Revised by: Dr. Nikravesh

page 53:

Deep Dissection of the Neck

11. Trace the internal jugular vein downwards to the root of the neck

where it forms a dilatation known as the inferior bulb. Observe that

this vein is joined by the subclavian vein to form the brachiocephalic

vein. At the junction of the internal jugular and subclavian veins, look

for the entry of the thoracic duct on the left side and the right

lymphatic duct on the right.

12. Cut the internal jugular vein near its termination and lift it upwards.

Note that the cervical part of the thoracic duct ascends on the left side of

the oesophagus and runs behind the carotid sheath to arch forwards in

front of the subclavian artery, after which it descends to its termination.

13. Divide the common carotid artery at the root of the neck and turn it

upwards. Examine the subclavian artery whose course is divided by

the scalenus anterior muscle into three parts. Note that the first part

which lies proximal to the muscle gives off:

(a) the vertebral artery;

(b) the internal thoracic artery; and

(c) the thyrocervical trunk which in turn gives off the inferior

thyroid, suprascapular and transverse cervical arteries.

14. Trace the right recurrent laryngeal nerve which is given off by the

right vagus as it descends in front of the subclavian artery. Observe

that this nerve curves under the subclavian artery to ascend in the

groove between the trachea and oesophagus where it has been dissected.

15. Observe the costocervical trunk arising from the second part of the

subclavian artery which lies behind the scalenus anterior muscle. Follow

this trunk as it curves backwards over the apex of the lung where it

divides into the superior intercostal and deep cervical branches at

the neck of the first rib. The superior intercostal artery enters the thorax

across the neck of the first rib where it has been examined.

16. Follow the third part of the subclavian artery from the lateral border

of the scalenus anterior muscle to the outer border of the first rib where

it continues as the axillary artery.

 

page 54:

17. Now return to the upper part of the neck. Cut the sling which attaches

the intermediate tendon of the digastric to the hyoid bone and reflect

the muscle laterally. Carefully clean the stylopharyngeus muscle

which arises from the medial surface of the styloid process and secure

its nerve supply from the glossopharyngeal nerve which winds round

the posterior border of the muscle. Note that the muscle runs downwards

and forwards between the internal and external carotid arteries to

gain insertion into the inner aspect of the pharynx by passing through

the interval between the superior and middle constrictors.

18. Clean the glossopharyngeal nerve and note that it emerges between

the internal jugular vein and the internal carotid artery. It then follows

the stylopharyngeus muscle between the internal and external carotid

arteries to the side of the pharynx after which the nerve reaches the

posterior part of the tongue where it breaks up into its terminal branches.

19. Trace the stylohyoid ligament from the tip of the styloid process to the

lesser horn of the hyoid bone and note its relationship to the

glossopharyngeal nerve and lingual artery.

20. Turn your attention to the vagus nerve and note that it pursues a vertical

course at first between the internal jugular vein and the internal carotid

artery, and then between the vein and the common carotid artery. Try

to identify the pharyngeal branch passing between the internal and

external carotid arteries and the superior laryngeal nerve passing deep

to both the arteries. Trace the vagus nerve upwards and look for the two

ganglia which contain the cell bodies of the sensory fibres of this nerve.

21. Trace the accessory nerve which first descends between the internal

jugular vein and internal carotid artery, and then inclines backwards

superficial to the internal jugular vein before it enters the

sternocleidomastoid. Its further course in the roof of the posterior

triangle of the neck has already been seen.

22. Now trace the hypoglossal nerve, which after emerging from the

hypoglossal canal, lies posteromedial to the internal carotid artery and

internal jugular vein. Observe that it then winds round the vagus to emerge

between the artery and the vein. Its further course has already been seen.

23. Clean the internal carotid artery and trace it upwards and note that it

enters the cranial cavity through the carotid canal. Observe that this

artery does not give any branches in the neck.

24. Review the branches of the external carotid artery. Note that the

ascending pharyngeal artery runs upwards along the side of the

pharynx. It supplies the pharynx and neighbouring structures near

the base of the skull.

