A MEDICOLEGAL VIEW OF HEAD TRAUMA COMPLICATIONS

Thesis Submitted for full fulfillment of M.D. Degree in Forensic Medicine and Clinical Toxicology By Ahmed Ibrahim Mohammed Ewis Forensic medicine Society - Beni Suef Government- Ministry of Justice M.Sc.in forensic medicine and clinical toxicology

Under supervision of Prof. Mervate Hamdy Abd El Salam

Professor of Forensic Medicine and Clinical Toxicology Faculty of Medicine - Cairo University Prof. Abla Abd El Rahman Ali

Assistant Professor of Forensic Medicine and Clinical Toxicology Faculty of Medicine - Cairo University Prof. Amany Salah Mohammed

Assistant Professor of Forensic Medicine and Clinical Toxicology Faculty of Medicine - Cairo University Dr. Mohammed Adly Mohammed

Lecturer of Forensic Medicine and Clinical Toxicology Faculty of Medicine - Cairo University

Faculty of Medicine Cairo University 2012

Acknowledgment First of all thanks to Allah

With the deepest feeling of gratitude , I would like to express my appreciation to Prof.Dr. Usama Ibrahim El-Barrany. Prof. and Head of forensic medicine and toxicology department, Faculty of medicine, Cairo University, for his continuous support and encouragement.

I am deeply indebted to Prof. Dr.Mervate Hamdy Abd El- Salam. Prof. of forensic and toxicology for her unlimited help, meticulous supervision and sincere supervision during the preparation of this work which are above all commentaries.

My sincere thanks and gratitude to Prof.Dr.Abla Abd El- Rahman Ali. Prof. of forensic and toxicology for her great support, valuable suggestions and encouragement.

I would like to express my deepest gratitude to Prof. Dr.Amany Salah Mohammed. Prof.of forensic and toxicology, for her grateful effort, help guidance, valuable assistance and guidance throughout this work.

I would like to present my sincere thanks to Dr. Mohammed Adly Mohammed. Lecturer of forensic and toxicology, for his great support and encouragement.

I am deeply indebted to Prof. Dr. Dina Shokry. Prof. of forensic and toxicology, for her kind care, close supervision and her worthy remarks are beyond my words of thanks.

My abundant thanks and gratitude to Prof. Dr. Aly Gamal El-Din Abd El- Aal. Prof. of forensic and toxicology, for his kind care, for his continuous support and encouragement.

I would like to present my great thanks to Faculty of Medicine- Cairo university (Kasr El Aini hospital), Faculty of Medicine of Beni Suef University, General hospital of Beni Suef, Psychiatry hospital of Beni Suef, Al Eman center of radiology at Beni Suef and hospital of Ophthalmology of Beni Suef.

I am deeply indebted to all my professors and colleagues in the forensic and toxicology department, Faculty of medicine, Cairo university, for their constructive guidance, effective help and enthusiastic cooperation.

Table of Contents

Topic Page  List of Abbreviations I

 List of Tables II

 List of Figures III-IV

 List of Charts V

 Abstract VI

 Introduction and Aim of the work (1-2)

 Review of literature:

- Chapter –I: Anatomy of Head (3-15)

- Chapter – II: Anatomy of Cranial Nerves. (16-22)

- Chapter – III: Pathology of Head Injury (23-40)

- Chapter – IV: Complications of Head Trauma (41-56)

 Subjects and Methods (57- 72)

 Results and figures of investigations (73-114)

 Discussion (115- 122)

 Summary, Conclusions and Recommendations (123- 133)

 References (134- 152)

