Nursing 3rd Note (2) PDF

Axial Skeleton A. Taha Demirbaş, Asst Prof Anatomy  The skeleton is divided into two parts Appendicular skeleton: The bones of the upper limb and pectoral girdle, and bones of the lower limb and pelvic girdle Axial skeleton: Cranium, vertebral column, ribs and sternum Vertebr...

Axial Skeleton A. Taha Demirbaş, Asst Prof Anatomy  The skeleton is divided into two parts Appendicular skeleton: The bones of the upper limb and pectoral girdle, and bones of the lower limb and pelvic girdle Axial skeleton: Cranium, vertebral column, ribs and sternum Vertebral Column Physically supports the skull and trunk Allows for their movement Protects the spinal cord, and Absorbs stresses produced by walking, running, and lifting Provides attachment for the limbs, thoracic cage, and postural muscles Although commonly called the backbone, it consists not of a single bone but a chain of 33 vertebrae with intervertebral discs  The vertebrae are divided into five groups: 7 cervical vertebrae in the neck 12 thoracic vertebrae in the chest, 5 lumbar vertebrae in the lower back 5 sacral vertebrae at the base of the spine, and 4 tiny coccygeal vertebrae  Beyond the age of 3 years, the vertebral column is slightly S-shaped with four bends called The cervical, thoracic, lumbar, and pelvic curvatures Thoracic and pelvic curvatures are primary and occur C-shape The secondary curvatures are cervical and lumbar Abnormal Spinal Curvatures Scoliosis, an abnormal lateral deviation Kyphosis, an exaggerated thoracic curvature common in old age Lordosis, an exaggerated lumbar curvature common in pregnancy and obesity General Structure of a Vertebra Vertebral body: A mass of spongy bone covered with a thin shell of compact bone. This is the weight- bearing portion of the vertebra Vertebral foramen: Forms the vertebral canal Vertebral arch: Pedicle+lamina Spinous process: Prominent prominence (palpable) extending at the top of the arch Transvers process: Protrusion between lamina and pedicle. It is an attachment point for soft tissues  Intervertebral Discs An intervertebral disc is a cartilaginous pad located between the bodies of two adjacent vertebrae There are 23 discs—the first one between C2-C3 and the last one between the L5-S1 The discs help to bind adjacent vertebrae together, enhance spinal flexibility, support the weight of the body, and absorb shock Under stress—for example, when you lift a heavy weight—the discs bulge laterally. Excessive stress can cause a herniated disc Regional charactheristics of vertebrae The cervical vertebrae (C1–C7) are relatively small Their function is to support the head and allow for its movements The first two (C1 and C2) have unique structures for this purpose Transverse foramina occur in no other vertebrae and thus provide an easy means of recognizing a cervical vertebra  There are 12 thoracic vertebrae (T1–T12), corresponding to the 12 pairs of ribs attached to them; no other vertebrae have ribs One function of the thoracics is to support the thoracic cage enclosing the heart and lungs  There are five lumbar vertebrae (L1–L5) Their most distinctive features are a thick, stout body adapted for bearing the weight of the upper body  The five sacral vertebrae (S1–S5) of a child begin to fuse around age 16, and by age 26 they are usually fused into a single bony plate, the sacrum The sacrum forms the posterior wall of the pelvic cavity and protects the organs within Four (sometimes five) tiny coccygeal vertebrae (Co1 to Co4 or Co5) fuse by the age of 20 to form the coccyx sacr = great, prominent coccyx = cuckoo (named for resemblance to a cuckoo’s beak) Pelvic Girdle or Pelvis The pelvis is a bowl-shaped structure Composed of sacrum, coccyx ant two hip bones (coxae) as well as their ligaments and the muscles that line the pelvic cavity and form its floor The pelvic girdle supports the trunk on the lower limbs and Encloses and protects the viscera of the pelvic cavity—mainly the lower colon, urinary bladder, and internal reproductive organs  The pelvis has a bowl-like shape with the broad greater (false) pelvis between the flare of the hips and the narrow lesser (true) pelvis below The two are separated by a somewhat round margin called the pelvic brim The greater pelvis forms the walls of the lower abdominal cavity, whereas the lesser pelvis encloses the pelvic cavity The opening circumscribed by the brim is called the pelvic inlet— an entry into the lesser pelvis through which an infant’s head passes during birth. The lower margin of the lesser pelvis is called the pelvic outlet  The pelvis is the most sexually dimorphic part of the skeleton—that is, the one whose anatomy most differs between the sexes The average male pelvis is more robust (heavier and thicker) than the female’s, owing to the forces exerted on the bone by stronger muscles The female pelvis is adapted to the needs of pregnancy and childbirth The Thoracic Cage The thoracic cage consists of the thoracic vertebrae, sternum, and ribs It forms a roughly conical enclosure for the lungs and heart and provides attachment for the pectoral girdle and upper limb Sternum