Appendicular Skeleton PDF

The Appendicular Skeleton 1  The Upper Limb Each upper limb has 32 bones Two separate regions 1. The pectoral (shoulder) girdlewhich attaches upper limb to trunk  2 bones: Clavicle and Scapula 2. The free part (30 bones): 1 Humerus (arm) 1 Ulna + 1...

The Appendicular Skeleton 1  The Upper Limb Each upper limb has 32 bones Two separate regions 1. The pectoral (shoulder) girdlewhich attaches upper limb to trunk  2 bones: Clavicle and Scapula 2. The free part (30 bones): 1 Humerus (arm) 1 Ulna + 1 Radius (forearm) 8 Carpal bones (wrist) 5 Metacarpals and 14 Phalanges (hand) 2 The Pectoral (Shoulder) Girdle: 3 4 The Clavicle (Collarbone): ◼ Subcutaneous “S” shaped ◼ The medial round end articulates with the manubrium of the sternum ◼ The lateral broad end articulates with the acromion process of scapula ◼ Medially, the clavicle is convex anteriorly. Laterally, the clavicle is concave anteriorly. ◼ Function 1. Transmits forces from the upper limb to the axial skeleton 2. Provides attachment for muscles 3. A strut that holds the arm away from the trunk 5 The clavicle mid region is the most frequent fracture site 6 The Scapula (Shoulder blade): ◼ Triangular in shape 7 ◼ Located on the posterior aspect of the rib cage level with the 2nd to 7th ribs. ◼ 2 surfaces: anterior (costal) surface featuring the subscapular fossa. Posterior surface divided by the spine into upper supraspinous fossa and lower infraspinous fossa. ◼ 3 borders: superior, medial and lateral. ◼ 3 angles: inferior, superior and lateral. The lateral (Superolateral) angle presents the glenoid cavity for articulation with the head of the humerus forming the shoulder joint. ◼ 3 processes: Spine – Acromion – Coracoid process 8 9 Tailors 10 The Humerus: ◼ Longest and largest bone of the free part of the upper limb. 11 ◼ The Upper End features 1. Head that articulates with the glenoid cavity of the scapula to form the shoulder joints. 2. Anatomical neck. 3. Greater & Lesser tubercle 4. Intertubercular (bicipital) groove: Long tendon of biceps. 5. Surgical neck: (the most common site of humerus fracture) ◼ The Shaft: ◼ Deltoid tuberosity (middle of lateral surface): attachment of the Deltoid muscle 12 The Lower End features 1. Laterally, the round Capitulum which articulates with the head of the radius 2. Medially, the pulley-shaped trochlea which articulates with trochlear notch of the ulna. 3. Lateral and Medial epicondyles (more prominent–Ulnar nerve) for the attachments of the forearm muscles. 13 14 The Ulna: ◼ The longer and medial of the two forearm bones ◼ Upper End: 1.Trochlearnotch- a deep fossa that articulates with the trochlea of the humerus. Bounded by two processes A. Olecranon- the larger process, “tip of your elbow” B.Coronoidprocess - the anterior “lip” of the proximal ulna. 15 2. Shaft: triangular with a sharp lateral (interosseous) border. 3. Lower End: features the head of ulna and the Styloid proces 16 17 The Radius: ◼ Lies lateral to the ulna ◼ The head (disc-shaped) and neck are at the proximal end ◼ The head articulates with the Capitulum of the Humerus ◼ Radial (bicipital) tuberosity - attachment site for biceps brachii muscle ◼ Shaft triangular with a sharp medial border (interosseous) ◼ the styloid process ◼ Inferior surface of the lower end participates in the wrist joint (Radiocarpal (wrist) joint) 18 19 The Bones of the Hand: The Carpal Bones (Carpus): ◼ Consists of 8 small bones (carpals) of Two rows ◼ Proximal row (L M) - scaphoid, lunate, triquetrum, pisiform ◼ Distal row – Trapezium (thumb), trapezoid, capitate (largest), hamate ◼ Five metacarpals - numbered I, II, III. IV and V, lateral to medial ◼ 14 phalanges - two in the thumb (pollex - Latin) and three in each of the other fingers ◼ Each metacarpal and phalanx has a base, shaft, and head (proximal to distal) 20 21  The Lower Limb ◼ Each lower limb has 31 bones ◼ Two separate regions 1. The pelvic girdlewhich attaches lower limb to trunk  2 hip bones 2. The free part (30 bones): 1 Femur (thigh) 1 Patella 1 Tibia + 1 Fibula (leg) 7 Tarsal bones 5 Metatarsal bones and 14 Phalanges (foot) The lower limbs are divided into the gluteal region, the thigh, the knee, the leg, the ankle, and the foot. 19 The Hip (Coxal) Bone: 23 ◼ Each hip bone consists of three bones that fuse together: ilium, pubis, and ischium ◼ The two hip bones are joined anteriorly by the pubic symphysis (fibrocartilage) ◼ Joined posteriorly by the sacrum forming the sacroiliac joints 24 Pubic arch  The 3 bones fuse at and participate in the formation of the acetabulum  The obturator foramen is bounded by the pubis and ischium. 