)0-5( انمهخص انعربي  Arabic Summary

List of abbreviations

CSF Cerebrospinal fluid LOC Loss of consciousness duration CN I Olfactory nerve SIADH Syndrome of inappropriate antidiuretic hormone CN II Optic nerve CSW Cerebral salt wasting CN III Oculomotor nerve DI Diabetes insipidus CN IV Trochlear nerve AH Anterior hypopituitarism CN V Trigeminal nerve PAI Primary adrenal insufficiency CN VI Abducent nerve GRH Gonadotropin-releasing hormone CN VII Facial nerve LH Luteinizing hormone CN VIII Vestibulocochlear nerve FSH Follicular stimulating hormone CN X Vagus nerve ANS Autonomic nervous system CN XI Spinal accessory nerve PTM Post-traumatic meningitis CN XII Hypoglossal nerve UMNL Upper motor neurone lesion TBI Traumatic Brain Injury LMNL Lower motor neurone lesion MVCs Motor Vehicle Collisions ENG Electronystagmography SDH Subdural haematoma MRA Magnetic resonance Angiography ICP Intracranial pressure IQ Intelligence quotient ASDH Acute subdural hematoma Hge. Haemorrhages SAH Subarachnoid haemorrhage Fig. Figure ICH Intracerebral haemorrhage Isol. Isolated IVH Intraventricular haemorrhage PCS Post-concussion syndrome DAI Diffuse axonal injury ICU Intensive care unit aPTT activated partial thromboplastin Freq. Frequency time PT Prothrombin time M Motor complication CBC Complete blood count Cn Cranial nerves affection ABG Arterial blood gases E Epilepsy IV Intravenous C Cognitive complications CT Computerized tomography S Sensory complications MRI Magnetic resonance image Au Autonomic disturbance CBF Cerebral blood flow HBO Hyperbaric oxygen PTE Posttraumatic epilepsy SIADH Syndrome of inappropriate antidiuretic hormone PTA Post-traumatic amnesia CSW Cerebral salt wasting GCS Glasgow Coma Scale DI Diabetes insipidus PVS Permanent Vegetative State AH Anterior hypopituitarism VS Vegetative State PAI Primary adrenal insufficiency PTSD Post-traumatic stress disorder GRH Gonadotropin-releasing hormone CRF Corticotropin-releasing factor LH Luteinizing hormone HPA Hypothalamic-pituitary-adrenal FSH Follicular stimulating hormone axis Isol. Isolated Cn Cranial nerves affection PCS Post-concussion syndrome E Epilepsy ICU Intensive care unit C Cognitive complications Freq. Frequency S Sensory complications M Motor complication Au Autonomic disturbance

I

List of tables

No of Topic of table page table 1 Glasgow Coma Scale 37 2 Levels of TBI severity 42 3 TBI severity using PTA alone 42 4 Head trauma types within different age groups (years) 87 5 Severity of head trauma regarding to consciousness level (GCS) and death incidence within 89 different age groups (years) 6 Head trauma regarding to open or closed within different age groups (years) 91 7 Head trauma types within gender 93 8 Head trauma severity regarding to conscious level (GCS) and death incidence within gender 95 9 Head trauma types regarding to open or closed within gender 97 10 Head trauma sequelae within gender 99 11 Head trauma severity regarding to conscious level (GCS) and death incidence within different 101 types of head trauma 12 Sequelae of head trauma within different age groups (years) 103 13 Sequelae head trauma within types of head trauma 105 14 Head trauma severity regarding to conscious level (GCS) and death incidence within different 107 sequelae of head trauma 15 Head trauma regarding to open or closed with sequelae of head trauma 109

II

List of figures

No of Topic of figure page figure

1 Layers of head (cross section) 49 2 Anterior view of skull 49 3 Lateral view of skull 50 4 Skull base (external view) 50 5 Skull base (internal view) 51 Anatomy of meninges 51ِ 6 7 Anatomy of the brain (external view) 52 8 Brain stem (anteroinferior view) 52 9 Longitudinal section of brain 53 10 Longitudinal section of brain (ventricules) 53 11 Anatomy of cranial nerve nuclei 54 12 Plain x- ray (anteroposterior view) shows depressed fracture with radiating fractures, at onset of trauma.

13 Plain x-ray (anteroposterior view) shows comminuted depressed fractures at left temporal and parietal bone with numerous skull fracture radiating from it, at onset of trauma. 14 Plain x-ray (anteroposterior view) shows inlet of firearm shots at occipital bone with distribution of shots allover brain, at onset of trauma.

15 Plain x ray shows two firearm bullets inside skull, at onset of trauma.

16 CT scan with 3 dimensions reveals depressed fractures of skull vertex with extension of fissure fractures into parietals bilaterally, at onset of trauma.

17 CT scan with 3 dimensions reveal depressed fracture with bone loss at left parietal with brain contusion, at onset of trauma.

