Introduction to human anatomy Introduction n A strong

Introduction to human anatomy

Introduction n A strong, yet light, internal support for the human body The skeleton is adapted for the protection, locomotor, and manipulative functions The upright stance increases the ability of the skeletal muscle to resist gravity

Introduction n The skeleton maintains its upright position through a series of compensating curves The skeleton accounts for approximately 20% of the body mass The 206 bones of the body are grouped into the axial and appendicular skeleton

Introduction Axial skeleton n Forms the long axis of the body n 80 bones in three major regions – skull – vertebral column – bony thorax • Ribs • Sternum Appendicular n Bones of upper & lower extremities and girdles n 126 bones in three major regions – Girdles • Shoulder girdle • Pelvic girdle – upper extremity – lower extremity

The Skull n n The skull is the body’s most complex bony structure It is formed by two sets of bones, the 8 cranial bones and the 14 facial bones These 22 bones combine to form the cranial cavity and the facial features In addition, there are 3 bones in each inner ear to assist in sound transmission

The Skull: Introduction n The bones of the skull provide. . . – A case to house the brain, the cranium – A framework for the face – Cavities to house the organs of sight, taste, and smell – Passages for air and food – Attachment sites for the teeth – Attachment sites for muscle

The Skull: Introduction n Most bones of the skull are flat bones Except for the mandible, all bones are firmly united by interlocking sutures The major sutures of the skull are. . . – Coronal – Sagittal – Squamosal – Lambdoidal n (Between Frontal & Parietal) (Between Parietal bones) (Between Parietal & Temporal) (Between Parietal & Occipital) Other skull sutures connect facial bones and are named after these structures

________ Sagittal

Coronal Lambdoid Squamous

Overview of Skull Geography n n Facial bones form the anterior aspect The cranial bones enclose the brain

Vault n n The cranial vault or calvaria forms the superior, lateral, and posterior aspects of skull The cranial base forming the inferior aspect of skull

Cranial Base n n Cranial base forms the skull’s inferior aspect Three prominent ridges divide the base into fossae The brain rests on these cranial fossae completely enclosed by the cranial vault The brain occupies the cranial cavity

Cavities of the Skull n In addition to the large cranial cavity there are many smaller cavities – Middle and inner ear cavities – Nasal cavity – Orbits of the eyes – Several bones contain air filled sinuses • Sinuses surrounding the nasal cavity are referred to as the paranasal sinuses

Study Note n n As you read about the bones of the skull, locate each bone on the different skull views in Figures 7. 2, 7. 3, 7. 4 The skull bones and their important markings and features are summarized in Table 7. 1 on pages 213 -214

Cranium n n The 8 cranial bones include; 2 parietal, 2 temporal frontal, occipital, sphenoid, ethmoid Cranium is self- bracing allowing the bones to be thin, yet strong

Frontal bone n Forms the anterior portion of the cranium, the forehead, roofs of the orbits, and most of the anterior cranial fossa

Frontal bone - landmarks n n n n Frontal squama Supraorbital margins Supraorbital foramen Orbits Anterior cranial fossa Glabella Frontal sinuses

Parietal bones n n Forms most of the superior & lateral aspects of the skull Articulates with other cranial bones to form four major sutures Parietal

Parietal bones - landmarks n The four largest sutures cranial sutures, Coronal, Sagittal, Lambdodial, Squamosal

Occipital bone n n Forms most of the posterior wall and base of skull Articulates with parietal & temporal Joins w/ sphenoid in the cranial floor Forms internal walls of posterior cranial fossa

Occipital bone Ext. landmarks n Foramen magnum, Occipital condyles, External occipital protuberance, Nuchal lines, External occipital crest

Occipital bone - Int. landmarks n Hypoglossal canal, Posterior cranial fossa

Temporal Bone n n n Forms the inferolateral aspects of the skull Parts of the cranial floor Divided into four regions; squamous tympanic, mastoid, and petrous-(int)

Temporal Bone n n The internal petrous region contributes to the cranial base The petrous region and the sphenoid bone form the middle cranial fossa

Temporal Bone - landmarks n Zygomatic process – Meets the zygomatic bone – Forms the cheek n Mandibular fossa – Receives condyle of mandible

Temporal Bone - landmarks n External Auditory Meatus – Middle and inner ear n Styloid process – Muscle of tongue n Mastoid process – Muscles of neck

Temporal bones - landmarks n Jugular foramen – Entry point for the Jugular artery n Internal acoustic meatus – Entry point for the auditory nerve Jugular Foramen

Temporal bones - landmarks n Stylomastoid foramen – exit for facial nerve n Carotid canal – entrance for the carotid artery which supplies blood to cerebral hemispheres

