, arterial supply, and their clinical implications is crucial for recognizing conditions like epidural hematoma.