18 CT scan reveals depressed fracture of right frontal bone, at onset of trauma.

19 CT scan (A, B) reveal depressed comminuted fracture of right parietal bone with right parietal lobe contusion and laceration, at onset of trauma.

20 CT scan reveals huge extradural hge. at left temproparietal area with right shift of midline, at onset of trauma.

21 MRI shows huge extradural hge at left temproparietal

III area compressing left lateral ventricle, at onset of trauma. 22 CT scan (A,B) show tunnel fracture (tangential single bullet) of left temporal and parietal bones, loss of bones,comminuted depressed fractures with extradural haemorrhage and left temporal and parietal lobes contusions, at onset of trauma.

23 MRI shows subgaleal calcified haematoma, after 6 months of trauma.

24 MRI reveals prominent ventricular system, after 6 months of trauma.

25 CT scan reveals bilateral parietal large extradural haemorrhage. at right,.at left side, after 6 months of trauma.

26 CT scan reveals bilateral frontoparietal subdural hygroma, after 6 months of trauma.

27 MRI shows left high parietal encephalomalacia, left parietal fracture, after 6 months of trauma.

28 MRI reveals right parietal large area of encephalomalacia with depressed fracture of right parietal bone, after 6 months of trauma . 29 CT scan reveals site of trephine operation at right parietal bone with depressed fracture with right extradural hge.with mild shift of middle line to opposite side, after 6 months of trauma. 30 CT scan reveals comminuted depressed fracture of frontal bone with right frontal encephalomalcia, after 6 months of trauma.

IV

List of charts

No of chart Topic of chart Page 1 Head Trauma within Age Groups 69 2 Head Trauma within the Gender 70 3 Types of Head Trauma 71 4 Sites of Head Trauma 72 5 Causative Agents of Head Trauma 73 6 Open or Closed Head Trauma 74 7 Head Trauma Severity regarding to Consciousness Level (GCS) and Death 75 incidence 8 Skull Fractures at Onset of Head Trauma 76 9 Intracranial Haemorrhages at Onset of Head Trauma 77 10 Intracerebral Findings at Onset of Head Trauma 78 11 Follow-up of Scalp findings 79 12 Follow-up of skull findings 80 13 Follow-up of Intracranial Haemorrhages 81 14 Follow-up of Intracerebral findings 82 15 Head Trauma Sequelae 83 16 Deaths due to Head Trauma 84 17 Permanent Infirmity types of Head Trauma 85 18 Death Causes resulting from Head Trauma 86 19 Types Head Trauma within Age Groups (years) 88 20 Severity of Head Trauma regarding to Consciousness level (GCS) and Death 90 incidence within Age Groups (years) 21 Open or Closed Head trauma within Age Groups (years) 92 22 Head trauma Types within the Gender 94 23 Head trauma Severity regarding to Conscious Level (GCS) and Death Incidence 96 within the Gender 24 Open or Closed Head Trauma within the gender 98 25 Head trauma Sequelae within the Gender 100 26 Head trauma Severity regarding to Conscious level (GCS) and Death incidence 102 within Types of Head Trauma 27 Sequelae of Head Trauma within Age Groups (years) 104 28 Head Trauma Sequelae within Types of Head Trauma 106 29 Head Trauma Severity regarding to Conscious level (GCS) and Death incidence 108 within Sequelae of Head Trauma 30 Open or Closed Head Trauma with Sequelae of Head Trauma 110

V

Key words Forensic Medicine- Homicidal trauma-Traumatic brain injury- Pathological complications – Clinical complications

Abstract

Purpose: assessment of different types of head trauma with correlation with age, sex, causative agents, prognosis, severity of trauma, pathological and clinical complications.

Methodology: This study was done on 100 cases who were referred to forensic department of Beni Suef of males and females, age (4 up 65), dead (26) and living (74) with investigation of dead cases with plain x-ray, CT scan and autopsy procedure and follow up living cases for 6 months with history taking , neuropsychiatry assessment, plain x-ray, CT scan, MRI, MRI angiograph, eye examinations, hearing tests, EEG, IQ tests.

