Anatomy And Diagnostics

Question 1

Outline directional terms in anatomy

Answer 1

1) Superior = towards the top of the head
2) Inferior = towards the feet
3) Anterior = front of the body or brain
4) Posterior = back of the body or brain
5) Dorsal = the back of the spinal cord // shift at the brainstem-diencephalon junction so also the superior portion of the brain
6) Ventral = the abdomen or front of the spinal cord // shift at the brainstem-diencephalon junction so also the inferior portion of the brain
7) Rostral = up towards the head // towards the anterior portion of the brain
8) Caudal = down towards the end of the spinal cord // towards the anterior part of the brain
9) Sagittal section = slice down the middle of the brain, dividing into separate halves
10) Horizontal/transverse section = slice brain perpendicular to the long axis of the body
11) Coronal/frontal section = slice made parallel to the long axis of the body
12) Medial = parts of the brain closer to the midline
13) Lateral = parts of the brain closer to the sides

Question 2

How do x-rays work?

Answer 2

X-rays are partially blocked by intervening material between the ray, the cathode ray tube and the screen. The more the rays are blocked, the lighter the image appears, as there is more obstruction on the silver coated plate.

Question 3

How do images appear in an a modern X-ray radiograph?

Answer 3

1) Bone: appears white, as it contains calcium and blocks many X-rays
2) Soft tissue/fluid: are intermediates
3) Fat: also an intermediate
3) Air: appears white, as X-rays are not blocked at all

Question 4

What is innate contrast in the body by X-ray scans, related to?

Answer 4

Innate contrast in the body is related to tissue density.

Cortical bone > soft tissue/fluid > fat > air

Question 5

What are the disadvantages of plain X-rays?

Answer 5

1) All of the structures are super-imposed, meaning that there can be no depth perception. Therefore, 2 different viewpoints may be required to identify a particular pathology.

Question 6

What are the advantages plain X-rays?

Answer 6

1) Can differentiate between air densities: normal aerated lung and a “whiteout” lung, which could be caused by fluid, pus, or a collapsed lung.

Question 7

Outline nomenclature in a frontal chest radiograph

Answer 7

1) Right: on the left hand side of the film
2) Left: on the right hand side of the film
3) Cranial: the top of the film
4) Caudal: the bottom of the film, “towards the tail”

Question 8

Outline the nomenclature in a lateral chest radiograph

Answer 8

1) Anterior: by the sternum, front of the chest
2) Posterior: by the spine, back of the chest
3) Cranial: the top of the film
4) Caudal: the bottom of the film

Question 9

Outline the nomenclature of a foot/hand radiograph

Answer 9

1) Plantar: the base of the foot
2) Dorsal: the back of the foot/hand
3) Palmar: the front of the hand, towards the palms
4) Medial: towards the middle of the body (inside of the foot)
5) Lateral: towards the outside of the body (outside of the foot)
6) Proximal: towards the rest of the body
7) Distal: further out than the rest of the body

Question 10

What is used in areas without an innate contrast?

Answer 10

Barium sulphate can be used for gastrointestinal fluoroscopy. For example, a patient swallows a solution of barium,allowing the radiograph to follow the barium down, through the oesophagus and right down into the gastroesophageal junction and then into the stomach. Air can also be provided within the viscous, such as the stomach or the bowel, either by swallowing fizzy bubbles/effervescent fluid together with the barium, or placing a tube into the jejenum, where the barium and air can be infiltrated into the small bowel to give a clear anatomic image.

Question 11

When are x-rays used with injected dye?

Answer 11

It is used to visualise the cerebral vasculature, with modern technology being able subtract out the underlying bone, leaving just the view of the vasculature.

Question 12

What is coronary angiography?

Answer 12

This is when contrast is injected into the arteries, to widen stenosis and demonstrate the structures of the arteries.

Question 13

Where can contrast media be injected?

Answer 13

It can be injected into almost any portion of the body, anything with a lumen. This allows many structures to be visible, which aren’t normally visible from their own contrast densities.

Question 14

What is Computed Tomography (CT) scanning?

Answer 14

This is a great way for anatomy to be demonstrated, as there is no problem of overlapping structures. A CT scanner obtains a series of images of the body (slices) in the axial plane. The different densities between the bone and the soft tissue can be readily seen. In the brain, the differences between the great matters, white matter and cerebrospinal fluid can also be seen.

Question 15

What are the differences in CT scanning?

Answer 15

CT scans can be non-contrast or have iodinated contrast (delivered intravenously), which gives some extra information.

