The Axial Skeleton (contd.) & The Appendicular Skeleton

Name: The Axial Skeleton (contd.) & The Appendicular Skeleton
Uploaded: 2017-08-16T09:37:39+00:00
Duration: PTM44S51
Channel: Jennifer Davis
Description: The Axial Skeleton (contd.) & The Appendicular Skeleton

The Axial Skeleton (contd.) & The Appendicular Skeleton
Human Anatomy Sonya Schuh-Huerta, Ph.D.

The Vertebral Column Formed from 26 bones in the adult
Transmits weight of trunk to lower limbs Surrounds & protects spinal cord

The Vertebral Column Serves as attachment sites for muscles of the neck and back Held in place by ligaments Anterior & posterior longitudinal ligaments Ligamentum flavum

The Vertebral Column Cervical curvature (concave) 7 vertebrae, C1 – C7
2 Cervical curvature (concave) 7 vertebrae, C1 – C7 3 4 5 6 7 T Spinous process 1 2 Transverse processes 3 4 5 Thoracic curvature (convex) 12 vertebrae, T1 – T12 6 7 8 9 Intervertebral discs 10 11 Intervertebral foramen 12 L 1 Lumbar curvature (concave) 5 vertebrae, L1 – L5 2 3 4 5 Sacral curvature (convex) 5 fused vertebrae sacrum Coccyx 4 fused vertebrae Anterior view Right lateral view

Regions & Normal Curvatures
The Vertebral column has 5 major regions 7 cervical vertebrae of the neck region 12 thoracic vertebrae 5 lumbar vertebrae Sacrum  five fused bones Inferior to lumbar vertebrae Coccyx  inferior to sacrum

Curvatures of the spine Cervical & lumbar curvatures Concave posteriorly Thoracic & sacral curvatures Convex posteriorly

Curvatures increase resilience of spine Thoracic & sacral curvatures Primary curvatures Present at birth Lumbar curvature Develops when baby begins to walk (~1 year)

Ligaments of the Spine Major supporting ligaments
Anterior longitudinal ligament Attaches to bony vertebrae & intervertebral discs Prevents hyperextension Posterior longitudinal ligament Narrow & relatively weak Attaches to intervertebral discs

Ligaments of the Spine Posterior longitudinal ligament
Intervertebral disc Supraspinous ligament Transverse process Anterior longitudinal ligament Sectioned spinous process Intervertebral foramen Ligamentum flavum Posterior longitudinal ligament Interspinous ligament Anulus fibrosus Nucleus pulposus Inferior articular process Sectioned body of vertebra Posterior longitudinal ligament (a) Median section of three vertebrae, illustrating the composition of the discs and the ligaments Anterior longitudinal ligament Body of a vertebra Intervertebral disc (b) Anterior view of part of the spinal column

Intervertebral Discs Are cushion-like pads between vertebrae
Composed of: Nucleus pulposus Anulus fibrosus

Intervertebral Discs Nucleus pulposus  derived from notocord
Gelatinous inner sphere Absorbs compressive stresses Annulus fibrosus Outer rings formed of ligament Inner rings formed of fibrocartilage Surround the nucleus pulposus

Intervertebral Disc MRI of lumbar region of vertebral column in
Vertebral spinous process (posterior aspect of vertebra) Spinal cord Spinal nerve root Nucleus pulposus of intact disc Transverse process Herniated portion of disc Anulus fibrosus of disc Nucleus pulposus of disc Herniated nucleus pulposus (c) Superior view of a herniated intervertebral disc MRI of lumbar region of vertebral column in sagittal section showing normal & herniated discs

General Structure of Vertebrae
Posterior Lamina Vertebral arch Spinous process Transverse process Superior articular process and facet Pedicle Vertebral foramen Body (centrum) Anterior

General Structure of Vertebrae
Common structures to all regions Body Vertebral arch Vertebral foramen Spinous process Transverse process Superior & inferior articular processes Intervertebral foramina

Movement of the Vertebrae
Specific regions of the spine perform specific functions Types of movement that occur between vertebrae Flexion & extension Lateral flexion Rotation in the long axis

