Main bones included:Main bones included:

Somatic bonesSomatic bones

Skull with mandibleSkull with mandible

Cervical vertebrae (all 7)Cervical vertebrae (all 7)

The hyoid bone develop from 2The hyoid bone develop from 2ndnd &3 &3rdrd brachial archesbrachial arches

The following bonesThe following bones

The mandible The hyoid bone

The cervical vertebrae

Points to rememberPoints to remember

Skull cap is developed by intramembraneous Skull cap is developed by intramembraneous ossification i.e. a 1 stage process.ossification i.e. a 1 stage process.

Base of skull is developed by intracartilaginious Base of skull is developed by intracartilaginious ossification i.e. is 2 stage process.ossification i.e. is 2 stage process.

We cannot feel the weight of brain because it We cannot feel the weight of brain because it floats in the cerebrospinal fluid.floats in the cerebrospinal fluid.

All joints are mostly sutures in skull; only a few All joints are mostly sutures in skull; only a few are primary cartilaginous & 1 pair of synovial are primary cartilaginous & 1 pair of synovial joint i.e. TMJ.This is the only mobile joint.joint i.e. TMJ.This is the only mobile joint.

Introduction to skullIntroduction to skull

Definition: skeleton of head is called skull.Definition: skeleton of head is called skull.

Several bones joint together to form Several bones joint together to form “cranium”.“cranium”.

Consist of overall 22 bones.Consist of overall 22 bones.

Skull is further divided into two Skull is further divided into two parts:parts:

calvaria/ brain box.calvaria/ brain box.

Facial skeleton.Facial skeleton.

1. calvaria/brain box1. calvaria/brain box

Upper of cranium which Upper of cranium which encloses the brain.encloses the brain.Composes of the Composes of the following “8” bones.following “8” bones.

A.A. Paired bonesPaired bones1.1. ParietalParietal2.2. TemporalTemporalB.B. Unpaired bonesUnpaired bones1.1. FrontalFrontal2.2. OccipitalOccipital3.3. SphenoidSphenoid4.4. ethemoidethemoid

2. Facial skeleton2. Facial skeleton

rest of the skull excluding the rest of the skull excluding the calvaria along with the calvaria along with the mandible.mandible.Composed of 14 bones:Composed of 14 bones:

A.A. Paired bonesPaired bones1.1. MaxillaMaxilla2.2. ZygomaticZygomatic3.3. NasalNasal4.4. LacrimalLacrimal5.5. PalatinePalatine6.6. Inferior nasal cochaInferior nasal cochaB.B. Unpaired bonesUnpaired bones1.1. MandibleMandible2.2. vomervomer

The faceThe face

Facial vein communicates Facial vein communicates with the cranial venous with the cranial venous sinuses. Thus infection sinuses. Thus infection from the face thus can from the face thus can each the brain.each the brain.The most dangerous area The most dangerous area of the face is between the of the face is between the nasal opening and upper nasal opening and upper lip but the whole face is lip but the whole face is overall considered overall considered dangerous from the dangerous from the infection point of view.infection point of view.

The scalpThe scalp

The extent of scalp:The extent of scalp:

Anteriorly :extends from supra orbital marginAnteriorly :extends from supra orbital margin

posteriorly:extends from external occipital posteriorly:extends from external occipital protuberances and superior nucchal linesprotuberances and superior nucchal lines

Structure of the scalpStructure of the scalp

Has 5 layers:Has 5 layers:1.1. Skin:Skin: Outermost layerOutermost layer Thick and hairyThick and hairy Contains large number of sebaceous glands Contains large number of sebaceous glands

hence liable to have sebaceous cysthence liable to have sebaceous cyst Richly supplied by blood vessels.Richly supplied by blood vessels. It is adherent to epicranial aponeurosis through It is adherent to epicranial aponeurosis through

the dense superficial fascia, as in palms and the dense superficial fascia, as in palms and solessoles

2.2. Superiorficial fascia Superiorficial fascia Second layerSecond layer Dense and fibrous in middle and thin in the Dense and fibrous in middle and thin in the

periphery.periphery. It has vessels and nervesIt has vessels and nerves Clinical significance: injury to scalp deep up to Clinical significance: injury to scalp deep up to

this layer causes profuse bleeding, bleeding this layer causes profuse bleeding, bleeding can be arrested by pressing against the skull. can be arrested by pressing against the skull. inflammation of this layer causes little swelling inflammation of this layer causes little swelling and more pain.and more pain.