25 It’s the largest foramen in the body. 26 The Ilium: ◼ Largest of the three hip bones (superior) ◼ Consists of a superior alaand inferior body which participates in the formation of the acetabulum (the socket for the head of the femur) ◼ Superior border - iliac crest. Possess iliac tubercle (5cm). ◼ Has four prominent projections: the superior and inferior anterior and posterior iliac spines 27 ◼ Greater sciatic notch - allows passage of sciatic nerve. Located between the posterior inferior iliac spine and the ischial spine. The Ischium and Pubis: Ischium Inferior and posterior part of the hip bone (L shape) Most prominent feature is the ischial tuberosity, it is the part that meets the chair when you are sitting Ischial spine – a prominent projection. Below the spine we have the lesser sciatic notch 28 The ischial ramus meets the inferior ramus of the pubis Pubis Inferior and anterior part of the hip bone Superior and inferior rami and body Pubic crest and tubercle False and True Pelvis: ◼ Pelvic brim - a line from the sacral promontory to the upper part of the pubic symphysis ◼ False pelvis - lies above this line 29 ◼ True pelvis - the bony pelvis inferior to the pelvic brim, has an inlet, an outlet and a cavity 30 Comparing Male and Female Pelvis: 31  These features of female pelvis create more space in the true pelvis to permit an easier process of child birth The Femur: ◼ Femur - longest, heaviest, and strongest bone in the body ◼ Proximal End: Features 32 1. Head articulates with the acetabulum. 2. fovea capitis small depression for ligament attachment. 3. Neck 4. Greater and lesser trochanters. 33 34 ◼ Shaft: Its middle third is triangular. The posterior border of the triangle is called the linea aspera – site for muscle attachment. ◼ Distal End: 1. Medial and lateral condyles that articulates inferiorly with the tibia and anteriorly with the patellae. 2. Intercondylar notch posteriorly 3. Patellar surface anteriorly. 4. Medial and lateral epicondyles for muscle attachment. 35 36 The Patella: Ligamentum patellae Connect Patella & Tibia ◼ Largest sesamoid bone in the body ◼ Triangular in shape. The base is superior. The narrow apex is inferior ◼ Forms the patellofemoral joint ◼ Thick articular cartilage lines the posterior surface ◼ Increases the leverage of the quadriceps femoris muscle 37 The Tibia (Shin Bone): ◼ The largest, medial weight-bearing bone of the leg ◼ Proximal End: 1. Lateral and medial condyles articulate with the femur condyles to form the knee joint. 38 ◼ Shaft: Exhibits the tibial tuberosity for attachment of the ligamentum patellae. The lateral border of the shaft is the sharp interosseous border. ◼ Distal End: It articulates distally with the talus at the ankle joint. Features the medial malleolus The Fibula: ◼ The smaller, laterally placed bone of the leg ◼ Non-weight bearing. ◼ Serves for muscle attachment 39 ◼ The head forms the proximal tibiofibular joint ◼ Shaft – medial interosseous border ◼ Distal end, articulates with the tibia and the talus forming ANKLE JOINT. ◼ Features the lateral malleolus. 40 41 42  The Skeleton of the Foot: ◼ Seven tarsal bones 1. Talus: articulates with tibia and fibula: ANKLE JOINT 2. Calcaneus: (heel bone): largest and strongest 3. Navicular 4. Cuboid 5. Three cuneiforms 43 ◼ Five metatarsals: Medial to lateral (I-V) (base, shaft, head) ◼ 14 phalanges: Big toe (Hallux I) has two phalanges 44 45  Arches of the Foot: ◼ Two longitudinal (MEDIAL and LATERAL) & One TRANSVERSE arches support the weight of the body ◼ Provide spring and leverage to the foot when walking ◼ The arches flex when body weight applied ◼ Flatfoot - the arches decrease or “fall” ◼ Clawfoot - too much arch occurs due to various pathologies The body weight on standing is distributed through a foot via the heel (calcaneus) behind and six points of contact with the ground in front, namely, the two sesamoid bones under the 46 head of the first metatarsal and the heads of the remaining four metatarsals. 