Neuroanatomy Flashcards
What is the crista galli?
projection of ethmoid bone - anterior attachment of the falx cerebri
What are the 4 projections of the temporal bone
- zygomatic (forward)
- Petrous projection (inwards)
- mastoid (inferior for sternocleidomastoid muscle)
- styloid - very sharp and pointy - for oral cavity and pharynx muscle
Describe the features of the sphenoid bone?
contributes to the cranial base. Body (turkish saddle contains pituitary) Lesser wing (more superior) above the superior orbital fissure, Greater wing - below SOF and contains 4 foramina
Name the foramen of the middle cranial fossa?
Optic canal, SOF, foramen rotundum, foramen ovale, foraemen spinosum, foramen lacerum
Name the foramen in the posterior cranial fossa
Internal auditory meatus, jugular foramen, foramen magnum, hypoglossal canal
What is the emissary vein? why is it important?
drains blood from the scalp to the dural sinuses ->important as risk of infection spread.
What is the Diploic vein what does it drain?
Drains the spongy middle layer of the skull bone (diploe) into the dural sinuses
Where do the cerebral veins drain? what is important about this?
drain to the dural venous sinuses - are susceptible to injury from tearing in elderly when brains atrophy with age -> leading to a subdural bleed
Describe the dural venous sinuses in the cranial cavity
Superior sagittal sinus runs in the superior margin of the falx cerebri, the inferior sagittal sinus runs in the inferior portion of the falx cerebri. Inferior sagittal sinus joins with the Great cerebral vein to form the straight sinus, which can or cannot join with the superior sagittal sinus to form the transverse sinus which run in the tentorium cerebelli then form the sigmoid sinus at the border with the petrous part of the temporal bone, Sigmoid sinus runs though the jugular foramen to become the internal jugular vein.
What is the tentorium cerebelli?
“tent over the cerebellum” horizontal projection of dura
What are the Cavernous sinuses?
in the dural lining of the body of the sphenoid -> important structures run through the sinuses to access their foraminae
Where does the middle meningeal artery branch from? where does it run?
branch of the maxillary artery and gives off the middle meningeal artery which enters the skull (foramen spinosum) and divides into anterior and posterior branches run between the 2 layers of dura mata. Branches groove the bone and run in the region of the pterion.
Where is the central sulcus?
fold of the cerebral cortex that lies between the frontal lobe and parietal lobe (coronal plane)
Where is the lateral fissure (Sylvian fissure)?
Lies between the frontal and parietal lobes superiorly and the temporal lobe inferiorly
What are the components of the brainstem?
Midbrain, Pons and Medulla
What structures are derived from the neural crest cells?
PNS - DRG, enteric ganglia, parasympathetic and sympathetic ganglia, schwann cells
Melanocytes
Muscle, cartilage and bone of skull, face, jaws and pharynx
Dentine
What are the components of the forebrain (prosencephalon)?
Telencephalon (cortex, basal ganglia, hippocampus)
Diencephalon (thalamus, hypothalamus)
What are the mature derivatives of the mesencephalon?
Midbrain
What are the mature derivatives of the rhombencephalon?
Hindbrain
Metencephalon (pons and cerebellum)
Myelencephalon (medulla)
How are the brain cells formed from the neural tube?
Stem cells at ventricular surface give rise to cells which then migrate to outer surface of brain forming the layers of the cortex
What is the function of the radial glia?
straight structures like train tracks that form scaffolding to facilitate the migration of cells to the cortex
How do axons grow? What determines the direction of growth?
Growth cone (like “tractor”) pulls out of cell body which adds material to form growing/extending axon. GC responds to local cues (signals) which tells it where to go.
critical period
A concept that there is a specific time in an organism’s development during which external factors have a unique and irreversible impact - ie external experiences influence the refinement of neural connections. Ie otitis media in infants can lead to deafness due to transient loss of neural activity failing to stimulate the reinforcement of the connections needed for developing proper hearing.
What are the 4 types of mechanoreceptors?
Meissner corpuscles
Merkel complexes
Ruffini organs
Pacifism corpuscles
Which mechanoreceptors are located superficially in the epidermis?
Meissner corpuscles
Merkel complexes
What mechanoreceptors are located in the dermis/subcutaneous tissue?
Ruffini corpuscle
Pacinian corpuscle
What are Pacinian corpuscles mainly involved in? What is the size of their receptor fields?
