Lecture 8 Notes & study guide

1. Pectoral Girdle and Upper Limb Attachment

• Components: Clavicle (collarbone) and Scapula (shoulder blade).

• Union with Axial Skeleton: The pectoral girdle does not directly articulate with the vertebral column. Instead, the clavicle articulates anteriorly with the sternum (part of the axial skeleton), and the scapula articulates with the clavicle and humerus. This arrangement allows for significant mobility of the upper limb.

  • Clavicle: S-shaped bone that extends horizontally across the superior anterior thorax. Its medial end articulates with the sternum at the sternoclavicular joint, and its lateral end articulates with the acromion of the scapula at the acromioclavicular joint.

  • Scapula: Triangular, flat bone located on the posterior aspect of the thorax. It has a glenoid cavity that articulates with the head of the humerus, forming the glenohumeral (shoulder) joint.

2. Bones of the Upper Limb

• Arm (Brachium):

  • Humerus: The single bone of the upper arm. Its proximal end has a head that articulates with the glenoid cavity of the scapula. Distally, it articulates with the radius and ulna.

• Forearm (Antebrachium):

  • Radius: Located on the lateral (thumb) side of the forearm. Its head articulates with the capitulum of the humerus and the radial notch of the ulna. Distally, it articulates with the scaphoid and lunate carpals.

  • Ulna: Located on the medial (little finger) side of the forearm. Its olecranon and coronoid process articulate with the humerus. Distally, its head articulates with the ulnar notch of the radius.

• Wrist (Carpus):

  • Composed of eight carpal bones arranged in two rows:

    • Proximal Row (lateral to medial): Scaphoid, Lunate, Triquetrum, Pisiform.

    • Distal Row (lateral to medial): Trapezium, Trapezoid, Capitate, Hamate.

• Hand (Manus):

  • Metacarpals: Five bones that form the palm of the hand, numbered I-V from the thumb side.

  • Phalanges: Bones of the fingers. Each finger (digits II-V) has three phalanges (proximal, middle, distal). The thumb (digit I) has two phalanges (proximal, distal).

3. Pelvic Girdle and Lower Limb Attachment

• Components: Two hip bones (ossa coxae or coxal bones), which unite anteriorly at the pubic symphysis and posteriorly with the sacrum (part of the axial skeleton) at the sacroiliac joints.

  • Each hip bone consists of three fused bones: Ilium, Ischium, and Pubis. They meet at the acetabulum, which forms the socket for the head of the femur.

• Union with Axial Skeleton: The pelvic girdle forms a strong, stable attachment for the lower limbs to the axial skeleton, designed for weight bearing and locomotion.

4. Features of the Pelvis: Male vs. Female Differences

Differences facilitate childbirth in females and provide greater muscle attachment in males.

5. Bones of the Lower Limb

• Thigh (Femoral Region):

  • Femur: The single bone of the thigh and the longest, strongest bone in the body. Its head articulates with the acetabulum of the hip bone. Distally, it articulates with the tibia and patella.

  • Patella: (kneecap) A sesamoid bone embedded in the quadriceps tendon, anterior to the knee joint. It protects the knee joint and improves leverage for the quadriceps muscles.

• Leg (Crural Region):

  • Tibia: The larger, medial bone of the lower leg, commonly called the shin bone. It bears most of the body's weight from the femur. Its proximal end articulates with the femur and fibula. Distally, it articulates with the talus.

  • Fibula: The slender, lateral bone of the lower leg. It does not bear significant weight but provides muscle attachment and contributes to the ankle joint. Its proximal end articulates with the tibia. Distally, its lateral malleolus forms the lateral aspect of the ankle.

• Ankle (Tarsus):

  • Composed of seven tarsal bones:

    • Talus: Articulates with the tibia and fibula superiorly to form the ankle joint.

    • Calcaneus: The heel bone, the largest tarsal bone.

    • Navicular

    • Cuboid

    • Cuneiforms (Medial, Intermediate, Lateral)

• Foot (Pes):

  • Metatarsals: Five bones that form the sole of the foot, numbered I-V from the medial side (great toe).

  • Phalanges: Bones of the toes. Each toe (digits II-V) has three phalanges (proximal, middle, distal). The great toe (digit I) has two phalanges (proximal, distal).