Sphenoid bone n n n Bone spanning the width of middle cranial fossa Articulates as central wedge of all cranial bones Consists of central body and three processes; greater and lesser wings and pterygoid process (pos. view)

Sphenoid - landmarks n n n Sella turcica (enclosure for pituitary gland) Optic foramina (passage of optic nerves) Superior orbital fissure (Nerves III, IV, V enter orbit) Foramen rotundum & ovale (Cranial Nerve V to face) Foramen spinosum (Middle meningeal artery)

Ethmoid bone n n n Forms most of the area between the nasal cavity & orbits of eyes Lies between nasal bones & sphenoid Complex shape gives rise to nasal septum, sinuses and cribiform plate

Ethmoid bone - landmarks n Cribiform plates – Forms roof of nasal cavity n Olfactory formina – Olfactory nerves enter brain n Crista galli – Attachment of the dura mater which secures brain in cavity

Ethmoid bone - landmarks n Perpendicular plate – Forms superior part of nasal septum n Lateral mass – House ethmoid sinuses n Nasal concha – Project into nasal cavity n Orbital plates – Medial walls of orbits

Facial bones n n Consists of 14 bones w/ only mandible and vomer unpaired Others include maxillae, lacrimals, nasals, zygomatics, inferior nasal conchae, and palatines (not pictured)

Mandible n n Forms the lower jaw Largest, strongest bone of the face It has a body and two upwardly projecting sections called rami Houses lower dentition

Mandible - landmarks n n n n Mandibular angle Mandibular notch Coronoid process Mandibular condyle Alveolar margin Mandible formina Mental formina Ramus of mandible

Maxillary bone n n n Forms upper jaw and central portion of facial skeleton Fused medially Articulates with all facial bones except mandible Upper dentition Forms 2/3 of hard palate of the mouth Zygomatic process Maxillary bone

Maxillary bones - landmarks n Alveolar margin – Upper dentition n Frontal process – Forms lateral aspects of nose n Zygomatic process – Articulates with zygomatic bone n Maxillary sinuses – (Fig. 7. 11)

Maxillary bones - landmarks n Palatine processes – Forms roof of mouth n Incisive fossa – Passage of nerves and blood vessels n Infraorbital foramen – Infraorbital nerve and blood vessel to face Palatine Process

Maxillary bones - landmarks n Inferior orbital fissure – Located deep within the orbit – Permits passage of the zygomatic nerve, maxillary nerve, and blood vessels to reach face

Zygomatic bones n n n Commonly called the cheekbones Form prominences of cheeks and inferolateral margins of orbits Articulate with the Zygomatic process of temporal bone and Zygomatic process of maxallae Zygomatic Process of Temporal Zygomatic bone

Nasal bones n n n Forms bridge of the nose Thin, rectangular shape Fused medially Articulate with the frontal bone and maxillary bones laterally Nasal cartilages – (Fig. 6. 1)

Lacrimal Bones n n n Forms part of the medial border of each orbit Articulates with frontal, ethmoid & maxillae Forms part of Lacrimal fossa – Permits tears to drain from orbit to nasal cavity

Lacrimal Bones n Lacrimal fossa – Permits tears to drain from orbit to nasal cavity

Palatine bones n n The horizontal plates forms the posterior portion of hard palate Vertical plate forms part of the posterolateral wall of nasal cavity and a small portion of orbit

Palatine bones - landmarks n Horizontal plate – Posterior section of hard palate n Vertical plate – Part of the posteriolateral walls of nasal cavity n Orbital surface – Part of inferior medial aspect of orbit

Vomer n n Forms part of the nasal septum Discussed with the nasal cavity

Vomer - landmarks n Plow shape – Divides nasal septum into right and left parts

Inferior Nasal Conchae n n n Form lateral walls of nasal cavity Project medially from the lateral walls of nasal cavity Largest of nasal conchae

Inferior Nasal Conchae - Landmark n n The Inferior nasal conchae is just one of three in the nasal cavity Superior and middle concha are on the Ethmoid bone

The Orbits n n n The orbits are bony cavities within which the eyes are encased and cushioned by fatty tissue The muscles that move the eyes and the tear producing lacrimal glands are housed within the orbit Formed by frontal, sphenoid, maxilla, zygomatic, lacrimal palatine & ethmoid Contain superior & inferior orbital fissures Optic foramina

The Orbits

Nasal cavity n n The nasal cavity is constructed of bone and hyaline cartilage The cavity is divided into right and left parts by the nasal septum Superior, middle and inferior nasal concha project into the cavity The nasal septum and conchae are lined with mucus-secreting mucosa