 

page 55:

25. Clean the internal jugular vein near the base of the skull and note that

it is a continuation of the sigmoid sinus and has a superior bulb in the

jugular fossa. Review its tributaries which are the inferior petrosal

sinus, pharyngeal veins, facial vein, lingual veins and superior and

middle thyroid veins.

26. Clean the sympathetic trunk which runs along the roots of the

transverse processes of the cervical vertebrae. Identify the superior

and middle cervical ganglia. Note that the superior ganglion lies

opposite the second and third cervical vertebrae and gives grey rami

communicantes to the upper four cervical nerves. It continues

superiorly as the internal carotid nerve which later gives rise to the

internal carotid plexus. The superior ganglion also gives off

pharyngeal, external carotid and cardiac branches.

27. Identify the middle cervical ganglion lying opposite the sixth cervical

vertebra. Note that it gives off grey rami communicantes to the fifth and

sixth cervical nerves, branches to the thyroid gland, a cardiac branch

and the ansa subclavia. This ansa is a loop connecting the middle and

cervicothoracic ganglia, and passes round the subclavian artery.

28. Replace the sternocleidomastoid muscle in position and revise its deep

relations.

29. Divide the trachea and oesophagus near the root of the neck and

separate them from the vertebral column. Clean the prevertebral fascia

which covers the prevertebral muscles. The fascial space between it

and the pharynx is called the retropharyngeal space.

30. Examine the cervical plexus which lies in front of the scalenus medius

muscle. Note that this plexus is formed by the ventral rami of the upper

four cervical nerves. Its branches are:

(a) a communicating branch from C1 to the hypoglossal nerve;

(b) the lesser occipital, greater auricular, transverse cervical and

supraclavicular nerves;

(c) branches to the levator scapulae, sternocleidomastoid, trapezius

and the prevertebral muscles;

(d) the phrenic nerve (C3, 4, 5) to the diaphragm; and

(e) the inferior root of the ansa cervicalis (C2, 3) which joins the

superior root (C1), a branch of the hypoglossal nerve, to form

the ansa cervicalis.

 

page 56:

31. Quickly note the attachments of the prevertebral muscles on either side:

(a) scalenus anterior arises from the transverse processes of the third,

fourth, fifth and sixth cervical vertebrae and is inserted into the

scalene tubercle of the first rib in front of the subclavian artery;

(b) scalenus medius arises from the transverse processes of all the

cervical vertebrae and is inserted into the upper surface of the first

rib behind the groove for the subclavian artery;

(c) scalenus posterior arises from the transverse processes of the

lower cervical vertebrae and is inserted into the second rib;

(d) rectus capitis anterior and lateralis are two small muscles

extending between the atlas and occiput;

(e) longus colli muscle is attached cranially to the anterior tubercle

of the atlas and caudally to the bodies of the third, fourth, fifth

and sixth cervical vertebrae and the bodies of the upper three

thoracic vertebrae; and

(f) longus capitis arises from the transverse processes of the third,

fourth, fifth and sixth cervical vertebrae and gains insertion into the basiocciput.

32. Look at the following structures in relation to the cervical pleura at

the root of the neck lying medial to the scalenus anterior muscles:

(a) the vertebral vein which emerges from the foramen

transversarium of the sixth cervical vertebra and passes in front

of the subclavian artery to enter the brachiocephalic vein;

(b) the vertebral artery which arises from the subclavian artery and

passes upwards behind the vertebral vein to enter the foramen

transversarium of the sixth cervical vertebra. This is the first part

of the artery;

(c) deep to the vertebral artery, look for the sympathetic

cervicothoracic ganglion which lies on the neck of the first rib.

Note it has a cardiac branch as well as branches to the vertebral

and subclavian plexuses. The ganglion is a fusion of the inferior

cervical and first thoracic ganglia; and

(d) the internal thoracic artery which arises from the subclavian

artery and passes downwards over the apex of the lung where it is

crossed by the phrenic nerve.

