Week 27 PHA112 Skeletal System 2023-24 Part 2 Student Handout PDF

WEEK 28 MPharm Programme Skeletal System –Bones (2) PHA112 Dr Praveen Bhugra Slide 1 of 26 PHA112 Skeletal System WEEK 28 Learning objectives (The Axial Skeleton) • By the end of this lecture you should be able to: – Describe the bones of the skull (face and cranium) – Explain the function...

WEEK 28 MPharm Programme Skeletal System –Bones (2) PHA112 Dr Praveen Bhugra Slide 1 of 26 PHA112 Skeletal System WEEK 28 Learning objectives (The Axial Skeleton) • By the end of this lecture you should be able to: – Describe the bones of the skull (face and cranium) – Explain the function of the sinuses and fontanelles of the skull – Explain the characteristics of the typical vertebra – Explain the structure of vertebral column – Explain the movement and function of vertebral column – Describe the bones of forming the thoracic cage – Explain the function of the thoracic cage Slide 2 of 26 PHA112 Skeletal System WEEK The Axial Skeleton 28 • Forms the longitudinal part of the body • Divided into three parts – Skull – Vertebral column – Bony thorax Slide 3 of 26 PHA112 Skeletal System Function of the Axial Skeleton WEEK 28 • Supports and protects organs in the cranial and spinal cavities and the ventral body cavities • Provides an extensive surface area for the attachment of muscles – adjust the positions of the head, neck, and trunk – perform respiratory movements – stabilize or position parts of the appendicular skeleton, which supports the limbs. • The joints of the axial skeleton permit limited movement, but they are very strong and are supported and strengthen with ligaments Slide 4 of 26 PHA112 Skeletal System WEEK The Skull 28 • Two sets of bones – Cranium – Facial bones • Bones are joined by sutures • Only the mandible is attached by a freely movable joint • The bones of the skull protect the brain and guard the entrances to the digestive and respiratory systems. Slide 5 of 26 PHA112 Skeletal System WEEK The Skull 28 • The skull contains 22 bones: – 8 form the cranium, or braincase – 14 are associated with the face • 7 addition bones are associated with the skull: – 6 auditory ossicles are situated within the temporal bones of the cranium – the hyoid bone is connected to the inferior surfaces of the temporal bones by a pair of ligaments. Slide 6 of 26 PHA112 Skeletal System The Skull (Cranium) WEEK 28 • Occipital – back • Parietal – top and most of the sides • Frontal – anterior • Temporal – form the lower sides of the skull • Sphenoid and ethmoid bones – floor • Ear ossicles are the smallest bones of the body • Malleus • Incus • Stapes Slide 7 of 26 PHA112 Skeletal System SPHENOID BONE ETHMOID BONE OCCIPITAL BONE CRANIUM ASSOCIATED BONES Auditory Ossicles (6) Hyoid bone (1) Within the temporary bones Occipital bone Parietal bones Frontal bone Temporal bones Sphenoid Ethmoid 8 1 2 1 2 1 1 The Skull (Face ) WEEK 28 • Maxillary bone – form the upper jawbone • Palatine – form the anterior portion of the palate • Nasal bones – fuse together to form the bridge of the nose • Vomer – a thin bone that divides the nasal cavity • Inferior nasal conchae – articulates with the ethmoid, maxillary, pallatine and lacrimal bones ; creates turbulence in air passing from the nasal cavity Slide 8 of 26 PHA112 Skeletal System LACRIMAL BONE NASAL BONE ZYGOMATIC BONE MAXILLARY BONES VOMER MANDIBLE FACE Maxillary bones 14 2 Palatine bones 2 Nasal bones Vomer Inferior nasal conchae Zygomatic bones Lacrimal bones Mandible 2 1 2 2 2 1 The Skull (Face ) WEEK 28 • Zygomatic – form the prominence of the cheeks • Lacrimal bone – smallest bone of the face articulates with the frontal , maxillary and ethmoid • Mandible – forms the lower jaw bone Slide 9 of 26 PHA112 Skeletal System LACRIMAL BONE NASAL BONE ZYGOMATIC BONE MAXILLARY BONES VOMER MANDIBLE FACE Maxillary bones 14 2 Palatine bones 2 Nasal bones Vomer Inferior nasal conchae Zygomatic bones Lacrimal bones Mandible 2 1 2 2 2 1 Unique Features of Skull WEEK 28 • Sutures: immovable joint between skull bones – Coronal, sagittal, lambdoid, squamous • Paranasal sinuses: cavities – Located in bones near nasal cavity • Fontanels: soft spot in foetal skull – Allow deformation at birth – Calcify to form sutures Slide 10 of 26 PHA112 Skeletal System WEEK Paranasal Sinuses 28 • Hollow portions of bones surrounding the nasal cavity • Functions of paranasal sinuses – Lighten the skull – the mucous membrane lining them produces mucus that moistens and cleans the air in and adjacent to the sinus – Give resonance and amplification to voice Medial aspect Anterior aspect Slide 11 of 26 PHA112 Skeletal System WEEK 28 The Foetal Skull • Fontanelles – fibrous membranes connecting the cranial bones – Allow the brain to grow – Convert to bone within 24 months after birth Slide 12 of 26 PHA112 Skeletal System WEEK The Hyoid Bone 28 • Supports the larynx and is the attachment site for muscles of the larynx, pharynx, and tongue. • The body of the hyoid is an attachment site for muscles of the larynx, tongue, and pharynx. • The greater horns, help support the larynx and are attached to muscles that move the tongue. • The lesser horns, are attached to the stylohyoid ligaments; from these ligaments. Slide 13 of 26 PHA112 Skeletal