47 48  Joints A joint, also called an articulation or arthrosis is a point of contact between two bones, between bone and cartilage, or between bone 49 and teeth. Joints are sites where two or more bones meet. Classification of Joints: ◼ The structural classification of joints (according to type of tissue that connects the bones): 1. Fibrous joints (bones held together by dense collagen fibers – no cavity) 2. Cartilaginous joints (bones held together by cartilage – no cavity) 50  3. Synovial joints (bones held together by articular capsule, ligaments – with cavity) ◼ The functional classification of joints (according to degree of movement): 1. Synarthrosis (an immovable joint) 2. Amphiarthrosis (a slightly movable joint) 3. Diarthrosis (a freely movable joint - All diarthroses are synovial joints.) Fibrous Joints: Fibrous joints permit little or no movement 51  ◼ Example: 1. Sutures - Occur only between bones of the skull of bone 52 2. 1st rib and the manubrium sterni 3. Pubic symphysis between the anterior surfaces of the hip bones. Cartilaginous Joints: Example: 1. Epiphyseal (growth) plate between diaphysis and epiphysis 53 4. Intervertebral joints between the vertebrae Synovial Joints: 1) Articular surfaces of bones are covered by hyaline articular cartilage 2) Synovial cavity allows a joint to be freely movable 3) Articular Capsule  A sleeve-like capsule encloses the synovial cavity. 4) Synovial membrane 4) Synovial Fluid 54  The synovial membrane secretes synovial fluid  Functions to reduce friction by: ◼ Lubricating the joint ◼ Absorbing shocks ◼ Supplying oxygen and nutrients to the cartilage ◼ Removing carbon dioxide and metabolic wastes from the cartilage 5) Accessory Ligaments and Articular Discs A. Collateral ligaments of the knee joint (Extracapsular) B. Anterior and posterior cruciate ligaments (Intracapsular) of the knee joint C. Menisci ◼ Pads of cartilage lie between the articular surfaces of the bones 55 ◼ Allow bones of different shapes to fit together more tightly ◼ Knee joint 56 57 6) Nerve and Blood Supply  Nerve endings convey information about pain from the joint to the spinal cord and brain and respond to the degree of movement and stretch at a joint  Arterial branches from several different arteries merge around a joint before penetrating the articular capsule 7) Bursae ◼ Sac-like structures containing fluid similar to synovial fluid ◼ Located between tendons, ligaments and bones ◼ Cushion the movement of these body part 58  47 Types of movements in Synovial Joints: ◼ Movements are grouped into four main categories: 1) Gliding 2) Angular movements 3) Rotation 4) Special movements 60 1) Gliding Simple movement back-and-forth and from sideto- side There is no significant alteration of the angle between the bones Limited in range Intercarpal joints Patellofemoral joints 62 49 2) Angular Movements  Increase or a decrease in the angle between articulating bones  Angular movements include ◼ Flexion ◼ Extension ◼ Lateral flexion ◼ Hyperextension ◼ Abduction ◼ Adduction ◼ Circumduction 64  ◼ Flexion  Decrease in the angle between articulating bones  Bending the trunk forward ◼ Extension  Increase in the angle between articulating bones  Flexion and extension  Wrist joint are opposite movements ◼ Hyperextension  Continuation of extension beyond the normal extension  Bending the trunk backward ◼ Lateral flexion  Movement of the trunk sideways to the right or left at the waist  Trunk intervertebral joints51 66 Abduction Hip joint  Movement of a bone away from the midline  Moving the humerus laterally at the shoulder joint Adduction  Movement of a bone toward the midline  Movement that returns body parts to normal position from abduction 68 53 ◼ Circumduction  Movement of a body part in a circle  Moving the humerus in a circle at the shoulder joint 70  A continuous sequence of flexion, abduction, extension, adduction, and rotation of the joint 72 3) Rotation  A bone revolves around its own longitudinal axis 1. Turning the head from side to side as when you shake your head “no” 73 2. Medial Rotation (internal) is the rotation of a limb so that the anterior surface of the bone faces medially 3. Lateral Rotation (external) is the rotation of a limb so that the anterior surface of the bone