Anatomy of the Head, Neck and Spine

Question 1

What is a suture?

Answer 1

A fibrous joint permitting little or no movement.

Question 2

What happens to the periosteal dura at the foramen magnum?

Answer 2

It fuses with the skull.

Question 3

What is a fontanelle?

Answer 3

A large membranous and unossified gap between the bones of the skull in foetuses and newborns. Fontanelles allow the head to deform through the birth canal and allow postnatal growth.

Question 4

Relate the positions of the fontanelles to the positions of suture intersections.

Answer 4

Bregma = position of the anterior fontanelle
Lambda = position of posterior fontanelle.

Question 5

Which meningeal layer contains the meningeal arteries.

Answer 5

The periosteal layer of the dura mater - which is firmly attaches to the inner surface of the skull and serves as the periosteum of the cranial cavity.

Question 6

At what locations is the periosteal dura mater continuous with the periosteum on the outer-surface of the skull?

Answer 6

At the foramen magnum and other intracranial foramina.

Question 7

What 2 types of structure are formed by the separation of the periosteal and meningeal dura mater.

Answer 7

Intracranial venous structures; dural partitions.

Question 8

Detail the 4 dural partitions.

Answer 8

Falx cerebri is between the 2 cerebral hemisphere.

Tentorium cerebelli is a horizontal projection of meningeal dura mater which covers the cerebellum in the posterior cranial fossa from the posterior parts of the cerebral hemispheres.

Falx cerebelli is a small midline projection in the posterior cranial fossa.

Diaphragma sellae is small horizontal shelf of meningeal dura which covers the hypophyseal fossa in the sella turcica of the sphenoid bone. Infundibulum passes through an opening in the centre of the diaphragma sellae.

Question 9

What are diploic veins?

Answer 9

Diploic veins run between the internal and external tables of compact bone in the roof of the cranial cavity, and drain into venous sinuses.

Question 10

What are emissary veins?

Answer 10

Veins which drain from outside the cranial cavity to the dural venous sinuses. These veins are important as they can be a conduit through which infections can enter the cranial cavity because they have no valves.

Question 11

Which venous sinus connects the superior and inferior sagittal sinuses?

Answer 11

The straight sinus.

Question 12

Which sinuses drain to and from the confluence of sinuses?

Answer 12

Superior sagittal sinus, straight sinus, right and left transverse sinuses.

Question 13

How is venous blood drained from the brain?

Answer 13

Left and right transverse sinuses continue as sigmoid sinuses to the internal jugular vein.

Question 14

Describe the circle of Willis.

Answer 14

Basilar artery (formed by the convergence of the 2 vertebral arteries) bifurcates into 2 posterior communicating arteries (which give off posterior cerebral arteries). After the merger of the internal carotids, which continue as middle cerebral arteries, the arteries continues as anterior cerebral arteries, with the circle completed by a small anterior communicating artery.

Question 15

Name the cranial base foramina from anterior to posterior.

Answer 15

Cribriform plate, optic canal, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum, carotid canal, internal acoustic meatus, jugular foramen, hypoglossal canal, foramen magnum.

Question 16

What is the only groove which the arachnoid mater enters?

Answer 16

Longitudinal fissure.

Question 17

What passes through the jugular foramen?

Answer 17

Glossopharyngeal, vagus, spinal accessory nerves and sigmoid sinuses (continuing to the internal jugular vein).

Question 18

What structures pass through the internal acoustic meatus?

Answer 18

Facial and vestibulocochlear nerves and labyrinthine artery.

Question 19

What passes through the foramen spinosum?

Answer 19

Middle meningeal artery and vein.

Question 20

Which foramina do each of the branches of the trigeminal nerve pass through?

Answer 20

Ophthalmic branch passes through the superior orbital fissure.
Maxillary division passes through the foramen rotundum.
Mandibular division passes through the foramen ovale.

Question 21

What passes through the superior orbital fissure?

