1. HEAD and NECK ..3 Fascial Compartments of the Neck The orbital region
Meninges (review)
Dural venous sinuses (review)
BAAB
23/05/2016

2. Fascial Compartments of the Neck
Fascial spaces (also termed fascial tissue spaces or tissue spaces) are potential spaces that exist between the fasciae and underlying organs and other tissues.
The fascial spaces are different from the fasciae themselves, which are bands of connective tissue that surround structures, e.g. muscles.
Fascia is a layer of fibrous tissue that surrounds muscles, vessels and nerves.
In the neck, there are several layers of fascia, which act to support and compartmentalise the structures present.

3. Fascial Compartments of the Neck
The spaces filled with loose areolar connective tissue may also be termed clefts.
Other contents such as salivary glands, blood vessels, nerves and lymph nodes are dependent upon the location of the space. Those containing neurovascular tissue (nerves and blood vessels) may also be termed compartments.

4. Fascial Compartments of the Neck
Boundaries of the Neck
The superior boundary of the neck is demarcated by the superior nuchal line of the cranium and the lower margin of the mandible.
The inferior boundary of the neck is demarcated by the suprasternal notch, the clavicle and the first rib.
Clearly, these boundaries are irregular and difficult to define precisely, because of the continuity of structures running from one region to another (i.e. between thorax and neck and between neck and head).
The neck is conveniently thought of as the tissue surrounding the 7 cervical vertebrae.

5. Fascial Compartments of the Neck
Fascial Compartments of the Neck are divided into superficial and deep parts.
The superficial fascia (tela subcutanea) surrounds the entire neck, but does not contribute to the compartmentalization.
The superficial cervical fascia lies between the dermis and the deep cervical fascia.

6. Fascial Compartments of the Neck
Fig; The platysma muscle, located within the superficial cervical
fascia

7. Fascial Compartments of the Neck
The superficial cervical fascia contains various structures:
Neurovascular supply to the skin
Superficial veins (e.g the external jugular vein)
Superficial lymph nodes
Fat
Platysma muscle
In obese individuals, extra fat is deposited in the superficial fascia, creating the ‘double chin’.

8. Fascial Compartments of the Neck
The platysma muscle is situated on the anterior aspect of the neck.
It has two heads, which originate from the fascia of the pectoralis major and deltoid.
Fibres from the two heads cross the clavicle, and meet in the midline, fusing with the muscles of the face.
Motor innervation to the platysma is via the cervical branch of the facial nerve.

9. Fascial Compartments of the Neck
The deep cervical fascia is located underneath the superficial fascia, and is organised into several layers. These layers act like a shirt collar, supporting the structures and vessels of the neck.
The deep fascia also has a superficial and a deep fasciae.
1. One superficial layer of deep fascia is called investing fascia, surrounding the whole neck.

10. Fascial Compartments of the Neck
Fig: Transverse section of the neck. The investing layer of fascia in
highlighted in blue. Note how the fascia completely envelopes the
SCM and trapezius.

11. Fascial Compartments of the Neck
It surrounds all the structures in the neck. Where it meets the trapezius and SCM muscles, by splitting into two, completely surrounding them.
The investing fascia can be thought of as a tube; with superior, inferior, anterior and posterior attachments:
Superior: attaches to the external occipital protuberance and the superior nuchal line.
Anterior: attaches to the hyoid bone.
Inferior: attaches to the spine and acromion of the scapula, the clavicle, and the manubrium of the sternum.
Posterior: attaches along the ligamentum nuchae.

12. Fascial Compartments of the Neck
There are four layers of deep fascia that separate the neck into compartments.
2. The prevertebral layer (yellow in the fig), which surrounds muscles attached to the vertebral column.
The prevertebral fascia surrounds the vertebral column and its associated muscles (scalene, prevertebral, and deep muscles of the back). It has attachments along the antero/posterior and supero/inferior axes:
Superior: attaches to the base of the skull.
Anterior: attaches to the transverse
processes and vertebral bodies of the vertebral column.

13. Fascial Compartments of the Neck
Posterior: attaches along the ligamentum nuchae.
Inferior: fuses with the endothoracic fascia of the ribcage.
The anterolateral portion of prevertebral fascia forms the floor of the posterior triangle of the neck. It also surrounds the brachial plexus and subclavian artery as they leave the neck, forming the axillary sheath. The axillary sheath continues from the prevertebral layer and surrounds the brachial plexus

14. Fascial Compartments of the Neck
Transverse section of the neck. The carotid sheaths and prevertebral sheaths are highlighted.