faces laterally 74 4) Special Movements ◼ Elevation  Upward movement of a part of the body  Closing the mouth  Its opposing movement is depression ◼ Depression  Downward movement of a part of the body  Opening the mouth ◼ Protraction  Movement of a part of the body anteriorly  Thrusting the mandible outward  Its opposing movement is retraction ◼ Retraction 75   Movement of a protracted part of the body back to normal ◼ Opposition  Movement of the thumb in which the thumb moves across the palm to touch the tips of the fingers on the same hand ◼ Inversion ( ◼ Movement of the foot (sole) medially  Its opposing movement is eversion ◼ Eversion ()  Movement of the sole laterally ◼ Dorsiflexion  Bending of the foot at the ankle in an upward direction  Its opposing movement is plantar flexion ◼ Plantar flexion 76   Bending of the foot at the ankle in a downward direction ◼ Supination  Movement of the forearm so that the palm is turned forward  Its opposing movement is pronation ◼ Pronation  Movement of the forearm so that the palm is turned backward 77 78 79 80  Types Synovial Joints: ◼ Synovial joints are classified based on type of movement into A. Planar B. Hinge C. Pivot D. Condyloid E. Saddle F. Ball-and-socket 81 1. Planar Joints  Primarily permit back-and-forth and side-to-side movements (Gliding)  Intercarpal joints 2. Hinge Joints  Permit only flexion and extension  Knee (modified) and elbow The ankle joint is a synovial hinge joint. 82 3. Pivot Joints 83 ◼ Saddle Joints  Flexion, extension, abduction and adduction  Carpometacarpal joint of the thumb (Trapezium and first metacarpal (#I)) ◼ Ball-and-Socket Joints(Circumdection)  Flexion, extension, abduction, adduction and rotation  Shoulder and hip joints 84 2- The Shoulder (Glenohumeral) Joint: Synovial ball-and-socket joint formed by the head of the humerus and glenoid cavity of the scapula 85  More freedom of movement than any other joint of the body which comes at the expense of stability  The articular capsule is thin and extends from the glenoid cavity to the anatomical neck of the humerus. It’s weak inferiorly  Ligaments: coracohumeral, glenohumeral and transverse humeral (between the tuberosities)  Bursae: subacromial and subscapular  Glenoid labrum: a narrow rim of fibrocartilage around the edge of the glenoid cavity that slightly deepens it 86  Most of the strength results from the muscles that surround the shoulder joint The shoulder joint is weakest inferiorly which is the most common site of dislocation 87  Most of the strength results from the muscles that surround the shoulder joint Rotator cuff injury Supraspinatus Rotator Cuff Muscles The Rotator Cuff Muscles tendons all blend with the capsule of the shoulder joint, thus help in stabilizing it. 88 3- The Elbow Joint:  A synovial hinge joint between the humerus, ulna and radius  Only flexion and extension of the forearm occur at this joint  Articular Capsule: extends from the humerus proximally to the radius and ulna distally  Ligaments: The triangular ulnar and radial collateral ligaments on the sides of the joint. The anular radial ligament surrounds the head of the radius 89  Ulnar nerve passes behind the medial epicondyle of the humerus Tennis elbow 90 91 4- The Hip (Coxal) Joint:  Synovial ball-and-socket joint formed by the head of the femur and the acetabulum of the hip bone  A very stable joint on the expense of decreasing range of movement  The articular capsule is thick and strong. It extends from the acetabulum to the neck of the femur  Ligaments of the joint include: iliofemoral, pubofemoral, ischiofemoral ligaments and the ligament of the head of femur 92  Acetabular labrum: a narrow rim of fibrocartilage around the edge of the acetabulum that deepens it 93 94 5- The Knee Joint:  Synovial modified-hinge joint formed by the femur, tibia and patella It’s the largest and most complex joint in the body  The articular capsule is strengthened by ligaments and muscles  Ligaments: Tibial and fibular collateral ligaments. Inside the joint we have the anterior and posterior cruciate ligaments  Bursae: prepatellar, suprapatellar and infrapaerllar 95  Menisci: Two fibrocartilage discs between the tibial and femoral condyles help compensate for the irregular shapes of the bones and circulate synovial fluid 96 97 98