Gross and Clinical Anatomy of the Skull and Scalp

Sixty practice flashcards covering the gross and clinical anatomy of the skull and scalp based on lecture notes.

What are the two primary divisions of the cranium?

The upper part (neurocranium) and the lower part (viscerocranium).

Which bones make up the neurocranium?

1 frontal, 2 parietal, 2 temporal, 1 sphenoid, 1 occipital, and 1 ethmoid bone.

Where is the sagittal suture located?

In between the two parietal bones.

What is the junction between the frontal bone and the two parietal bones called?

The Coronal Suture.

Which suture represents the junction between the two parietal bones and the occipital bone?

The Lambdoidal Suture.

What is the Bregma?

The junction of the two parietal bones and the frontal bone, representing the previous site of the anterior fontanelle.

Which landmark is defined as the highest point of the skull?

The Vertex.

What is the Lambda?

The junction between the two parietal and occipital bones, representing the previous site of the posterior fontanelle.

What is another name for the external occipital protuberance?

The Inion.

What are the superciliary arches?

Two prominent ridges on the frontal bone that mark the junction of the face and scalp, marked externally by the eyebrows.

Why is the Pterion clinically significant?

It is the thinnest part of the cranium where the middle meningeal artery passes underneath, and a fracture here can cause an epidural hematoma.

What are the four bones that meet at the Pterion?

The frontal, parietal, temporal, and sphenoid bones.

What is the origin of the middle meningeal artery?

The maxillary artery.

Through which foramen does the middle meningeal artery enter the skull?

The foramen spinosum.

Which branch of the middle meningeal artery lies close to the motor area of the cerebral cortex?

The anterior branch.

Where can the superficial temporal artery be palpated?

As it crosses the zygomatic arch, immediately in front of the auricle (ear).

What are the origin and insertion of the temporalis muscle?

The origin is the temporal fossa and the insertion is the coronoid process of the mandible.

What is the action of the temporalis muscle?

It elevates and retracts the mandible to close the mouth.

Which nerve innervates the temporalis muscle?

$V3$ (the mandibular division of the Trigeminal nerve).

How many bones compose the viscerocranium?

14 bones.

Which bones of the viscerocranium are unpaired?

The vomer and the mandible.

What landmark divides the anterior and middle cranial fossae?

The lesser wing of the sphenoid.

What landmark divides the middle and posterior cranial fossae?

The petrous part of the temporal bone.

What happens to a patient if the medulla oblongata passes through the foramen magnum?

The patient is herniating and will die; normally, the spinal cord passes through here.

What nerve passes through the perforations of the cribriform plate?

The Olfactory nerve (CN I).

What is anosmia?

An abnormality or loss of the sense of smell.

What are the clinical signs of an anterior cranial fossa fracture involving the orbital plate?

Raccoon’s eye (panda sign) and exophthalmos (protrusion of the eyeball).

Which nerve passes through the optic canal?

The Optic nerve (CN II).

How is visual acuity tested for CN II?

Using a Snellen chart at a distance of $6\,m$. or by checking counting fingers, hand movement, and perception of light.

What is anisocoria?

Unequal pupil size.

Which nerves are transmitted through the superior orbital fissure?

CN III (oculomotor), IV (trochlear), VI (abducens), and branches of $V1$ (nasociliary, frontal, lacrimal).

What are the definitions of ptosis, nystagmus, and strabismus?

Ptosis is eyelid paralysis, nystagmus is eye oscillation, and strabismus is being cross-eyed.

What opening transmits the maxillary division ($V2$) of the Trigeminal nerve?

Foramen rotundum.

What opening transmits the mandibular division ($V3$) of the Trigeminal nerve?

Foramen ovale.

Which nerves are tested via the corneal reflex?

The afferent limb is $V1$ and the efferent limb is CN VII.

What is CSF otorrhea?

CSF leakage from the ears, often seen in middle cranial fossa fractures.

Which nerves pass through the internal acoustic meatus?

CN VII (facial) and VIII (vestibulocochlear).

Which nerves pass through the jugular foramen?

CN IX (glossopharyngeal), X (vagus), and XI (spinal accessory).

Why is CN XII injury rare in skull fractures?

Because of the strong bony walls of the hypoglossal canal.

What is the Battle sign?

A hematoma formation at the nape of the neck or near the mastoid process indicating a posterior cranial fossa fracture.

Where does the spinal part of the spinal accessory nerve exit the cranium?

The foramen magnum.

When does the anterior fontanelle typically close?

At 18 months.

What clinical information can be gathered from touching a baby's fontanelle?

Degree of hydration (depressed = dehydration) and state of intracranial pressure (bulging = increased ICP).

What is the ratio of the face to the cranium in a neonatal skull?

$$1:8$$

What is a pond fracture?

A localized depression in a neonatal skull without splintering, similar to a dent in a table tennis ball.

Why are adult skull fractures often likened to eggshell fractures?

Because the inner table is particularly brittle and produces splintering when hit.

What is an epidural hematoma?

A collection of blood between the bone and the dura mater, typically caused by a tear in the middle meningeal artery.

How does an epidural hematoma appear on a CT scan?

As a lens-shaped, biconvex hyperdensity that does not cross the suture lines.

What are the boundaries of the scalp?

Anterior: superciliary arches; Posterior: external occipital protuberance and superior nuchal lines; Lateral: temporal lines.

What does the acronym S-C-A-L-P stand for?

Skin, Connective tissue, Aponeurotic, Loose areolar tissue, Pericranium.

What structure forms within the skin of the scalp if a sebaceous gland duct is obstructed?

A sebaceous cyst.

Why do scalp wounds in the connective tissue layer bleed profusely?

The layer is rich in blood vessels held in place by fibrous septa, preventing them from retracting or constricting.

Which arteries of the scalp are branches of the internal carotid artery?

The supratrochlear and supraorbital arteries.

Which nerve supplies the scalp anterior to the ear up to the vertex?

The Trigeminal nerve.

Which nerve supplies the scalp posterior to the ear?

Cervical spinal nerves (e.g., Greater Occipital nerve).

What is Caput Succedaneum?

Subcutaneous scalp edema resulting from difficult vaginal delivery; it crosses suture lines.

Which layer of the scalp is responsible for wounds gaping?

The aponeurotic layer (Galea Aponeurotica), due to the opposing pulls of the occipitalis and frontalis muscles.

Why is the loose areolar tissue called the dangerous layer of the scalp?

It contains valveless emissary veins that can spread infection from the scalp to the intracranial venous sinuses.

Which nerves are found in the sides of the cavernous sinus?

CN III, IV, $V1$, and $V2$.

Where does the lymph from the occipital part of the scalp drain?

Into the occipital nodes.