Chapter 8 The Skeletal System PDF

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Dr. Deeba Ahmad...

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Chapter 8: Overview of the Skeleton WHAT YOU NEED TO DO 1. What sits in the cranial cavity? 2. Sutures of the cranium 3. Bones that are closely associated with the skull 4. Identify the cavities in the skull 5. Distinguish between cranial and facial bones 6. Which bone make up the orbit? 7. General features of the vertebrae 8. Label the vertebrae 9. Lab portion: pictures on a PowerPoint with arrows to identify 10. Identification of real bones (bones out) 11. Spelling of all the bones, not the features 12. Names of the long bones 13. Know facial bones 14. Know cranial bones 15. Bones that make up the TMJ 16. Inner ear- ear drum protects the inner ear canal that leads to the brain 17. 3 sections of the sternum 18. Proximal and distal ends of the humerus 19. Where is the lateral and medial epicondyle, anterior and posterior of the bone

SECTION 8.1 axial skeleton- forms the central supporting axis of the body, includes the skull, auditory ossicles, hyoid bone, vertebral column, and thoracic cage. Appendicular skeleton- bones of the upper limb and pectoral girdle and the bones of the lower limb and pelvic girdle

Bones of the Skeletal System Born with 270 bones Average adult bone count is 206 bones This # varies even among adults because of sesamoid bones and sutural bones. Sesamoid bones- bones that form within some tendons in response to strain. Sutural bones- bones in the skull

Skull bones (22) Cranial bones Frontal, Temporal, Parietal, Sphenoid, Occipital, Ethmoid Facial bones Maxillae, Nasal, Palatine, Vomer, Zygomatic, Lacrimal, Inferior nasal conchae, Mandible Auditory ossicles Malleus, stapes, incus Hyoid bone Veterbral Column (26) Cervical vertebrae, sacrum, thoracic vertebrae, coccyx, lumbar vertebrae Thoracic cage (26) Ribs, sternum

Appendicular Skeleton Pectoral Girdle (4) Scapulae, Clavicles Upper limbs Humerus, carpal bones, radius, metacarpal, ulna, phalanges Pelvic girdle Hip bones Lower limbs Femurs, tarsal, patellae, metatarsal, tibiae, phalanges, fibulae Anatomical Features of Bones BONE MARKINGS Term

Description and Example

ARTICULATIONS (Joints) Condyle –A rounded knob that articulates with another bone (occipital condyles of the skull Facet –A smooth, flat, slightly cocave or convex articular surface (articular facets of the vertebrae)

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Head –The prominent expanded end of a bone, sometimes rounded (head of the femur) EXTENSIONS AND PROJECTIONS Crest –A narrow ridge (iliac crest of the pelvis) Epicondyle –An expanded region superior to a condyle (medial epicondyle of the femur) Line –A slightly raised, elongated ridge (nuchal lines) Process –Any bony prominence (mastoid process of the skull) Protuberance –A bony outgrowth or protruding part (mental protuberance of the chin) Spine –A sharp, slender, or narrow process (mental spines of the mandible) Trochanter –2 massive processes unique to the femur Tubercle –A small, rounded process (greater tubercle of the humerus) Tuberosity –A rough elevated surface (tibial tuberosity) DEPRESSIONS Alveolus –A pit or socket (tooth socket) Fossa –A shallow, broad, or elongated basin Fovea –A small pit Sulcus –A groove for a tendon, nerve, or blood vessel PASSAGES AND CAVITIES Canal –A tubular passage or tunnel in a bone Fissure –A slit through a bone Foramen –A hole through a bone, usually round Meatus –A canal Sinus –An air-filled space in a bone

SECTION 8.2 Sutures- immovable joints that connect bones Cranial cavity –encloses the brain Orbits- eye sockets Nasal cavity Oral cavity Middle/inner ear cavities

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Paranasal sinuses- act as chambers that add resonance to the voice; lighten the skull Sinuses- front, sphenoid, ethmoid, and maxillary sinuses Foramina- holes that allow passage for nerves and blood vessels

Foramina of the Skull and the Nerves and Blood vessels Bones and Their Foramina

Structures Transmitted

FRONTAL BONE Supraorbital foramen or notch –Supraorbital nerve, artery, and vein; ophthalmic nerve TEMPORAL BONE Carotid canal –Internal carotid artery External acoustic meatus –Sound waves to eardrum Jugular foramen –Internal jugular vein; glossopharyngeal, vagus, and accessories OCCIPITAL BONE Foramen magnum –spinal cord; accessory nerve; vertebral arteries Hypoglossal canal –Hypoglossal nerve to muscles of tongue ***SPHENOID BONE Foramen ovale –Mandibular division of trigeminal nerve; accessory meningeal artery Foramen rotundum –Maxillary division of trigeminal nerve Optic canal –Optic nerve; ophthalmic artery Superior orbital fissure –Oculomotor, trochlear, and abducens nerves; ophthalmic division of trigeminal nerve; ophthalmic veins MAXILLA Inferior orbital fissure –Infraorbital nerve, zygomatic nerve, infraorbital vessels Infraorbital foramen –Infraorbital nerve and vessels MANDIBLE Mental foramen –Mental nerve and vessels Mandibular foramen –Inferior alveolar nerves and vessels to the lower teeth

Cranial bones Cranial bones- those that enclose the brain, collectively, compose the cranium.

