08 Introduction to head & neck anatomy.pptx

Introduction to The Head And Neck Anatomy Meninges & The Brain AAUP- faculty of medicine Anatomy Dept. 1 The Head Skull. The skull can be divided into two parts: ▪ The neurocranium ▪ The viscerocranium. ❑ Neurocranium. The neurocranium consis...

Introduction to The Head And Neck Anatomy Meninges & The Brain AAUP- faculty of medicine Anatomy Dept. 1 The Head Skull. The skull can be divided into two parts: ▪ The neurocranium ▪ The viscerocranium. ❑ Neurocranium. The neurocranium consists of the flat bones of the skull (i.e., cranial vault) and the base of the skull, which include the following eight bones: Frontal bone, occipital bone, ethmoid bone, sphenoid bone, paired parietal bones, and paired temporal bones. ❑ Viscerocranium. The viscerocranium consists of the bones of the face that develop from the pharyngeal arches in embryologic development, which include the following 14 bones: Mandible, vomer, paired lacrimal bones, paired nasal bones, paired palatine bones, paired inferior turbinate bones, paired maxillary bones, and paired zygomatic bones. 2 3 ❑ Sutures fibrous joints connect skull bones together called sutures. There are five sutures: 1. Frontal/ Coronal suture: Lies between the frontal bone and the two parietal bones. 2. Sagittal suture: Lies between the two parietal bones. 3. Lambdoid suture: Lies between the two parietal bones and the occipital bone. 4. Squamous (Squamoparietal) suture: Lies between the parietal bone and the squamous part of the temporal bone. 4 ❑ Junctions of the Cranial Sutures 1. Lambda Intersection of the lambdoid and sagittal sutures. 2. Bregma Intersection of the sagittal and coronal sutures. 3. Pterion A craniometric point at the junction of the frontal, parietal, and temporal bones and the great wing of the sphenoid bone. 4. Asterion A craniometric point at the junction of the parietal, occipital, and temporal (mastoid part) bones. 5. Nasion A point on the middle of the nasofrontal suture (intersection of the frontal and two nasal bones). 6. Inion Most prominent point of the external occipital protuberance, which is used as a fixed point in craniometry. 5 6 7 8 ❑ Fontanelles Fontanelles are large fibrous areas where several sutures meet. There are six fontanelles: 1. Anterior fontanelle- closes at 18-24monthes 2. Posterior fontanelle 3. Two sphenoid fontanelles 4. Two mastoid fontanelles 9 ❑ Foramina of the Skull The floor of the cranial cavity can be divided into the: ▪ Anterior cranial fossa ▪ Middle cranial fossa ▪ Posterior cranial fossa all of which contain foramina and fissures through which blood vessels and cranial nerves (CNs) are transmitted. 10 Foramina of the Skull 11 The rest of the foramina will be explained in the integrated system 12 ❑ Scalp. The scalp is composed of five layers. The first three layers constitute the scalp proper, which moves as a unit. The five layers include the following. 1. Skin. 2. Connective Tissue. 3. Aponeurosis (Galea Aponeurotica). 4. Loose Connective Tissue. 5. Pericranium. 13 ❑ Meninges Three membranes (meninges) surround and protect the brain in the skull. From superficial to deep, these are: ▪ The dura mater, ▪ Arachnoid mater, and ▪ Pia mater. They are mostly continuous with the spinal meninges that surround the spinal cord in the vertebral column 14 Dura Mater The dura mater is conventionally described as two layers: ▪ The endosteal layer ▪ The meningeal layer The dural folds/ Four septa 1. Falx cerebri 2. Falx cerebelli 3. Tentorium cerebelli 4. Diaphragma sellae 15 The main arterial supply of the dura mater is by the middle meningeal artery/ anterior +middle+ posterior branches (a branch of the maxillary artery) 16 17 Dural venous sinuses Classification The dural venous sinuses are classified into two types, unpaired and paired 18 Arachnoid mater Arachnoid mater is a thin, transparent membrane lying between the pia mater internally and dura mater externally. It invests the brain loosely and continues as spinal arachnoid at the foramen magnum, which ends at the level of second sacral vertebra. Sub arachnoid space contains CSF Arachnoid villi Arachnoid granulations 19 Pia mater Pia mater is thin transparent vascular membrane which closely invests the surface of the brain. It follows the surface irregularities of the cerebral hemisphere, and dips in every sulcus forming folds. All the blood vessels to brain run on it before entering the brain. 