**Arches of the Foot

1. Pectoral Girdle and Upper Limb Attachment

• Components: Clavicle (collarbone) and Scapula (shoulder blade).

• Union with Axial Skeleton: The pectoral girdle does not directly articulate with the vertebral column. Instead, the clavicle articulates anteriorly with the sternum (part of the axial skeleton), and the scapula articulates with the clavicle and humerus. This arrangement allows for significant mobility of the upper limb.

  • Clavicle: S-shaped bone that extends horizontally across the superior anterior thorax. Its medial end articulates with the sternum at the sternoclavicular joint, and its lateral end articulates with the acromion of the scapula at the acromioclavicular joint.

  • Scapula: Triangular, flat bone located on the posterior aspect of the thorax. It has a glenoid cavity that articulates with the head of the humerus, forming the glenohumeral (shoulder) joint.

2. Bones of the Upper Limb

• Arm (Brachium):

  • Humerus: The single bone of the upper arm. Its proximal end has a head that articulates with the glenoid cavity of the scapula. Distally, it articulates with the radius and ulna.

• Forearm (Antebrachium):

  • Radius: Located on the lateral (thumb) side of the forearm. Its head articulates with the capitulum of the humerus and the radial notch of the ulna. Distally, it articulates with the scaphoid and lunate carpals.

  • Ulna: Located on the medial (little finger) side of the forearm. Its olecranon and coronoid process articulate with the humerus. Distally, its head articulates with the ulnar notch of the radius.

• Wrist (Carpus):

  • Composed of eight carpal bones arranged in two rows:

    • Proximal Row (lateral to medial): Scaphoid, Lunate, Triquetrum, Pisiform.

    • Distal Row (lateral to medial): Trapezium, Trapezoid, Capitate, Hamate.

• Hand (Manus):

  • Metacarpals: Five bones that form the palm of the hand, numbered I-V from the thumb side.

  • Phalanges: Bones of the fingers. Each finger (digits II-V) has three phalanges (proximal, middle, distal). The thumb (digit I) has two phalanges (proximal, distal).

3. Pelvic Girdle and Lower Limb Attachment

• Components: Two hip bones (ossa coxae or coxal bones), which unite anteriorly at the pubic symphysis and posteriorly with the sacrum (part of the axial skeleton) at the sacroiliac joints.

  • Each hip bone consists of three fused bones: Ilium, Ischium, and Pubis. They meet at the acetabulum, which forms the socket for the head of the femur.

• Union with Axial Skeleton: The pelvic girdle forms a strong, stable attachment for the lower limbs to the axial skeleton, designed for weight bearing and locomotion.

4. Features of the Pelvis: Male vs. Female Differences

Differences facilitate childbirth in females and provide greater muscle attachment in males.

5. Bones of the Lower Limb

• Thigh (Femoral Region):

  • Femur: The single bone of the thigh and the longest, strongest bone in the body. Its head articulates with the acetabulum of the hip bone. Distally, it articulates with the tibia and patella.

  • Patella: (kneecap) A sesamoid bone embedded in the quadriceps tendon, anterior to the knee joint. It protects the knee joint and improves leverage for the quadriceps muscles.

• Leg (Crural Region):

  • Tibia: The larger, medial bone of the lower leg, commonly called the shin bone. It bears most of the body's weight from the femur. Its proximal end articulates with the femur and fibula. Distally, it articulates with the talus.

  • Fibula: The slender, lateral bone of the lower leg. It does not bear significant weight but provides muscle attachment and contributes to the ankle joint. Its proximal end articulates with the tibia. Distally, its lateral malleolus forms the lateral aspect of the ankle.

• Ankle (Tarsus):

  • Composed of seven tarsal bones:

    • Talus: Articulates with the tibia and fibula superiorly to form the ankle joint.

    • Calcaneus: The heel bone, the largest tarsal bone.

    • Navicular

    • Cuboid

    • Cuneiforms (Medial, Intermediate, Lateral)

• Foot (Pes):

  • Metatarsals: Five bones that form the sole of the foot, numbered I-V from the medial side (great toe).

  • Phalanges: Bones of the toes. Each toe (digits II-V) has three phalanges (proximal, middle, distal). The great toe (digit I) has two phalanges (proximal, distal).