Question 16

How are CT scans acquired?

Answer 16

CT scans are always acquired in the axial plane (looking down from above).

Question 17

Outline CT nomenclature

Answer 17

1) Right: on the left hand side of the image
2) Left: on the right hand side of the image
3) Sagittal view: sidewards on view of the image
4) Coronal view: looking at the image en face, face on towards the heart

Question 18

Which scans using ionising radiation?

Answer 18

1) X-ray
2) CT scan
3) Nuclear medicine imaging investigations:
> Bone scan
> PET/CT
> PET/MR
These may all cause radiation-induced cancer, decades later. It is therefore recommended to avoid using ionising radiation, where possible, and to use the lowest dose radiation possible.

Question 19

What is ultrasound?

Answer 19

This is often used to demonstrate anatomy as it does not using ionising radiation. Nowadays, ultrasound machines are widely available, low cost and mobile. However, ultrasounds are used depending, meaning that they require some skill in training, and ultrasound waves cannot penetrate freely through air, dense bone or obesity.

Question 20

What is magnetic resonance imaging (MRI)?

Answer 20

Provides significantly more options for characterising the different tissues in the body. Cerebral spinal fluid appears dark in signal intensity, whereas subcutaneous fat is very bright intensity, the spinal cord shows intermediate spinal intensity.

Question 21

What are the 2 types of MRI?

Answer 21

1) T1 weighted: can be fat saturated
2) T2 weighted: water is always bright, CSF is bright white, the spinal cord outlined by the fluid and the fat remains quite bright.

Question 22

Outline the nomenclature for MRI

Answer 22

1) Axial view: Looking downwards
2) Sagittal view: sidewards on view of the image
3) Coronal view: looking at the image en face, face on towards the heart

Question 23

Which imaging techniques are more functional than anatomical?

Answer 23

1) FDG-PET/CT: used for imaging glucose uptake

2) FDG-PET/MR

Question 24

What are the 4 primary types of tissues?

Answer 24

The four primary types of tissues in the body are: epithelial tissue, connective tissue, muscular tissue, and nervous tissue.

Question 25

Define histology

Answer 25

This is the study of cells and tissues.

Question 26

Define gross anatomy

Answer 26

This is dissections using only the naked eye

Question 27

Define microscopic anatomy

Answer 27

This is the use of histological preparations and microscopes.

Question 28

Outline the embryonic origin of tissues of the body

Answer 28

19 day old embryonic membranes show 3 germ layers: ectoderm, mesoderm and endoderm. All cells and tissues of the Jody are delved from these 3 germ layers.

Question 29

Outline the origin and function of Connective Tissue (CT)

Answer 29

It is derived from the mesodermal layer of the embryo and occurs everywhere in the body, forming a “packing material”. It also provides mechanical and metabolic support. The components of this tissue are cells and the extracellular matrix.

Question 30

What are the types/subdivisions of Connective Tissue?

Answer 30

1) Loose aerolar CT, Dense CT, Reticular CT
2) Adipose (fat) CT
3) Cartilage and bone
4) Blood and Lymph

Question 31

Outline the origin of epithelial tissue

Answer 31

It is derived from all three embryonic germ layers: ectoderm, mesoderm and endoderm. These tissues can regenerate very easily, and so if there’s any damage to a layer, the worn off part can be replaced quickly.

Question 32

What are the 2 groups of epithelial tissue?

Answer 32

1) Covering/lining of surface epithelia: oral cavity, skin, vagina, respiratory tract, alimentary tract
2) Glandular epithelia (closely packed): sebaceous, salivary and mammary gland, exocrine and endocrine gland.

Question 33

What are the 2 types of squamous surface epithelia?

Answer 33

1) Simple squamous epithelium: this is the simplest form of the epithelium, being only one cell layer thick and resting on the basement membrane. It is found in structures where the transmission of fluid or gases takes places such as the capillary (where it is called endothelium), and in the alveolar epithelium in the lungs.
2) Stratified squamous epithelium: this epithelium is several layers thick, allowing it to function as a protect layer on the skin, mouth and vagina.

Question 34

What are cuboidal and columnar surface epithelia?

Answer 34

1) Simple cuboidal epithelium: this is a single layer if cuboidal cells that line salivary gland ducts and kidney tubules. In addition to providing protection, these cells are involved in diffusion of substances.
2) Simple columnar epithelium: these are formed by long cells resting on a basement membrane. These epithelia are found in the stomach, intestine and gall bladder, having various diffusion and absorption functions in these tissues.
3) Simple columnar ciliated epithelium: similar to the simple columnar, but have microcilia attached at the distal and luminal ends, which helps in moving substances. This epithelium is found in the Fallopian tube.
4) Pseudostratified columnar ciliated epithelium: These are usually found in the respiratory tract and are columnar cells that appear as two layers, but are in actual fact a single layer. This also contains cilia.

