WR1 - Skull & Scalp Flashcards
What type of joint is found between bones in the skull?
Fibrous joints called ‘suture joints’
What are the 3 parts of the skull?
Neuro-cranium
Facial skull (viscera-cranium)
Mandibe
What are the layers of the skull bone?
Top and bottom are Compact bone
Middle layer is called the ‘Diploe’ ,is Spongey bone and contains red marrow
Identify dem bones
yes
Identify the sutures
What bones do they join?
Sagittal: Parietal to parietal
Coronal: Frontal to parietal
Lambdoid: Parietal to occipital
What type of bones make up the facial skeleton?
Irregular bones
What muscles are attached to the bones of the face?
Muscles of the:
tongue
Mastication
pharynx
What is this bony prominence?
Occipital protuberance
of the occipital bone
Identify this
Mastoid process of temporal bone
What is the zygomatic arch and what makes it up?
Zygomatic and temporal bone
What are these?
Styloid processes of the temporal bone
serves as an anchor point for several muscles associated with the tongue and larynx
What are these?
Occipital condyles of the occipital bone
These articulate with the first vertebra (atlas)
What are the three fossae of the skull floor?
Anterior cranial fossa
Middle “ “
Posterior “ “
What bone is this?
Sphenoid bone
- This makes up part of the floor of the skull
- The ‘greater wing’ is the part that does this
What is the largest foramen in the skull floor?
What passes through it?
Foramen MAGNUM
- Medulla
- Meninges
- R&L Vertebral arteries
- Ant & Post Spinal arteries
- Some other things
What are the ‘orbits’ of the skull?
The sockets for the eyeball
What are air sinuses/sacks in skull bones?
What is their purpose
Air spaces present within the skull bone. They play a role in decreasing the weight of the skull. AIr sinuses are present in bones around the nasal cavity and open into it
What are the ear ossicle bones?
Maleus - hammer
Incus - Anvil
Stapes - stirrup
What is the canal in the skull which is used for hearing?
External auditory meatus (external ear canal)
Which bone is the external auditory meatus found on?
Temporal bone
What are the boundaries of the scalp?
- Anteriorly to eyebrows
- Posteriorly to superior nuchal lines
- Laterally to superior temporal line
Where is the superior nuchal line?
Superior temporal line?
At the top of temporal fossa (but is still on parietal bone)
What type of joint is present between the two bones of the zygomatic arch?
Zygomatic - Temporal
‘Oblique suture’ - Fibrous joint
What are the layers of the scalp?
Skin
Connective tissue (dense)
Aponeurosis (of occipitalfrontal muscle)
Loose connective tissue*
- Spongelike - allows free movement of the scalp proper (upper 3 layers)
Pericranium*
- Dense layer of connective tissue
*not easily visible
The 3rd layer of the scalp is the aponeurosis. What does it join?
Anterior (frontal) and posterior (occipital) bellies of the occipitofrontalis muscle
This is a muscle of facial expression (elevates raises eyebrows)
Cutaneous innervation of the scalp comes through two sources. What are these?
Anterior part
- The 3 branches of Trigeminal nerve (CN V)
Posterior part
- Cutaneous branches of cervical spinal nerves C3 & C4
- Both ventral & dorsal rami suppy the scalp
(Anterior/posterior to external ear canal)
What structure forms from the ventral rami of C5 to T1 spinal nerves?
Brachial plexus
What are the branches of the Trigeminal nerve?
Opthalmic - V1
Maxillary - V2
Mandibular - V3
Idenfity these facial dermatomes.
(these vary a lot across different diagrams)
What is the link with herpes zoster and dermatomes?
Dermatome affected on the skin corresponds to the nerve which supplies it
So patient with herpes zoster on left upper facial area = Left opthalmic nerve (V1)
In which layer(s) of the sculp are blood vessels contained?
What characterises these blood vessels?
Dense connective tissue layer
Vessels within this layer are unable to fully constrict so lacerations can cause profuse bleeding
What are the 2 main arteries that supply the scalp?
External carotid (posterior)
Opthalmic artery (anterior)
- Large branch of the internal carotid
What are the branches of the External carotid and Opthalmic artery that supply the scalp?
Identify them
When it says Indirect branches of Internal carotid - it means via Opthalmic artery
These are all anastamosing branches
What two veins in the neck recieve (most of) the drainage from the scalp?
Internal jugular vein (the big one)
External jugular vein
Identify the superficial veins that drain skull
Superficial temporal is fed into by Frontal and parietal tributaries
In addition to anastamosing with each other in the scalp, what other veins do the scalp veins anastamose with?
Diploic veins in the skull bones (and through these to the venous sinuses of the brain) through valveless veins called ‘Emissary veins’
What is the purpose of emissary veins?
Connect the extracranial venous system with the intracranial venous sinuses.
They connect the veins outside the cranium to the venous sinuses inside the cranium (ie providing an alternative route for venous drainage)
What potential grave complication could arise from scalp infections due to the presence of emissary veins?
- Rupturing of emissary veins = Subdural haematoma
- Also provides route for infection spread (meningitis etc)
