2 Flashcards
(65 cards)
1
Q
What is the difference in appearance between the internal jugular vein and the external jugular vein?
A
- internal does not have branches in neck
- external branches out straight away
2
Q
Describe the common carotid artery in the neck
A
- does not bifurcate in neck
- bifurcates further up to give off external and internal carotid arteries
3
Q
On the right side of the body where do the subclavian and common carotid arteries arise from?
A
Arise from brachiocephalic trunk
4
Q
What arteries arise from the left subclavian artery?
A
-vertebral, internal thoracic, and thyrocervical arteries
5
Q
Where does the left common carotid artery arise from?
A
Arch of aorta
6
Q
Describe the passage of vertebral arteries
A
- arise from the subclavian arteries
- supply the posterior neck and posterior parts of the brain
- vertebral artery ascends through the transverse foramina of c-spine EXCEPT C7 and enters subarachnoid space just between the atlas and occipital bone
- then passes through the foramen magnum
7
Q
Describe the passage of the basilar artery?
A
- arises from the vertebral artery
- runs along the anterior aspect of the brain stem
8
Q
What is ABC for right side of body?
A
Arch of aorta
Brachiocephalic trunk
Carotid artery
9
Q
Why is the left common carotid slightly longer than the right?
A
-because it courses for about 2cm in the superior mediastinum before entering the neck
10
Q
What is the carotid sheath?
A
- fascial envelope enclosing the carotid artery, IJV and vagus nerve
- runs deep to the sternocleidomastoid muscle
- sheath is thin over vein but thicker around the artery
- ANV: artery (medial), nerve (behind and between), vein (lateral)
- sympathetic chain lies outside of the sheath, medially and behind
11
Q
Where does the common carotid bifurcate?
A
At C4 level
-upper border of thyroid cartilage
12
Q
Why is the internal carotid artery more bulbous the bifurcation? Why is this clinically important?
A
- this is the location of the carotid sinus
- rubbing this area firmly can alleviate supra-ventricular tachycardia
- aka carotid massage
- press on sinus, maintain pressure which will send a message to the brain to increase parasympathetic flow and reduce sympathetic flow
13
Q
Describe the passage of the internal carotid artery
A
- no branches in neck
- enters base of skull through the carotid canal in petrous part of temporal bone
- turns medially and horizontally then makes S-shaped bend
- courses through intracranially and passes through the cavernous sinus and goes on either side of the sphenoid bone
- after passing cavernous sinus it gives off its branches which supply the brain and eye
14
Q
Describe the eight branches of the external carotid artery
A
Some Anatomists Like Freaking Out Poor Medical Students
- Superior thyroid (supplies superior lobe of thyroid gland)
- Lingual (tongue)
- Facial (face and around mouth): pulse can be felt at inferior border of mandible, anterior to masseter muscle
- Ascending pharyngeal (pharynx)
- Occipital (back of scalp)
- Posterior auricular (back of ear)
- Superficial temporal (terminal branch, tissues of scalp)
- Maxillary (terminal branch of deep tissues and bone structures of face, gives a branch called middle meningeal artery which runs through base of skull and supplies the meninges and skull bones)
- terminal branches travel through the parotid gland and is its major source of blood
15
Q
Describe the facial vein.
A
- where most of the structures of the face drain
- runs from medial angle of eye towards the inferior border of mandible (with facial artery)
- then joins IJV
- connects with the superior and inferior ophthalmic veins which directly connect with cavernous sinus and pterygoid venous plexus
- blood draining via facial vein can drain INTRACRANIALLY
16
Q
Describe the carotid triangle
A
- Located in the neck
- surrounded by: anterior border of sternocleidomastoid, superior belly omohyoid and posterior belly of digastric
- contains bifurcati9n if common carotid and vagus nerve
- where carotid sinus massage is done
- important for surgical approach to the carotid arteries or IJV
17
Q
What are the implications of blood draining the face via facial vein? Give example
A
- it has potential to drain INTRACRANIALLY
- has implications for infections involving the face as they can spread to intracranial structures
- septic thrombi within facial vein can travel via ophthalmic veins to the cavernous sinus and cause a cavernous sinus thrombosis
18
Q
Where in the carotid artery can atheromas commonly form?
