Human Anatomy Lesson 2 PDF (2024-2025)

Human Anatomy Lesson 2 A. Y. 2024-2025 Prof. Ilham EL Atiallah [email protected] Divisions of the Skeletal System Forms the central supporting axis of the body Copyright 2009, John Wiley...

Human Anatomy Lesson 2 A. Y. 2024-2025 Prof. Ilham EL Atiallah [email protected] Divisions of the Skeletal System Forms the central supporting axis of the body Copyright 2009, John Wiley & Sons, Inc.  Axial Skeleton skull vertebral column thoracic cage 22 bones braincase face the cranial cavity consists of 8 14 facial bones form bones that immediately surround the structure of the and protect the brain face Bones  SKULL CRANIUM FACIAL SKELETON Interior of the Cranial Cavity  Interior of the Cranial Cavity The bones forming the floor of the cranial cavity, from anterior to posterior, are the frontal, ethmoid, sphenoid, parietal, temporal, and occipital bones  Interior of the Cranial Cavity The relatively shallow anterior cranial fossa is crescent-shaped and accommodates the frontal lobes of the brain.  Interior of the Cranial Cavity The middle cranial fossa, which drops abruptly deeper, is shaped like a pair of outstretched bird’s wings and accommodates the temporal lobes.  Interior of the Cranial Cavity The posterior cranial fossa is deepest and houses a large posterior division of the brain called the cerebellum..  Interior of the Cranial Cavity A horizontal cribriform plate forms the roof of the nasal cavity. This plate has a median blade called the crista galli, an attachment point for the dura mater. On each side of the crista is an elongated depressed area perforated with numerous holes, the cribriform (olfactory) foramina. A pair of olfactory bulbs of the brain, concerned with the sense of smell, rests in these depressions, and the foramina allow passage for olfactory nerves from the nasal cavity to the bulbs  Interior of the Cranial Cavity Several foramina can be seen in the floor of the middle fossa. These allow nerves and blood vessels to pass through the skull  Interior of the Cranial Cavity Several foramina can be seen in the floor of the middle fossa. These allow nerves and blood vessels to pass through the skull. The optic canal permits passage of the optic nerve and ophthalmic artery. The foramen rotundum and foramen ovale are passages for two branches of the trigeminal nerve.. A major artery to the meninges (the membranes around the brain) passes through the foramen spinosum The sphenoid bone has a complex shape with a thick median body and outstretched greater and lesser wings, which give the bone as a whole a ragged mothlike shape. The central region of the sphenoid bone is modified into a structure resembling a saddle, the sella turcica, which contains the pituitary gland.  Interior of the Cranial Cavity The internal jugular vein passes through the jugular foramen. The large foramen magnum, through which the spinal cord joins the brain.  Boundaries of cranial fossae 1: Sphenoidal limbus 2: Posterior borders of the lesser wings of the sphenoid 3: Dorsum sellae of the sphenoid bone 4: Superior borders of the petrous part of the temporal bone 5: Groove for transverse sinus of the occipital bone Purple: Anterior cranial fossa Blue: Middle cranial fossa Green: Posterior cranial fossa Base of Skull Viewed from Below  Base of Skull Viewed from Below The hard palate forms the floor of the nasal cavity and the roof of the mouth. The anterior two-thirds of the hard palate is formed by the maxillae, the posterior one-third by the palatine bones. The connective tissue and muscles that make up the soft palate extend posteriorly from the hard, or bony, palate. The hard and soft palates separate the nasal cavity and nasopharynx from the mouth, enabling us to chew and breathe at the same time. The hard and soft palates separate the nasal cavity and nasopharynx from the mouth, enabling us to chew and breathe at the same time.  Base of Skull Viewed from Below Two long, pointed styloid processes project from the inferior surface of the temporal bone. The muscles involved in moving the tongue, the hyoid bone, and the pharynx (throat) originate from this process. The mandibular fossa, where the mandible articulates with the temporal bone, is anterior to the mastoid process  Base of Skull Viewed from Below Many of the same foramina that are visible in the interior of the skull can also be seen in the base of the skull, when viewed from below, with the mandible removed. The foramen magnum is located in the occipital bone near the center of the skull base. Occipital condyles, the smooth points of articulation between the skull and the vertebral column, are located beside the foramen magnum  External Skull Viewed from anterior view The shape is oval, but the upper part is wider than the lower one. In frontal norm the bones can be divided into three floors: -The superior floor of the visceral cranium corresponds to the forehead. -The middle floor includes the orbits and the nasal cavity. -The inferior floor corresponds to the oral cavity. External Skull Viewed from anterior view  The orbit The infraorbital foramen provides passage for a blood vessel to the face and a nerve that receives sensations from the nasal region and cheek. The inferior and superior orbital fissures allow passage for blood vessels and nerves from the face.  