Cervical Vertebrae 7 cervical vertebrae (C1–C7)  smallest & lightest vertebrae C3–C7 are typical cervical vertebrae Body is wider laterally Spinous processes are short & bifid (except C7) Vertebral foramen are large & triangular Transverse processes contain transverse foramina Superior articular facets face superoposteriorly

Cervical Vertebrae

Cervical Vertebrae Dens of axis Transverse ligament of atlas
C1 (atlas) C2 (axis) C3 Inferior articular process Bifid spinous process Transverse processes C7 (vertebra prominens) (a) Cervical vertebrae

The Atlas C1 is termed  atlas Lacks a body & spinous process
Supports the skull Superior articular facets receive the occipital condyles Allows flexion & extension of neck Nodding the head “yes”

The Atlas C1 Posterior Posterior tubercle Posterior arch Lateral
masses Transverse foramen Superior articular facet Anterior arch Anterior tubercle (a) Superior view of atlas (C1)

The Atlas Posterior Posterior Posterior tubercle arch Inferior
articular facet Transverse process Lateral masses Anterior Transverse foramen arch Facet for dens Anterior tubercle (b) Inferior view of atlas (C1)

The Axis Has a body & spinous process
Dens (odontoid process) projects superiorly Formed from fusion of the body of the atlas with the axis Acts as a pivot for rotation of the atlas & skull Participates in rotating the head from side to side (‘nodding no’)

The Axis Posterior C2 Spinous process Lamina Inferior articular
Pedicle Superior articular facet Transverse process Dens Body (c) Superior view of axis (C2)

Thoracic Vertebrae (T1—T12)
All articulate with ribs Have heart-shaped bodies from the superior view Each side of the body of T1–T10 bears demifacts for articulation with ribs T1 has a full facet for the first rib T10–T12 only have a single facet

Thoracic Vertebrae

Thoracic Vertebrae Spinous processes are long & point inferiorly
Vertebral foramen are circular Transverse processes articulate with tubercles of ribs Superior articular facets point posteriorly Inferior articular processes point anteriorly Allows rotation & prevents flexion and extension

Lumbar Vertebrae (L1—L5)
Bodies are thick & robust Transverse processes are thin & tapered Spinous processes are thick, blunt, & point posteriorly Vertebral foramina are triangular Superior & inferior articular facets directly medially Allows flexion & extension  rotation prevented

Lumbar Vertebrae

Lumbar Vertebrae Superior articular process Transverse Body process
Intervertebral disc Inferior articular process Spinous process (c) Lumbar vertebrae

Sacrum (S1—S5) Shapes the posterior wall of pelvis
Formed from 5 fused vertebrae Superior surface articulates with L5 Inferiorly articulates with coccyx Sacral promontory Where the first sacral vertebrae bulges into pelvic cavity Center of gravity is 1 cm posterior to sacral promontory Ala  develops from fused rib elements

Sacrum Sacral foramina Ventral foramina Dorsal foramina
Passage for ventral rami of sacral spinal nerves Dorsal foramina Passage for dorsal rami of sacral spinal nerves

Sacrum Body Sacral promontory Facet of superior Sacral
articular process Sacral canal Ala Body of first sacral vertebra Auricular surface Lateral sacral crest Transverse ridges (sites of vertebral fusion) Median sacral crest Anterior sacral foramina Posterior sacral foramina Apex Sacral hiatus Coccyx Coccyx (a) Anterior view (b) Posterior view

Coccyx Is the “tailbone” Formed from 3–5 fused vertebrae
Offers only slight support to pelvic organs Easily injured

The Thoracic Cage Forms the framework of the chest Components
Thoracic vertebrae – posteriorly Ribs – laterally Sternum and costal cartilage – anteriorly Protects thoracic organs Supports shoulder girdle and upper limbs Provides attachment sites for muscles

