Head & Neck
•Head & Neck anatomy
focuses on the structure of the
head and neck of the human
body, including “ brain, bones,
muscles, blood vessels,
nerves, glands, sinuses,
mouth and teeth”.
•In this course the focus will be
on bones, paranasal sinuses,
TMJ, muscles, vascularity,
nerve supply, lymphatic
drainage, salivary glands, oral
cavity (soft and hard tissues).
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Head & Neck anatomy
I- Skull
* Bones
- Cranium
- Facial
- Maxilla
- Mandible
* TMJ
* Paranasal sinuses
II- Muscles
- Cervical
- Facial expressions
- Muscles of mastication
- Hyoid muscles
- Tongue
- Soft Palate & pharynx
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Bones of the head:
The head is positioned upon the
superior portion of the vertebral
column, attaching the skull upon
C-1 (the atlas).
• The skull can be divided into:
1. Cranium, (8 bones):
a) 1-Frontal
b) 2-Parietal
c) 1-Occipetal
d) 2-Temporal
e) 1-Sphenoid
f) 1-Ethmoid
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2. Facial bones, (14 bones):
a) 2-Zygomatic
b) 2-Maxillary
c) 2-Palatine
d) 2-Nasal
e) 2-Lacrimal
f) 1-Vomer
g) 2-Inferior Conchae
h) 1-Mandible
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Skull
• It has several flat irregular bones
that protect the brain.
• The joints (sutures) between the
skull bones are fibrous joints, and
they don not move in the mature
adult skull.
• The bones have numerous
openings for passage of blood
vessels, nerves & lymph vessels.
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•The bones of the upper skull meet along sutures, which provide
growing room for the rapidly expanding brain.
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I Cranium
Frontal bone: Comprised of
1.
2.
3.
4.
Forehead.
Orbital cavities
Prominent ridges above the eyes (supraorbital margins).
2 air filled sinuses open in the nasal cavities.
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Parietal bones:
• These bones form the sides & roof of the skull
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Occipital bone:
• Forms the back of the head & part of the base of the skull.
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• The occipital bone has 2 condyles that form a hinge with the first vertebra (The
ATLAS).
• Between the condyles there is foramen magnum through which the spinal
cord passes.
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Sphenoid Bone:
• It is located in the middle portion of the skull & articulate with the
temporal, parietal & frontal bones.
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• On the superior (upper) part of the sphenoid bone lies the Sella turcica,
(on this sella turcica sits the pituitary gland).
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• Inside the body of the spehnoid bone there are large air sinuses
(sphenoid sinuses) with openings in the nasal cavities
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Ethmoid bone:
•
Occupies the anterior part of the base
of the skull.
•
It forms parts of the following bones:
1. Orbital cavity
2. Nasal septum
3. Lateral walls of the nasal cavity
4. On the sides of the nasal cavity, there
are 2 bony projections (the upper and
the lower nasal conchae= turbinates)
1. Frontal bone
2. Nasal bone
3. Lacrimal bone
4. Maxillary bone
5. Zygomatic bone
6. Temporal bone
7. Parietal bone
8. Greater wing of sphenoid bone
9. Zygomatic process of temporal bone
10. Lesser wing of sphenoid bone
11. Ethmoid bone
12. Palatine bone
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Ethmoid bone is a delicate bone & contains many air sinuses and
opens in the nasal cavity.
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II Facial bones
Zygomatic bones:
• They are called cheek bones.
• They form the prominence of the
cheeks & part of the floor & lateral
walls of the orbital cavities.
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Maxilla:
• It is the upper jaw bone.
• Originally they are 2 bones, but
fuse before birth to form one
bone otherwise a cleft palate
exists.
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Alveolar ridge is a process projects downwards & carries the upper
teeth
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Maxillary sinuses:
• Large sinuses, one on each side opens into the nasal cavities.
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Nasal bones:
• They are 2 small flat bones.
• They form the greater part of the
lateral & superior surfaces of the
bridge of the nose.
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Lacrimal bones:
• They are 2 small bones located
lateral & posterior to the nasal
bones.
• They form part of the medial
walls of the orbital cavities.
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Vomer bone:
• It is a thin flat bone extends upwards from the middle of the hard palate to
form the main part of the nasal septum.
• It articulates with the perpendicular plate of the ethmoidal bone.
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Palatine bones:
•
2 L-shaped bones
1. Horizontal parts: they unit
to form the posterior part of
the hard palate.
2. Perpendicular parts: they
projects upwards to form
part of the lateral walls of
the nasal cavities.
•
At their upper parts they
form part of the orbital
cavities.
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Inferior conchae
( turbinated bones):
• Each conchae is a
scroll-shaped bone.
• It forms part of the
lateral wall of the nasal
cavity & projects into it
below the middle
conchae.
• The superior and
middle conchae are
parts of the ethmoidal
bone.
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Hyoid bone:
• A horse-shoe shaped bone, lying in the soft tissues of the neck above the
larynx & below the mandible.
• It is an isolated bone that does not articulate with any other bone.
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Hyoid bone:
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Mandible
•
The ONLY movable bone of the
skull.