Nasal cavity The nasal cavity is divided in the midline by the nasal septum. The nasal septum contains bone and hyaline cartilage. It Is composed of the maxillary bone (the crest), the Perpendicular plate of ethmoid bone, Septal nasal cartilage, and Vomer bone.  THE PERPENDICULAR PLATE OF ETHMOID BONE The labyrinth is named for the fact that internally, it has a maze of air spaces called the ethmoidal cells. The medial surface of the labyrinth gives rise to two curled, scroll-like plates of bone called the superior concha and middle nasal concha. The conchae occupy most of the nasal cavity, leaving little open space. By filling space and creating turbulence in the flow of inhaled air, they ensure that the air contacts the mucous membranes that cover these bones, which cleanse, humidify, and warm the inhaled air before it reaches the lungs. External Skull Viewed from lateral view Face (anterior) Temporal region (middle) Occipital region (posterior)  the temporal bone The temporal bone can be divided into four parts: The squamous part, shows two main features: (a) the zygomatic process, which extends anteriorly to form part of the zygomatic arch with the temporal process of zygomatic bone; and the mandibular fossa, a depression where the mandible articulates with the cranium.  the temporal bone The mastoid part lies posterior to the tympanic part. It bears a heavy mastoid process, which you can palpate as a prominent lump protruding behind the earlobe. It is filled with small air sinuses that communicate with the middle-ear cavity  the temporal bone The tympanic part is a small ring of bone that borders the opening of the external acoustic meatus, or ear canal, which lead the inner of the ear. It has a pointed spine on its inferior surface, the styloid process. The styloid process provides attachment for muscles of the tongue, pharynx, and hyoid bone. Te mandibolar fossa is the depression in the temporal bone that articulates with the mandible.  the temporal bone The petrous part can be seen in the cranial floor, where it resembles a little mountain range separating the middle cranial fossa from the posterior fossa. It houses the middle- and inner-ear cavities. The internal acoustic meatus, an opening on its posteromedial surface, allows passage of a nerve that carries signals for hearing and balance, from the inner ear to the brain.  External Skull Viewed from lateral view: the ear Semicircular canals Malleus Incus Stapes Petrous part Vestibulocochlear nerve Tympanic part cochlea Vestibular apparatus Styloid process The ear has t hree main functions: To collect sound waves and channel them into the ear canal (external auditory meatus), where the sound is amplified (Auditory ossicles). To convert mechanical signals from the middle ear into electrical signals, which can transfer to the auditory pathway in the brain. To maintain balance by detecting position and motion. External Skull Viewed from posterior view  External Skull Viewed from superior view The skull is seen from the upper part, and it has an oval shape  External Skull Viewed from lateral view The skull is seen from the lateral side. Norma lateralis exposes to our sight the temporal, temporal, infratemporal and pterygopalatine fossae.  External Skull Viewed from lateral view Temporal fossa Pterion Boundaries: Anterior: Zygomatic process of frontal bone + zygomatic bone Superior & Posterior: Temporal lines Inferior: Zygomatic arch Infratemporal fossa Zygomatic arch  External Skull of intracranial regions The Neurocranium (calvaria and cranial base) contains the brain, the intracranial portions of the cranial nerves, blood vessels, meninges and cerebrospinal fluid. Internal regions Internal surface of calvaria Internal surface of cranial base  Hyoid Bone The hyoid bone is an unpaired, U-shaped bone. It is not part of the skull and has no direct bony attachment to the skull. Muscles and ligaments attach it to the skull. The hyoid bone provides an attachment for some tongue muscles, and it is an attachment point for important neck muscles that elevate the larynx (voice box) during speech or swallowing Vertebral Column Divisions of the Skeletal System Copyright 2009, John Wiley & Sons, Inc.  Vertebral Column THE VERTEBRAL COLUMN The vertebral column, or backbone, is the central axis of the skeleton, extending from the base of the skull to slightly past the end of the pelvis. In adults, it usually consists of 26 individual bones, grouped into five regions. -7 cervical vertebrae -12 thoracic vertebrae -5 lumbar vertebrae -1 sacral bone -1 coccyx bone. The adult sacral and coccyx bones fuse from 5 and 3–4 individual bones, respectively. For convenience, each of the five regions is identified by a letter, and the vertebrae within each region are numbered: VERTEBRAE C1–C7, T1–T12, L1–L5, S, and CO.. Vertebral Column The vertebral column is a curved linkage of individual bones: vertebrae Functions: to protect the spinal cord and nerves to support the trunk to provide attachments for muscles an important site of haemopoiesis Vertebral Column The vertebral column is curved in several places, a result of human bipedal evolution. Curves increase the vertebral column's - strength - flexibility, - ability to absorb shock - Stabilizes the body in an upright position. When the load on the spine is increased, the curvatures increase in depth (become more curved) to accommodate the extra weight. They then spring back when the weight is removed. The thoracic curve, concave forward, begins at the middle of the second and ends at the middle of the twelfth thoracic vertebra. Its most prominent point behind corresponds to the spinous process of the seventh thoracic vertebra. This curve is known as a kyphotic curve.  