Answer 21

Oculomotor, trochlear, ophthalmic division of trigeminal and abducens nerves and superior ophthalmic vein.

Question 22

Define primary and secondary curvatures of the vertebral column.

Answer 22

A primary curvature is present in the foetal position (concave anteriorly). THORACIC; SACRAL
A secondary curvature is not present in foetuses (concave posteriorly). CERVICAL; LUMBAR

Question 23

What is a kyphosis, lordosis and scoliosis?

Answer 23

Kyphosis = excessive thoracic curvature ("hunch-back")
Lordosis = excessive lumbar curvature
Scoliosis = lateral curvature.

Question 24

What is the filum terminale?

Answer 24

A continuation of the pia mater from the conus medullaris which anchors the spinal cord. It is a white filament.

Question 25

What are the features of a typical vertebra?

Answer 25

A vertebral body (which is the major weight bearing part). A vertebral arch. Pedicles - which anchor the vertebral arch to the vertebral body.

Question 26

Give the different shapes of the vertebral bodies and arches for different regions of the vertebral column.

Answer 26

CERVICAL: 'rectangular' body with triangular vertebral foramen. THORACIC: heart-shaped body with relatively small circular vertebral foramen. LUMBAR: kidney-shaped body with triangular, intermediate-sized vertebral foramina.

Question 27

What is atypical about C1 (atlas)?

Answer 27

It doesn't have a vertebral body. Instead, the axis (C2) has a dens of axis which slots through the foramen for dens of axis in the atlas. This allows rotation.

Question 28

Between which structures are the atlanto-occipital and atlanto-axial joints?

Answer 28

``` Atlanto-occipital = between skull and C1 Atlanto-axial = between C1 and C2 ```

Question 29

Briefly describe the different ligaments of the vertebral column.

Answer 29

Anterior and posterior longitudinal ligaments on the vertebral bodies. Supraspinous ligament connects the spinous processes. Interspinous processes between the spinous processes. Ligamentum flavum between the laminae.

Question 30

Why is C7 called the vertebra prominens?

Answer 30

Because of its long spinous process, it is usually the first spinous process one can visualise and easily palpate.

Question 31

What is the usual number of anterior spinal arteries and veins and posterior spinal arteries and veins?

Answer 31

1 anterior spinal artery: 2 posterior spinal arteries. | 3 anterior and posterior spinal veins.

Question 32

Describe the ligamenta flava.

Answer 32

Each ligamentum flavum runs between the POSTERIOR SURFACE of the lamina on the vertebra below to the ANTERIOR SURFACE of the lamina on the surface above. Ligamenta flava resist separation of the laminae in flexion.

Question 33

Describe the ligamentum nuchae.

Answer 33

A triangular, sheet-like structure in the median sagittal plane. The base of the triangle is attached to the skull from the external occipital protuberance to the foramen magnum. The apex is attached to the tip of the spinous process of C7. The deep side of the triangle is attached to the posterior tubercle of vertebra C1 and the spinous process of other cervical vertebrae. The ligamentum nuchae supports the head and resists flexion. It facilitates returning the head to the anatomical position.

Question 34

How do you test cranial nerves III, VIII, X and XI?

Answer 34

III (oculomotor) = look for pupillary light reflex VIII (vestibulocochlear) = whisper a number in their ear and ask them to enunciate it. X (vagus) = ask them to say "aah" and observe the uvula rise. XI (accessory) = ask them to shrug their shoulders. Move head from side to side.

Question 35

How do you test trigeminal nerve function, CN V?

Answer 35

Sensory divisions: get them to close their eyes and gently touch each of the 3 dermatomes bilaterally with cotton wool. Motor function: palpate masseter and temporalis as they clench their teeth.

Question 36

How do you test facial nerve function (CN VII)?

Answer 36

Ask the patient to raise their eyebrows (look for creasing of forehead as frontalis contracts); keep eyes closed against resistance (orbicularis oculis) and bare their teeth (risorius).

Question 37

How do you test the hypoglossal nerve, CN XII?

Answer 37

Only motor nerve to tongue: ask them to stick their tongue out.

Question 38

How do you test CN I?

Answer 38

Olfactory nerve tested by presenting olfactory stimuli to a patient with their eyes closed, such as an orange or coffee, and asking them to identify the smell.

Question 39

The loss of taste sensation over the tongue indicates damage to which cranial nerves?

Answer 39

Anterior 2/3 indicates facial nerve defect. | Posterior 1/3 indicates glossopharyngeal (CN IX) defect.

Question 40

Other than the posterior 1/3 of the tongue, where is CN IX the main sensory nerve?

Answer 40

Oropharynx. | Test by eliciting gag reflex.

Question 41

What are the 2 openings of the oral (buccal) cavity?

Answer 41