3.Deep fascia(epicranial aponeurosis/galea aponeurotic)3.Deep fascia(epicranial aponeurosis/galea aponeurotic) Third layerThird layer Freely movable on the pericranium along with the skin Freely movable on the pericranium along with the skin

and superficial fasciaand superficial fascia Anteriorly,it has insertion of frontalis muscle and Anteriorly,it has insertion of frontalis muscle and

posteriorly insertion of occipitalis and is attached to the posteriorly insertion of occipitalis and is attached to the external occipital protuberances and to the highest external occipital protuberances and to the highest nuctal lines between occipital bellies.nuctal lines between occipital bellies.

Each side of aponeurosis is attached to the superior Each side of aponeurosis is attached to the superior temporal line but sends a thin expansion to the temporal temporal line but sends a thin expansion to the temporal fascia and is attached to the zygomatic archfascia and is attached to the zygomatic arch

4. Alveolar tissue4. Alveolar tissueFourth layerFourth layerExtends anteriorly to the eyelids because Extends anteriorly to the eyelids because

frontalis muscles doesn’t have any bony frontalis muscles doesn’t have any bony attachment;posteriorly to highest and attachment;posteriorly to highest and superior nuchal lines and to the superior superior nuchal lines and to the superior temporal fascia.temporal fascia.

5. Pericranium 5. Pericranium Fifth layer of the scalpFifth layer of the scalpLoosely attached to the boneLoosely attached to the boneBut at the sutures it is firmly bounded with But at the sutures it is firmly bounded with

endocranium.endocranium.

The scalp layersThe scalp layers

Nerve supplyNerve supply(innervations)(innervations)

There are total 10 nerves which supplies There are total 10 nerves which supplies scalp and temple.scalp and temple.

5 nerves behind the auricle and 5 infront of 5 nerves behind the auricle and 5 infront of the auricle.the auricle.

5 nerves infront of the 5 nerves infront of the auricle are:auricle are:

1.1. Supratrochelar nerve of Supratrochelar nerve of the frontal.(optalmic the frontal.(optalmic division of the trigeminal division of the trigeminal nerve)nerve)

2.2. Supraorbital nerve of Supraorbital nerve of frontal.(optalmic dividion frontal.(optalmic dividion of trigeminal nerve)of trigeminal nerve)

3.3. Zygomaticotempral Zygomaticotempral branch of zygomatic branch of zygomatic nerve(maxillary division nerve(maxillary division of trigeminal nerve)of trigeminal nerve)

4.4. Auriculotemporal branch Auriculotemporal branch of the mandibular division of the mandibular division of trigeminal nerveof trigeminal nerve

5.5. Motor nerve:temporal Motor nerve:temporal branch of facial nervebranch of facial nerve

5 nerves back of the 5 nerves back of the auricle:auricle:

1.1. Posterior division of Posterior division of great auricle nerve great auricle nerve (C2,C3) from cervical (C2,C3) from cervical plexus.plexus.

2.2. Lesser occipital nerve of Lesser occipital nerve of C2 of cervical plexus.C2 of cervical plexus.

3.3. Greater occipital nerve Greater occipital nerve of division of C2of dorsal of division of C2of dorsal ramusramus

4.4. Third occipital nerve of Third occipital nerve of C3 of dorsal ramusC3 of dorsal ramus

5.5. Motor nerve:posterior Motor nerve:posterior auricular branch of facial auricular branch of facial nerve.nerve.

Arterial supplyArterial supply

Two sets of arteries 5 on each side,3 are Two sets of arteries 5 on each side,3 are before backward auricle:before backward auricle:

1)1) Pre auricular:Pre auricular:Supratrochelar –opthalmic branch of internal Supratrochelar –opthalmic branch of internal

carotid sheathcarotid sheathSupraorbicular-opthalmic branch of internal carotid Supraorbicular-opthalmic branch of internal carotid

sheathsheathSuperficial temporal-external carotid sheathSuperficial temporal-external carotid sheath2)2) Two arteries behind the auricle:Two arteries behind the auricle:Posterior auricular arteryPosterior auricular arteryOccipital arteryOccipital artery