15. Fascial Compartments of the Neck
3. The pretracheal or visceral layer (red), which is found surrounding the anterior organs.
The pretracheal layer of fascia is situated anteriorly in the neck. It spans between the hyoid bone and the thorax, where it fuses with the pericardium.
The trachea, oesophagus, thyroid gland and infrahyoid muscles are enclosed by the pretracheal fascia. It can be anatomically divided into two parts:
Visceral  – encloses the thyroid gland, trachea and oesophagus.
Muscular – encloses the infrahyoid muscles.
The posterior aspect of the muscular fascia is formed by contributions from the buccopharyngeal fascia (a fascial covering of the pharynx).

16. Fascial Compartments of the Neck
Fig – Transverse section of the neck, showing the pretracheal fascia in red.

17. Fascial Compartments of the Neck
4. The carotid sheath (green), which is formed by condensation of the investing fascia , prevertebral and pretracheal layers, surrounds the carotid artery, the jugular vein and the vagus nerve.
The carotid sheaths are paired structures.
The contents of the carotid sheath are :
Common carotid artery (which bifurcates within the sheath into the external and internal carotid arteries).
Internal jugular vein.
Vagus nerve.
Cervical lymph nodes.
The carotid fascia is organised into a column, which runs from the base of the skull to the thoracic mediastinum. This is of clinical importance as a pathway for the spread of infection.

18. Fascial Compartments of the Neck
Fig: The carotid sheaths (green)

19. Fascial Compartments of the Neck
Clinical Relevance: Spread of Infections
The neck fascia compartmentalises the structures within the neck. These layers of tough fascia define where infection can spread (e.g a superficial skin abscess is prevented from spreading further into the neck by the investing fascia).

20. The orbital region
Introduction Bones of the orbit Boundaries Contents Structures associated Clinical correlates

21. The orbital region
Introduction:
The orbit is a bonny pyramidal cavity or bonny socket of the facial skull in which the eye and its appendages are situated.
it has a base in front and the apex behind.
In the adult human, the volume of the orbit is 30 mL, of which the eye occupies 6.5 mL.
Bones of the orbit:
There are seven bones that form the orbit: Frontal bone Lacrimal bone Ethmoid bone Zygomatic bone Maxillary bone Palatine bone Sphenoid bone Nasal bone (illustrated but not part of the orbit)

22. The orbital region
The seven bones that form the orbit: yellow = Frontal bone green = Lacrimal bone brown = Ethmoid bone blue = Zygomatic bone purple = Maxillary bone aqua = Palatine bone red = Sphenoid bone teal = Nasal bone (illustrated but not part of the orbit)

23. Superior margin: frontal bone and sphenoid
The orbital region
Borders:
The base, which opens in the face, has four borders. The following bones take part in their formation:
Superior margin: frontal bone and sphenoid
Inferior margin: maxilla, palatine and zygomatic
Medial margin: ethmoid, lacrimal bone, and
maxillary bone
Lateral margin: zygomatic and sphenoid
The roof (frontal and sphenoid bones)
lateral wall: zygomatic and sphenoid bones
The floor: maxilla, zygomatic, and palatine bones
medial wall: ethmoid, lacrimal, and frontal bones

24. Contents of the orbit are grouped into
The orbital region
Contents of the orbit are grouped into
Nerves: Ophthalmic nerve, Oculomotor, trochlear and abducent nerves (III, IV, VI), Optic nerve.
Vessels: Ophthalmic vessels
Muscles: Muscles of eyeball (extraocular muscles)
Eyelids
Conjunctiva
Lacrimal apparatus
Ophthalmic nerve the first division of the trigeminal (fifth cranial) nerve
afferent nerve that supplies the globe and conjunctiva, lacrimal gland and sac, nasal mucosa and frontal sinus, external nose, upper eyelid, forehead, and scalp

25. The orbital region
It passes through the superior orbital fissure and traverse the orbit.
The oculomotor (third cranial) nerve supplies all the muscles of the eyeball except the superior oblique and the lateral rectus muscles.
pass through the superior orbital fissure within the common tendinous ring
It passes through the superior orbital fissure within the common tendinous ring
The nerve also conveys preganglionic parasympathetic nerve fibers to the orbit

26. The orbital region
The trochlear (fourth cranial) nerve supplies only the superior oblique muscle of the eyeball
It passes through the superior orbital fissure just superior to the tendinous ring.
The abducent (sixth cranial) nerve supplies only the lateral rectus muscle of the eyeball.
It passes through the superior orbital fissure within the common tendinous ring.
The ciliary ganglion is the peripheral ganglion of the parasympathetic system of the eye.

27. The orbital region

28. Optic nerve The optic (second cranial) nerve is the nerve of sight
The orbital region
Optic nerve
The optic (second cranial) nerve is the nerve of sight
it extends from the eye to the optic chiasm.
Developmentally, it may be considered as a tract between the retina (a derivative of the brain) and the brain
It is surrounded by meningeal sheaths continuous with those of the brain, and also by the subarachnoid space.
is pierced by the central vessels of the retina, and passes through the optic canal to enter the middle cranial fossa.

