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The Appendicular Skeleton
Chapter 8 The Appendicular Skeleton
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Appendicular Skeleton
126 bones Allows us to move and manipulate objects Bones that compose upper and lower extremities Includes bones of the pectoral and pelvic girdles
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Appendicular Skeleton
Pectoral (shoulder) Girdles: Attach upper (arms) extremities to the axial skeleton at the manubrium Positions shoulders Provides a base for arm movement Comprised of the clavicle and scapula Clavicle - “Collarbone” articulates with scapula and manubrium of the sternum of the axial skeleton. Medial STERNAL end articulates with the manubrium of sternum Lateral ACROMIAL end articulates with the scapula at acromion Conoid tubercle – attachment site for conoid ligament to scapula Costal tuberosity – attachment site for costoclavicular ligament which attaches clavicle to sternum
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Appendicular Skeleton
Scapula: “Shoulderblade” - Triangular shaped Held in place with muscles; that articulate with the arm bone (humerus) and clavicle; supports upper limbs and arm movement Skeletal muscles support and position has no bony or ligament contact with thoracic cage. Supports Spine: posterior bony ridge Acromion: sole attachment point of scapula and the upper limb to the rest of the skeleton; extension of the spine Coracoid process: provides attachment for tendons of the biceps brachii and other arm muscles Glenoid cavity: lateral cavity that articulates with head of humerus---forms glenohumeral joint (shoulder joint) Appendicular Skeleton Suprascapular notch – conspicuous notch on superior border provides passage for the suprascapular nerve Subscapular fossa- anterior surface
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Appendicular Skeleton
Scapula:
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Upper Limb Brachium -Arm Humerus Antebrachium -Forearm Radius Ulna
Carpus-Wrist Carpals Manus -Hand Metacarpals Phalanges Olecranon fossa Olecranon process Head of radius ulna Neck of radius radius ulna ulna carpals metacarpals phalanges
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Upper Extremity HUMERUS- Articulates with the
scapula proximally and with the bones of the forearm (ulna and radius) distally. Head: articulates with glenoid cavity of scapula Anatomical neck: just distal to head Greater and lesser tubercle: lateral and anterior projections just distal to anatomical neck Intertubercular sulcus: groove between greater and lesser tubercles Surgical neck: area distal to tubercles; humerus narrows Body: shaft of the bone Radial groove: depression that marks the path of the radial nerve that extends the elbow Radial groove
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HUMERUS Deltoid tuberosity: lateral projection; attachment site for tendon of deltoid muscle Medial and lateral epicondyles: projections on the distal humerus; attachment points for muscles of the forearm Ulnar nerve crossing medial epicondyle produces numbness / odd sensation when struck: “funny bone” CONDYLES: Capitulum: rounded structure on distal humerus (lateral); articulates with radius Trochlea: medial to the capitulum; shaped like an hourglass on its side; articulates with the ulna Coronoid fossa: depression above the trochlea; receives the coronoid process of the ulna when forearm flexed Olecranon fossa: posterior fossa receives olecranon process of ulna Radial fossa: fossa above the capitulum receives the head of the radius when the arm is flexed
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Humerus
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Humerus- Review Greater tubercle Lesser tubercle Anatomical neck
Head Greater tubercle Lesser tubercle Anatomical neck Surgical neck Body (Shaft) Deltoid tuberosity Coronoid fossa Olecranon fossa Radial fossa Med/Lat Epicondyles Capitulum Trochlea
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Upper Extremity Antebrachium Forearm
Composed of the radius and the ulna Articulate with humerus to form elbow joint Interosseous membrane Connects lateral margin of ulnar shaft to radius Radius Ulna
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Upper Extremity Radius
Radial head: disc shaped; articulates with the capitulum of humerus / rolls into the radial fossa Radial tuberosity: bony projection medially located; attachment site for biceps brachii muscle Styloid process: process on lateral aspect of radius; attachment site for brachioradialis muscle; can be palpated near thumb; stabilizes wrist joint (radius and carpal bones) Ulnar notch: notch that articulates with the head of the ulna
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Upper Extremity Ulna –medial forearm
Trochlear notch: articulates with trochlea of humerus; between coronoid process and olecranon process Coronoid process: anteriorly located; fits in coronoid fossa of humerus when elbow flexed (bent) Olecranon process: posteriorly located bony process of the elbow. Fits in olecranon fossa of humerus when elbow extended (straightened) Radial notch: articulates with the head of the radius Styloid process: affords attachment to the ulnar ligament of the wrist-joint.