The sternum (breastbone) is a bony plate anterior to the heart It is subdivided into three regions: the manubrium, body, and xiphoid process manubrium = handle xiphoid: resembling like sword  Ribs (costae) There are 12 pairs of ribs The ribs increase in length from 1 through 7 and become progressively smaller again through rib 12 First 7 ribs are called true ribs Ribs 8 through 12 are called false ribs because they lack independent cartilaginous connections to the sternum In 8 through 10, the costal cartilages sweep upward and end on the costal cartilage of rib 7 The ribs 11 and 12 are called floating ribs, don’t reach to the sternum costa = rib; al = pertaining to  The skull is the most complex part of the skeleton Although the skull may seem to consist of only the mandible (lower jaw) and “the rest,” it is composed of 22 bones and sometimes more (why?) Most of them are rigidly joined by sutures joints that appear as seams on the cranial surface  The skull contains several prominent cavities The largest, with an adult volume of about 1,300 mL, is the cranial cavity, which encloses the brain Other cavities include; the orbits (eye sockets), nasal cavity, paranasal sinuses, oral cavity (mouth or buccal cavity), and middle- and inner-ear cavities  The paranasal sinuses are named for the bones in which they occur the frontal, ethmoid, sphenoid, and maxillary sinuses These sinuses are connected with the nasal cavity, lined by a mucous membrane, and filled with air They lighten the anterior portion of the skull and act as chambers that add resonance to the voice  Bones of the skull have especially conspicuous foramina that allow passage for nerves and blood vessels  Cranial bones are those that enclose the brain; collectively, they compose the cranium The delicate brain tissue does not come directly into contact with the cranial bones, but is separated from them by three membranes called the meninges The thickest and toughest of these, the dura mater lies loosely against the inside of the cranium in most places but is firmly attached to it at a few points  The cranium is a rigid structure with an opening, the foramen magnum (literally “big hole”), where the spinal cord meets the brain The cranium consists of two major parts— the calvaria and the base The calvaria (skullcap) is not a specific bone but simply the dome of the top of the head, composed of parts of multiple bones  In study skulls, it is often sawed so that the top can be lifted off for examination of the interior This reveals the base (floor) of the cranial cavity, which exhibits three depressions called cranial fossae These correspond to the contour of the inferior surface of the brain The relatively shallow anterior cranial fossa is crescent-shaped and accommodates the frontal lobes of the brain The middle cranial fossa, which drops abruptly deeper, is shaped like a pair of outstretched bird wings and accommodates the temporal lobes The posterior cranial fossa is deepest and houses a large posterior division of the brain called the cerebellum Skull Neurocranium (cranial bones): Encompasses the cranial cavity 8 bones, totally - 4 single (occipital, sphenoidal, frontal, ethmoidal) - 2 paired (temporal, parietal) Splanchnocranium- viscerocranium (face bones): Made up the face skeleton 14 bones, totally - 6 paired (maxilla, concha nasalis inferior, palatin, zygomatic, nasal, lacrimal - 2 single (mandible, vomer)  Cranial Bones Frontale bone: Articulates with nasal, maxilla, zygomatic, lacrimal, ethmoidal, sphenoid bones and joins the orbit Connects with parietal bones posteriorly (coronal suture) Lambda Parietale bones: - Articulates with its pair in the midline (sutura sagittalis) Bregma - Articulates with occipital bone posteriorly (sutura lambdoidea) - Laterally, connects with temporal and Coronal suture sphenoidal bone - The touch point between the sagittal suture Sagittal suture and coronal suture is called Bregma; - The touch point between the sagittal suture and lambdoid suture is called Lambda; Lambdoid suture - In infants, bregma is; anterior fontanel, and lambda is; posterior fontanel  Occipital bone: - Includes foramen magnum - Palpable protrusion is external occipital protuberance - Occipital condyle is for the articulation with atlas Temporal bone: - Zygomatic process: Forms the zygomatic arch with the zygomatic bone - Mandibular fossa: For temporo- mandibular joint (TMJ) - External acustic pore: Opening for outer ear - Articulates with occipital, parietal, sphenoid, zygomatic and mandible  Sphenoidal bone: Body: Hypophyseal fossa houses the pituitary gland Ethmoidal bone: Lesser wing: In between two roots of it there is optic - Participates in the structures of nasal canal Greater wing: Forms the majority of the middle cavity, anterior cranial fossa, nasal cranial fossa septum, and orbit *articulates with vomer, ethmoidal, frontal, occipital, pariyetal, temporal, zygomatic and palatin bones - Superior and meddle nasal conchae belong to ethmoidal bone Splanchnocranium (face bones) Maxilla Palatine bone: Zygomatic bone Inferior nasal conchae Lacrimal bone Nasal bone Mandible Vomer