The Thoracic Cage Jugular notch Clavicular notch Manubrium
Sternal angle Body Sternum Xiphisternal joint True ribs (1–7 Xiphoid process False ribs (8–12) Intercostal spaces L1 Vertebra Costal cartilage Floating ribs (11, 12) Costal margin (a) Skeleton of the thoracic cage, anterior view

The Thoracic Cage T2 Jugular notch T3 Sternal angle T4 Heart
Xiphisternal Xiphisternal joint T9 (b) Midsagittal section through the thorax, showing the relationship of surface anatomical landmarks of the thorax to the vertebral column

Sternum Formed from three sections Manubrium—superior section
Articulates with medial end of clavicles Body—bulk of sternum Sides are notched at articulations for costal cartilage of ribs 2–7 Xiphoid process—inferior end of sternum Ossifies around age 40

Sternum Anatomical landmarks Jugular notch Sternal angle
Central indentation at superior border of the manubrium Sternal angle A horizontal ridge where the manubrium joins the body Xiphisternal joint Where sternal body and xiphoid process fuse Lies at the level of the 9th thoracic vertebra

Ribs All ribs attach to vertebral column posteriorly
True ribs - superior seven pairs of ribs Attach to sternum by costal cartilage False ribs—inferior five pairs of ribs Ribs 11–12 are known as floating ribs

Ribs Facets for articulation with vertebrae Articular facet
on tubercle Head Neck Shaft Junction with costal cartilage Costal groove Costal angle (a) A typical rib (rib 6, right), posterior view Transverse costal facet (for tubercle of rib) Angle of rib Superior costal facet (for head of rib) Body of vertebra Head of rib Intervertebral disc Neck of rib Tubercle of rib Shaft Sternum Cross- section of rib Costal groove Costal cartilage (b) Vertebral and sternal articulations of a typical true rib

Ribs Articular facet on tubercle of rib Spinous process Shaft
Transverse costal facet (for tubercle of rib) Ligaments Neck of rib Body of thoracic vertebra Head of rib Superior costal facet (for head of rib) (c) Superior view of the articulation between a rib and a thoracic vertebra

Disorders of the Axial Skeleton
Cleft palate A common congenital disorder Right & left halves of palate fail to fuse medially Can involve entire palate & lip – minor to severe Stenosis of the lumbar spine Narrowing of the vertebral canal Can compress roots of spinal nerves

Disorders of the Axial Skeleton
Abnormal spinal curvatures Scoliosis—an abnormal lateral curvature Kyphosis—an exaggerated thoracic curvature Lordosis—an accentuated lumbar curvature; “swayback”

The Axial Skeleton Throughout Life
Membrane bones begin to ossify in second month of development Bone tissue grows outward from ossification centers Fontanels Unossified remnants of membranes

Fontanelles Frontal suture Frontal bone Anterior fontanelle
Ossification center Parietal bone Posterior fontanelle Occipital bone (a) Superior view

Fontanelles Parietal bone Frontal bone Ossification center Sphenoidal
Posterior fontanelle Temporal bone (squamous portion) Mastoid fontanelle Occipital bone (b) Lateral view

Many bones of the face & skull form by intramembranous ossification Endochondral bones of the skull are: Occipital bone Sphenoid Ethmoid bones Parts of the temporal bone

Aging of the axial skeleton: Water content of the intervertebral discs decreases By age 55, loss of a few centimeters in height is common! Thorax becomes more rigid Bones lose mass with age

The Appendicular Skeleton, Ch 8 (also to be used as Lab Guide)

The Appendicular Skeleton
Pectoral girdle Attaches the upper limbs to the trunk Pelvic girdle Attaches the lower limbs to the trunk Upper & lower limbs differ in function Share the same structural plan

The Pectoral Girdle Consists of the clavicle & scapula
Pectoral girdles do not quite encircle the body completely Medial end of each clavicle articulates with the manubrium and first rib Laterally  the ends of the clavicles join the scapulae Scapulae do not join each other or the axial skeleton

The Pectoral Girdle Provides attachment for many muscles that move the upper limb Girdle is very light & upper limbs are mobile Only clavicle articulates with the axial skeleton Socket of the shoulder joint (glenoid cavity) is shallow Good for flexibility, bad for stability

