Chapter 7 - Skeletal System PDF

BIOL243 – HUMAN ANATOMY & PHYSIOLOGY I Charles Smith, PhD CSCS HUMAN ANATOMY & PHYSIOLOGY Ch. 7 – The Human Skeleton THE SKELETON Skeletal System is composed of bones, cartilages, joints, and ligaments Mostly bone Cartilage in isolated areas (usually joint articulations)...

BIOL243 – HUMAN ANATOMY & PHYSIOLOGY I Charles Smith, PhD CSCS HUMAN ANATOMY & PHYSIOLOGY Ch. 7 – The Human Skeleton THE SKELETON Skeletal System is composed of bones, cartilages, joints, and ligaments Mostly bone Cartilage in isolated areas (usually joint articulations) Ligaments connect bones & reinforce joints 20% of total body mass 2 Major Divisions: Axial Skeleton Appendicular Skeleton AXIAL SKELETON 80 Bones, 3 Regions Skull Vertebral Column Thoracic Cage 3 Functions: 1. Form longitudinal axis of body To which appendages attach 2. Support head, neck trunk 3. Protection Brain Spinal cord Thoracic organs (i.e., heart, lungs) THE SKULL Most complex bony structure in body Cranial Bones (cranium) Hold brain in cranial cavity Attachment site for head & neck muscles Facial Bones Facial framework Cavities for sensory organs of taste, sight, smell Anchor facial muscles used for speech and expression Infant skulls have more bones than adult because some still unfused Infant skull bones connected by fontanelles instead of sutures Eases birthing process & allows brain growth Anterior Fontanelle = “soft spot” THE SKULL Bones are flat & firmly interlinked by sutures Coronal: separates parietal & frontal bones Sagittal: separates R & L parietal bones Lambdoid: separates parietal & occipital bones Squamous: separates parietal & temporal bones 85 named openings Foramina canals, fissures Passage for spinal cord (and CSF), blood vessels, and cranial nerves CRANIAL & FACIAL BONES 8 Cranial bones: Frontal Parietal (R & L) Occipital Temporal (R & L) Sphenoid Ethmoid 14 Facial bones: Mandible (lower jaw) Maxilla (upper jaw) Zygomatic (R & L; cheekbones) Nasal (nasal bridge; R&L) Lacrimal (R & L; near tear ducts) Palatine Vomer (nasal septum) Inferior nasal conchae (R & L) HYOID BONE Not a bone of the skull But helps with some functions Base for tongue & attachment point for muscles involved with speech & swallowing Only bone that does not directly articulate with another bone Anchored by ligaments to neck, inferior to mandible ORBITAL BONES “Eye Socket” Fusion of 7 Craniofacial Bones: Frontal Sphenoid Zygomatic Maxilla Palatine Lacrimal Ethmoid PARANASAL SINUSES Yes…those sinuses Create mucus-lined, air-filled space Warm & humidify air Lighten skull Enhance vocal resonance Formed from 5 craniofacial bones Frontal Sphenoid Ethmoid Maxillae VERTEBRAL COLUMN AKA “spine” or “spinal column” Functions: Direct weight of trunk to lower limbs Surround & protect spinal cord Attachment point for ribs & abdominothoracic musculature Made up from 26 vertebrae running from skull down to pelvis 5 Regions (superior to inferior): 1. Cervical (7 vertebrae) 2. Thoracic (12 vertebrae) 3. Lumbar (5 vertebrae) 4. Sacral (5 fused vertebrae) 5. Coccygeal (4 fused vertebrae) SPINAL CURVATURES Your spine has curves no…not that kind 2 Types: “concave” posteriorly = Lordotic Secondary curvature Cervical & Lumbar spines Accentuated lumbar curve = hyperlordosis (swayback) “convex” posteriorly = Kyphotic Primary curvature Thoracic & Sacral spine Accentuated thoracic curve = hyperkyphosis (hunchback) Help to effectively deal with loads of head and body Scoliosis: abnormal lateral rotation (or curve) in spine INTERVERTEBRAL DISCS Between each vertebra are discs Cushion-like shock absorbing pads Also provides some freedom for movement 2 Parts: Nucleus pulposus Inner gelatinous nucleus Elasticity & compressibility Anulus fibrosus Outer ring of collagen & fibrocartilage Limits nuclear expansion under compression If these tear, nucleus will protrude out Herniated (prolapsed) disc Compress nerves causing pain, numbness, weakness Usually caused by actions involving simultaneous compression & rotation VERTEBRAL STRUCTURE C-, T-, & L-vertebra are different but share a common structural pattern Body: anterior, weight-bearing portion Intervertebral discs sit here between vertebra Vertebral Arch: posterior portion from which processes protrude Pedicles: short pillars forming arch sides Laminae: fused, flat plates making posterior arch Vertebral Foramen: opening allowing spinal cord passage Intervertebral Foramina: lateral openings between vertebrae allowing spinal nerves to exit Processes: protrude off arch Spinous process: projects posteriorly Can palpate on someone Transverse processes: project laterally Superior articular processes: protrude superiorly Inferior articular