Vertebral Column SECONDARY CURVES Convex anteriorly The thoracic and sacral curves are termed primary curves because they are present in the fetus. PRIMARY CURVES The thoracic and sacral curves are concave concave anteriorly anteriorly The cervical and lumbar curves are compensatory, or secondary, and are developed after birth. SECONDARY CURVES convex The cervical and lumbar curves are anteriorly convex anteriorly PRIMARY CURVES concave anteriorly  Vertebral Column The adult vertebral column has four major curvatures In newborn Single curve, concave anteriorly Lumbosacral angle appears during development In adult Primary curves (concave anteriorly) − Thoracic and sacral are formed during fetal development Secondary curves (convex anteriorly) − Cervical is formed when infant raises head at 4 months − Lumbar forms when infant sits up and begins to walk at 1 year Vertebral Column In the upright position the body weight is transmitted to the inferior limb trough the column In humans, most of the body weight is anterior to the body axis: curves align the body weight with the axis  Vertebral Column Various conditions may exaggerate the normal curves of the vertebral column: Scoliosis Kyphosis Lordosis Abnormal vertebral curvatures are not uncommon. Abnormal vertebral curvatures are not uncommon. The curve is usually "S"- or "C"-shaped over Kyphosis is an exaggerated Lordosis is an exaggerated three dimensions thoracic curvature lumbar curvature Copyright 2009, John Wiley & Sons, Inc.  General Plan of the Vertebrae Each vertebra consists: - Body is the weight-bearing portion of each vertebra - Arch surround and protect the spinal cord - Various processes attach muscles and legament Lateral view  General Plan of the Vertebrae Each vertebral arch consists of two pedicles, which extend from the body to the transverse process of each vertebra, and two laminae, which extend from the transverse processes to the spinous process. A transverse process extends laterally from each side of the arch, between the pedicle and lamina, and a single spinous process projects dorsally from where the two laminae meet The spinous processes can be seen and felt as a series of lumps down the midline of the back. The transverse and spinous processes Lateral view provide attachment sites for the muscles that move the vertebral column  General Plan of the Vertebrae The vertebral arch surrounds a large opening called the vertebral foramen. the vertebral foramina of all the vertebrae forms the vertebral canal, where the spinal cord is located. The vertebral canal protects the spinal cord from injury. Lateral view  General Plan of the Vertebrae Each vertebra has a superior and an inferior articular process where the vertebrae articulate with each other. Each articular process has a smooth “little face” called an articular facet Lateral view General Plan of the Vertebrae Each vertebra has a superior and an inferior articular process where the vertebrae articulate with each other. Each articular process has a smooth “little face” called an articular facet  Vertebral foramen Superior Articolar Process And Body facet Transverse Pedice process Vertebral arch Spinous Lamina process Inferior articular process and facet structural elements of a vertebra General Plan of the Vertebrae Spinal nerves exit the spinal cord through the intervertebral foramina, which are formed by notches in the pedicles of adjacent vertebrae. General Plan of the Vertebrae The vertebral bodies are separated by intervertebral disks, which are formed by fibrocartilage. Content : – Fibrocartilagenous ring (anulus fibrosus) Concentric layers Collagen bundles oriented in an alternative oblique directions – Pulpy center (nucleus pulposus) Gelatinous material General Plan of the Vertebrae - Functions to: Form strong joints Permit various movements of the vertebral column Absorb vertical shock  inner fibrous Outer fibrous Ring area Ring area Nucleus polposus Fibrous ring Regional Differences in Vertebrae  Cervical vertebrae The cervical vertebrae have very small bodies, except for the atlas, which has no body. Because the cervical vertebrae are relatively delicate and have small bodies, dislocations and fractures are more common in this area than in other regions of the vertebral column. Each of the transverse processes has a transverse foramen through which the vertebral arteries pass toward the brain  Atlas The first cervical vertebra is called the atlas because it holds up the head. This name remembers the classical