Question 35

What is transitional surface epithelia?

Answer 35

These appear as several layers of cells found in the inner lining of the bladder and in the urinalysis tract. The surface cells are more globular on appearance, whereas the cells near the basement membrane are more columnar in appearance. It is called transitional as in an empty bladder, the cells would be shrunk together and formed a multilayered appearance, but when the bladder is filled, the cell layers get stretched and appear 2-3 cells thick. Their main function is to protect the bladder wall and underlying tissues.

Question 36

Outline the origin and function of muscle tissue

Answer 36

Muscle tissue is derived from the mesodermal layer of the embryo, and its function is to produce movement.

Question 37

What are the 3 types of mushiest fibres?

Answer 37

1) Skeletal (striated): found everywhere in the body, all the named muscles are skeletal muscles. These cells are long (length varying from 1mm-2feet) and multi-nucleated. These muscles are under voluntary control by the somatic nervous system.
2) Cardiac: a special type of striated muscle with branched, multinucleated cells. The muscle has its own inherent power of contraction. The heart is also modified by the sympathetic and parasympathetic nervous system. This muscle does not undergo fatigue.
3) Smooth: found mainly in the visceral structures like the gastrointestinal tract, respiratory tract, gallbladder and blood vessels. These cells are short, spindle shaped and uninucleated. These muscles are under involuntary control by the autonomic nervous system.

Question 38

Outline the origin and function of nerve tissue

Answer 38

It is derived from the ectoderm of the embryo and its function is to generate and conduct electric impulses.

Question 39

What are the components of nerve tissue?

Answer 39

1) Neurons/nerve cells - excitable cells
2) Nerve fibres - axons and dendrites
3) Neuroglia - supportive cells

Question 40

Outline peripheral nerves

Answer 40

These all arise from the CNS and travel long distances to different parts of the body.

Question 41

What is the Pterion

Answer 41

This is the weak spot found on the Sphenoid bone, where if a blow lands, can cause an intracranial bleed.

Question 42

What is the Occipital bone?

Answer 42

This is the main bone that can be seen from the inferior view, around the frame and magnum at the base of the skull. The inferior part of the temporal bone on both sides and the mandible can also be seen in the inferior view.

Question 43

What does the superior view of the cranium given insight into?

Answer 43

It gives insight into the main sutures of the cranial vault.

Question 44

What is the coronal suture?

Answer 44

This is the fibrous joint found along the superior aspect of the cranium. It is the articulation site located between the parietal margin of the frontal bone and the frontal borders of both the right and left parietal bones.

Question 45

What is the sagittal suture?

Answer 45

It is a fibrous joint found along the superior aspect of the cranium. It is the articulation site located between the sagittal borders of both the right and left parietal bones.

Question 46

What is the Lambdoid suture?

Answer 46

This is a lambda shaped, fibrous joint found along the posterior aspect of the cranium. It is the articulation site located between the lambdoid border of the occipital bone and the occipital borders of both the right and left parietal bones.

Question 47

What is a bregma?

Answer 47

This is a craniometric point found along the midline on the superior aspect of the cranium. It is formed by the frontal bone and the right and left parietal bones and is located at the area where the sagittal and coronal sutures meet.

Question 48

What is the Anterior Fontanelle

Answer 48

This is an area of unfused bone found in the neonatal cranium, also known as the ‘soft spot’ on top of the baby’s head. The fact that the bones haven’t yet fused, gives the skull a little bit of flexibility, in case the birth canal is a little bit tight. This usually closes up between 18-24 months.

Question 49

What are the foranima?

Answer 49

These are the holes found at the base of that skull that allow the passage of structures from one region to another. In the skull base, there are numerous foramina that transmit cranial nerves, blood vessels and other structures – these are collectively referred to as the cranial foramina. The brain stem goes through the foranima magnum.

Question 50

What are cranial fossae?

Answer 50

Cranial fossae are formed by the floor of the cranial cavity. There are three distinct cranial fossae: the anterior cranial fossa, the middle cranial fossa and the posterior cranial fossa.

Question 51

What sits in the anterior cranial fossa?

Answer 51

The frontal lobe of the brain.

Question 52

What sits in the middle cranial fossa?

