Introduction to Computed Tomography (CT): Cross Sectional Anatomy
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79 terms
Terms | Definitions |
|---|---|
 Axial | Also referred to as transverse plane Transects the body from anterior to posterior and from side to side. Divides the body into superior and inferior portions |
| Coronal | A longitudinal plane dividing the body into anterior and posterior portions. Passes from superior (coronal suture of the skull) to inferior and from side to side |
| Sagittal | A longitudinal plane dividing the body into right and left portions Passes from superior (sagittal suture of the skull) to inferior and from anterior to posterior. Any plane parallel to the mid-sagittal is median plane |
| Oblique | A longitudinal or transverse plane that is at an angle or slant and not parallel to the sagittal, coronal or horizontal planes. |
| Bones and other dense material | white |
| Air and lower-density material | - black |
| Fat, muscle, and organs | various shades of gray |
| Baseline for CT numbers is | water with a CT number of 0 |
| Bone has a value of | +150 or up to +1000 |
| Dense bone has a value of | +1000 to + 3000 |
| Air has a CT value of | -1000 |
| Lower numbers - structures (soft tissues) | that are more easily penetrated by x-rays, appear closer to black. |
| Higher numbers - | more radiopaque structures (bones), lighter gray or white. |
| Frontal | Forms the anterior surface of the skull, with a vertical portion that corresponds to the forehead and horizontal portion that forms the roof of the orbits |
| Parietal (x 2) | Roughly square-shaped bones that articulate with the frontal bone at the coronal suture Both parietal bones form the superior aspect or vertex and connected by the sagittal suture |
| Occipital | Posterior aspect of skull; composed of a squamous and basilar portion |
| Foramen Magmun | Large opening within squamous portion that allows passage of spinal cord into the brain |
| Temporal (x 2) | Form part of the lateral walls of the cranium |
| Squamous | Thin, fan-shaped, superior to the external ear |
| Tympanic | Surrounds external ear canal |
| Mastoid | Posterior to ear, perforated by many air-filled cavities |
| Petrous | Dense ridge of bone within the cranium which protects the organs of hearing and balance |
| Ethmoid | Found within the cranium and forms the medial walls of the orbits and part of the lateral walls of the nasal cavity. |
| Cribriform plane | horizontal portion |
| Crista Galli | small ridge projecting superiorly from the cribriform plate |
| Perpendicular plate and two (2) labyrinths | Vertical portion forms the superior part of the bony nasal septum |
| Sphenoid | At the center of the base of the skull, articulates with all the cranial bones. Referred to as the "anchor bone of the cranium" |
| Sphenoid ***BODY | contains the sella turcica A cup shaped bone that surrounds and protects the pituitary gland |
| Two (2) sets of wings | lesser and greater |
| Pterygoid portion | Projects inferiorly from the body of the sphenoid and forms the posterior walls of the nasal cavity |
| 14 facial bones, come in pairs except for | vomer and mandible |
| Lacrimal | Found in the medial wall of the orbit between maxilla and labyrinth of the ethmoid bones |
| Nasal | Found in the medial wall of the orbit between maxilla and labyrinth of the ethmoid bones |
| Zygomatic | Forms the inferolateral walls of the orbits |
| Maxilla | Large bone that forms inferior surface of each orbit, lateral walls of the nasal cavity, and anterior portion of the roof of the mouth and the bony attachment of the maxillary teeth |
| Inferior nasal conchae | Scroll-shaped bones found in the nasal cavity |
| Palatine | L-shaped bones which form the posterior portion of hard palate |
| Vomer | Forms inferior portion of the bony nasal septum |
| Mandible | Consists of a body and 2 rami forming the alveolar ridge in which the lower teeth are embedded |
| The brain is surrounded by three protective layers called meninges | Pia matter (inner most) Arachnoid (middle) Dura mater (outer) |
| Pia matter (inner most) | Adheres directly to the brain Made up of capillaries and supporting tissue |
| Arachnoid (middle) | A delicate membrane that resembles a cobweb |
| Subarachnoid | Lies between arachnoid and pia mater; CSF circulates in this space. |
| Dura mater (outer) | Most external of the meninges, double layered |
| Cerebrum | - largest structure Divided by the longitudinal fissure into 2 hemispheres |
| Corpus Callosum | white matter tract that connects the hemisphere RT/LT. |
| Brainstem | Composed of the midbrain, pons and medulla oblongata |
| Cerebellum | Lies in the postero-inferior region of the cranium Smaller in size than the cerebrum but similar in composition |
| Ventricles | produce Cerebrospinal Fluid (CSF) |
| Lateral ventricles | largest ventricle, found in each cerebral hemisphere |
| 3rd ventricle | Found between the cerebral hemispheres inferior to the lateral ventricles CSF passes into the midline 3rd ventricle through the interven-tricular foramina |
| 4th ventricle | between the cerebellum and the brainstem |
| Four major arteries supply the brain and it's related structures. | 2 internal carotid arteries 2 vertebral arteries |
| 2 internal carotid arteries | Supply the anterior structures of the brain |
| 2 vertebral arteries | Transverse the neck and enter the posterior skull by way of the foramen magnum |
| Circle of Willis | prevents blood loss in the brain by a unique arterial anastomosis |
| Venous drainage in the cranium is accomplished by two systems | Cerebral veins Dural venous sinuses |
| Cerebral veins | One of the major veins within the skull |
| Dural venous sinuses | Created by gaps formed between the inner and outer layers of the dura- mater |
| T-spine Vertebra | Each of the 12 vertebra are subdivided in to a body and vertebral arch |
| Vertebral foramen is the | opening between divisions of vertebra |
| Vertebral arch | formed by 2 pedicles, 2 laminae, 2 transverse processes, 1 spinous process. |
| Ribs | 12 pairs curl around lateral thorax to protect lungs and heart |
| Costo-vertebral joint | junction of rib and thoracic vertebra |
| Sternum | Lies in the midline of anterior chest wall. |
| Sternal, or jugular, notch | lies at the level between 2nd and 3rd thoracic vertebra. |
| Clavicles | "S" shaped bones that extend across the upper anterior thorax |
| SC joint | articulation of the medial end of clavicle with sternum |
| AC joint | - articulation of lateral extremity of the clavicle to the acromion process of the scapula. |
| Scapulae | Triangular bone in superior posterior thorax |
| Surfaces | anterior and posterior |
| Borders | superior, medial and lateral |
| Angles | superior, lateral and inferior |
| Trachea | Originates at C6 Bifurcates into right and left bronchi at T4-T5 |
| Carina | last cartilage ring of the trachea |
| Lungs | Enclosed in thoracic cavity by double walled pleural membrane. |
| Apex | the portion of the lung that lies superior to the clavicle |
| Base | rests on the diaphragm |
| Costophrenic angle | most posterior and inferior portion of the base |
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