33. Note that the second part of the vertebral artery passes through the

foramina transversaria of the upper six cervical vertebrae. The further

course of the vertebral artery will be seen in the suboccipital triangle.

 

page 57:

Summary

In the submandibular region the mylohyoid muscles form the oral diaphragm

separating the neck from the oral mucosa. Related to the muscle is the

submandibular salivary gland. Its nerve supply is conveyed by the chorda

tympani nerve from the facial nerve. The fibres of the chorda tympani contain

preganglionic parasympathetic fibres which relay in the submandibular

ganglion before supplying the gland with postganglionic secretomotor fibres.

Note that salivary calculi are most common in the submandibular duct. The

relationships of the facial artery and the adjacent veins must be borne in

mind during surgical removal of the gland.

The deep fascia of the neck has important components, viz superficial,

pretracheal and prevertebral layers. The superficial layer encloses both the

trapezius and sternocleidomastoid muscles. The pretracheal fascia lies deep

to the infrahyoid muscles and provides the fascial capsule for the thyroid

gland. Between the superficial and pretracheal layers is a potential space of

the neck which passes into the anterior mediastinum in front of the heart.

The prevertebral fascia, which is thick and well defined, lies in front of the

prevertebral muscles. Between the fascia and pharynx in front, is the

retropharyngeal space which permits the movements of the pharynx during

swallowing. Moreover, as the retropharyngeal space leads down into the

thorax, retropharyngeal abscesses can track down from the neck into the

mediastinum.

As in the rest of the body, the lymphatics of the head and neck can be

conveniently divided into superficial and deep sets. The superficial

lymphatics usually drain into the superficial lymph nodes which, in general,

are distributed along the superficial veins. For example, the pericervical

collar formed by the occipital, posterior auricular, parotid,

submandibular and submental lymph nodes can all be regarded as being

situated along the occipital, posterior auricular, superficial temporal, facial

and anterior jugular veins. The superficial nodes distributed along the

anterior jugular and external jugular veins are known as the anterior and

superficial cervical lymph nodes respectively. The lymphatics from the

superficial regions of the head and neck, after reaching the superficial lymph

nodes eventually pass to the deep cervical nodes distributed along the internal

jugular vein. The intermediate set of lymph nodes draining various organs

are found along the branches of arteries supplying these organs or the

corresponding veins accompanying the arteries. For example, the pre- and

paratracheal nodes draining the thyroid can be regarded as being situated

along the tributaries of the superior and inferior thyroid veins. From these

nodes, the lymphatics eventually pass along the superior and inferior thyroid

veins into the deep cervical and brachiocephalic nodes. Thus the deep

lymphatics may be said to accompany the deep veins. However, there

are exceptions to these generalisations, e.g. the tip of the tongue drains not

only into the submental nodes but may also reach the juguloomohyoid

node situated on the internal jugular vein where the vein is crossed by the

omohyoid muscle. The remainder of the lymphatics of the tongue follow

the veins of the tongue.

The lymphatics of the tongue, thyroid and larynx are important as these

organs are common sites of cancer. Moreover, the cervical lymph nodes

become enlarged in infections such as tuberculosis.

 

page 58:

SUBMANDIBULAR REGION

Objectives:

1. Define the extent and surfaces of the submandibular gland.

2. Demonstrate the relations of the submandibular gland.

3. Review the course of the facial artery.

4. Discuss the anatomical aspects of:

(a) submandibular salivary calculi; and

(b) veins related to the submandibular gland.

 

DEEP STRUCTURES OF THE NECK

Objectives:

1. Surface mark the common and external carotid arteries.

2. Review the area of distribution of the branches of the external carotid artery.

3. Enumerate the branches of the subclavian artery.

4. Describe the course and relations of the internal jugular vein, and

enumerate its tributaries.

General objective 2:

Comprehend the basic anatomy of the nervous structures in the region.