•
Originally 2 parts, units at midline.
•
Each half has 2 parts
1. Curved body with alveolar ridge
that host the lower teeth.
2. Ramus which projects upwards
almost at right angle to the body at
the posterior end.
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•
The ramus divides at the upper end into 2 parts:
1. Condylar process which articulates with the temporal bone to form
the temporomandibular joint (TMJ).
2. Coronoid process that gives attachment to muscles & ligamnets.
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TMJ
•The mandible articulates with the temporal bone at the
temporomandibular joint (TMJ).
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• The TMJ is formed between the articular surface of the squamous part of
the temporal bone & the head of the condyle.
• It is separated into upper & lower cavities by a fibrocartilagenous disc
within the joint.
• Lateral ptregoid muscle pierces the capsule attaching to the head of the
condyle
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TMJ
•Movements possible at this joint include depression and elevation of the
mandible, protraction and retraction, side to side movements.
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TMJ
•The joint has an intra-articular disc.
• The articular disc is attached
around its periphery to the inside of
the capsule.
• Anteriorly is attached near the
head of the mandible & posteriorly it
is attached near the temporal bone.
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Paranasal sinuses:
•
The Paranasal sinuses are air-containing spaces within the skull.
• The function of the sinuses:
The biological role of the sinuses is debated, but a number of possible functions
have been proposed:
1. Decreasing the relative weight of the front of the skull, and especially the bones
of the face.
2. Increasing resonance of the voice.
3. Providing a buffer against blows to the face.
4. Insulating sensitive structures like dental roots and eyes from rapid
temperature fluctuations in the nasal cavity.
5. Humidifying and heating of inhaled air because of slow air turnover in this
region.
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The sinuses are named for the bones in which they are located.
These are:
1. The maxillary sinuses, the largest of the nasal sinuses.
2. The frontal sinuses, located within the forehead just above the left
and right eye.
3. The ethmoid sinuses, irregularly shaped air cells separated from
the orbital cavity by a very thin layer of bone.
4. The sphenoid sinuses, located close to the optic nerves, where an
infection may damage vision.
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F= Frontal sinuses; E=Ethmoid sinuses; M=Maxillary sinuses;
O=Maxillary sinus ostium; ST=Superior turbinate; T=Middle
turbinate; IT= Inferior turbinate; SM=Superior meatus;
MM=Middle meatus; S=Septum
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Muscles of the head and neck
•
Seven groups of muscles
1. Cervical muscles
2. Muscles of facial expressions
3. Muscles of mastication
4. Hyoid muscles
5. Muscles of the Tongue
6. Muscle of the soft palate
7. Muscles of the pharynx.
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1. Cervical muscles:
A. Sternocleidomastoid
muscle: divides the neck
into anterior and posterior
cervical triangles.
B. Trapezius muscle: lift the
clavicle & scapula
(shoulder blade), as when
the shoulder are
shrugged.
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2. Muscles of facial expression
•
Paired muscles on each side.
A. Orbicularis oris
B. Buccinator muscle
C. Mentalis muscle
D. Zygomatic major
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Orbicularis oris:
• Closes & puckers the lips.
• Helps in chewing & speaking by pressing the lips against the teeth.
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Buccinator muscle:
• It compresses the cheeks against the teeth & retracts the angle of
the mouth.
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Mentalis muscle:
• Raises & wrinkles the skin of the chin & pushes up the lower lip
Zygomatic major muscle:
• Draws the angles of the mouth upwards & backwards, as in laughing.
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Muscles of Mastication
1. Temporalis muscle: raises the mandible & closes the jaws, posterior fibers
draw protruding mandible backwards.
2. Masseter muscles: raises the mandible & closes the jaw.
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3. Medial ptreygoid muscles: closes jaw & by acting with lateral ptreygoid
on same side, pulls mandible to one side.
4. Lateral ptreygoid muscles: depresses the mandible to open the jaw.
•
when both muscles contract together, the main action is to bring the lower
jaw forward, thus causing protrusion of the mandible.
•
If one lateral ptregoid muscle is contracted, the lower jaw shifts to the
opposite side, causing lateral deviation of the mandible
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Muscles of the floor of the mouth
1. Mylohyoid muscle: forms the floor of the mouth, raises the tongue &
depresses the mandible.
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2. Digastric muscles: each digastric muscle (anterior belly + posterior belly)
demarcates the superior portion of the anterior cervical triangle.
• forming with the mandible a submandibular triangle on each side of the neck
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3. Stylohyoid muscle: assist in swallowing by raising the hyoid bone.
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4. Geniohyoid muscle: draw the tongue & hyoid bone forward.
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Muscles of the Tongue:
1. Genioglossus muscles: depresses & protrudes the tongue.
2. Hyoglossus muscle: retracts & pulls down the side of the tongue.
3. Styloglossus muscle: retracts the tongue.
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Major muscles of the posterior of the mouth
1. Palatoglossus muscle: elevates the base of the tongue, arching the
tongue against the soft palate toward the tongue.
2. Palatopharyngeus muscle: forms the posterior pillar of fauces.
• also serves to narrow the fauces & help to shut off the nasopharynx.
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