Articulated Pectoral Girdle
Clavicle Acromio- clavicular joint Scapula (a) Articulated pectoral girdle

Clavicles Extend horizontally across the superior thorax
Sternal end articulates with the manubrium Acromial end articulates with scapula

Clavicles Sternal (medial) end Posterior Anterior Acromial (lateral)
(b) Right clavicle, superior view Acromial end Anterior Trapezoid line Sternal end Posterior Tuberosity for costoclavicular ligament Conoid tubercle (c) Right clavicle, inferior view

Clavicles Provide attachment for muscles
Hold the scapulae & arms laterally Transmit compression forces from the upper limbs to the axial skeleton

Scapulae Lie on the dorsal surface of the rib cage
Located between ribs 2–7 Have 3 borders Superior Medial (vertebral) Lateral (axillary) Have 3 angles Lateral, superior, & inferior

Structures of the Scapula
Acromion Suprascapular notch Superior border Coracoid process Superior angle Glenoid cavity Subscapular fossa Lateral border Medial border (a) Right scapula, anterior aspect Inferior angle

Structures of the Scapula
Coracoid process Suprascapular notch Superior angle Acromion Supraspinous fossa Glenoid cavity at lateral angle Spine Infraspinous fossa Lateral border Medial border (b) Right scapula, posterior aspect

The Upper Limb 30 bones form each upper limb
Grouped into bones of the: Arm Forearm Hand

Arm Region of the upper limb between the shoulder & elbow Humerus
The only bone of the arm Longest & strongest bone of the upper limb Articulates with the scapula at the shoulder Articulates with the radius & ulna at the elbow

Arm Humerus Many structures of the humerus provide sites for muscle attachment Other structures of the humerus provide articulation sites for other bones

Structures of the Humerus of the Right Arm
Greater tubercle Head of humerus Head of humerus Greater tubercle Lesser tubercle Anatomical neck Anatomical neck Intertubercular sulcus Surgical neck Radial groove Deltoid tuberosity Deltoid tuberosity Medial supracondylar ridge Lateral supracondylar ridge Coronoid fossa Olecranon fossa Radial fossa Medial epicondyle Medial epicondyle Lateral epicondyle Capitulum Trochlea Trochlea (b) Posterior view (a) Anterior view

Structures of the Humerus of the Right Arm
Coronoid fossa Olecranon fossa Capitulum Medial epicondyle Olecranon process Lateral epicondyle Medial epicondyle Head of radius Trochlea Coronoid process of ulna Head Radial tuberosity Neck Radial notch Radius Ulna Ulna Radius (c) Anterior view at the elbow region (d) Posterior view of extended elbow

Forearm Formed from the radius & ulna
Proximal ends articulate with the humerus Distal ends articulate with carpals

Forearm Radius & ulna articulate with each other
At the proximal & distal radioulnar joints The interosseous membrane Interconnects radius & ulna In anatomical position; the radius is lateral and the ulna is medial

Ulna Main bone responsible for forming the elbow joint with the humerus Hinge joint allows forearm to bend on arm Distal end is separated from carpals by fibrocartilage Plays little to no role in hand movement

The Radius & Ulna Olecranon process Radial notch of the ulna
Head of radius Head Trochlear notch Neck Neck of radius Radial tuberosity Coronoid process Proximal radioulnar joint Interosseous membrane Interosseous membrane Ulna Ulna Radius Ulnar notch of the radius Ulnar notch of the radius Radius Head of ulna Head of ulna Styloid process of radius Styloid process of ulna Distal radioulnar joint Styloid process of ulna (a) Anterior view (b) Posterior view Styloid process of radius

Radius & Ulna Olecranon process View Trochlear notch Coronoid process
Radial notch (c) Proximal portion of ulna, lateral view Ulnar notch of radius Articulation for lunate Articulation for scaphoid Styloid process View Head of ulna Styloid process (d) Distal ends of the radius & ulna at the wrist