Specific objectives:

1. Identify the carotid canal, jugular foramen and hypoglossal canal in

the base of the skull.

2. Enumerate the structures traversing the above foramina and illustrate

the relationships between the last four cranial nerves at the base of the skull.

3. Indicate the course of the last four cranial nerves enumerating their

branches in sequence.

4. Deduce the effects of lesions of the last four cranial nerves both alone

and in combination.

5. Identify the cervical sympathetic trunk and the superior, middle and cervicothoracic ganglia.

6. Illustrate the sympathetic innervation of the heart.

7. Illustrate the formation and branches of the cervical plexus.

8. Describe the relationships of the hypoglossal nerve, submandibular

duct, lingual nerve and lingual artery to the hyoglossus muscle.

9. Give an account of the main branches of the subclavian artery, including

an account of the relationship of the artery to the scalene muscles.

10. Describe the course of the vertebral artery.

11. Give an account of the sympathetic innervation of the structures in the head and neck.

12. Describe the major fascial compartments of the neck, including the

structures contained in each.

13. Describe the course of the thoracic duct from the cisterna chyli to its termination.

 

page 59:

QUESTIONS FOR STUDY:

1. What muscle forms the floor of the mouth? What is the relationship of

this muscle to the submandibular gland and its duct?

2. What functional components are found in the lingual nerve proximal

to its union with the chorda tympani? Distal? What functional deficits

would result from accidental sectioning of this nerve during surgery

for removal of a lower third molar?

3. Extensive atherosclerosis of the internal carotid artery can be surgically

treated by a procedure, termed a carotid endartectomy, during which

the artery in the neck is opened and carefully cleaned. What nerves in

the neck may be at particular risk during such a procedure?

4. How do sympathetic nerve fibres reach their target organs in the head?

5. What is Horner’s syndrome?

6. How might a chylothorax be produced in an attempted brachiocephalic

venipuncture on the left side?

7. Where would one find the deep cervical lymph nodes? Where do

efferent vessels from these nodes drain?

 

 DEEP STRUCTURES OF THE BACK OF THE NECK

Relevant skeletal features:

occipital bone - superior and inferior nuchal lines; foramen

magnum;

temporal bone - mastoid process;

vertebral column - atlas; posterior tubercle; posterior arch;

transverse processes;

axis; dens of axis; spine; vertebral arch;

typical vertebra; spinous process; laminae;

pedicle;

transverse processes; articular process;

Subcutaneous structures:

greater occipital nerve; occipital artery.

Deep fascia:

Ligaments:

ligamentum nuchae; supraspinous; interspinous; ligamenta flava; anterior

and posterior atlantooccipital membranes.

 

page 60:

Muscles:

splenius capitis; semispinalis capitis; rectus capitis posterior major

and minor; obliquus capitis superior and inferior; erector spinae;

transversospinalis.

Nerves:

suboccipital; posterior and anterior rami of spinal nerves.

Arteries:

vertebral.

Veins:

suboccipital plexus.

Joints of the skull:

sutural joints between skull bones; primary cartilaginous joint between

basisphenoid and basiocciput; peg and socket joints between teeth and

alveolus.

Joints of the cervical vertebrae:

secondary cartilaginous joints between vertebral bodies;

synovial joints: between atlas and occiput; between dens of axis and

atlas; between articular processes of adjacent vertebrae.

Ligaments:

anterior and posterior atlantooccipital membranes; membrana tectoria;

cruciate ligament; transverse ligament of atlas; apical; alar; anterior and

posterior longitudinal; ligamentum nuchae; supraspinous; interspinous;

ligamenta flava.

 

DEEP STRUCTURES OF THE BACK OF THE NECK

1. Place the body in the prone position. Remove the remains of the

trapezius muscle. Note that the occipital artery ascends across the

superior nuchal line after emerging from under cover of the mastoid

process and the muscles attached to it. It supplies the back of the scalp.

2.  Trace the posterior layer upwards over the thoracic region,

 and note that it thins out and is replaced by the

splenius capitis muscle over the back of the neck.