``` Anterior = oral fissure Posterior = oropharyngeal isthmus. ```

Question 42

What passes through the foramen magnum?

Answer 42

Vertebral arteries, medulla of brainstem, spinal roots of accessory nerve.

Question 43

What major structures are at each level of the C-spine?

Answer 43

``` C1 = open mouth C2 = Superior cervical ganglion C3 = Body of hyoid C4 = Upper border of thyroid cartilage, bifurcation of common carotid artery. C6 = Middle cervical ganglia, cricoid cartilage C7 = inferior cervical ganglia. ```

Question 44

Describe the borders of the 2 triangles of the neck.

Answer 44

Anterior triangle: base = mandible. Hypotenuse = sternocleidomastoid. Posterior triangle: base = middle 1/3 of clavicle, hypotenuse is also the sternocleidomastoid and the trapezius is the posterior border.

Question 45

What structures are in the anterior triangle of the neck?

Answer 45

Mainly muscles: platysma, mylohyoid, digastric, infrahyoid. | Also carotid arteries, internal jugular vein, accessory nerve.

Question 46

What structures are in the posterior triangle of the neck?

Answer 46

Mainly blood vessels and nerves: external jugular vein, subclavian artery and vein, trunks of brachial plexus; phrenic, vagus and accessory nerves.

Question 47

Briefly describe swallowing and the muscles involved.

Answer 47

Lift and retract tongue (styloglossus) Bolus into oropharynx (palatoglossus). Close off nasopharynx by raising soft palate Raise the larynx, close off trachea by epiglottis Peristaltic wave of constrictor muscles (sensory CN IX, motor CN X). Relax cricopharyngeus, open oesophagus.

Question 48

Describe the 3 main salivary glands.

Answer 48

Parotid (mainly serous) - CN IX - travels via parotid duct which opens next to 2nd upper molar. Submandibular (mainly serous) - CN VII Sublingual (mainly mucous) - CN VII

Question 49

Describe the musculature of the tongue.

Answer 49

3 extrinsic: styloglossus (retracts tongue, to move the bolus into the pharynx), hyoglossus (tongue --> hyoid, depresses the tongue), genioglossus (tongue --> mandible, protrudes the tongue). Intrinsic muscles.

Question 50

Describe innervation of the tongue.

Answer 50

All muscles with "glossus" in their names supplied by XII for motor function, except palatoglossus (X). Sensation: anterior 2/3 is trigeminal (CN V) via LINGUAL nerve. Taste for anterior 2/3 is facial (CN VII) via CHORDA TYMPANI. Both taste and sensation of posterior 1/3 of tongue is supplied by glossopharyngeal nerve (CN IX).

Question 51

Give the muscles of mastication.

Answer 51

Superficial: masseter and temporalis elevate mandible Lateral pterygoid depresses and protracts mandible to open mouth. Medial pterygoid elevates, protracts and lateral movements of mandible for mastication.

Question 52

The internal carotid artery has no branches once it bifurcates from the common carotid artery at C4. What are the branches of the EXTERNAL carotid artery?

Answer 52

``` Superior thyroid Ascending pharyngeal. Lingual Facial Occipital Posterior auricular Maxillary Superficial temporal. "Some anatomists like freaking out poor medical students" ```

Question 53

What are the branches of the facial nerve from superior to inferior?