Radius Superior surface of the head of the radius articulates with the capitulum Medially – the head of the radius articulates with the radial notch of the ulna Contributes heavily to the wrist joint Distal radius articulates with carpal bones When radius moves, the hand moves with it

Hand Includes the following bones: Carpus (carpals)  wrist
Metacarpals  palm Phalanges  fingers

Carpus Forms the true wrist  the proximal region of the hand
Gliding movements occur between carpals Composed of 8 marble-sized bones

Carpus Carpal bones Are arranged in 2 irregular rows
Proximal row from lateral to medial: Scaphoid, lunate, triquetral, & pisiform Distal row from lateral to medial: Trapezium, trapezoid, capitate, & hamate A mnemonic to help remember carpals: Sally Left The Party To Take Carmen Home!

Bones of the Hand Phalanges Distal Middle Proximal Metacarpals Head
Sesamoid bones Shaft Carpals Base 4 3 2 5 1 Hamate Carpals 2 3 4 1 5 Carpals Capitate Trapezium Hamate Pisiform Trapezoid Capitate Triquetrum Scaphoid Triquetrum Lunate Lunate Ulna Radius Ulna (a) Anterior view of right hand (b) Posterior view of right hand

Metacarpus 5 metacarpals radiate distally from the wrist
Metacarpals form the palm Numbered 1–5, beginning with the pollex (thumb) Articulate proximally with the distal row of carpals Articulate distally with the proximal phalanges

Phalanges Numbered 1–5, beginning with the pollex (thumb)
Except for the thumb, each finger has 3 phalanges Proximal, middle, & distal

Pelvic Girdle Attaches lower limbs to the spine
Supports visceral organs Attaches to the axial skeleton by strong ligaments Acetabulum is a deep cup that holds the head of the femur Lower limbs have less freedom of movement Are more stable than the arm

Bones of the Pelvic Girdle
Consists of paired hip bones (coxal bones) Hip bones unite anteriorly with each other Articulates posteriorly with the sacrum Pelvic girdle  a deep, basin-like structure Formed by: Coxal bones, sacrum, & coccyx

Bones of the Pelvic Girdle
Base of sacrum Iliac crest Sacroiliac joint Iliac fossa Anterior superior iliac spine llium Sacral promontory Coxal bone (os coxae or hip bone) Anterior inferior iliac spine Sacrum Pubis Coccyx Pelvic brim Acetabulum Pubic tubercle Ischium Pubic crest Pubic symphysis Pubic arch

The Pelvic Girdle Consists of 3 separate bones in childhood
Ilium, ischium, & pubis Bones fuse, retain separate names to regions of the coxal bones Acetabulum A deep hemispherical socket on lateral pelvic surface

Ilium Large, flaring bone Forms the superior region of the coxal bone
Site of attachment for many muscles Articulation with the sacrum forms sacroiliac joint

Ischium Forms posteroinferior region of the coxal bone
Anteriorly – joins the pubis Ischial tuberosities Are the strongest part of the hip bone

Pubis Forms the anterior region of the coxal bone
Lies horizontally in anatomical position Pubic symphysis The two pubic bones are joined by fibrocartilage at the midline Pubic arch  inferior to the pubic symphysis Angle helps distinguish male from female pelves

Bones of the pelvic girdle
Tubercle of the iliac crest Ilium Ala Anterior gluteal line Iliac crest Posterior gluteal line Anterior superior iliac spine Posterior superior iIiac spine Inferior gluteal line Posterior inferior iliac spine Anterior inferior iliac spine Greater sciatic notch Acetabulum Ischial body Ischial spine Lesser sciatic notch Pubic body Pubis Ischium Ischial tuberosity Ilium Inferior ramus of pubis Ischium Ischial ramus Pubis (b) Lateral view, right hip bone

True & False Pelves Bony pelvis is divided into 2 regions
False (greater) pelvis  bounded by alae of the iliac bones True (lesser) pelvis  inferior to pelvic brim Forms a bowl containing the pelvic organs

Pelvic Structures & Childbearing
Major differences between male & female pelves: Female pelvis is adapted for childbearing Pelvis is lighter, wider, & shallower than the male’s Provides more room in the true pelvis