A
- at the bifurcation site
- will cause stenosis of the artery
- rupture of the clot can cause embolus to travel to brain
19
Q
What is the carotid sinus?
A
- swelling at region of bifurcation
- location of baroreceptors for detecting changes in arterial BP (nerve endings are stretch sensitive)
- where you do the carotid sinus massage
20
Q
What is the carotid body?
A
- peripheral chemoreceptors which detect arterial O2
- innervated by the glossopharyngeal nerve
- bulge/swelling for nerves
21
Q
What is a carotid endarterectomy?
A
-surgery to pull out plaque in order to restore normal blood flow
22
Q
Other than the internal carotid artery, what else is contained in the cavernous sinus?
A
- plexus of extremely thin-walled veins on upper surface of sphenoid
- cranial nerve 3 (oculomotor)
- cranial nerve 4 (trochlear)
- cranial nerve 6 (abducent)
- 2 branches of trigeminal nerve (ophthalmic and maxillary)
23
Q
What are the two branches of the ophthalmic artery?
A
- supratrochlear artery
- supra-orbital artery
24
Q
What arteries make up the blood supply to the scalp?
A
- From internal carotid: supra-orbital, supratrochlear
- From external carotid: superficial temporal, posterior auricular, occipital
- many anastomoses
25
What are the layers of the scalp?
```
SCALP
Skin
Connective tissue (dense)
Aponeurosis
Loose connective tissue
Periosteum
-vessels of the scalp lie in the subcutaneous ct layer
```
26
What is the clinical relevance of the blood supply to the scalp?
- walls of arteries closely attached to ct, limits constriction, can get profuse bleeding if cut
- many anastomoses, profuse bleeding
- deep cuts into epic racial aponeurosis will cause profuse bleeding because of opposing pull of the occipitofrontalis muscle
27
If there is a loss of scalp why won’t there be bone necrosis?
-because blood supply to skull is mostly from middle meningeal artery
28
What are the superficial arteries of the face?
- Supra-orbital (from internal carotid)
- Supratrochlear (from internal carotid)
- Transverse facial
- Angular
- Lateral nasal
- Maxillary
- Superior and inferior labial
- Facial
- rest are branches of external carotid
29
What are the branches of the maxillary artery? Describe them
- Both are terminal branches from external carotid
- Middle meningeal: supplies skull and meninges in brain
- Sphenopalatine: forms anastomoses with other arteries in nasal septum and important in nose bleeds
30
Describe the blood supply to the nasal septum
- 2 main branches
- Septal branch of sphenopalatine artery
- anterior ethmoidal arteries (from ophthalmic artery)
- anastomoses of arteries in Kiesselbach area
- Kiesselbach area common site for nose bleeds
31
describe the blood supply to the dura and skull
- middle meningeal artery passes through the foramen spinosum
- anterior branch of middle meningeal passes very close to pterion (where temporal, sphenoid and parietal bone join)
- veery thin area of bone so common site of rupture of middle meningeal artery
- can cause an extramural haemorrhage or biconvex haemorrhage
32
What is a craniotomy?
- helps to gain access to cranial cavity
| - bone flap and scalp flap are reflected to keep arteries intact and preserve blood supply
33
Describe the venous drainage of the scalp
- Superficial veins generally accompany arteries: superficial temporal, occipital, posterior auricular veins
- supraorbital and supratrochlear veins unite at medial angle of eye to form angular vein which drains into the facial vein
- some deep parts of scalp in temporal region have veins which drain into pterygoid venous plexus
- look at diagram
34
Why is the connection between venous drainage of scalp and dural venous sinuses clinically important?
- veins of scalp connect to diploic veins of skull through several emissary veins and thus to dural venous sinuses
- emissary veins connect these blood vessels and are valveless so they are a potential route for infection of the scalp which can spread to the cranial cavity and affect meninges
35
Describe the venous drainage of the face
- supraorbital and supratrochlear drain into angular vein
- superior and inferior labial veins drain into facial vein
- common facial vein drains into IJV
36
What is the danger triangle of the face?