20 ❑ Muscles of the Head A. Muscles of the Face and Scalp include the occipitofrontalis, orbicularis oculi, orbicularis oris, levator labii superioris, zygomaticus minor, buccinator, zygomaticus major, levator anguli oris, risorius, depressor anguli oris, depressor labii inferioris, mentalis, and platysma. All these muscles are innervated by CN VII. B. Muscles of Mastication include the temporal, masseter, lateral pterygoid, and medial pterygoid. innervated by Mandibular nerve (V3). C. Muscles of the Soft Palate include the tensor veli palatini, levator veli palatini, palatoglossus, palatopharyngeus, and musculus uvulae. D. Muscles of the Tongue include the genioglossus, hyoglossus, styloglossus, and palatoglossus. Muscles of the Face = facial expressions 21 22 ❑ Arterial Supply ▪ Branches of the Arch of the Aorta 1. Brachiocephalic Artery ✔ Right subclavian artery ✔ Right common carotid artery 2. Left Common Carotid Artery 3. Left Subclavian Artery ▪ External Carotid Artery ✔ Middle Meningeal Artery ▪ Internal Carotid Artery ▪ Vertebral Arteries Circle of willis 23 ❑ Venous Drainage ▪ Facial and Scalp Areas 1. The facial vein 2. Diploic Veins 3. Emissary Veins ▪ Dural Venous Sinuses 24 THE BRAIN 25 ❑ Brain development The telencephalon develops into the cerebrum and lateral ventricles. The diencephalon forms the thalamus, hypothalamus, epithalamus, and third ventricle. The metencephalon becomes the Pons, cerebellum, and upper part of the fourth ventricle. The myelencephalon forms the medulla oblongata and lower part of the fourth ventricle. The mesencephalon (mes-en-SEF-a-lon), or midbrain, gives rise to the midbrain and aqueduct of the midbrain (cerebral aqueduct). 26  ❑ Brainstem The brainstem is the stalk-like part of the brain which connects the spinal cord with the forebrain. From below upwards it consists of three parts: medulla oblongata, pons, and midbrain. It contains important autonomic reflex centres (vital centres) associated with the control of respiration heart rate and blood pressure. 27 ❑ Diencephalon The diencephalon is the part of brain between the cerebrum and the brainstem. The cavity within it is termed third ventricle. components Pars dorsalis lies above (dorsal) to the hypothalamic sulcus and consists of: 1. Thalamus, 2. Metathalamus 3. Epithalamus / pineal body (gland), Pars ventralis lies below (ventral) to the hypothalamic sulcus and consists of: 4. Subthalamus, and 5. Hypothalamus. Functionally, the thalamus is generally considered as the great sensory gateway to the cerebral cortex. 28 29 ❑The cerebrum The cerebrum is the largest part of the human brain that fills most of the cranial cavity. The cerebrum is a heavily, convoluted bilobed structure. The two lateral halves are called cerebral hemispheres. A deep median cleft, the longitudinal cerebral fissure, incompletely separates the two cerebral hemispheres. The corpus callosum which is a large mass of white fibres joins the two cerebral hemispheres across the median plane. Lateral ventricles. 30 31 ❑ Lobes of Cerebral Hemisphere Insula The frontal lobe The parietal lobe The temporal lobe The occipital lobe Insula 32  Central sulcus Precentral gyrus- motor Post central gyrus- somatosensory Wernicke's area- comprehension of speech. Broca's area- motor speech. Aphasia 33 ❑ The cerebellum Lobes 34 Cerebellum- regulates equilibrium, muscle tone, postural control, fine movement and coordination of voluntary muscle movement. 35 ❑ Brain Blood flow ❑ Internal carotid ❑ Vertebral arteries ❑ The dural venous sinuses drain into the internal jugular veins to return blood from the head to the heart. 36 ❑ Circle of Willis 37 ❑ Cranial Nerves 38 39 middle meningeal artery bridging veins 40 41 The Neck 42 ❑ Muscles of the Neck ▪ Muscles of the Superficial Neck include the platysma, sternocleidomastoid, and trapezius. ▪ Muscles of the Anterior Cervical Region include the mylohyoid, geniohyoid, stylohyoid, digastric, sternohyoid, omohyoid, sternothyroid, and thyrohyoid. ▪ Muscles of the Prevertebral Area include the longus colli, longus capitis, rectus capitis anterior, anterior scalene, rectus capitis lateralis, splenius capitis, levator scapulae, middle scalene, and posterior scalene. ▪ Muscles of the Larynx include the cricothyroid, thyroarytenoid, posterior cricoarytenoid, lateral cricoarytenoid, transverse and oblique arytenoids, and vocalis. ▪ Muscles of the Pharynx include the superior constrictor, middle constrictor, inferior constrictor, palatopharyngeus, salpingopharyngeus, and stylopharyngeus. 43 Cervical Plexus The cervical plexus is formed by the ventral primary rami of C1 to C4 and has both sensory and motor branches. Phrenic Nerve is formed by C3, C4, and C5 cervical nerves and innervates the diaphragm (motor and sensory). 44 ❑ Cervical Triangles of the Neck The anterior triangle The anterior triangle is situated at the front of the neck. It is bounded: Superiorly – inferior border of the mandible (jawbone). Laterally – anterior border of the sternocleidomastoid. Medially – sagittal line down the midline of the neck. It is subdivided further into four triangles Carotid Triangle, Submental Triangle, Submandibular Triangle,and Muscular Triangle. The contents of the anterior triangle include muscles, nerves, arteries, veins and lymph nodes. 45 The posterior triangle Borders The posterior triangle of the neck has three borders: Anterior – posterior border of the sternocleidomastoid. Posterior – anterior border of the trapezius muscle. Inferior – middle 1/3 of the clavicle. Contains many muscles, which make up the borders and the floor of the area, Blood vessels, Nerves 46 The orbit , ear, eye, Larynx, pharynx, thyroid & parathyroid, Parotid, Temporal, infratemporal, pterygoid fossae, neck fascia and all other details will be covered in the integrated system 47 Thank you! 48