Results: This study declared some important findings such as predominance of head trauma frequency between age group 25- less than50 years (61%) where it was more severe and decreasing in frequency and severity with age extremities, predominance of head injury in males where male cases represented 84% and female cases represented 16%. Deaths at day of head trauma represented 88% of death cases which decreases with time interval.There was a great correlation between severity of head trauma and prolonged sequelae. Clinical sequelae of head trauma were 39% ended with permanent infirmity, 35% completely recovered and 26% died. Pure cranial nerve sequelae represented 7%.

Conclusion: According to the present study, Age group 25-less than 50 years was the predominant group for exposure to head trauma. Glasgow coma scale was a good prognostic factor. Deaths due to head trauma occurs mainly at day of trauma.

VI Introduction and aim of the study

Introduction

Head injury is the most common cause of death and acquired disability among children and adults in developed countries and, even when adequate treatment is provided, traumatic head injury commonly causes neuronal loss (Bone et al., 1991). The underlying pathophysiology highlights the importance not only of the primary injury, but also of the secondary processes occurring after injury, which may lead to cerebral hypoxia and ischemia (Baker et al., 2004).Secondary brain injury is the leading cause of in-hospital deaths after traumatic brain injury (Bochicchio et al., 2005). Moreover, the outcome of head injury varies from center to center depending on the availability of modern neurosurgical and neuroradiological facilities and qualified expertise (Bahloul et al., 2004). Survivors are susceptible to irreversible neurological damage that represents an important socioeconomic problem.Head injury is the most frequent cause of mortality and morbidity in any age.Finally, prognosis may be influenced by the presence of extracranial pathology (Campbell et al., 2004).

The Glasgow Coma scale at the time of admission is the single most important predictor of outcome. Pre-hospital hypothermia, intra-cranial hypertension, hypoxia, associated injuries and delayed transportation lead to secondary insults to already injured brain.Preventing secondary brain insults will remain the goal of management for the foreseeable future.Primary severe head injury can be prevented by strict public laws, observation of safety measures and mass education about the consequences of severe head injury and of course an efficient medical transfer system.Aconcept of centers of excellence and an educational programmes. “Advance Brain Life Support” has been proposed to decrease the mortality and morbidity (Tarek et al., 2004).

Traumatic brain injury can cause not only focal deficits of motor activity or language, but also a variety of potentially disabling psychiatric symptoms and syndromes. These include mood and anxiety disorders; personality disturbances; aggression; and, occasionally, psychosis. Treatment is complicated by cognitive deficits, lack of motivation, and lack of awareness of deficits. Controlled treatment trials for head injury are lacking. Pharmacological treatment may include a wide range of medications, such as antidepressants, antipsychotics, mood stabilizers, and stimulants. Family and individual counseling is particularly important in helping

1 Introduction and aim of the study the patient and the family reconcile themselves to the reality of the behavioral changes in the patient post-TBI (Kim et al., 2007).

Aim of the study

The study was designed to evaluate the complications of isolated traumatic head injury referred to forensic department of Beni suef for dead cases through Plain x-ray, CT, autopsy and living cases through complete neuropsychiatry evaluation and investigations with Plain x-ray, CT, MRI, MRI angiography, fundoscopy, vision acuity test, hearing tests, electroencephalography, IQ tests, to define simple predictive factors which can be used in routine practice as an indicator of poor prognosis and diagnosis of final sequelae after 6 months.

2 Review of literature: Head Anatomy

Chapter –I

Head Anatomy

1-Scalp

The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly. Layers of scalp: (Figure 1) (Gray, 2005) It is usually described as having five layers, which can be remembered with the mnemonic "SCALP": S: The skin on the head from which head hair grows. It is richly supplied with blood vessels. C: Connective tissue, a thin layer of fat and fibrous tissue lies beneath the skin. A: The aponeurosis called epicranial aponeurosis (or galea aponeurotica) is the next layer. It is a tough layer of dense fibrous tissue which runs from the frontalis muscle anteriorly to the occipitalis posteriorly. L: The loose areolar connective tissue layer provides an easy plane of separation between the upper three layers and the pericranium. In scalping the scalp is torn off through this layer. It also provides a plane of access in craniofacial surgery and neurosurgery. This layer is sometimes referred to as the "Danger Zone" because of the ease by which infectious agents can spread through it to emissary veins which then drain into the cranium (Knight et al., 1996). P: The pericranium is the periosteum of the skull bones and provides nutrition to the bone and the capacity for repair. It may be lifted from the bone to allow removal of bone windows (craniotomy). The clinically important layer is the aponeurosis. Scalp lacerations through this layer mean that the "anchoring" of the superficial layers is lost and gaping of the wound occurs; this requires suturing (American Association of Anatomists, 2009).