Answer 52

The temporal lobe of the brain.

Question 53

What sits in the posterior cranial fossa?

Answer 53

The cerebellum and the brain stem. This fossa is covered by a layer of the meninges in life.

Question 54

What are the meninges?

Answer 54

These are the membranes that cover the brain and line the skull. Structurally, the meninges help to stabilise and protect the brain and they also form the sinuses through which venous blood circulates in the cranial cavity.

Question 55

Outline the 3 layers of the meninges

Answer 55

1) Dura mater (outermost layer): thick inelastic and formed of 2 of its own layers - periosteal and meningeal. The 2 layers do open up occasionally to form venous sinuses between them, where the venous blood circulates with the cranium. The superior sagittal sinus is the biggest venous sinus. When the 2 layers of the dura mater rejoin, they form a tough fold that separates the halves of the brain, helping to stabilise the brain within the cranial cavity.
2) Arachnoid mater: elastic and forms spider like projections the the subarachnoid space. Cerebral spinal fluid is also found in the subarachnoid space, which helps to protect the brain against movement and supplies nutrients to the brain. Often when looking at the surface of a brain specimen, it’s this layer that is seen, as it collapses onto the surface of the brain, as all the CSF has drained away.
3) Pia mater (innermost layer): the thinnest and most delicate membrane, not really a membrane, but a 2 cell thick surface of the brain.

Question 56

Outline the relation between the dura mater and the bones of the skull

Answer 56

This relationship changes between the skull and the vertebral column. Normally the dura mater is very closely adherent to the bone in the skull, meaning that there is no space between them in the cranial cavity. However, coming out of the foramen magnum, an extra dual space is formed between the dura mater and the column. Anaesthetists take advantaged of this extramural space as this is where they apply extradural or epidural anaesthetic, particulate in mothers who are in labour and are in need of pain relief.

Question 57

What are the main dural folds?

Answer 57

1) Falx cerebri: the fold of the dura between the two halves of the brain, that provides structural support to the brain.
2) Tentorium cerebelli (tent of the cerebellum): provides structural support for the brain by stopping it from moving too much.

Question 58

What are the cranial nerves?

Answer 58

The order of the 12 cranial nerves is based on their anatomical location, from the front (anterior aspect) to the back (posterior aspect) of the brain.
> Cranial nerves I and II, are the only cranial nerves not to originate from the brain stem, both having pathways to the cerebral cortex above the brain stem. > Cranial nerves III and IV have nuclei located in the midbrain.
> Cranial nerves V, VI, VII and VIII, have a nuclei predominantly within the pons.
> Cranial nerves IX, X, XI and XII, have nuclei mostly in the medulla oblongata.

Question 59

Outline the name and function of all 12 cranial nerves

Answer 59

I) Olfactory: sense of smell
II) Optic: vision (acuity), visual fields and pupillary light reflex (afferent limb)
III) Oculomotor: eyelid elevation, eye movements (elevation, abduction, depression in abduction) and pupillary light reflex (efferent limb)
IV) Trochlear: eye movements (intorsion and depression in abduction)
V) Trigeminal: motor to muscles of mastication (chewing) and sensation from face, sinuses, teeth, etc.
VI) Abducens: eye movement - abduction.
VII) Facial: motor to muscles of facial expression, sensory taste (anterior 2/3 of tongue) and sensory to the external auditory meatus and naso-pharynx
VIII) Vestibulochocholear: sense of hearing and sense of balance
IX) Glossopharyngeal: motor to the stylopharyngeus muscle, sensory taste (posterior 2/3 and general sensation from the tongue) and mucosa of the nasopharynx and middle ear.
X) Vagus: motor to the vocal muscles, sensory from the pharynx, larynx and lateral aspect of the face; parasympathetic innervation to the gastrointestinal tract, heart and lungs
XI) Accessory: motor to the sternocleidomastoid and trapezium
XII) Hypoglossal: motor to tongue muscle

Question 60

Outline the function of the olfactory nerve (CN I)

Answer 60

It is a specialised sensory nerve, which transmits information relating to the sense of smell. The sense of smell is detected by olfactory receptors in the nasal epithelium, their axons forming the olfactory nerves, which enter the intra-cranial cavity by passing through the cribriform plate in the ethmoid bone. The sensory information ultimately reaches the primary olfactory cortex in the temporal lobe of the brain which is the area of the brain devoted to smell.

Question 61

How is the function of the olfactory nerve assessed?