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Meninges- 3 membranes that separate the brain tissue from the bones Dura mater- thickest and toughest meninge that is pressed against the inside of the cranium Foramen Magnum –opening where the spinal cord meets the brain Calvaria –Skull cap, not a single bone but simply the dome of the top of the skull Base –floor of the cranial cavity, which exhibits 3 paired depressions called cranial fossae Anterior cranial fossa –Crescent shaped and accommodates the frontal lobes of the brain Middle cranial fossa- deeper, shaped like a pair of outstretched bird's wings and accommodates the temporal lobes Posterior cranial fossa –deepest and houses a large posterior division of the brain called the cerebellum 8 CRANIAL BONES 1 frontal bone, 1 occipital bone 2 parietal bones, 1 sphenoid bone 2 temporal bones, 1 ethmoid bone

The Frontal Bone Frontal bone –extends from the forehead back to a prominent coronal suture, which Crosses the crown of the head from right to left and joins the frontal bone to the parietal bones Supraorbital margin –Deep to the eyebrows it has a ridge Supraorbital foramen –each margin is perforated by this, provides passage for a nerve, artery, and veins. Glabella –smooth area of the frontal bone just above the root of the nose Diploe –layer of spongy bone in the middle of the cranial bones The Parietal Bones Parietal bones- form most of the cranial roof and part of its wall Sagittal suture –between the parietal bones Coronal suture –at the anterior margin Lambdoid suture –at the posterior margin

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Squamous suture –lateral border Parietal foramen –near the corner of the lambdoid and sagittal sutures Inferior temporal lines –form an arc across the parietal and frontal bones for the attachment of the temporalis muscle. The Temporal Bones PROFESSOR SAID NOT TO STUDY THIS PART EXCEPT WHAT IS HIGHLIGHTED, she said she'll make a small list of these to study Temporal bone –forms the lower wall and part of the floor of the cranial cavity 1. Squamous part- is relatively flat and vertical, and is encircled by: a. Zygomatic process- extends anteriorly to form part of the zygomatic arch (cheekbone) b. Mandibular fossa –depression where the mandible articulates with the cranium 2. Tympanic part –small ring of bone that borders the opening of: a. External acoustic meatus –ear canal b. Styloid process –provides attachment for muscles of the tongue, pharynx, and hyoid bone 3. Mastoid part –lies posterior to the tympanic part a. Mastoid process –you can palpate as prominent lump behind the earlobe b. Mastoid notch –lies medial to the mastoid process c. Stylomastoid foramen –a passage for the facial nerve d. Mastoid foramen –passes a small artery and vein from the brain 4. Petrous part- cranial floor, resembles a little mountain range separating the middle cranial fossa from the posterior fossa (houses middle and inner cavities) a. Internal acoustic meatus –opening on its posteromedial surface, allows passage of a nerve that carries signals for hearing and balance from the inner ear to the brain b. Carotid canal –passage for the internal carotid artery, major blood supply to the brain c. Jugular foramen –a large, irregular opening just medial to the styloid prcess, between the temporal and occipital bones --------------------------------------------------------------------------------------------------------------------Temporomandibular Joint (TMJ)- Inferior to the zygomatic process --------------------------------------------------------------------------------------------------------------------The Occipital Bone Occipital bone –forms the rear of the skull and much of its base Foramen magnum- admits the spinal cord to the cranial cavity Dura matter –attached to the rim of this foramen

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Basilar part- thick median plate of the occipital bone Occipital condyle –smooth knob on both sides of the foramen magnum, where the skull rests on the vertebral column Hypoglossal canal –each anterolateral edge of each condyle has a canal for the hypoglassal nerve that passes through it to innervate the muscles of the tongue External occipital protuberance –medial bump Nuchal ligament –binds the skull to the vertebral column