Answer 53

Temporal, zygomatic, buccal, mandibular, cervical.

Question 54

How many of each type of tooth are in each quadrant of the buccal cavity?

Answer 54

2 incisors (central and lateral incisors), 1 canine, 2 premolars and 3 molars.

Question 55

Describe the structure of the nasopharynx.

Answer 55

3 conchae, with 3 meatuses between them (inferior). Conchae warm and humidify air, help trap pathogens. Frontal sinus superior to superior concha. Sphenoidal sinus posterior to conchae. Sinuses reduce the weight of the skull, provide crumple zones and help with resonance (project the voice).

Question 56

What are the 2 vocal cords called?

Answer 56

The 2 medial "true" vocal cords are called vocal folds. | The 2 lateral "false" vocal cords are called vestibular folds.

Question 57

Describe the innervation of the larynx.

Answer 57

Vagus. Gives off a superior branch called the superior laryngeal nerve. Splits into internal and external laryngeal nerves. Internal branch supplies sensation above vocal cords. External branch supplies cricothyroid. Gives off an inferior branch: the recurrent laryngeal nerve. Left recurrent laryngeal loops round the ligamentum arteriosum. The right recurrent laryngeal loops around the right subclavian artery. Both travel with inferior thyroid arteries. The inferior branch supplies all muscles except the cricothyroid muscle, which tenses the vocal cords. Sensation below vocal cords.

Question 58

How do we cough?

Answer 58

Afferents via vagus nerve. Inspiration - intrathoracic pressure raised (epiglottis closed, abdominal muscles contract) Soft palate raised and tenses against posterior wall of pharynx. Sudden abduction of vocal folds to release intrathoracic pressure through mouth.

Question 59

How do we sneeze?

Answer 59

Afferents via V2 (Maxillary nerve). Inspiration - intrathoracic pressure raised (epiglottis closed, abdominal muscles contract) Soft palate depressed against tongue. Sudden abduction of vocal folds to release intrathoracic pressure through nose.

Question 60

What structure of the auricle overlaps the external acoustic meatus?

Answer 60

The tragus.

Question 61

What does the facial nerve supply and what does it pass through?

Answer 61

Passes through internal acoustic meatus and then parotid gland (without innervating it) - except chorda tympani which goes through petrotympanic fissure to supply taste to the anterior 2/3 of the tongue. Motor (large) - muscles of facial expression, stapedius, posterior belly of digastric, stylohyoid. Parasympathetic sensory = lacrimal glands, mucous glands, hard and soft palates, sublingual and submandibular glands. General sensation from external acoustic meatus and deeper parts of auricle.

Question 62

What are the bones of the orbit?

Answer 62

Roof = orbital plate of frontal bone Floor = orbital plate of maxilla Lateral wall = zygoma and greater wing of sphenoid Medial wall = frontal process of maxilla, lacrimal bone, orbital plate of ethmoid, lesser wing of sphenoid.

Question 63

What passes through each of the orbital foramina?

Answer 63

Optic canal = optic nerve + ophthalmic artery. Inferior orbital fissure = maxillary nerve (V2) and infraorbital vessels. Superior orbital fissure = ophthalmic artery (V1), abducens, trochlear, oculomotor, ophthalmic vessels and sympathetic fibres.

Question 64

Detail the extrinsic eye muscles.

Answer 64

Inferior, superior, medial and lateral recti, all originating from the common tendinous ring at the back of the orbit and inserting into the sclera, 5mm behind the corneal margin. All oculomotor (III) except lateral rectus which is abducens (VI). Inferior and superior oblique. Oculomotor and trochlear (IV) innervation respectively. LPS (levator palpebrae superioris) innervates upper eyelid. Oculomotor and sympathetic.