2-Skull bones

The head is positioned upon the superior portion of the vertebral column, attaching the skull upon C-1. The skeletal section of the head and neck forms the superior segment of the axial skeleton and comprises skull, hyoid bone, auditory ossicles, and cervical spine. The skull can be further subdivided into: (Figures 2, 3, 4 and 5)

3 Review of literature: Head Anatomy

(a) Cranium (8 bones: frontal, 2-parietal, occipital, 2-temporal, sphenoid and ethmoid), and (b) Facial bones (14 bones: 2-zygomatic, 2-maxillary, 2-palentine, 2-nasal, 2- lacrimal, volmer, 2-inferior conchae, mandible), and (c)Skull base: The skull base forms the floor of the cranial cavity and separates the brain from other facial structures (Gray, 2005).

1- Anterior cranial fossa: The anterior limit of the anterior skull base is the posterior wall of the frontal sinus. The anterior clinoid processes and the planum sphenoidale, which forms the roof of the sigmoid sinus, mark the posterior limit . The frontal bone forms the lateral boundaries. The frontal bone houses the supraorbital foramina, which, along with the frontal sinuses, form 2 important surgical landmarks during approaches involving the anterior skull base (Gray, 2005).

2- Middle cranial fossa: The greater wing of the sphenoid helps form the anterior limit of the middle skull base. The posterior limit is the clivus . The greater wing of the sphenoid forms the lateral limit as it extends laterally and upward from the sphenoid body to meet the squamous portion of the temporal bone and the anteroinferior portion of the parietal bone. The greater wing of the sphenoid forms the anterior floor of the fossa. The anterior aspect of the petrous temporal bone forms the posterior floor of the middle cranial fossa (Gray, 2005)

3-Posterior cranial fossa: The posterior skull base consists of primarily the occipital bone, with contributions from the sphenoid and temporal bones.The basal portion of the occipital bone (the basiocciput) and the basisphenoid form the anterior portion the posterior skull base. These 2 regions combine to form the midline clivus (Gray, 2005).

3-Meninges

The meninges (singular meninx) are the system of membranes which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system (Kandel, 2000). (Figure 6)

4 Review of literature: Head Anatomy

1- Dura mater: The dura mater is a thick, durable membrane, closest to the skull. It consists of two layers, the periosteal layer, closest to the calvaria and the inner meningeal layer. It contains larger blood vessels which split into the capillaries in the pia mater (Spitz et al., 1993). It is composed of dense fibrous tissue, and its inner surface is covered by flattened cells like those present on the surfaces of the pia mater and arachnoid. The dura mater is a sac which envelops the arachnoid and has been modified to serve several functions. The dura mater surrounds and supports the large venous channels (dural sinuses) carrying blood from the brain toward the heart (Kandel, 2000).

2- Arachnoid membrane: The middle element of the meninges is the arachnoid membrane, so named because of its spider web-like appearance. It provides a cushioning effect for the central nervous system. The arachnoid mater exists as a thin, transparent membrane. It is composed of fibrous tissue and, like the pia matter, is covered by flat cells also thought to be impermeable to fluid (Spitz et al., 1993). The arachnoid does not follow the convolutions of the surface of the brain and so looks like a loosely fitting sac. In the region of the brain, particularly, a large number of fine filaments called arachnoid trabeculae pass from the arachnoid through the subarachnoid space to blend with the tissue of the pia mater (Kandel, 2000).

3- Pia mater: The pia or pia mater is a very delicate membrane. It is the meningeal envelope which firmly adheres to the surface of the brain and spinal cord. As such it follows all the minor contours of the brain (gyri and sulci) (Zigmond, 1999). It is a very thin membrane composed of fibrous tissue covered on its outer surface by a sheet of flat cells thought to be impermeable to fluid. The pia mater is pierced by blood vessels which travel to the brain and spinal cord, and its capillaries are responsible for nourishing the brain (Spitz et al., 1993).