The Sphenoid Bone Sphenoid bone- complex shape with a thick median body and outstretched greater and lesser wings Optic canal –found in the lesser wing that forms the posterior wall of the orbit, which permits passage of the optic nerve and ophthalmic artery Anterior clinoid processes –appears to guard the optic foramina Superior orbital fissure – angles upward lateral to the optic canal Sella turcica –body of the sphenoid bone contains a pair of sphenoid sinuses and has a saddle like surface feature Foramen rotundum/ foramen ovale-passages for 2 branches of the trigeminal nerve Foramen spinosum –about the diameter of a pencil lead, provides passage for an atery of the mininges Foramen lacerum –occurs at the junction of the sphenoid, temporal, and occipital bones Posterior nasal apertures/ choanae –internal openings of the nasal cavity Medial/ lateral pterygoid plates –parallel plates exhibited by the sphenoid bone Pterygoid process –Each plate has a narrower inferior extension The Ethmoid Bone Ethmoid bone –an anterior cranial bone located between the eyes 1. Vertical perpendicular plate –thin median plate of the bone that forms the superior 2/3s of the nasal septum 2. Nasal fossae –divides the nasal cavity into right and left air spaces 3. Cribriform plate –forms the roof of the nasal cavity 4. Crista galli –attachement point for the dura mater 5. Cribriform (olfactory) foramina –elongated depressed area perforated with numerous holes on each side of the crista 6. Labyrinth –large mass on each side of the perpendicular plate

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7. Ethmoidal cells –labyrinth is named for the fact that interally, it has a maze of air spaces 8. Orbital plate –seen on the medial wall of the orbit 9. Superior/middle nasal conchae –medial surface of the labyrinth gives rise to 2 curled, scroll-like plates of bone

FACIAL BONES Facial bones- do not enclose the brain but lie anterior to the cranial cavity Support: orbital, nasal, and oral cavities, shape the face, provide attachment for the muscles of facial expression and mastication 14 facial bones 2 maxillae, 2 nasal bones, 2 palatine bones, 2 inferior nasal conchae 2 zygomatic bones, 1 vomer, 2 lacrimal bones, 1 mandible The maxillae Maxillae –are the largest facial bones, form the upper jaw and meet each other at a median intermaxillary suture. Largest facial bones Forms upper jaw and meets at median intermaxillary suture 1. Alveolar process bony points between teeth 2. Alveolus: sockets that hold teeth 3. Cleft palate and cleft lip occur when the 2 maxillae fail to join at the suture. Forms inferomedial wall of orbit 1. Infraorbital foramen –provides passage for a blood vessel to the face and a nerve that receives sensations from the nasal region and cheek 2. Inferior orbital fissure- a gash exhibited by the maxilla on part of the floor of the orbit Forms most of the hard palate (roof of the mouth and floor of the nasal cavity) that is formed by horizontal extensions of the maxilla (palatine processes) 1. 2. 1. 1.

Forms roof of mouth and floor of nasal cavity Allows us to chew while breathing Palatine process -horizontal extensions of the maxilla Incisive foramen -median pit, a passafe for an atery to the palate and a nerve to the lower part of the nsal septum and 6 front teeth of the maxilla 3. Separate the nasal cavity from the oral cavity Forms a fleshy soft palate posteriorly

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The Palatine Bones Palatine bones- divide the oral and nasal cavities from each other posteriorly. Greater palatine foramen –nerve passage to the palate.

The Zygomatic Bones Zygomatic bones –form angles of the cheeks at the infolateral margins of the orbits and part of the lateral wall of each orbit; they extend about halfway to the ear. Zygomaticofacial foramen – inverted T shape near the intersection of the stem and crossbar of the T. (nerve passes through here to supply the skin on the prominence of the cheek.

The Lacrimal Bones Lacrimal bones –form part of the medial wall of each orbit. Lacrimal fossa –houses a membranous lacrimal sac in life, tears from the eye collect in this sac and drain into nasal cavity

The Nasal Bones Nasal bones –2 small rectangular bones form the bridge of the nose and support cartilages that shape its lower portion.

The Vomer Vomer –forms the inferior half of the nasal septum

The Mandible Mandible –strongest bone of the skull and the only one that can move significantly Body –horizontal portion, bearing the teeth Ramus –vertical to oblique posterior portion Angle –2 portions meet at a corner Mental Symphysis –mandible develops as separate Mental protuberance –point of the chin itself

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The inferior Nasal conchae Inferior nasal concha –largest of the 3, separate bone Mental foramen –permits the passage of the nerves and blood vessels of the chin Condylar process –posterior branch of the ramus Mandibular condyle –an oval knob that articulates with the mandibular fossa of the temporal bone TMJ temporomandibular joint –meeting of this condyle with the temporal bone forms a hinge Coronoid process –anterior branch of the ramus is a blade Mandibular notch –U-shaped arch between the 2 processes Mandibular foramen –below the notch, on the medial surface of the ramus

Bones Associated with the Skull Auditory ossicles –named malleus (hammer), incus (anvil), and stapes (stirrup, circular bone with a hole) for hearing (all smaller than a penny) Hyoid bone –slender U shaped bone between the chin and larynx (right about thyroid cartilage the adams apple), connected by a stylohyoid muscle to the styloid process, the 2 longer parts of the hyoid are called greater horns, while the small small ones that the muscle conencts to is called the lesser horns. Body –median of the hyoid is flanked on either side by hornlike projections Greater/lesser horns (cornua) -hyoid serves for attachment of several muscles that control the mandible, tongue, and larynx. Larynx- voice box, suspended from the hyoid bone by a broad ligament, and hyoid serves for attachment of several muscles that control the mandible, tongue, and larynx.

