Untitled

Bones of the Hand

• Radiographic Overview

  • Photographic representation shows the positioning of bones in the hand.

  • Carpal Bones: Form the base of the hand; arranged in a U-shaped grouping.

  • Strong ligament called the flexor retinaculum spans the top of this U-shape.

  • Attached laterally to trapezium and scaphoid; medially to hamate and pisiform.

  • Creates a passageway known as the carpal tunnel.

    • Walls and floor: Carpal bones.

    • Roof: Flexor retinaculum.

  • Carpal Tunnel Functionality:

  • Houses nine muscle tendons and a significant nerve from the anterior forearm into the hand.

  • Overuse or wrist injury can lead to carpal tunnel syndrome:

    • Symptoms: Pain, numbness, muscle weakness in areas supplied by the involved nerve.

• Metacarpal Bones

  • Description: The palm consists of five elongated metacarpal bones.

  • Articulation:

  • Proximal ends articulate with distal carpal bones (carpometacarpal joints).

  • Distal ends articulate at metacarpophalangeal joints with the proximal phalanx of fingers and thumb, forming knuckles.

  • Numbering: Metacarpals are numbered 1 through 5 starting from the thumb:

  • First metacarpal (thumb) has independent movement, crucial for thumb mobility.

  • Second and third metacarpals are immobile; fourth and fifth allow limited anterior-posterior mobility, vital for gripping actions.

• Phalanx Bones

  • Overview: Fingers and thumb consist of 14 phalanx bones (digits).

  • Thumb (pollex): Two phalanges (proximal and distal).

  • Digits 2-5: Each has three phalanges (proximal, middle, distal).

  • Joint Types: Interphalangeal joints form articulations between adjacent phalanges.

Appendicular System: Fractures of Upper Limb Bones

• Impact of Injuries:

  • Significant loss of function arises from injuries to hands and upper limbs.

  • Commonly results from falls onto an outstretched hand, leading to fractures in the humerus, radius, or scaphoid.

  • Higher incidence in the elderly due to weakened bones from osteoporosis.

• Fracture Types:

  • Humerus Fractures:

  • Can occur from falls onto the hand or direct trauma to the arm.

  • Notable fractures include:

    • Surgical neck fractures leading to impacted fractures.

    • Transverse or spiral fractures from blows to the arm.

  • Fractures may compress arteries causing ischemia, risking forearm muscle damage.

  • Colles Fracture:

  • Most common forearm fracture due to falling onto an outstretched hand.

  • Complete transverse fracture of the distal radius with posterior displacement, creating a “dinner fork” bend.

  • Common in individuals over 50, particularly those with osteoporosis or in high-speed sports.

  • Scaphoid Fracture:

  • Most frequently fractured carpal bone.

  • Results from falling on the hand, presenting as deep pain lateral to the wrist initially diagnosed as a sprain.

  • Delayed radiographic diagnosis may show fracture after swelling subsides, slow healing due to limited blood supply.

The Pelvic Girdle and Pelvis

• Pelvic Girdle Overview:

  • Formed by the hip bone (coxal bone), attaches lower limb to the axial skeleton via sacrum.

  • Bony pelvis consists of both hip bones, sacrum, and coccyx.

  • Bones of the pelvis are closely united for a stable, weight-bearing structure.

• Hip Bone Composition:

  • Each hip bone formed by fusion of three bones (ilium, ischium, pubis) by late teenage years.

  • Ilium: Largest, fan-shaped; articulates at sacroiliac joint.

  • Ischium: Posteroinferior region; supports body when seated.

  • Pubis: Anteromedial portion, joining in the center at the pubic symphysis.

• Specific Bony Landmarks:

  • Ilium:

  • Iliac Crest: Easily felt on the waist; prominent bony landmark.

  • Iliac Spines: Anterior superior and inferior serve as muscle attachment sites; posterior spines involved in ligament support.

  • Greater Sciatic Notch: Indentation on the ilium’s posterior side.

  • Ischium:

  • Ischial Tuberosity: Supports body weight when sitting; muscle attachment point.

  • Ischial Spine: Separates lesser sciatic notch and greater sciatic notch.

  • Pubis:

  • Pubic Symphysis: Joint where pubis bones meet.

  • Pubic Arch: Configuration formed by pubic symphysis and adjacent rami.

Pelvic Functions and Adaptations

• Pelvis Functions:

  • Supports upper body weight; transfers weight during bipedal posture.

  • Muscles and internal organs are attached and protected by the pelvic structure.

• Greater and Lesser Pelvis:

  • Greater Pelvis: Broad area supporting intestines, part of false pelvis.

  • Lesser Pelvis: Surrounds bladder and pelvic organs; known as the true pelvis.

• Sexual Dimorphism:

  • Notable differences between male and female pelvises:

  • Male: Thicker, heavier; narrower greater sciatic notch.

  • Female: Wider for childbirth, larger subpubic angle, broader pelvic cavity.

  • Table 8.1 outlines these differences in detail.

Bones of the Lower Limb

• Structure Overview:

  • The lower limb consists of 30 bones divided into:

  • Thigh: Femur.

  • Leg: Tibia and fibula.

  • Foot: Tarsal bones, metatarsals, and phalanges.

  • Total Bones: Includes the longest (femur) and a kneecap (patella).

• Femur:

  • Longest and strongest bone, approximately one-quarter of a person's height.

  • Articulates with the hip bone at hip joint (acetabulum).

  • Key features include:

  • Pelvic Ligaments: Involved in joint relations and connected muscles.

  • Greater and Lesser Trochanters: Important muscle attachment areas; roughened lines facilitate traction.

• Patella:

  • Largest sesamoid bone, incorporated into the quadriceps tendon.

  • Prevents tendon damage during joint movement; increases leverage power.

• Tibia and Fibula:

  • Tibia: Main weight-bearing bone; articulates both at the knee and ankle joints.

  • Contains distinct areas like the medial malleolus and various muscle attachment sites.

  • Fibula: Slender, non-weight bearing; primarily for muscle attachment.

• Foot Anatomy and Arches:

  • Comprised of tarsal bones, metatarsals, and phalanges.

  • Arch Types:

  • Transverse arch (distributes weight).

  • Medial and lateral longitudinal arches (shock absorption upon contact).

  • Arches formed by tarsal and metatarsal arrangements; supported by ligaments to maintain integrity during weight-bearing activities.

  • Conditions: Prolonged stretching may lead to flat feet (pes planus).

Development of the Appendicular Skeleton

• Embryogenesis:

  • Appendicular skeleton originates from mesenchyme and develops limb buds around the fourth week of embryonic growth.

  • Limb buds appear with an apical ectodermal ridge facilitating growth patterns in upper and lower limbs, leading to primary and secondary ossification centers as development progresses.