System WEEK The Orbits 28 • Orbits are bony cavities in which eyes are firmly encased and cushioned by fatty tissue • The muscles that move the eyes and the tear producing lacrimal glands are also housed in the orbits • The walls of the orbit are formed by seven bones Slide 14 of 26 PHA112 Skeletal System WEEK 28 The Vertebral Column • Functions – Encloses spinal cord – Supports head – Point of attachment for muscles of back, ribs and pelvic girdle • Regions (from superior to inferior) – 7 cervical – 12 thoracic – 5 lumbar – 1 sacrum and 1 coccyx Slide 15 of 26 PHA112 Skeletal System WEEK 28 Normal Curves in Column • Four normal curves – Cervical and lumbar curves are convex (bulge anteriorly) – Thoracic and sacral curves are concave (bulge posteriorly) • Curves increase strength, help in balance and absorb shocks Slide 16 of 26 PHA112 Skeletal System WEEK 28 Structure of Vertebra • Body: disc-shaped anterior portion • Vertebral arch: posteriorly back from body – With the body, creates a hole called vertebral foramen • Seven processes from this arch – Transverse process extending laterally on each side – Spinous process extending dorsally – Two each of superior and inferior articular processes that form joints with vertebrae Slide 17 of 26 PHA112 Skeletal System WEEK Cervical Area 28 • Cervical (C1-C7 from superior to inferior) – Spinous process often bifid with transverse foramina on transverse processes • C1: atlas – Articulates with head, specialized to support head – Lacks body and spinous process • C2: axis – Has body and spinous process – Called dens (“tooth”) that creates a pivot for head rotation Slide 18 of 26 PHA112 Skeletal System WEEK Other Vertebrae 28 • Thoracic (T1-T12 ) – Larger than cervical – Have facets for articulations with ribs • Lumbar (L1-L5) – Largest and strongest; spinous processes short and thick Figure: Lumbar Vertebrae Slide 19 of 26 PHA112 Skeletal System WEEK Other Vertebrae 28 • Sacrum (S1-S5 fused into one unit) – Foundation for pelvic girdle – Contain sacral foramina for nerves and blood vessels • Coccyx: 4 coccygeal vertebrae fused into 1 Figure: Sacrum and Coccyx Slide 20 of 26 PHA112 Skeletal System WEEK 28 General Features of the Vertebral Column • Adult vertebral column averages 71 cm (28 in.) long – Intervertebral discs account for about one-quarter of its length – Person is 1% shorter when in bed – Compression squeezes water out during the day and absorbs water when compression is removed during sleep Slide 21 of 26 PHA112 Skeletal System Anterior view Posterior view Atlas (C1) Axis (C2) Cervical vertebrae C7 T1 Thoracic vertebrae T12 L1 Lumbar vertebrae L5 S1 Sacrum S5 Coccyx Coccyx WEEK Functions of the Vertebral Column 28 • Provides strong bony protection for the delicate spinal cord lying within it • Providing access to the spinal cord for spinal nerves, blood vessels and lymph vessels. • Individual vertebrae with their intervertebral discs allow movement of the whole column • Support for the skull • Act as shock absorbers protecting the brain • Attachment to the ribs, shoulder girdle and upper limbs and the pelvic girdle and lower limbs Slide 22 of 26 PHA112 Skeletal System WEEK 28 Abnormal Spinal Curvatures • From disease, paralysis of trunk muscles, poor posture, pregnancy, or congenital defect • Scoliosis—abnormal lateral curvature – – – – Most common Usually in thoracic region Particularly of adolescent girls Developmental abnormality in which the body and arch fail to develop on one side of the vertebrae • Kyphosis (hunchback)— exaggerated thoracic curvature – Usually from osteoporosis, also osteomalacia or spinal tuberculosis, or wrestling or weight lifting in young boys • Lordosis (swayback)— exaggerated lumbar curvature – From pregnancy or obesity Slide 23 of 26 PHA112 Skeletal System (a) Scoliosis Key Normal Pathological (b) Kyphosis (“hunchback”) (c) Lordosis (“swayback”) WEEK The Bony Thorax 28 • Thoracic cage: sternum, costal cartilages, ribs and bodies of T1T12 • Sternum: form by 3 portions fused by about age 25 years: Manubrium, body, xiphoid process • Ribs: 12 pairs – True ribs (vertebrosternal ribs) are #1-7: articulate with sternum directly by costal cartilages – False ribs (vertebrochondrail ribs) are #8-12: do not articulate with sternum directly by costal cartilages Slide 24 of 26 PHA112 Skeletal System Thoracic Cage (Anterior View) WEEK The Bony Thorax 28 • Two of these joints are formed between facets on the head of the rib and facets on the bodies of the two vertebrae • Ten of the ribs also form joints between the tubercle of the rib and the transverse process of the of the lower vertebra. • The inferior surface of the rib is deeply grooved, providing a channel along which intercostal nerves and blood vessels run. Slide 25 of 26 PHA112 Skeletal System WEEK Further Reading Refer to the Following Textbooks 28 • Ross and Wilson Anatomy and Physiology in Health and illness 13th Edition • Gerard J. Tortora and Byran H. Derrickson Principles of Anatomy and Physiology 13th Edition • Frederic H. Martini Fundamentals of Anatomy & Physiology 7th Edition • Elaine N. Marieb and Katja Hoehn Human Anatomy & Physiology 8th Edition • VanPutte, Regan and Russo Seeley’s Anatomy and Physiology 12th Edition Slide 26 of 26 PHA112 Skeletal System