Blood supply of meninges:

1- Middle meningeal artery: The middle meningeal artery (Latin arteria meningea media) is typically the third branch of the first part (retromandibular part) of the maxillary artery; one of the two terminal branches of the external carotid artery. After branching off the

5 Review of literature: Head Anatomy maxillary artery in the infratemporal fossa, it runs through the foramen spinosum to supply the dura matter (the outermost meninges) and the calvaria (DeMyer, 1998). The middle meningeal artery is the largest of the three (paired) arteries which supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery (Walker, 2003). Clinical relevance: An injured middle meningeal artery is the cause of an epidural hematoma. A head injury (e.g., from a road traffic accident or sports injury) is required to rupture the artery. Emergency treatment requires decompression of the haematoma, usually by craniotomy. The middle meningeal artery runs in a groove on the inside of the cranium. This can clearly be seen on a lateral skull X-ray, where it may be mistaken for a fracture of the skull (Walker, 2003).

2- Posterior meningeal artery: The posterior meningeal artery is a small vessel branched of the ascending pharyngeal artery which supply the dura mater (Walker, 2003).It passes through the mastoid foramen before entering the cranium via the jugular foramen (Carpenter, 2003).

3- Anterior (meningeal) ethmoidal artery: It accompanies the nasociliary nerve through the anterior ethmoidal canal, supplies the anterior and middle ethmoidal cells and frontal sinus, and enters the cranium (DeMyer, 1998).

4-Cerebral cortex

The cerebral cortex is a structure within the brain that plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. In preserved brains, the outermost layer of the cerebrum has a gray color, hence the name "gray matter" (Zigmond, 1999). Cortex may be classified on the basis of gross topographical conventions into four lobes: Frontal Lobes Parietal Lobes Temporal Lobes Occipital Lobes (Alexandre et al., 2007). (Figure 6)

6 Review of literature: Head Anatomy

Brain lobes:

1-Frontal lobe: The frontal lobe has three main areas, known as the precentral cortex, prefrontal cortex and the orbitofrontal cortex. These three areas are represented in both the left and the right cerebral hemispheres.The precentral cortex or primary motor cortex is concened with the planning, initiation and control of physical movement. The prefrontal cortex in the left hemisphere is involved with verbal memory while the prefrontal cortex in the right hemisphere is involved in spatial memory (Gelder et al., 2000). The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex. The dopamine system is associated with attention, long-term memory, planning, and drive. Dopamine tends to limit and select sensory information arriving from the thalamus to the fore-brain (Blakemore et al., 2005).

2- Parietal lobe: The parietal lobe is positioned above the occipital lobe and behind the frontal lobe (Blakemore, 2005). The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the dorsal stream of the visual system. This enables regions of the parietal cortex to map objects perceived visually into body coordinate positions (Blakemore, 2005).

3- Temporal Lobe: The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both the left and right hemispheres of the brain.The temporal lobe is involved in auditory processing and is home to the primary auditory cortex. It is also important for the processing of semantics in both speech and vision. The temporal lobe contains the hippocampus and plays a key role in the formation of long-term memory (Blumer et al., 2001).

4- Occipital lobe: The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1 (visual one). Human V1 is located on the medial side of the occipital lobe within the calcarine sulcus; the full extent of V1 often continues onto the posterior pole of the occipital lobe. Visually driven regions outside V1 are called extrastriate cortex (Blakemore, 2005).

7 Review of literature: Head Anatomy

5- SUBCORTICAL STRUCTURES

1- Basal ganglia: The basal ganglia is a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. Mammalian basal ganglia are associated with a variety of functions: motor control, cognition, emotions, and learning (Gilies, 2005).

2- Thalamus: The thalamus is a paired and symmetric part of the brain. It constitutes the main part of the diencephalon. In the caudal (tail) to rostral (head) sequence of neuromeres, the diencephalon is located between the mesencephalon (cerebral peduncule, belonging to the brain stem) and the cerebrum (Gray, 2005).

3- Hypothalamus: The hypothalamus is located below the thalamus, just above the brain stem. In the terminology of neuroanatomy, it forms the ventral part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is roughly the size of an almond The hypothalamus is responsible for certain metabolic processes and other activities of the autonomic nervous system. It synthesizes and secretes neurohormones, often called hypothalamic-releasing hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones. The hypothalamus controls body temperature, hunger, thirst, fatigue, and circadian cycles (Gray, 2005).