Question 65

How do you test the trochlear nerve?

Answer 65

Ask the patient to first adduct the eye (medial rectus) and then DEPRESS it.

Question 66

What are the palpebral fissure, limbus, lateral canthus, caruncle and punctum?

Answer 66

Palpebral fissure = space between eyelids. Limbus = delineation between iris and sclera Lateral canthus = lateral corner of eye Caruncle = medial corner of eye Punctum = where tears drain in medial corner of eye.

Question 67

Describe the tear film.

Answer 67

Maintains smooth cornea-air surface. Oxygen supply to cornea (normal cornea is avascular). Removal of debris (tear film and blinking), bactericide. 3 layers: superficial oily layer to reduce tear film evaporation. Aqueous tear film (very thick). Mucinous layer on corneal surface to maintain surface wetting.

Question 68

What is the conjunctiva?

Answer 68

The thin, transparent tissue that covers the outer surface of the eye. Begins at outer edge of cornea. Covers visible part of eye and lines insides of eye lids. Nourished by tiny blood vessels.

Question 69

What are the 3 layers that coat the eye?

Answer 69

Sclera - the eye's outer protective layer, high in water content. Choroid - pigmented and vascular Retina - neurosensory tissue

Question 70

What is the cornea and what are its layers?

Answer 70

The transparent, dome-shaped window covering the front of the eye. It is a powerful refracting surface, providing 2/3 of focusing power. 5 layers: epithelium, Bowman's membrane, stroma, Descemet's membrane, endothelium.

Question 71

What is the iris?

Answer 71

The coloured ring surrounding the pupil, embedded with tiny muscles which contract and dilate the pupil.

Question 72

What is the lens?

Answer 72

A transparent structure which provides 1/3 of the focusing power of the eye. Accommodates vision (is elastic). Loses transparency with age (cataracts). Suspended by a fibrous ring: the lens zonules.

Question 73

How is the anterior chamber of the eye (between the cornea and lens) nourished?

Answer 73

Aqueous fluid - secreted by ciliary body. Drained by trabecular meshwork drains (Schlemm's canals).

Question 74

What is the role of the fovea (the centre of the macula)?

Answer 74

Reading, facial recognition, colour vision. | It is the most sensitive part of the retina, with the highest concentration of cones and lowest of rods.

Question 75

What are the layers of the retina?

Answer 75

Outer layer = photoreceptors (1st order neuron) which detects light. Middle layer = bipolar cells (2nd order) - local signal processing to improve contrast sensitivity. Inner layer = retinal ganglion cells (3rd order) - transmission to brain.

Question 76

Describe dark adaptation.

Answer 76

Biphasic process. Cone adaptation in 7 mins. Rod adaptation in 30mins. Regenerates RHODOPSIN.

Question 77

Describe light adaptation.

Answer 77

Occurs over 5 mins - bleaching of photo-pigments. Inhibition of rod/cone function.

Question 78

What is emmetropia?

Answer 78

Adequate correlation between axial length and refractive power - parallel light rays fall on retina.

Question 79

What is ametropia? Give causes.

Answer 79

Mismatch between axial length and refractive power. Near-sightedness = myopia (parallel rays converge at focal point anterior to retina). Excessive refractive power = refractive myopia (more common) or excessively long globe (axial myopia). Far-sightedness = hyperopia. Excessively short globe or insufficient refractive power.

Question 80

What is presbyopia?

Answer 80

A naturally occurring loss of accommodation - the loss of power means distant vision is preserved but close objects are blurred. Due to hardening of lens or weakening of ciliary muscles, so the lens is less flexible, onset 40Y+ - distant vision intact. Corrected by reading glasses (convex lens).

Question 81

Briefly describe how you test the function of the sternocleidomastoid muscle, and which nerves innervate this muscle?

Answer 81

Ask the patient to turn their head right or left against resistance. Innervated by accessory nerve and C3,4.