Gross Anatomy - Scalp & Skull

Gross Anatomy - Scalp & Skull

• Overview of Head: Composed of structures supporting special sensory systems, respiratory and digestive systems. Includes one cranial cavity, 2 ears, 2 orbits, 2 nasal cavities, and 1 oral cavity.
• Skull Function: Protects the brain and sensory organs, providing attachment sites for head muscles.
• Skull Structure: Divided into the neurocranium (calvaria/base) and viscerocranium (facial skeleton)
• Scalp Layers: Consists of five layers: skin, dense connective tissue, aponeurotic layer (epicranial aponeurosis), loose connective tissue, and pericranium (periosteum).
• Dangerous Area of Scalp : Loose connective tissue transmits infections to the cranial cavity via emissary veins.
• Sensory Innervation of Scalp: Primarily from trigeminal nerve branches (ophthalmic, maxillary, and mandibular divisions) and cervical nerves (C2 and C3).
• Scalp Arteries: Primarily supplied by the ophthalmic artery (internal carotid) and branches of the external carotid artery (superficial temporal, posterior auricular, and occipital).
• Scalp Veins: Drain into the ophthalmic vein, retromandibular vein, and external jugular vein. Occipital veins drain into internal jugular veins.
• Lymphatic Drainage: Occurs from occipital to upper deep cervical nodes, upper scalp from mastoid (retro/posterior auricular) to upper deep cervical, and upper scalp anterior to vertex to pre-auricular and parotid nodes. All drain into the jugular trunk of the neck.
• Cranial Bones: 22 bones divided for protection and structure.

Cranium

• Calvaria (Skull Cap): Superior aspect of the cranium. It has the paired parietal bones, anterior frontal bone, posterior occipital bone, and paired temporal bones.
• Sutures (Skull Joints): Immovable fibrous joints connecting cranial bones (e.g., coronal, sagittal, lambdoid, squamous).
• Fontanelles: Membranous gaps between cranial bones that allow for head deformation during childbirth. They typically close within the first year of life.
• Base of Cranium: Formed by frontal, ethmoidal, occipital, sphenoid, and temporal bones.
• Regions of Cranium: Anterior, Middle, and Posterior Cranial Fossa. Each fossa has a specific location of brain and vessels within the skull.

Facial Skeleton

• Facial Bones (General): Paired (nasal, maxilla, zygomatic, lacrimal, inferior nasal conchae, palatine bones) and unpaired (vomer).

• External Foramina: Openings in the face. For example, supraorbital, infraorbital, zygomaticofacial, mental; these contain nerves and vessels, specific features on specific bones.

• Features of Specific Cranial Bones: Sphenoid bone has specific features unique to itself (e.g., carotid canal, pharyngotympanic tube (auditory tube), foramen lacerum, foramen rotundum, foramen ovale, and foramen spinosum, and pterygoid canal). Occipital bones have features that are unique to themselves (e.g., foramen magnum, hypoglossal canal, jugular foramen, and condylar canal). Temporal bones, etc.

###Internal Foramina

• Internal Foramina and Associated Structures: Descriptions of specific locations of internal openings and what structures pass through them. For example, foramen magnum: continuation of spinal cord and major nerves. Internal acoustic meatus: facial nerve and vestibulocochlear nerve. Jugular foramen: internal jugular vein, glossopharyngeal and vagus nerves.
• Anterior, Middle, and Posterior Cranial Fossae: Each fossa contains specific parts of the brain. The structures that pass through the internal foramina are specifically identified and the bones are noted.