processes: protrude inferiorly CERVICAL VERTEBRAE C1 – C7 lightest, smallest vertebra Oval-shaped bodies; Large vertebral foramens C1 (Atlas) & C2 (Axis) are unique Atlas has no body or spinous process but anterior & posterior arches with two lateral masses Axis has a knob-liked dens projecting posteriorly into anterior arch of Atlas “pivot point” for rotation Together allow for head movement C7/T1 processes can be felt through the skin and are used as landmarks Vertebra prominens C3 fracture also referred to as “hangman’s fracture” Hope was that force from noose & “drop” would cause this vertebra to break Cuts off communication to diaphragm…stop breathing THORACIC VERTEBRAE T1 – T12 progressively increase in size Articulate with the ribs Via transverse costal facets on transverse processes Long, sharp spinous processes point inferiorly Heart-shaped bodies Circular vertebral foramens LUMBAR VERTEBRAE L1 – L5 largest vertebrae Receives greatest amount of stress “small of the back” Flat, spatulated spinous process Triangular vertebral foramen Short, thick pedicles & laminae SACRUM & COCCYX Sacrum: triangular bone shaping posterior wall of pelvis 5 fused vertebra Articulates superiorly with L5, inferiorly with coccyx Lateral articulations with pelvic ileum bones making sacroiliac (SI) joints Coccyx: 3 – 5 fused vertebra aka “tailbone” Little function Often fractured through falls THORACIC CAGE T1 – T12 (posteriorly) Sternum & costal cartilages (anteriorly) Sternal body articulates with xipihoid process inferiorly Blow to chest can push xiphoid process into liver or heart = massive hemorrhaging Sternal manubrium has jugular notches CPR performed by compressing at mid-sternum Costal cartilages allow rib articulation with sternum 12 Rib pairs (laterally) 1st ten ribs articulate with sternum Rib pairs 1 – 7 = true ribs attaching to sternum directly Rib pairs 8 – 10 = false ribs attaching to sternum via costal cartilage Rib pairs 11 & 12 = floating ribs; no sternal attachment AXIAL SKELETON SUMMARY Comprised of skull, spine, rib cage & sternum Major job is to protect the central nervous system & thoracic organs Bones of skull structured to house brain, eyes, sinuses, etc. Fused together by sutures Spinal column has 5 segments 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 (fused) sacral vertebrae 3 – 5 (fused) coccygeal vertebrae Spine has discs between vertebrae to provide cushion & support for weight bearing and freedom of movement Spine’s curvature (kyphotic & lordotic) also aid weight bearing Rib cage and sternum encase lateral and anterior aspects of thoracic cavity SAMPLE QUESTIONS 1. Which craniofacial bones make up the “eye socket”? 2. Which segments of the spine have kyphotic curves? 3. C1 and C2 are also referred to as what? 4. Which portions of the spine have no intervertebral discs? 5. A tear in an intervertebral disc’s annular fibers causing the nucleus to protrude through is also called what? APPENDICULAR SKELETON Bones of the limbs and their girdles Pectoral Girdle: attaches upper limbs to trunk Aka shoulder girdle Clavicles (anteriorly); scapulae (posteriorly) Attachment site for muscles moving upper limbs High degree of mobility Scapulae not attached to axial skeleton Shoulder joint socket is shallow = ↑ movement freedom Pelvic Girdle: attaches lower limbs to trunk Aka hip girdle 2 hip or coxal bones & sacrum 1 Coxal bone = fused ilium, ischium, pubis Transmit weight of upper body onto lower limbs, supports pelvic organs Attachment point for muscles moving lower limbs & stabilization Less mobile but more stable than shoulder girdle PECTORAL & PELVIC GIRDLES BONES OF THE PECTORAL GIRDLE Clavicles aka “collarbones” Sternal ends articulate medially with clavicular notches on manubrium of sternum Acromial ends articulate laterally acromion processes of scapular spines Articulation makes the acromioclavicular (A-C) joint Blunt trauma can damage joint creating a “separated shoulder” Scapulae Located on dorsal surface of rib cage 3 borders (superior, medial, lateral) 3 major features Spine: prominent, posterior ridge Acromion: lateral projection stemming off spine & articulating with lateral clavicle Coracoid process: anterior projection which anchors biceps muscle HUMERUS (UPPER ARM) Articulates with glenoid cavity of scapula (proximally) & radius and ulna (distally) 5 Major Features: Head: proximal end articulating with glenoid cavity Tubercles: greater and lesser; attachment sites for rotator cuff muscles Intertubercular (bicipital) sulcus runs between guiding biceps tendon Surgical Neck: most frequently fractured Deltoid Tuberosity: site of deltoid muscle insertion Midway down shaft Demarcates the distal “point” of the “deltoid diamond” shape Medial & Lateral Epicondyles: distally located protrusions Attachment points for forearm muscles FOREARM Radius: lateral bone of forearm (thumb-side) Head articulates with capitulum of humerus & radial arch of ulna (proximally) Shape and interaction with ulna allow for pronation & supination movements Ulnar notch articulates with ulna (distally) Radial styloid process anchors ligaments of “wrist” Colles’ Fracture: break in distal end of radius Common from falls with outstretched hands Ulna: medial bone of forearm (pinky-side) Forms major portion of elbow joint with humerus Olecranon & coronoid processes “hook” onto trochlea of humerus creating hinge joint Radial notch: articulates with head of radius (proximally) Ulnar head: knob-like distal portion, articulates with carpal bones Ulnar styloid process: anchors ligaments of “wrist” Nursemaid’s Elbow (Pulled Elbow): radial head subluxation (not quite dislocates) HAND Carpals: 8 bones, 2 rows Proximal Row (Lateral to Medial): only ones that make “wrist” joint Scaphoid, Lunate, Triquetrum, Pisiform “Sally Left the Party…” Distal Row (Lateral to Medial): Trapezium, Trapezoid, Capitate, Hamate “…to Take Cindy Home” Carpal Tunnel Syndrome: median nerve gets impinged in “carpal tunnel” travelling over wrist Caused by overuse, inflammation compressing on nerve Tingling & numbness felt (esp. in digits I – IV) Metacarpals: palm 5 metacarpals; labelled I to V from lateral (thumb) to medial (pinky) Most commonly fractured in fights/punching Fracture of 5th metacarpal = Boxer’s/Barroom Fracture Phalanges: fingers Fingers (digits) labelled I to V similarly to metacarpals 1st digit (pollex) has two bones All other digits have three bones – proximal, middle, distal phalanx BONES OF THE PELVIC GIRDLE Ilium Superior region of coxal bone Auricular surface articulates with sacrum (SI joint) Ischium Posteroinferior part coxal bone What you sit upon Pubis Anterior portion of coxal bone L & R pubis join at pubic symphysis 3 bones make up the false pelvis True pelvis denoted by pelvic brim (inlet) Female (or AFAB) pelvis tends to be wider, shallower, and rounder than Male (or AMAB) due to necessities for childbearing FEMUR & PATELLA (THIGH) Femur: Largest & strongest bone in body Makes up 25% of total body height Articulates with acetabulum of hip (coxal) bone (proximally) & tibia and patella (distally) 3 Major Features: Trochanters: greater & lesser Proximally located near femoral neck Muscle attachments sites Condyles: lateral & medial Distal aspects articulate with tibial plateau Superior half of knee joint Epicondyles: lateral & medial Protrude off lateral & medial condyles Muscle attachment sites Patella: Sesamoid bone in quadriceps tendon Protects knee joint TIBIA & FIBULA (LEG/SHANK) Tibia: Medial leg bone receiving weight from femur & transmits to foot Also receives impact forces from foot and transfers to femur Major Features: Condyles: medial & lateral Attachment point for muscles, tendons & ligaments Tibial tuberosity: Attachment point for patellar tendon anchoring patella & quadriceps muscle Inflammation can lead to Osgood-Schlatter’s Disease (Jumper’s Knee) Medial Malleolus: Demarcates medial border to ankle joint Prolonged, untreated shin splints can cause stress fractures in the tibial shaft Fibula: Non-weight bearing Articulates with tibia @ proximal & distal ends Major Features: Head Lateral Malleolus: Demarcates lateral border to ankle joint Commonly fractured FOOT Tarsals: 7 Tarsal Bones Body weight & impacts predominantly carried/absorbed talus and calcaneus (heel) Also include: cuboid, navicular, and medial, intermediate & lateral cuneiforms Metatarsals: “balls of feet” Labelled I to V from hallux to little toe Phalanges: toes Labelled I (hallux, big toe) to V (little toe) Digit I (hallux) has 2 bones, like hand Digits II – V have 3 bones, like hand APPENDICULAR SKELETON SUMMARY Refers to the bones of the limbs/extremities Beginning at the Shoulder and Pelvic girdles Extend down to hands and feet Accurate identification of these bones and their landmarks is important for: Identification of fracture locations Understanding muscle actions Understanding how body weight and impact forces are dealt with Understanding of joint formations (coming up next) SAMPLE QUESTIONS 1. Name the proximal row of carpal bones 2. Are phalanges on the hands labelled laterally to medially or medially to laterally? 3. The olecranon process articulates/“hooks” onto which bony landmark of the humerus? 4. Which bone of the shank is non-weight bearing? 5. Upon which pelvic bone do we typically sit?  COPYRIGHT © Pearson Edited by Charles Smith, PhD CSCS 2024