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Carpal Bones 8 bones form wrist 2 rows of 4 bones > proximal row
allow movements of flexion, extension, abduction and adduction 2 rows of 4 bones > proximal row scaphoid, lunate, triquetrum, and pisiform (“pie' si form”) > distal row: trapezium, trapezoid, capitate, and hamate “Sally Left The Party To Take Charlie Home”
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Wrist Joint Wrist joint is formed from the distal end of radius with the carpal bones scaphoid and lunate. NOTE: the ulna does not directly articulate at the wrist but is functionally part of the wrist joint
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Upper Extremity Metacarpals Phalanges -“fingers”
5 long bones of the hand Numbered I–V from lateral (thumb) to medial Phalanges -“fingers” 14 bones for each hand (each bone called a phalanx) 4 fingers: 3 bones each Proximal, middle, distal Each thumb has 2 bones proximal and distal phalanx Thumb also known as the pollex
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The Pelvic Girdle Complete ring composed of two hip bones (coxal bones); connected via pubic symphysis Strong to bear body weight, stress of movement Bones more massive for weight bearing Articulations of the pelvic girdle Coxal bones Sides of the pelvis formed as cartilage, ossifies as 3 main bones that remain separate through childhood Ilium (articulates with sacrum) Pubis Ischium Ilium Pubis Ischium
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Coxal bones ILIUM: Posterolateral very rough for better contact of buttock and thigh muscles ILIAC crest- rest hands on hips feel this structure ILIAC SPINE - for hip and thigh muscle attachment. McBurney's point is the name given to the point one-third of the distance from the anterior superior iliac spine to the umbilicus (navel); roughly corresponds to the most common location of the base of the appendix Greater sciatic notch- allows nerve to enter thigh region Iliac fossa Iliac fossa- concave depression that supports abdominal organs/ area for muscle attachment
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ISCHIUM: Lesser sciatic notch –allows access for blood vessels and nerve Obturator foramen Attaches hip muscles Ischial spine- landmark for saddle block procedure Ischial tuberosity Bears weight of the body when sitting Massive ligament (sacrotuberous ligament) joins sacrum to tuberosity Helps to stabilize sacroiliac joint
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Hip bone
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Coxal bones PUBIS: Obturator foramen
Almost entirely closed by thin fibrous membrane which almost completely closes the obturator foramen. Both obturator muscle are connected with the membrane. Pubic symphysis padded with fibrocartilage ACETABULUM Also called the hip socket The meeting point of the ilium, ischium, and pubis Articulates with head of the femur Vinegar cup Vinegar is acetic acid
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Pelvic Girdle Pubic symphysis Pubic arch-
Pelvic inlet – opening that infant’s head must pass during birth Sacroiliac joint Articulation of posterior auricular surface of ilium with the sacrum Stabilized by ligaments of iliac tuberosity Weight of the body is transferred from the spine onto this joint
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Childbirth As labor begins, infants head enters the inlet with the forehead facing one ilium and the occipital region facing the other. The coccyx and ischial spines protrude into the outlet opening A sharply angled coccyx or large sharp spine can present problems in childbirth. As the baby passes through inlet it rotates so the forehead faces posteriorly and the occipital anteriorly. Born face down then turns. Animation:
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Male vs. Female Pelvis Male: (right side) Narrow
Female: (left side) Wider—allows for childbirth Pelvic arch >100 degrees Less curvature Smoother / lighter Less prominent surface markers/projections blunted Coccyx more moveable Wider circular pelvic inlet Sacrum wider Male: (right side) Narrow Pelvic arch < than 90 degrees Larger, heavier Large surface markers Pelvic inlet narrower Sacrum narrower
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The Lower Limbs Functions of the Lower Limbs
Weight bearing- transfers the weight of the body to the ground Motion Note: leg = lower leg thigh = upper leg 30 Bones of the Lower Limbs Femur (thigh) Patella (kneecap) Tibia and fibula (leg) Tarsals (ankle) (7) Metatarsals (foot) (5) Phalanges (toes) (14)
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Lower Extremity Femur: Largest, longest bone
Can sustain severe stress during jumping- 2 tons per square inch Length approx. 1/4th person’s height Proximal head articulates with acetabulum of coxal bone; via the ligament at the fovea capitis pit Neck- narrow area distal to head weakest area of the bone (common fracture site) Distal end articulates with TIBIA (leg bone) and PATELLA (knee cap) NOT the fibula! Gluteal tuberosity- vertical ridge Greater and lesser trochanters- posterior projections that serve as attachment sites for tendons of thigh and buttocks Linea aspera- attachment for thigh/hip muscles. Divides into a pair of ridges that continue with M/L epicondyles –part of knee joint
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Lower Extremity- Femur