Nasal cavity n n Roof of the cavity is the cribriform plates of ethmoid Lateral walls are the superior, middle, and inferior conchae, and vertical plates of palatines Cribriform plate

Nasal cavity n n Floor of cavity is formed by palatine processes of the maxillae and the palatine bones Septum is formed by vomer and the perpendicular plate of ethmoid

Paranasal sinuses n n Five skull bones; frontal, sphenoid, ethmoid, and the paired maxillary contain mucus-lined, air-filled sinuses Cluster around nasal cavity Connected to nasal cavity to allow air to enter and mucus to drain Lighten skull, warm and humidify air, enhance voice resonance

Paranasal sinuses n Note positioning around nasal cavity

Paranasal sinuses n n Sphenoid sinus Frontal sinus Ethmoid sinus Maxillary sinuses

Hyoid bone n n Not really a part of the skull, it is unique in that it is the only bone that does not articulate with any other bone Positioned just inferior to the mandible Anchored by stylohyoid ligaments to the styloid processes of temporal bone Acts as a movable base for the tongue

Hyoid bone n Body – Neck muscle attachment n Greater horn – Neck muscle attachment n Lesser horn

THE VERTEBRAL COLUMN SECTION II

Vertebral Column: General Characteristics n n n n Formed from 26 irregular bones It contains four distinct curvatures It provide axial support for the trunk Transmits weight of trunk to lower limbs Protects spinal cord Attachment site for ribs and muscles Separated by intervertebral discs There are 24 vertebrae, a sacrum (5 fused) and a coccyx (4 fused)

General Characteristics n Alignment – Anterior/ posterior – Lateral n Curvatures – Compensatory curves n Features – Weight bearing – Muscle attachment – Protection

Regional Characteristics n Cervical C 1 -C 7 – Neck / movable n Thorasic T 1 -T 12 – Rib cage / limited movement n Lumbar L 1 -L 5 – Low back / movable n Sacral 5 fused – Joins the pelvis n Coccyx 4 fused – Terminus

Clinical deviations n Scoliosis – An abnormal lateral curvature of the spinal column – Curvature can occur in an “S” or “C” deviation

Clinical deviations n Kyphosis – An exaggerated dorsal curvature in the dorsal region – Common is aged individuals because of osteoporosis

Clinical deviations n Lordosis – Accentuated lumbar curvature – Being overweight or pregnant causes an excessive load up front

Curves develop in response to: Upright posture Weight bearing Musculature

Characteristics - Ligaments n Ligaments hold the vertebral column in an upright position – The broad Anterior Longitudinal Ligament prevents hyperextension and is quite strong – The cord like Posterior Longitudinal Ligament prevents hyperflexion and is relatively weak

Characteristics - Ligaments n Ligaments also connect specific vertebra and support disc position – Supraspinos ligament – Ligamentum flavum – Interspinous ligament

Intervertebral Discs n n Intervertebral discs are cushion like pads interposed between vertebra The discs provide elasticity and compressibility Compression flattens discs Discs are thickest in the cervical and lumbar to provide flexibility

Characteristics - discs n Annulus fibrosus surrounds the outer margin – Collagen fibers n n Nucleus pulposus is the semi fluid substance which shifts under body weight & pressure Herniation of disc Herniation of disk

General structure of vertebrae n Common pattern – Body or centrum – Vertebral arch • lamina • pedicle – Vertebral foramen – Spinous process • Muscles attach – Transverse process • Muscles attach

General structure of vertebrae n Interlocking pattern – Superior and inferior processes interlock – The inferior from above and the superior from the vertebrae below form a movable joint – The movement contributes to spinal rotation Superior Articular Process

General structure n n Pedicles have notches on their superior and inferior borders Lateral openings are called intervertebral foramen – Spinal nerves from spinal cord exit through these foramina

Regional Characteristic: Cervical n n Body is oval, but wide side to side C 3 - C 7 Spinous process is short and bifid (split) except in C 7 Vertebral foramen is triangular Transverse processes contain foramina for blood vessels leading to brain

Cervical Vertebrae C 1 and C 2 n n n The first two cervical vertebrae are named the atlas and axis respectively There is no intervertebral disc between them They are highly modified for carrying the skull on top of the vertebral column The atlas (C 1) functions are a cradle to support the head The axis (C 2) functions as a pivot point for the rotation of the atlas

Cervical Vertebrae C 1 n Lateral masses articulates with the occipital condyles of the skull

Cervical Vertebrae C 1 Body of the Vertebrae is missing n Inferior articular surface articulates with C 2 below

