THE HEAD

AIZAZ
Demonstrator Surgical
KMU-IPMS Peshawar
• Formed mainly by the skull with the brain and its covering meninges enclosed
in the cranial cavity.

• The special senses, the eye and the ear, lie within the skull bones

or in the cavities bounded by them.

• The brain gives rise to 12 pairs of cranial nerves, which leave the brain and pass
through foramina and fissures in the skull.

• All the cranial nerves are distributed to structures in the head and neck, except
the 10th, which also supplies structures in the chest and abdomen.
Scalp
• The scalp refers to the layers of skin and subcutaneous tissue that cover the
bones of cranial vault.
• The scalp consists of five layers. The first three layers are tightly bound
together and move as a collective structure
• The scalp extends from the external occipital protuberance and superior
nuchal lines to the supraorbital margins.
• The scalp consists of 5 layers : the skin, connective tissue, epicranial
aponeurosis, loose areolar tissue, and pericranium.
• The first 3 layers are bound together as a single unit. This single unit can
move along the loose areolar tissue over the pericranium, which is adherent
to the calvaria.
Bones of the Skull
• The skull is composed of several separate bones united at immobile joints
called sutures.
• The connective tissue between the bones is called a sutural ligament.
• The mandible is an exception to this rule, for it is united to the skull by the
mobile temporomandibular joint
• The bones of the skull can be divided into those of the cranium and those of
the face.
• The vault is the upper part of the cranium, and the base of the skull is the
lowest part of the cranium
• The skull bones are made up of external and internal tables of compact bone
separated by a layer of spongy bone called the diploe.
• The internal table is thinner and more brittle than the external table.
• The bones are covered on the outer and inner surfaces with periosteum.
Bones of the Skull
• The cranium consists of the following bones, two of which are paired:
Frontal bone: 1
Parietal bones: 2

Occipital bone: 1

Temporal bones: 2

Sphenoid bone: 1

Ethmoid bone: 1
Bones of the Skull
• The facial bones consist of the following, two of which are single:
Zygomatic bones: 2

Maxillae: 2
Nasal bones: 2
Lacrimal bones: 2

Vomer: 1
Palatine bones: 2

Inferior conchae: 2

Mandible: 1
Sutures
• The sutures of the skull, also referred to as the cranial sutures, are fibrous
joints that connect the bones of the skull.
• The dense fibrous tissue that connects the sutures is made mostly out of
collagen.
• These joints are fixed, immovable, and they have no cavity.
• They are also referred to as the synarthroses.
• In fetal skull, the sutures are wide and allow slight movement during birth, but
later in life they become rigid and fixed
Sutures
Sutures are a type of fibrous joint that are unique to the skull. The main suture of
the Skull are…

Coronal suture: unites the frontal bone with the parietal bones

Sagittal suture: unites the 2 parietal bones in the midline

Lambdoid suture: unites the parietal bones with the occipital bone

Squamous suture: unites the squamous portion of the temporal bone with the
parietal bones
Sutures
Anterior Aspect
• Frontonasal suture: between the frontal bone and nasal bones
• Frontozygomatic suture: between the frontal bone and zygomatic bone
• Zygomaticomaxillary suture: between zygomatic and the maxilla
• Intermaxillary suture: between two maxilla
• Metopic suture: found in children; on the midline of the frontal bone
Posterior Aspect
• Sagittal suture: between two parietal bones
• Lambdoid suture: between the parietal bone and occipital bone
• Lambda: convergence of the sagittal and lambdoid suture
Sutures
Superior Aspect
• Coronal suture: between the frontal bone and the parietal bone
• Bregma: convergence of the saggital and coronal sutures
Lateral Aspect
• Squamous suture: between the parietal bone and temporal bone
• Sphenofrontal suture: between the frontal bone and sphenoid bone
• Sphenoparietal suture: between the sphenoid bone and parietal bone
• Occipitomastoid suture: between the occipital bone and mastoid process of the temporal
bone
• Temporozygomatic suture: between the temporal bone and zygomatic bone
Sutures
Inferior Aspect
• Median palatine suture: between the horizontal plates of the palatines
• Transverse palatine suture: between the palatine process of the maxillary bone and the
palatine bone
• Petro-occipital suture: between the occipital bone and petrous part of the temporal
bone
• Spheno-occipital suture: between the sphenoid bone and occipital bone
• Petrosquamous suture: between the petrous and squamous parts of the temporal bone
• Petrotympanic suture: between the temporomandibular joint and the tympanic cavity
Sutures
• In neonates, the incompletely fused suture joints give rise to membranous gaps
between the bones, known as fontanelles. The two major fontanelles are:

Frontal fontanelle: located at the junction of the coronal and sagittal sutures
Occipital fontanelle: located at the junction of the sagittal and lambdoid sutures
Neonatal Skull
• large cranium relative to the face.
• In childhood, the growth of the mandible, the maxillary sinuses, and the alveolar
processes of the maxillae results in a great increase in length of the face.
• The bones of the skull are smooth and unilaminar, there being no diploe present.
• Most of the skull bones are ossified at birth, but the process is incomplete, and the
bones are mobile on each other, being connected by fibrous tissue or cartilage.
• The bones of the vault are ossified in membrane; the bones of the base are ossified
in cartilage.
• The bones of the vault are not closely knit at sutures, as in the adult, but are
separated by unossified membranous intervals called fontanelles.
• Clinically, the anterior and posterior fontanelles are most important and are easily
examined in the midline of the vault.
Neonatal Skull
• The anterior fontanelle is diamond shaped and lies between the two halves of
the frontal bone in front and the two parietal bones behind.
• The fibrous membrane forming the floor of the anterior fontanelle is replaced
by bone and is closed by 18 months of age.
• The posterior fontanelle is triangular and lies between the two parietal bones
in front and the occipital bone behind.
• By the end of the 1st year, the fontanelle is usually closed and can no longer be
palpated
Neonatal Skull
• The tympanic part of the temporal bone is merely a C-shaped ring at birth,
compared with a C-shaped curved plate in the adult.
• This means that the external auditory meatus is almost entirely cartilaginous in
the newborn, and the tympanic membrane is nearer the surface. Although the
tympanic membrane is nearly as large as in the adult, it faces more inferiorly.
• During childhood, the tympanic plate grows laterally, forming the bony part of the
meatus, and the tympanic membrane comes to face more directly laterally.
• The mastoid process is not present at birth and develops later in response to the
pull of the sternocleidomastoid muscle when the child moves his or her head.
• At birth, the mastoid antrum lies about 3 mm deep to the floor of the suprameatal
triangle. As growth of the skull continues, the lateral bony wall thickens so that at
puberty the antrum may lie as much as 15 mm from the surface.
Neonatal Skull
• The mandible has right and left halves at birth, united in the midline with
fibrous tissue. The two halves fuse at the symphysis menti by the end of the 1st
year.
• The angle of the mandible at birth is obtuse, the head being placed level with
the upper margin of the body and the coronoid process lying at a superior level
to the head.
• It is only after eruption of the permanent teeth that the angle of the mandible
assumes the adult shape and the head and neck grow so that the head comes
to lie higher than the coronoid process.
• In old age, the size of the mandible is reduced when the teeth are lost. As the
alveolar part of the bone becomes smaller, the ramus becomes oblique in
position so that the head is bent posteriorly.