3. Clean the splenius capitis muscle, taking origin from the upper six

thoracic spines and the ligamentum nuchae. It gains insertion

into the transverse processes of the upper two or three cervical

vertebrae, the mastoid process and the adjoining superior nuchal line.

Detach this muscle from its origin and reflect it upwards.

4. Identify the massive semispinalis capitis muscle which arises from

the transverse processes of the lower cervical and upper thoracic

vertebrae to be inserted into the medial half of the area between the

superior and inferior nuchal lines. Observe the thick greater occipital

nerve which pierces this muscle. Detach the semispinalis capitis from

its insertion and carefully reflect the muscle downwards. This exposes

the suboccipital triangle.

 

page 61:

5. Examine the suboccipital triangle bounded by the rectus capitis

posterior major medially, the obliquus capitis superior above and

laterally, and the obliquus capitis inferior below. The floor of the

suboccipital triangle is made up of the posterior atlantooccipital

membrane above and the posterior arch of the atlas below. Note

that the greater occipital nerve (C2) winds round the lower border of

the obliquus capitis inferior and that rectus capitis posterior minor

lies medial to the rectus capitis posterior major.

6. Study the attachments of the suboccipital muscles:

The rectus capitis posterior major arises from the spine of the axis

while the rectus capitis posterior minor takes origin from the posterior

tubercle of the atlas. Both these muscles are inserted into the area

below the inferior nuchal line, the major being lateral to the minor.

The obliquus capitis inferior arises from the spine of the axis and is

inserted into the transverse process of the atlas.

The obliquus capitis superior arises from the transverse process of the

atlas and is inserted into the area between the nuchal lines lateral to the

semispinalis capitis.

7. Follow the third part of the vertebral artery medially under the

posterior atlantooccipital membrane. Observe the plexus of veins in

the suboccipital region.

 

page 62:

8. Observe that the synovial joints between the atlas and occipital

condyles (atlantooccipital joint) permit anteroposterior flexion

and extension as well as lateral flexion, while rotation of the head

occurs at the joint between the dens of the axis and the atlas.

9. Note that the anterior atlantooccipital membrane passes between

the anterior margin of the foramen magnum above and the anterior

arch of the atlas below. This membrane is a continuation of the

anterior longitudinal ligament.

10. The posterior atlantooccipital membrane passes between the

posterior margin of the foramen magnum above and the posterior

arch of the atlas below. Note that the membrane arches over the

vertebral artery and the C1 nerve laterally. The membrane

corresponds to the ligamenta flava.

11. Next examine the articulations between the atlas and axis, the

atlantoaxial joint. The joints between the inferior facets of the

atlas and the superior facets of the axis are synovial joints.

12. From each side of the apex of the dens an alar ligament passes

upwards and laterally to the medial side of each occipital condyle.

These two ligaments check excess rotation.

(h) The apical ligament ascends from the apex of the dens to the

anterior edge of the foramen magnum. This ligament contains

traces of the notochord.

13. Posterior to the alar and apical ligaments is the cruciate ligament.

This ligament consists of two parts: a longitudinal band which

extends upwards from the posterior aspect of the dens to the anterior

edge of the foramen magnum and a transverse ligament of the

atlas which passes behind the dens between the medial sides of

the lateral masses of the atlas.

14. Posterior to the cruciform ligament lies the upward continuation

of the posterior longitudinal ligament, the membrana tectoria,

which passes through the foramen magnum to be attached to the

inner aspect of the occipital bone.

 

page 63:

Summary

The joints between the atlas and occiput, and between the atlas and axis,

are specialised to meet the functional needs of nodding, lateral flexion and

rotatory movements of the head. Flexion and extension or nodding

movements occur between the atlas and occiput, while rotatory movements

take place between the dens of the axis and the anterior arch of the atlas.