6. Arches of the Foot

• Function: Support body weight, absorb shock, and provide leverage during locomotion.

• Main Arches:

  • Longitudinal Arch: Runs from front to back, composed of:

    • Medial Longitudinal Arch: Higher and more prominent, extends from calcaneus to talus, navicular, three cuneiforms, and first three metatarsals.

    • Lateral Longitudinal Arch: Lower and flatter, extends from calcaneus to cuboid and fourth and fifth metatarsals.

  • Transverse Arch: Runs from side to side in the midfoot, following the curve of the cuboid and cuneiforms.

• Support: Maintained by the interlocking shapes of the tarsal and metatarsal bones, ligaments (e.g., plantar fascia), and tendons of foot muscles.

7. Joints: Functional and Structural Classifications

• Functional Classification (based on amount of movement allowed):

  • Synarthroses: Immovable joints (e.g., sutures of the skull).

  • Amphiarthroses: Slightly movable joints (e.g., intervertebral discs).

  • Diarthroses: Freely movable joints (e.g., all synovial joints).

• Structural Classification (based on material binding bones and presence/absence of a joint cavity):

  • Fibrous Joints: Bones joined by fibrous connective tissue; no joint cavity.

  • Cartilaginous Joints: Bones joined by cartilage; no joint cavity.

  • Synovial Joints: Bones separated by a fluid-filled joint cavity.

8. Types of Structural Joints

• Fibrous Joints:

  • Characterized by bones being united by fibrous connective tissue. Most are immovable (synarthroses).

  • Sutures: Occur only between bones of the skull. Wavy articulating bone edges interlock, and the junction is completely filled by short connective tissue fibers (sutural ligament). Function: Protect the brain; in middle age, the fibrous tissue ossifies, forming a synostosis (bony junction). Example: Coronal suture between frontal and parietal bones.

  • Syndesmoses: Bones connected exclusively by ligaments (cords or bands of fibrous tissue). Amount of movement depends on the length of the connecting fibers. Example: Ligament connecting the distal ends of the tibia and fibula (short fibers, little movement). Example: Interosseous membrane connecting radius and ulna (long fibers, allows pronation/supination).

  • Gomphoses: A peg-in-socket fibrous joint. Example: The articulation of a tooth with its bony alveolar socket. The fibrous connection is the periodontal ligament.

• Cartilaginous Joints:

  • Characterized by bones being united by cartilage. Lack a joint cavity and are not highly movable.

  • Synchondroses: A bar or plate of hyaline cartilage unites the bones. Function: Nearly all are synarthrotic (immovable). Example: Epiphyseal plates in long bones of children. Example: Costal cartilage of the first rib with the sternum.

  • Symphyses: Articular surfaces of the bones are covered with articular (hyaline) cartilage, which is fused to an intervening pad of fibrocartilage. Function: Amphiarthrotic (slightly movable) joints designed for strength with flexibility. Example: Intervertebral joints (intervertebral discs). Example: Pubic symphysis of the pelvis.

• Synovial Joints:

  • Characterized by the presence of a joint cavity (synovial cavity) filled with synovial fluid. All are diarthrotic (freely movable).

  • General Structure:

    • Articular Cartilage: Hyaline cartilage covering opposing bone surfaces.

    • Joint (Articular) Cavity: Space containing synovial fluid.

    • Articular Capsule: Two-layered capsule enclosing the joint cavity.

      • Fibrous Layer: Outer layer of dense irregular connective tissue, continuous with periostea, strengthens the joint.

      • Synovial Membrane: Inner layer of loose connective tissue, lines entire joint capsule except articular cartilage, produces synovial fluid.

    • Synovial Fluid: Viscous, slippery fluid that lubricates and nourishes articular cartilage.

    • Reinforcing Ligaments: Capsular, extracapsular, intracapsular ligaments.

    • Nerves and Blood Vessels: Supply the joint.

  • Bursae and Tendon Sheaths: Often associated with synovial joints, reducing friction.

  • Types of Synovial Joints (based on articulating surfaces and movement):

    • Plane Joint: Flat articular surfaces, allows gliding/sliding movements. Example: Intercarpal joints.

    • Hinge Joint: Cylinder into trough, allows flexion/extension. Example: Elbow joint.

    • Pivot Joint: Rounded end into ring, allows rotation. Example: Proximal radioulnar joint.

