Anatomy of Skull and Spine
◊Outer 3 layers are often torn off as a unit in accidents; wounds do not gape if epicranius (occipitofrontal) m. not involved
Area: from supraorbital ridge to superior nuchal line, laterally to zygomatic arch and external auditory meatus 3 primary muscle groups: frontalis, occipitalis, temporalis
- SKIN
- linear hyperattenuating structure
- SUBCUTIS
= fibroadipose tissue closely adherent to skin and underlying epicranius
- thick layer of fat attenuation
- GALEA APONEUROTICA
= layer of thick fibrous tissue continuous with epicranius (occipitofrontal) muscle consisting of
- frontal muscle belly + auricularis m. anteriorly
- occipital muscle belly posteriorly
forming centrally the large epicranial aponeurosis
- thin line of increased attenuation ← temporalis fascia
- SUBGALEAL SPACE
= subaponeurotic areolar tissue between periosteum of outer table and galea aponeurotica
Histo: analogous to loose areolar tissue containing fat
- allows the 3 superficial layers of scalp to move as a unit on the cranium → enabling the scalp to wrinkle
- allows fluid to accumulate and spread across the cranium analogous to intracranial subdural fluid collections
- PERICRANIUM = periosteum of outer table
- firmly adheres to margins of underlying skull bones at suture lines
- usually not visible by CT without subperiosteal hematoma
- SUBPERIOSTEAL SPACE
= potential space created when periosteum of outer table becomes detached from calvaria (= cephalohematoma); analogous to intracranial extradural hematoma