The Lower Limb Carries the entire weight of the erect body
Bones of lower limb are thicker & stronger than those of upper limb Divided into 3 segments Thigh, leg, & foot

Thigh The region of the lower limb between the hip and the knee
Femur  the single bone of the thigh Longest & strongest bone of the body Ball-shaped head articulates with the acetabulum

Structures of the Femur
Neck Fovea capitis Greater trochanter Head Inter- trochanteric crest Lesser trochanter Intertrochanteric line Gluteal tuberosity Linea aspera Medial and lateral supracondylar lines Lateral condyle Lateral epicondyle Intercondylar fossa Medial condyle Lateral epicondyle Adductor tubercle Medial epicondyle Patellar surface Anterior view Posterior view

Patella Triangular sesamoid bone
Imbedded in the tendon that secures the quadriceps muscles Protects the knee anteriorly Improves leverage of the thigh muscles across the knee

Leg Refers to the region of the lower limb between the knee & the ankle Composed of the tibia & fibula Tibia  more massive medial bone of the leg Receives weight of the body from the femur Fibula  stick-like lateral bone of the leg Interosseous membrane Connects the tibia & fibula

Leg Tibia articulates with femur at superior end
Forms the knee joint Tibia articulates with talus at the inferior end Forms the ankle joint Fibula does not contribute to the knee joint It stabilizes the ankle joint

Structures of the Tibia & Fibula

The Foot Foot is composed of Important functions
Tarsus, metatarsus, & the phalanges Important functions Supports body weight Acts as a lever to propel body forward when walking Segmentation makes foot pliable & adapted to uneven ground

Bones of the Foot Phalanges Distal Middle Proximal 1 2 3 4 Metatarsals
5 Medial cuneiform Intermediate cuneiform Lateral cuneiform Navicular Cuboid Tarsals Talus Trochlea of talus Calcaneus (a) Superior view

Tarsus Makes up the posterior half of the foot
Contains 7 bones called tarsals Body weight is primarily borne by the talus & calcaneus Trochlea of the talus Site of articulation with the tibia Other tarsals are: Navicular Cuboid Medial Cuneiform Intermediate Cuneiform Lateral Cuneiform The (Talus) Caring (Calcaneus) Nurse (Navicular) Covers (Cuboid) Me (Medial Cuneiform) In (Intermed. Cuneiform) Love (Lateral Cuneiform)

Metatarsus Consists of 5 small long bones called metatarsals
Numbered 1–5 beginning with the hallux (=big toe) First metatarsal supports body weight

Phalanges of the Toes 14 phalanges of the toes
Smaller & less nimble than those of the fingers Structure & arrangement are similar to phalanges of fingers Except for the big toe, each toe has 3 phalanges Proximal, middle, & distal

Bones of the Foot Facet for lateral malleolus Navicular
Intermediate cuneiform Lateral cuneiform Talus Calcaneus Cuboid Fifth metatarsal (c) Lateral view

Lower Limb & Pelvis

Disorders of the Appendicular Skeleton
Bone fractures Hip dysplasia Head of the femur slips out of acetabulum Clubfoot Soles of the feet turn medially

The Appendicular Skeleton Throughout Life
Growth of the appendicular skeleton Increases height Changes body proportions Upper/lower body ratio changes with age At birth, head & trunk are 1.5 times as long as lower limbs Lower limbs grow faster than the trunk Upper/lower body ratio of 1 to 1 by age 10

The Appendicular Skeleton Throughout Life
Few changes occur in adult skeleton until middle age, when  Skeleton loses mass Osteoporosis & limb fractures become more common

Questions…. What’s Next
Questions…? What’s Next? Wed Lab: Appendicular Skeleton Mon Lecture: Append Skeleton contd. & Joints/Joint Movements Mon Lab: Finish Skeleton; Joints/Joint Movements

The Axial Skeleton (contd.) & The Appendicular Skeleton

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The Axial Skeleton (contd.) & The Appendicular Skeleton

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