Medial and lateral CONDYLES- articulate with tibial condyles (held in place with menisci)- part of the knee joint Lateral epicondyle smaller than the medial epicondyle, attachment to the fibular collateral ligament of the knee-joint. Medial epicondyle bony protrusion on the medial side of the bone's distal end; bears an elevation for the attachment of the "tendinous insertion", of the adductor magnus. Intercondylar fossa- found between condyles (posterior surface) Patellar surface- found on anterior surface
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Femur Review neck greater trochanter lesser trochanter
head neck greater trochanter lesser trochanter gluteal tuberosity linea aspera med/lateral condyles intercondylar fossa
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Lower Extremity PATELLA: “kneecap”
Sesamoid bone- cartilage at birth but ossifies once walking begins at 2yrs to puberty Primary functions are to protects the knee joint and extend the knee Patellar ligament / tendon connects apex of patella to tibia Upper 3/4 of the patella articulates with the femur. Secures anterior thigh muscles to the tibia It is attached to the tendon of the quadriceps femoris muscle Improves leverage of thigh muscles across knee joint by increasing the angle at which it acts. Patella action superior/inferior. Running on hard or slanted surfaces can result in “runner’s knee” –improper tracking of patella across patellar surface
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Lower Limb Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges
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Tibia Medial leg bone- “shin bone”
Supports weight of body-receives weight from femur and transfers to the foot Articulates with femur and fibula (proximally) Articulates with fibula and talus -ankle (distally) – Lateral malleolus Articulates with medial malleolus bony knob on inside of ankle at distal end; medial projection at the ankle Joined to fibula by interosseous membrane; allows little to no movement; less flexible stronger and more stable Medial and lateral condyles fairly flat articular surfaces articulates with femur condyles Intercondylar eminence – ridge separating condyles Tibial tuberosity – attachment of quadricep muscles; attaches patellar ligament Anterior crest – sharp, angular; not covered by muscle
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Lower Extremity Fibula Long, slender; lateral to tibia
Does NOT articulate with femur Does not bear any body weight- no transfer of weight to ankle or foot Attaches muscles for the feet and toes Does not contribute to knee joint Lateral malleolus- distal end—lateral “ankle”; bony protrusion laterally. Articulates with talus of the ankle and stabilizes the ankle joint Lower Extremity
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The Ankle (Tarsus) & Foot
7 bones Body weight is carried by the two largest bones Calcaneus forms heel attaches the calcaneal (Achilles tendon) When standing most body weight transfers to the tibia then to talus to calcaneus then to the ground Tendon enables the lifting of the heel to stand on tiptoes Talus most superior tarsal bone - forms ankle joint with the lateral and medial malleoli Carries weight from tibia across trochlea- pulley-shaped articular process Navicular articulates with talus and cuneiforms Cuboid Cuneiforms - medial, lateral, and intermediate The Ankle (Tarsus) & Foot M I cuneiform L navicular cuboid Talus Trochlea of the talus calaneus
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Lower Extremity Metatarsus: Five Phalanges:
Numbered I–V, medial to lateral Articulate with toes Phalanges: 14 bones of the toes Three phalanges (distal, medial, proximal) Hallux- (big toe); 2 phalanges =proximal and distal
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Foot Arches Bones of foot arranged into two arches
Ligaments and tendons hold them in place Distribute body weight—function as a spring Support body weight and provides balance while walking Provide leverage when walking and running (puts considerable stress on the feet) 3 arches in total Medial and Lateral horizontal arch Transverse arch
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Foot Arches The 3 springy arches absorb stress Longitudinal arch
Talar or medial from heel to hallux; curves well above the ground- causes a break in footprint leaving no mpression; elasticity provides shock absorption from sudden changes in weight bearing. Action of the posterior tibialis muscle Calcaneal or lateral longitudinal arch from heel to little toe; less curvature Transverse arch across middle of foot Distribute ½ of standing and walking weight to the heel; the other ½ to the heads of the metatarsals Held together by short, strong ligaments FLAT FEET –arches never form or fall- Less tolerance for long standing or walking (prevented enlistment in Army military service)
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Foot Disorders/Treatment
Club foot –Foot twisted medially; Treatment: orthopedic manipulations Flat feet – Longitudinal arch decreased; Treatment includes muscular exercise training while feet are still growing. Once development has arrested no change will occur with exercise. Claw feet / Pes cavus longitudinal arch increased; treatment includes custom shoes and/or surgery– stretching and strengthen exercises, massage Bunion- deformity of the big toe; surgery; orthotics
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