The dens is held in position by the transverse ligament of the atlas. This

ligament is so strong that fracture of the dens is more liable to occur than a

tear of the transverse ligament. During rotation, the alar ligaments become

tight and thus their function is to limit excessive rotation of the head.

The superior and inferior articular processes of the atlas and the superior

articular facets of the axis are developmentally different from the articular

processes, present in the other cervical vertebrae. Consequently the anterior

rami of C1 and C2 pass behind the articular processes, whereas the

anterior rami of the other cervical nerves pass in front of the corresponding

articular processes.

 

DEEP STRUCTURES OF THE BACK OF THE NECK

1. Enumerate the muscles of the medial, intermediate and lateral columns

of the erector spinae from medial to lateral.

2. Trace the continuity of these muscles in relays and define the

semispinalis capitis and longissimus capitis, which are the only muscles

to reach the skull.

3. Define the muscular boundaries of the suboccipital triangle.

4. Discuss the more important actions of the erector spinae and

suboccipital muscles.

 

page 64:

 NASAL CAVITY

Relevant features:

bony and cartilaginous parts of nasal septum;

superior, middle and inferior nasal conchae;

superior, middle and inferior nasal meatuses;

sphenoethmoidal recess and opening of sphenoidal sinus;

frontal sinus and frontonasal duct;

hiatus semilunaris of middle meatus and the opening of the maxillary sinus;

maxillary sinus and roots of upper molar teeth;

opening of nasolacrimal duct into inferior meatus;

sphenopalatine foramen;

opening of pharyngotympanic tube;

arterial supply of nasal cavity;

sensory nerve supply of nasal cavity.

1. Examine sagittal and frontal sections of prosected specimens and

models of the head and neck. Observe the external nose, and the more

deeply placed nasal cavity. Note the air-containing extensions of the

nasal cavity giving rise to the paired paranasal sinuses, namely, the

frontal, ethmoidal, sphenoidal and maxillary sinuses.

2. Examine the pyramid-shaped external nose in the cadaver and note

that it opens to the exterior by the nares or nostrils. These are separated

from each other by a nasal septum. This region is known as the

vestibule. Note that the framework of the lower part of the external

nose is cartilaginous.

 

page 65:

3. Identify the bony framework of the upper part of the bridge of the nose

formed by the two nasal bones articulating with each other. Lateral to

these are the frontal processes of the maxillae, while above the nasal

bones are the nasal processes of the frontal bone. Verify this in theskull.

4. Next, bisect the head and neck. For this, the following instruments should

be used: a frame-saw, a small amputation-saw, bone-cutting forceps

and a wooden block to support the head.

(a) Lay the body supine, with the neck on the block. In order to avoid

dropping debris on the floor, make sure that the head lies within

the edge of the table.

(b) Stand at the head of the body.

(c) The nose, which is often bent to one side, should be pushed back

into the midline and divided in the median plane with a scalpel as

deeply as you can.

(d) Insert the blade of the frame-saw into this incision and, keeping

your saw slightly off the median sagittal plane, start sawing through

the mandible and the bone of the forehead.

(e) When you have divided the mandible, use a scalpel to continue

the cut through the soft tissues of the floor of the mouth and upper

part of the neck in the median plane. Divide the hyoid bone with

bone-cutting forceps at its midpoint. Next divide the larynx and

trachea and the pharynx and oesophagus in the neck in the median

plane with a scalpel, the scalpel should reach the midline of the

cervical part of the vertebral column. At this point start sawing

again, with someone helping you by holding the head and neck

and guarding the divided soft tissues from the saw.

(f) Deepen the saw-cut as far as possible, until the handle of the saw

meets the table on which the body is lying.

(g) Turn the body over, and incise the skin over the occiput with a

scalpel, in line with the saw-cut (if not already done). The soft

tissues overlying the spinous processes should then be incised with

a scalpel until you reach the bone. Having done so, insert the saw

in the incision and saw forwards in the median plane as deeply as

possible. The saw-cut should be extended into the spinous processes.