Detect vibration - have a large receptor field
How do tactile(mechanoreceptors) differ from nociceptors?
Nociceptors respond over a higher range and reflect change in the tissue itself whereas tactile receptors tell us that the external enviro has changed
What are the layers of the scalp? (from exterior to brain surface)
Skin Connective tissue Aponeurosis Loose connective tissue Periosteum
cranial bones (outer compact layer, middle spongy layer Diploe) Dura mata (2 layers) Arachnoid mata (subarachnoid space) Pia mata BRAIN
Which of the layers of the meninges is vascular? which is not?
arachnoid mater is avascular, Pia matar is highly vascular
What are the 5 layers of the scalp how are these different in the face?
Skin, Connective tissue, Aponeurosis (of occipitalfrontalis muscle) Loose connective tissue, Pericranium/periosteum. Face has no layer 4 (loose connective tissue) and has muscles instead of aponeurosis (layer 3).
What are the boundaries of the scalp?
From the External occipital protuberance posteriorly to the supraorbital margins (ie includes the forehead)
Why do scalp wounds bleed profusely?
- rich anastomoses of blood vessels within the connective tissue layer2. Scalp wounds gape as wound margins are pulled apart by the attachments of occipitalis and frontalis muscle bellies to the underlying aponeurosis 3. Vasoconstriction of arteries is prevented via attachments to fibrous septa - this impedes clotting.
Muscles of the face are derived from which pharyngeal arch embryologically? what nerve are they innervated by?
2nd pharyngeal arch -> innervated by Facial Nerve (CNVII)
What is the sensory innervation to the face? how does this differ anteriorly and posteriorly to the ears?
Ant = 3 branches of Trigeminal Nerve (V1 Opthalmic, V2 Maxillary, V3. Mandibular). Posterior to the ears the skin is innervated by the dorsal rami of cervical spinal nerves
What is the blood supply to the face?
Majority of face is supplied by branches of the external carotid artery -> gives off the facial artery which runs a tortuous course to the medial border of the eye, superficial temporal artery supplies the lateral scalp. The middle forehead region is supplied by the Supratrochlear and Supraorbital branches of from the Opthalmic artery (a branch of the internal carotid)
What is the blood supply to the scalp?
- superficial temporal artery2. posterior auricular artery3. occipital artery=> ALL from ext carotid
How can infection spread from the face to the brain?
most of the blood from the face drains via the facial vein, however it can drain via emissary veins which enter the dural venous sinuses therefore providing a route of infection past the skull to the brain
What are the LN of the face/scalp?
- submental nodes (below the chin)2. Submandibular nodes3. Pre-auricular and parotid nodes4. Mastoid nodes5. Occipital nodes-> all drain to the upper deep cervical nodes
Describe the course of the parotid duct
Emerges from the anterior border of the parotid gland and runs on the masseter muscle until it turns inwards (at the anterior border of masseter) and pierces Buccinator and enters the oral cavity near the 2nd upper molar
What 4 structures are contained within the substance of the parotid gland?
- facial nerve (most superficial)2. retromandibular vein3. ext carotid artery (deepest)4. parotid LN -> scattered throughout
Describe the course of the facial nerve in relation to the parotid gland
forms a plexiform arrangment within the substance of the parotid gland (pes anserinus) giving off its 5 terminal branches (Temporal, Zygomatic, Buccal, Mandibular, Cervical)
After the external carotid artery enters the parotid gland what branches does it give off?
divides into its two terminal branches - maxillary and superficial temporal arteries
What important branch does the maxillary artery give off?
Middle meningeal artery
What common pathologies are associated with the facial nerve?
can be damaged during surgery to the parotid gland/face, can be affected by unknown mechanisms to cause Bell’s palsy
What is the corpus callosum
thick band of white matter that links the L and R cerebral hemispheres
Where does the 3rd ventricle lie?
in the midline between the right and left thalamus
What is the name of the connection between the lateral ventricle and the 3rd ventricle?
interventricular foramen
Where does the 4th ventricle lie?
between the cerebellum and the pons/medulla
How is the 3rd ventricle connected to the 4th ventricle?
via the cerebral aqueduct
Between what bones is the pterion formed? (be specific)
Temporal (squamous part)
Sphenoid (greater wing)
Frontal bone
Parietal bone