- the area of anastomoses between the facial vein, the cavernous sinus and pterygoid venous plexus
- infections around this area can potentially go intra-cranially to involve brain and other structures
- can spread through the venous system to the dural venous sinuses
37
Describe the passage of the IJV
- arises as a continuation of the sigmoid sinus which leaves the skull through the jugular foramina
- runs the length of the neck within the carotid sheath
- straight line running from lobule of ear to sternoclavicular joint
- sits deep to SCM
- but peeks out when SCM splits into clavicular and sternal head
- ends bu joining with subclavian vein to form brachiocephalic vein which then drains into the superior vena cava and then right atrium
- receives blood from facial vein and veins draining the thyroid gland and tongue
38
How is JVP taken?
- the gap where SCM splits is where central lines can be inserted into IJV
- also where JVP can be seen when patient is positioned at 45 degrees
- pulsation observed through the SCM since IJV sits deep to it
- measured in cmH20
- measure height from sternal angle +5cm
- right JVP is favoured over left as right has a straight more vertical route into RA and better reflects pressure within right side of heart
39
Describe the EJV and its passage
- formed by joining a number of veins that have drained he scalp and deep structures of the face
- runs just beneath the skin in the superficial cervical fascia so can be seen unlike IJV
- deep to platysma but superficial to SCM
- ultimately drains into subclavian vein after piercing the investing layer of deep cervical fascia at lower end of neck
40
What 2 parts is the cranium divided into?
Neurocranium (brain) and viscerocranium (face and jaw)
41
How many bones does the skull have?
22 bones
42
Describe the neurocranium
- 8 bones
- main function: to encase/protect brain
- consists of calvaria (skull cap) and cranial floor/cavity (base)
- calvaria made of two layers of compact bone separated by a layer os spongy bone (diploe) (gives strength without adding weight)
- “vault” bones begin as membranes (intramembranous ossification): floor/base begin as cartilage (endochondrial ossification)
- like a kinder egg With brain being the kinder surprise
- “holes” in cranial floor allow cranial nerves and blood vessels to enter and exit
43
What are the bones of the neurocranium?
- frontal bone
- parietal bones (2)
- greater wing of sphenoid bone
- temporal bone
- occipital bone
44
What are the sutures of the neurocranium?
- Coronal suture: intersection between frontal and parietal bones
- Sagittal suture: separates the two parietal bones
- Lamboid suture: Intersection between occipital and parietal bones
- Bregma: where coronal and sagittal suture meet
- Lambda: where lamboid and sagittal suture meet
45
What are fontanelles? Describe them
- large areas of unossified membranous gaps (soft spots) between flat bones of calvaria
- fontanelles become the intersection of different bone plates (Bregma and lambda)
- they allow growth and development of brain and also allow head size and shape to be altered during childbirth
46
What is the condition where there is early fusion of fontanelles and sutures?
Craniosynostosis (rare)
47
Describe the cranial floor
- three bowl-shaped depressions form the cranial floor
- anterior, middle and posterior cranial fossa
- seat different parts of the brain and its associated structures
- made up of numerous bones
- lots of foramina in cranial floor as well
48
Describe the periosteum of the individual skull bones
- each skull bone is “shrink-wrapped” in periosteum
- strongly adhered to bone edges at suture line and continuous through suture and onto inner table of same bone
- artery runs underneath periosteal layer and into inner table of bone
- if there is an injury, artery will fill the space between the periosteum and inner table with blood
- but it will stay attached because the sutures are not stripped off
49
Describe the frontal bone
- forms part of the anterior cranial floor
- has two orbital plates (roof of eyes)
- forms skeleton of forehead and articulates with nasal and zygomatic bones
- also articulates with lacrimal, ethmoid, and sphenoid bones to form the roof of the orbit
50
Describe the ethmoid bone
Small bone on top of nasal cavity
- sits in middle of cranial floor
- contains little holes called the cribiform foramina and is on the cribriform plate
51
Describe the sphenoid bone
- like a butterfly
- has lesser and greater wings
- greater wings form lateral part of skull
- forms part of the anterior cranial floor but mainly middle cranial floor
- sella turcica is the area where the pituitary gland sits
- it is a saddle-like depression
- the back end of the saddle is known as the dorsum sella
52
Describe the temporal bone
- has many different parts to it
- squamous part: flat, lateral area
- zygomatic process of temporal bone: part that forms the cheekbones
- mastoid process: bump behind the ear
- petrous bone: chunky, mountainous part which houses the inner and middle ear structures
53
Describe the occipital bone
- external occipital protuberance is palpable on the back of the head
- contains the superior nuchal line where the trapezius muscle attaches
- contains the foramen magnum where the brain stem continues to become spinal cord
54
What are skull fractures
- caused by significant trauma or force to skull
- thickness of cranial bones varies, resistance to fracture varies
- risk of injury to intracranial structures
- even if skull is not fractured patient can still have intracranial injury after a head injury
55
Describe the types of skull fractures in the cranial vault
- either linear or comminuted
- linear: one fracture line, fairly straight, involve no bone displacement
- comminuted: multiple fracture lines, fragments may or may not displace inwards towards the brain (depressed vs. Non depressed), lots of little fractures
56
What area of the cranial vault is most prone to fracture and why?