4- Limbic system: The limbic system is a set of brain structures includes the hippocampus, amygdala, anterior thalamic nuclei, and limbic cortex, which support a variety of functions including emotion, behavior, long term memory, and olfaction (Walker et al., 2005).

5- Pituitary gland: It is composed of two lobes: the adenohypophysis or anterior pituitary and the neurohypophysis or posterior pituitary. The pituitary gland is functionally linked to the hypothalamus by the pituitary stalk, whereby hypothalamic releasing factors are released and, in turn, stimulate the release of pituitary hormones. Although the pituitary gland is known as the master endocrine gland, both of its lobes are under the control of the hypothalamus, the master's master (Longscope et al., 2000).

8 Review of literature: Head Anatomy

6- Midbrain: The midbrain is divided into three parts. The first is the tectum, which is "roof" in Latin. The tectum includes the superior and inferior colliculi and is the dorsal covering of the cerebral aqueduct. The inferior colliculus, involved in the special sense of hearing sends its inferior brachium to the medial geniculate body of the diencephalon. Superior to the inferior colliculus, the superior colliculus marks the rostral midbrain. It is involved in the special sense of vision and sends its superior brachium to the lateral geniculate body of the diencephalon (Gray, 2005).

7- Brainstem: The brainstem is the lower part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Though small, this is an extremely important part of the brain as the nerve connections of the motor and sensory systems from the main part of the brain to the rest of the body pass through the brain stem (Dabbs et al., 2002). This includes the corticospinal tract (motor), the posterior column-medial lemniscus pathway (fine touch, vibration sensation and proprioception) and the spinothalamic tract (pain, temperature, itch and crude touch) (Gray, 2005). The most medial part of the medulla is the anterior median fissure. Moving laterally on each side are the pyramids. The pyramids contain the fibers of the corticospinal tract (also called the pyramidal tract), or the upper motor neuronal axons as they head inferiorly to synapse on lower motor neuronal cell bodies within the ventral horn of the spinal cord (Gerard, 2007).

8- Cerebellum: The cerebellum (Latin for little brain) is a region of the brain that plays an important role in the integration of sensory perception, coordination and motor control. In order to coordinate motor control, there are many neural pathways linking the cerebellum with the cerebral motor cortex (Fine et al., 2002). (Figures 7, 8, 9)

Ventricular system: (Figure 10) The ventricular system is a set of structures in the brain continuous with the central canal of the spinal cord. The system comprises four ventricles: right and left lateral ventricles, third ventricle and fourth ventricle (Purves et al., 2004).

9 Review of literature: Head Anatomy

Cerebrospinal fluid: Cerebrospinal fluid (CSF), Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space and the ventricular system around and inside the brain. Essentially, the brain "floats" in it. More specifically, the CSF occupies the space between the arachnoid mater (the middle layer of the brain cover, meninges) and the pia mater (the layer of the meninges closest to the brain).It acts as a "cushion" or buffer for the cortex, providing a basic mechanical and immunological protection to the brain inside the skull (Gray, 2005). It is produced in the brain by modified ependymal cells in the choroid plexus and the remainder is formed around blood vessels and along ventricular walls. It circulates from the choroid plexus through the interventricular foramina (foramen of Monro) into the third ventricle, and then through the cerebral aqueduct (aqueduct of Sylvius) into the fourth ventricle, where it exits through two lateral apertures (foramina of Luschka) and one median aperture (foramen of Magendie). It then flows through the cerebellomedullary cistern down the spinal cord and over the cerebral hemispheres (Gray, 2005). The CSF contains approximately 0.3% plasma proteins, or 15 to 40 mg/dL, depending on sampling site. CSF pressure ranges from 80 - 100 mmH2O or 4.4 - 7.3 mmHg in newborns, and <200mmH20 in normal children and adults (Edgley et al., 2004).

10 Review of literature: Head Anatomy

(Figure 1): Layers of head (cross section) (www.wikipedia.com, 2011).

(Figure 2): Anterior view of skull (Atabaki, 2007).

(Figure 3): Lateral view of skull (Atabaki, 2007).

11