mythology of Atlas, Movement between the atlas and the the man who held up occipital bone is responsible for a “yes” the world on his sho u motion of the head. It also allows a slight lders, tilting of the head from side to side. Atlanto-Occipital Joints: Synovial Condyloid joint Flexion/extension and lateral rotation  Axis The second cervical vertebra is called the axis because a considerable amount of rotation occurs at this vertebra, as in shaking the head “no.” This rotation occurs around a process called the dens, which protrudes superiorly from the axis Thoracic Vertebrae The thoracic vertebrae possess long, thin spinous processes that are directed inferiorly. The thoracic vertebrae also have extra articular facets on their lateral surfaces that articulate with the ribs. Lumbar Vertebrae The lumbar vertebrae have large, thick bodies and heavy, rectangular transverse and spinous processes. Because the lumbar vertebrae have massive bodies and carry a large amount of weight, ruptured intervertebral disks are more common in this area than in other regions of the column  Lumbar Vertebrae The superior articular facets of the lumbar vertebrae face medially, whereas the inferior articular facets face laterally. This arrangement tends to “lock” adjacent lumbar vertebrae together, giving the lumbar part of the vertebral column more strength. The articular facets in other regions of the vertebral column have a more “open” position, allowing for more rotational movement but less stability than in the lumbar region Lumbar Vertebrae The five sacral vertebrae are fused into a single bone called the sacrum. The spinous processes of the first four sacral vertebrae form the median sacral crest. The spinous process of the fifth vertebra does not form, leaving a sacral hiatus at the inferior end of the sacrum, which is often the site of “caudal” anesthetic injections given just before childbirth. Regional Differences in Vertebrae The coccyx, or tailbone, usually consists of four more or less fused vertebrae. The vertebrae of the coccyx do not have the typical structure of most other vertebrae. They consist of extremely reduced vertebral bodies, without the foramina or processes, usually fused into a single bone. The coccyx is easily broken when a person falls by sitting down hard on a solid surface or in women during childbirth Coccygeal cornu: union of 4 vertebrae (Co1 - Co4) by age 30 Vertebral Column Inserire immagine 6.21 Martini  THORACIC VERTEBRAE FEATURES: The spinous processes are relatively pointed and angle sharply downward. The body is somewhat heart-shaped, more massive than in the cervical vertebrae but less than in the lumbar vertebrae The body has small, smooth, slightly concave spots called costal facets for attachment of the ribs: - T1-T8 have two (superior and inferior) costal facets, as they articulate with two pairs of ribs - T9-T12 have only one single facet on each side - Vertebrae T1 through T10 have a shallow, cuplike trans-verse costal facet at the end of each transverse process. These provide a second point of articulation for ribs 1 to10. -There are no transverse costal facets on T11 and T12 because ribs 11 and 12 attach only to the bodies of those two vertebrae.  Rib Cage The rib cage protects the vital organs within the thorax and prevents the collapse of the thorax during respiration. It consists of the thoracic vertebrae, the ribs with their associated cartilages, and the sternum  Ribs and Costal Cartilages The true ribs, ribs 1–7, attach directly to the sternum by means of costal cartilages. The false ribs, ribs 8–12, do not attach directly to the sternum. The ribs 11 and 12 do not attach at all to the sternum and are called floating ribs  THORACIC VERTEBRAE Tubercle of rib Angle of rib A rib inserts between two vertebrae, so each vertebra contributes one-half of the articular surface. A rib articulates with the inferior costal facet of the upper vertebra and the superior costal facet of the vertebra below that. THORACIC VERTEBRAE  Ribs and Costal Cartilages The sternum, or breastbone, is divided into three parts: the manubrium, the body, and the xiphoid process.  Sternum At the superior end of the sternum, a depression called the jugular notch is located between the ends of the clavicles where they articulate with the sternum. A slight elevation, called the sternal angle, can be felt at the junction of the manubrium and the body of the sternum. This junction is important because it identifies the location of the second rib. This identification allows the ribs to be counted; for example, it can help a health professional locate the apex of the heart, which is between the fifth and sixth ribs  Sternum The xiphoid process is another important landmark of the sternum. During cardiopulmonary resuscitation (CPR), it is very important to place the hands over the body of the sternum rather than over the xiphoid process. Pressure applied to the xiphoid process can drive it into an underlying abdominal organ, such as the liver, causing internal bleeding.  Appendicular Skeleton consists of the bones of the upper and lower limbs, as well as the girdles, which attach the limbs to the axial skeleton  The end…