29. Muscles of eyeball (extraocular muscles)
The orbital region
Muscles of eyeball (extraocular muscles)
The eyeball is moved chiefly by six extrinsic muscles: four recti and two oblique muscles.
These skeletal muscles arise from the posterior aspect of the orbit (except for the inferior oblique muscle) and are inserted into the sclera.
The four recti arise from a common tendinous ring that surrounds the optic canal and a part of the superior orbital fissure
The eye is poised in the fascia and fat of the orbit, and equilibrium is maintained by all the muscles, none of which ever acts alone.

30. Paralysis of an extrinsic eye muscle is noted by
The orbital region
Moreover, the two eyes move together in unison (conjugately). Movements may be considered to be around a vertical axis (abduction and adduction), a lateromedial axis (elevation and depression) and even an anteroposterior axis (extorsion and intorsion).
Paralysis of an extrinsic eye muscle is noted by
(1) limitation of movement in the field of action of
the paralyzed muscle and
(2) the presence of two images (diplopia) that are
separated maximally when an attempt is made
to move the eye in the direction of primary
action of the paralyzed muscle.

31. The orbital region
Eyelids: These are musculofibrous folds in the anterior part of each orbit.
They are two sets, upper and lower lids
They perform reflex blinking, distribute tears and prevent drying of the cornea.
The free margin of each lid possesses hairs termed eyelashes (cilia).
The upper eyelid is composed of skin and subcutaneous tissue, muscle (the palpebral part of the orbicularis oculi and the levator palpebrae superioris), fibrous tissue (including the tarsal plate), and mucous membrane (the palpebral part of the conjunctiva).

32. The orbital region
Conjunctiva
The conjunctiva is a connection (conjunction) between the eyelids, sclera and cornea. It is the mucous membrane that lines the posterior surface of the eyelids (palpebral conjunctiva) and the anterior aspect of the globe (bulbar conjunctiva).
conjunctival sac is the potential space, lined by conjunctiva, between the lids and the globe.
palpebral fissure is the mouth of the conjunctival sac.
Fornix is the reflection of the conjunctiva from the lid to the globe; hence, superior and inferior fornices.
Limbus is a junction between the bulbar conjunctiva and the epithelial lining of the cornea.

33. Conjuntival innervation and blood supply.
The orbital region
Conjuntival innervation and blood supply.
The conjunctiva is supplied by branches of the ophthalmic nerve. The vessels of the bulbar conjunctiva are visible. They arise from (1) a peripheral palpebral arcade and (2) the anterior ciliary arteries. In acute conjunctivitis (e.g., from wind exposure or infection) the bulbar conjunctiva becomes brick-red (a "blood-shot eye"). In deeper conditions (e.g., diseases of the iris or ciliary body), in which branches of the anterior ciliary arteries are dilated, a rose-pink band of "ciliary injection" is produced around the margins of the cornea.

34. The orbital region
Lacrimal apparatus:
The lacrimal apparatus comprises (1) the lacrimal gland and its ducts and (2) associated passages for drainage: the lacrimal canaliculi and sac and the nasolacrimal duct
it lodges in a fossa anterolaterally at the roof of the orbit.
the main portion is the orbital part, but a process called the palpebral part projects into the upper lid
a dozen lacrimal ducts leave the palpebral part to enter the superior conjunctival fornix where small accessory lacrimal glands are also found.
tears secreted keep the eye moist and free of foreign bodies.
the half of the lacrimal secretions that does not evaporate drains into the lacrimal sac.

35. The orbital region

36. The orbital region
Review Questions :
1. Force applied to the rim of the orbit may be transmitted toward the side of the nose. Which thin bones are likely to be splintered?
2. Which nerve accompanies the ophthalmic artery?
3. Which is the most important branch of the ophthalmic artery?
4. Which cranial nerve is "the weakling of the cranial contents" because of its likely damage from increased intracranial pressure?
5. Where is the peripheral relay station of the parasympathetic fibers to the eye?
6. Which nerves enter the orbit within the common tendinous ring?
7. Which chief muscles and nerves are concerned with (a) closing the eyelids and (b) opening them?
8. What are the main features of Horner syndrome?
9. On looking downward and to the right, a patient's left pupil failed to descend. Which muscle is likely to be paralyzed?
10. On looking upward and to the left, a patient's right pupil failed to ascend. Which muscle is most likely to be involved?

37. Meninges

38. Meninges

39. Meninges

40. Meninges

41. Meninges
Lacrimal apparatus Conjunctiva Eyelids Optic nereve Muscles of eyeball (extraocular muscles) Oculomotor, trochlear and abducent nerves (III, IV, VI) Ophthalmic vessels Ophthalmic nerve

42. Meninges

43. Dural venous sinuses

44. Dural venous sinuses

45. Dural venous sinuses

46. Dural venous sinuses

47. Dural venous sinuses

48. Dural venous sinuses