    • Condylar (Ellipsoidal) Joint: Oval surface into oval depression, allows flexion/extension, abduction/adduction, circumduction. Example: Knuckle (metacarpophalangeal) joints.

    • Saddle Joint: Saddle-shaped surfaces, allows flexion/extension, abduction/adduction, circumduction. Example: Carpometacarpal joint of the thumb.

    • Ball-and-Socket Joint: Spherical head into cup-like socket, allows all movements (most freely movable). Example: Shoulder and hip joints.

9. Body Movements

• Introduction to Body Movements: Movements are typically described in relation to the anatomical position.

• Gliding Movements: Occur when flat (or nearly flat) bone surfaces glide past each other without angular or rotational movement. Examples: Intercarpal and intertarsal joints.

• Angular Movements (increase or decrease the angle between two bones):

  • Flexion: Decreases the angle of a joint (e.g., bending the elbow).

  • Extension: Increases the angle of a joint (e.g., straightening the elbow).

  • Hyperextension: Excessive extension beyond the anatomical position.

  • Abduction: Movement of a limb away from the midline of the body.

  • Adduction: Movement of a limb toward the midline of the body.

  • Circumduction: Movement of a limb in a cone-shaped path; involves flexion, abduction, extension, and adduction.

• Rotation (turning of a bone around its own long axis):

  • Medial (Internal) Rotation: Rotation toward the midline.

  • Lateral (External) Rotation: Rotation away from the midline.

  • Example: Rotation of the head, rotation of the humerus at the shoulder.

• Special Movements:

  • Supination: Rotating the forearm laterally so the palm faces anteriorly/superiorly.

  • Pronation: Rotating the forearm medially so the palm faces posteriorly/inferiorly.

  • Dorsiflexion: Lifting the foot so its superior surface approaches the shin (flexing the foot upward).

  • Plantarflexion: Depressing the foot (pointing the toes).

  • Inversion: Sole of the foot turns medially.

  • Eversion: Sole of the foot turns laterally.

  • Protraction: Anterior movement in the transverse plane (e.g., jutting out the jaw).

  • Retraction: Posterior movement (e.g., pulling the jaw back).

  • Elevation: Lifting a body part superiorly (e.g., shrugging shoulders).

  • Depression: Moving a body part inferiorly (e.g., dropping shoulders).

  • Opposition: Movement of the thumb to touch the tips of other fingers.

10. Structure of Specific Body Joints and the Movements Allowed by Each

• Shoulder (Glenohumeral) Joint:

  • Structure: A ball-and-socket joint formed by the head of the humerus and the glenoid cavity of the scapula. It has a large range of motion due to its shallow socket and loose joint capsule, but this also makes it less stable. Labrum (fibrocartilage ring) deepens the socket slightly.

  • Movements: Flexion, extension, hyperextension, abduction, adduction, circumduction, medial rotation, lateral rotation. (Most freely movable joint in the body).

• Elbow Joint:

  • Structure: A hinge joint formed by the articulation of the trochlea of the humerus with the trochlear notch of the ulna, and the capitulum of the humerus with the head of the radius. The anular ligament surrounds the head of the radius, allowing it to pivot.

  • Movements: Flexion and extension of the forearm. The proximal radioulnar joint (a pivot joint, part of the elbow complex functionally) allows supination and pronation of the forearm.

• Hip (Coxal) Joint:

  • Structure: A ball-and-socket joint formed by the head of the femur and the acetabulum of the hip bone. It is very stable due to the deep socket, strong ligaments, and thick joint capsule. The acetabular labrum enhances depth.

  • Movements: Flexion, extension, abduction, adduction, circumduction, medial rotation, lateral rotation (less range of motion than the shoulder, primarily due to stability requirements for weight bearing).

• Knee Joint:

  • Structure: The largest and most complex synovial joint, primarily a modified hinge joint. Formed by the femoropatellar joint (plane joint) and the tibiofemoral joint (modified hinge joint). It is stabilized by menisci (medial and lateral) that act as shock absorbers and improve fit, collateral ligaments (MCL, LCL), and cruciate ligaments (ACL, PCL) within the capsule.

  • Movements: Primarily flexion and extension. When the knee is flexed, some slight rotation is possible.