Cervical Vertebrae C 2 n n The axis has the odontoid process or dens is its unique feature The dens is the missing body of the atlas which fuses with the atlas during embryonic development

Regional Characteristic: Cervical n n Spinous processes project directly posteriorly Superior facets directed superoposteriorly Inferior facets directed inferoanteriorly Flexion/extension, lateral flexion and rotation

Regional Characteristic: Thoracic n n Body is larger than cervical; heart shaped Spinous process is long and sharp Vertebral foramen is circular Transverse processes project posteriorly and bear facets for ribs

Regional Characteristic: Thoracic n n n Body bears two costal demifacets Spinous processes projects inferiorly Superior facets directed posteriorly Inferior facets directed anteriorly Rotation, limited lateral flexion, flexion/extension prevented

Regional Characteristic: Lumbar n n Body is massive and kidney shaped Spinous processes are short and blunt Vertebral foramen is triangular Transverse processes are perpendicular to spinous process but has no special features

Regional Characteristic: Lumbar n n Spinous process projects posteriorly Superior facets directed medially Inferior facets directed laterally Flexion/extension, some lateral flexion, rotation prevented

Sacrum n n n The triangular shaped structure formed by five fused vertebrae Forms the posterior wall of the pelvis Articulates with L 5 of the vertebral column Articulates with the iliac bone of the pelvic girdle Transfers the weight of the upper torso and limbs to the lower extremities

Sacral n n Ala are fused remnants of transverse processes that articulate with hip bones to form the sacro iliac joints of the pelvis Sacral promontory – Center of gravity is 1 cm posterior of this point n n Transverse line are sites of vertebral fusion Sacral foramina transmit blood vessels and nerves Ala Sacral promontory

Sacral n n On the posterior aspect median sacral crest are fused spinous processes The vertebral canal continues inside the sacrum as the sacral canal Sacral hiatus is at the inferior end of the sacral canal Superior articular surface form a joint with the spinal column

Coccyx n Coccyx articulates with sacrum

The Bony Thorax n The thorax is the chest which includes – Thoracic vertebrae posteriorly – The ribs laterally – The sternum and costal cartilages anteriorly n n It is cone shaped with its broad opening inferiorly The thorax forms a bony cage around the heart, lungs and major blood vessels

Functions of The Bony Thorax n n n Protection Attachment point for muscles of the back, chest, and shoulders The intercostal muscles attach to the thorax to lift and depress the thorax during respiration

The Sternum n n The sternum lies in the anterior midline of the thorax It is three fused bones – Manubrium • Jugular notch • Clavicular notch – Sternal body • Sternal angle – Xiphoid process • Xiphisternal joint

Bony Thorax n n n Thorax is the chest and its bony underpinnings is called the thoracic cage Elements consist of the thoracic vertebrae, ribs, sternum, and costal cartilages which secure ribs to the sternum A cone opening inferiorly, the thorax provides a protective cage around the vital organs of the thoracic cavity (heart, lungs, great blood vessels)

Bony Thorax - continued n n n Provides support for the shoulder girdles Bony attachment points for muscles of the back, chest and shoulders Intercostal spaces between ribs are occupied by the intercostal muscles which lift and depress the thorax during breathing

Sternum n n n Located on the anterior midline of the thorax Consists of three fused bones; manubrium, body, and xiphoid process Manibrium articulates with clavicle & 2 ribs Body with ribs 2 - 7 Xiphoid attachment site for abdominal muscle

Thorax to Vertebral Column

Ribs

Ribs n n n Twelve pairs forming thoracic cage All attach posteriorly to thoracic vertebrae Curve inferiorly toward anterior body surface Ribs 1 -7 attach directly to sternum by separate costal cartilages and are referred to as true ribs Ribs 8 -10 attach indirectly to sternum by attaching to costal cartilages immediately above Ribs 11 -12 have no anterior attachments and are referred to as floating ribs

Ribs n n Ribs are bowed flat bones Long shaft Tear drop shaped with a costal groove on inner surface Head of rib has 2 facets to articulate with its vertebrae as well as the one above

Ribs n n Neck is just beyond the head Angle of rib Costal cartilages attach rib to sternum Attachments are secure but flexible

Ribs n n n Tubercle of rib articulates with transverse process Ligaments secure rib to transverse process Note how the transverse processes of thoracic vertebrae are angled posteriorly

The Appendicular Skeleton n n Appended to the axial skeleton Pectoral girdle is for manipulation and is a lighter, less heavily reinforced structure Pelvic girdle is for weight bearing and locomotion and is a heavier, more robust structure Differences appear in bone structure, joint structure, ligaments, and muscle