- pterion
- thinnest area of skull
- contains the underlying anterior branch of middle meningeal artery
- can lead to intracranial haemorrhage (extramural)
57
What is the fracture that occurs at the skull base? Describe it
- Basilar skull fracture
- rarer type of fracture
- can occur within anterior cranial fossa, middle cranial fossa, and posterior cranial fossa
- if “raccoon” eyes (bruising around eyes) then there is a fracture in the anterior cranial fossa
- if haemotympanum then fracture is in the middle cranial fossa
- some may experience Battle’s sign (bruising over mastoid process, behind ear)
- some may experience cerebrospinal fluid leak from the nose (CSF rhinorrhea) or ear (CSF otorrheoa)
58
Describe the viscerocranium
- 14 bones
- main function: facial skeleton and jaw
- bones begin as membranes or cartilage and ossify
- structures (most) develop from the pharyngeal arches
- contains the zygomatic bone, maxilla bone, nasal bone, lacrimal bone, and mandible bone
59
Describe a fracture of the supraorbital ridge (frontal bone)
- located just above the orbital margin, a sharp bony ridge
- aka supraciliary arch
- skin overlying this area can be easily split when there is a blunt force injury to this area of the head
60
Which fractures of the face are common? Which are rare
- fractures of the nasal bones, zygomatic bone and arch and mandible are common (most prominent bones on face)
- mandible almost always fractures at two points
- fractures of the maxillae are rare
61
Describe the Temporomandibular Joint (TMJ)
- articulation b/n temporal bone and mandible
- sits in the mandibular fossa
- synovial hinge-type joint divided into two synovial cavities by a fibrocartilaginous disc
- can get TMJ disorder: pain often in ear, jaw, lateral side of head, also clicking and lock-in
- can get dislocation secondary to trauma or due to yawning
- can get arthritis
- innervated by the auriculotemporal nerve (branch of mandibular division of trigeminal)
62
Describe the anatomy of the TMJ
- articular surface of bones lined with fibrocartilage and do not come into direct contact
- joint capsule is separated by a fibrocartilaginous disc
- splits the joint capsule into two synovial-lined cavities filled with synovial fluid
- stabilized by a joint capsule an d 3 extracapsular ligaments
63
Describe the movements of TMJ
Depression of mandible (open jaw)
- hinge (rotational) action occurs from inferior joint capsule
- gliding forward action occurs in superior half of joint where the chondyle slides onto articular tubercle
- simple retraction and protraction of mandible occurs in a gliding action at superior joint capsule
- pterygoids use the same gliding movement
64
What are the movements of the mandible at TMJ and what muscles are involved?
Elevation: masseter, temporalis, medial pterygoid
Depression: lateral pterygoid, gravity, against resistance (platysma, suprahyoids)
Protrusion: lateral pterygoid, medial pterygoid (assists)
Retraction: posterior fibres of temporalis (inserts into coronoid process of mandible)
Grinding: lateral and medial pterygoids laterally deviate mandible
65
How does dislocation of TMJ occur
- when the chondyle slips in front of the articular process
- normal situation: chondyle does not pass in front of the articular process
- cause: facial trauma or yawning
- jaw locks as joint fixes in open position
- contraction of muscles around joint keeps joint locked in anterior displacement
- solution: reduction technique