(h) Turn the body on its left side and transect all the soft tissues with

a scalpel just above the line of the right first rib. The incision

should pass between the subclavian vessels below and the lower

end of the thyroid gland above. Use a saw to carry the section

right through the vertebral column.

(i) Complete the median section of the bones of the skull and neck,

where necessary, with a small amputation-saw, until you can

separate the two halves.

 

page 66:

5. In your half of the head and neck, examine the nasal septum and note

that the upper part is lined by olfactory mucosa. In the lower part of

the septum identify the nasopalatine nerve, running along with the

sphenopalatine artery.

6. Remove the mucous membrane from the septum and examine its

framework, consisting of the vomer posteroinferiorly, the

perpendicular plate of the ethmoid posterosuperiorly, and the septal

cartilage which fits anteriorly into the angle between these two bones.

Carefully remove the skeletal framework of the septum, leaving the

mucous membrane of the opposite side intact (submucous resection of

the septum).

7. Dissect the nasopalatine nerve in the intact mucosa of the septum.

Follow the nerve backwards from the septum and then laterally across

the roof of the nasal cavity to the sphenopalatine foramen and thence

to the pterygopalatine ganglion lying in the pterygopalatine fossa.

Strip off the mucoperiosteum from the palatine bone with forceps, and

carefully remove the bone with bone forceps and follow the greater

palatine nerve as it descends from the ganglion on the lateral side of

the palatine bone to reach the palate at its posterolateral corner. Trace

it upwards to the ganglion.

8. Remove the remains of the septum and examine the lateral wall of the

nose. Identify the anteriorly situated vestibule carrying stiff hairs or

vibrissae. Further posteriorly, observe the three scroll like conchae.

The superior and middle nasal conchae are parts of the ethmoid while

the inferior nasal concha is a separate bony entity. Below each concha

identify a meatus of the nose. Thus there are three meatuses: superior,

middle and inferior. Above and behind the superior concha, identify

the sphenoethmoidal recess into which opens the sphenoidal air sinus.

Note the olfactory mucosa in the upper third of the lateral wall.

9. Identify the opening of the nasolacrimal duct into the inferior meatus.

10. Note that the posterior ethmoidal sinus opens into the superior meatus

and all other sinuses open into the middle meatus. The space leading

into the middle meatus from the nasal vestibule is called the atrium of

the middle meatus.

11. Follow the middle concha backwards and note that it leads to the

sphenopalatine foramen. Similarly, follow the inferior concha

posteriorly and observe that it leads to the opening of the

pharyngotympanic tube.

 

page 67:

12. Remove the anterior half of the inferior nasal concha. Pass a probe

through the nasolacrimal canal from the orbit above and locate its

lower opening in the nasal cavity. Next remove the other conchae

carefully with scissors and identify the prominent bulge towards the

centre of the middle meatus caused by the underlying middle ethmoidal

air cells. This is the bulla ethomoidalis. Note the semicircular groove

called the hiatus semilunaris lying below the bulla. Identify the

frontonasal duct at the anterior end of the hiatus. Some of the anterior

ethmoidal air cells and the frontal sinus drain by this common opening.

The main opening of the anterior ethmoidal sinus is just behind this

while the maxillary sinus opens further posteriorly in the middle of the hiatus.

13. Make an attempt to trace the branches of the pterygopalatine ganglion

and the branches of the maxillary and ethmoidal arteries supplying

the lateral wall of the nose. Strip the mucoperiosteum off the lateral

wall of the nose and study its skeletal framework. Observe that the

frontal process of the maxilla and the nasal bones are most anterior,

the medial surface of the maxilla and perpendicular plate of the palatine

bone lie behind and below. Note the bones covering the medial wall of

the maxillary sinus. These are the lacrimal in front, ethmoid above,

perpendicular plate of the palatine behind and inferior nasal concha

below. Finally explore the maxillary sinus by breaking through the

bones which constitute its medial wall. Try to see whether the tip of a

root of a premolar or molar tooth projects into the sinus.

 

Next pages

Back