SECTION 8.3 General Features of the Vertebral Column Vertebral column (spine) -physically supports the skull and trunk, allows for movement, protects the spinal cord, and absorbs stresses produced by walking, running, or lifting. Vertebrae w/intervertebral discs –consists of not a single bone but a flexible chain of 33 vertebrae/discs Cervical vertebrae: Atlas (C1-2), (C3-C7) Thoracic vertebrae: T1-T12

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Lumbar vertebrae: L1-L5 Sacrum: S1-S5 Coccyx: coccyx

Cervical curvature C1-C7 Thoracic curvature T1-T12 Lumbar curvature L1-L5 Pelvic curvature S1 Scoliosis –abnormal lateral curvature of the spine Kyphosis –hunchback, exaggerated thoracic curvature Lordosis–exaggerated lumbar curvature

General structure of a vertebra Body (centrum)- mass of spongy bone and red bone marrow covered with a thin shell of compact bone (weight bearing portion of the vertebra)

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Vertebral foramen- posterior to the body of each vertebra is a triangular space Vertebral Canal- vertebral foramina collectively forms this, a passage for the spinal cord

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Vertebral arch- composed of 2 parts on each side Pedicle (pillarlike) Lamina (platelike) Spinous process- directed posteriorly and downward Transverse process- extends laterally from the point where the pedicle and lamina meet Superior articular processes- projects upward from one vertebra and meets a similar pair of inferior articular processes that projects downward from the vertebra above

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Intervertebral foramen- 2 vertebrae are joined, they exhibit an opening between their pedicles Inferior vertebral notch- foramen is formed by these notches in the pedicle of the upper vertebra Superior vertebral notch- in the pedicle of the lower one

Intervertebral Discs Nucleus pulposus- surrounded by a ring of fibrocartilage Annulus fibrosus- ring of fibrocartilage 23 discs: first one between cervical vertebrae 2 and 3 and last one between the last lumbar vertebra and the sacrum Herniated disc- ruptured or slipped disc

The cervical vertebrae C1-C7 Function: support the head, allow movement C1 Atlas- supports the head, has no body, each side is a lateral mass with a deeply concave superior articular facet that articulates with the occipital condyle of the skull. Inferior articular facets- flat concave, articulate with C2.

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Anterior/posterior arch- connects lateral masses

Vertebra C2, axis- allows rotation of the head as in gesturing "no". Most distinctive feature is a prominent knob called the dens (odontoid process) Projects into the vertebral foramen of the atlas, nestled in a facet and held in place by a transverse ligament Atlanto-occipital joint- articulation between the atlas and the cranium Atlantoaxial joint- one between the atlas and axis Transverse foramen- 7 cervical vertebrae have this

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The thoracic vertebrae 12 thoracic vertebrae (t1-t12) encloses the heart and lungs

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Lack of transverse foramina Lack of bifid processes Spinous processes are relatively pointed and angle sharply downward Body is heart shaped More massive than in the cervical vertebrae Transverse costal facet- cuplike, end of each transverse

The lumbar vertebrae 5 lumbar vertebrae (L1-L5) Thick, stout body, and a blunt squarish spinous process for attachment of the strong lumbar muscles

The Sacrum Sacrum-bony plate that forms the posterior wall of the pelvic girdle

Anterior sacral (pelvic) foramina- 4 pairs, allow passage of nerves and arteries to the pelvic organs Median sacral crest- spinous processes of the vertebrae fuse into a ridge Lateral sacral crest- transverse processes fuse into a less prominent lateral sacral crest on each side of the median crest

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Posterior sacral foramina-posterior side of the sacrum, there are 4 pairs of openings for spinal nerves Sacral canal- runs through thre scarum and ends in an inferior opening that contains spinal nerve roots Sacral hiatus- inferior opening Auricular surface- each side of the sacrum is an ear-shaped region Sacroiliac (SI) joint- articulates with a similarly shaped surface on the hip bone and forms this joint Sacral promontory- body of vertebra S1 juts anteriorly to form this Superior articular processes- articulates with vertebra L5. Alae- lateral to these is a pair of large, rough, winglike extensions

The coccyx Coccygeal vertebae- fuse by age 20 to 30 years to form the coccyx (tailbone) Horns (cornua)- vertebra Co1 has a pair of horns, serve as attachment points for ligaments that bind the coccyx to the sacrum.

The...