Answer 61

Assessment of the olfactory nerve is typically the first cranial nerve to be examined in the cranial nerve examination. First, the patient should be asked if they have “noticed any changes in their taste or sense of smell”. When testing smell each nostril of the patient should be tested separately with a strong smell, such as mint or vanilla. The patient’s eyes should be shut when carrying out the testing.

Question 62

What is anosmia?

Answer 62

This describes the loss of smell. Temporary anosmia can be caused by a blocked nose from a common cold and other upper respiratory tract infections. Permanent anosmia has many causes such as; severe head injuries, or tumours that run along the olfactory nerves intracranial path. Also progressive anosmia may occur in neuro degenerative diseases, such as Alzheimer’s disease and some other brain disorders (such as multiple sclerosis).

Question 63

What is the pupillary light reflex?

Answer 63

The pupillary light reflex is a reflex that controls the size of the pupils in response to changes in the strength of light that lands on the retina of the eye. In a bright room (from the dark) pupils get smaller (constrict), which is partly to protect retina and assist vision. This is a reflex and both pupils have it. Each pupillary light reflex has an afferent limb (optic nerve) and two efferent limbs (parasympathetic fibres along the oculomotor nerves).

Question 64

What is the difference between the primary visual cortex and pupillary light reflex?

Answer 64

Light travels through the pupil of the eye and is turned into impulses by the rods and cones of the photo-receptor layer of the retina. These impulses are the transmitted from the retina through the intracranial cavity to the brain by the optic nerve (CN II) through the optic canal. These impulses then pass through the visual pathway within the brain to the primary visual cortex where we appreciate the vision. The pupillary light reflex takes a different and shorter path than the whole visual pathway, as the reflex does not require our appreciation of the light, it works independent of our thought and command. The optic nerve is the afferent limb of the pupillary light reflex, sending the sensory impulses via mid brain nuclei to trigger motor impulses through parasympathetic axons running along the oculomotor nerves (efferent limb) to innervate the pupillary sphincter muscles in the eye leading to pupillary constriction (miosis) of both the ipsilateral pupil (same side) and the contralateral pupil (other side).

Question 65

How is the pupillary light reflex tested?

Answer 65

This reflex is tested by shining a light in each eye individually and because of the two efferent limbs, there is not only a direct pupillary reflex but also a consensual pupillary light reflex.

1) Ask the patient to look at a distant target.
2) Inspect the pupils for size, shape and colour and any presence of ptosis (drooping of eye lid).
3) Shine one eye with a penlight - observe for the pupillary constriction in the same eye (ipsilateral).
4) T​ake away the light for a few seconds.
5) S​hine the penlight in the same eye - observe the pupillary constriction in the other eye (consensual).

When conducting this reflex, the patient’s pupils must be inspected in ambient light first before applying the light.

Question 66

Why are direct and consensual pupillary light reflexes tested?

Answer 66

These reflexes are tested to assess the integrity the function of both optic and oculomotor nerves. An Abnormal pupillary reflex can be caused by optic nerve damage, oculomotor nerve damage, brainstem injury, and depressant drugs.

Question 67

What is anisocoria?

Answer 67

This is a condition characterised by an unequal size of the eyes’ pupils. This affects 20% of the population, it can be an entirely harmless long term finding or can be a sign of more serious problem, especially in the drowsy or unconscious patient. The size and shape of the patient’s pupils must be inspected before testing the direct and consensual light reflexes with a pen torch.

Question 68

What does the testing of the Optic nerve (CN II) and the visual pathway function also include?

Answer 68

1) Peripheral visual fields
2) Blind spot
3) Visual Acuity
4) Colour vision

Question 69

What are the 3 main functions of the neck?

Answer 69

1) Structural -supports and moves the head
2) Visceral functions - contains the airway and oesophagus
3) Conduit for blood vessels and nerves

Question 70

What is fascia?

Answer 70

This is connective tissue mainly composed of collagen fibres and it organises the body into different compartments. It permits the spread of infection within compartments.

Question 71

What are the different fascia found in the neck?

Answer 71

1) Superficial fascia - most external fascial layer, containing the platysma, a thin muscle at the front of the neck.
2) Deep fascia - this is deep to the superficial fascia and is divided up into several layers (e.g. pretracheal fascia, carotid sheath, investing fascia and prevertebral fascia). These are all associated with different compartments housing different structures.
> Pretracheal fascia: surrounds some of the visceral components of the neck (e.g. components of the digestive system, respiratory system and endocrine glands).
> Carotid sheath: fascia that surrounds blood vessels, the vascular compartment.
> Prevertebral fasci a