Anatomical Language

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ANATOMICAL LANGUAGE Anatomical position In order to avoid confusion when describing the body, it is always described in the anatomical position. In the anatomical position, a person stands erect, legs together and arms by their sides, with their head, eyes, toes and palms of the hands facing forward. It is important to remember that the palms face forward as their relaxed position is generally facing inwards. The anatomical position allows us to describe the position of structures in relation to their surroundings, e.g. ‘the heart lies above the diaphragm’. The anatomical position avoids confusion as to whether the body is lying down or standing up. You should also bear in mind that when looking at a person in the anatomical position, their right side will be on your left. The structures will always be described as they are to the subject rather than as they appear to you. Anatomical planes and directions Planes There are three major anatomical planes; axial, coronal, and sagittal. Anatomical Position Description

Transcript of Anatomical Language

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ANATOMICAL LANGUAGE

Anatomical position

In order to avoid confusion when describing the body, it is always described in the anatomical position. In the anatomical position, a person stands erect, legs together and arms by their sides, with their head, eyes, toes and palms of the hands facing forward. It is important to remember that the palms face forward as their relaxed position is generally facing inwards.

The anatomical position allows us to describe the position of structures in relation to their surroundings, e.g. ‘the heart lies above the diaphragm’. The anatomical position avoids confusion as to whether the body is lying down or standing up.

You should also bear in mind that when looking at a person in the anatomical position, their right side will be on your left. The structures will always be described as they are to the subject rather than as they appear to you.

Anatomical planes and directions

Planes

There are three major anatomical planes; axial, coronal, and sagittal.

Anatomical Position DescriptionAxial (also know as the transverse plane)

This plane cuts the body horizontally, into superior (upper) and inferior (lower) portions.

Coronal (also known as the frontal plane)

This plane cuts the body vertically, into anterior (front) and posterior (back) portions.

Sagittal This plane cuts the body vertically, into left and right portions.

If the body is cut in the sagittal plane, exactly along the middle of the body, it is known as the median sagittal line/plane.

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ANATOMICAL PLANES

Direction

Direction is used, when the body is in the anatomical position to explain the location of a structure relative to the structures surrounding it.

Direction Description Example Anterior (or ventral)

Towards the front of the body (in front of).

The sternum lies anterior to the heart.

Posterior (or dorsal)

Towards the back of the body (behind).

The heart lies posterior the sternum.

Superior (or cranial) Above (on top of). The heart lies superior

to the diaphragm. Inferior (or Below (underneath). The diaphragm lies

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caudal) inferior to the heart.

Lateral Away from the mid line of the body (towards the sides).

The lungs lie lateral to the heart.

Medial Towards the mid line of the body (towards the middle).

The heart lies medial to the lungs.

Deep Away from the body surface (towards the inner body).

The heart is deep to the sternum.

Superficial Towards the external surface of the body.

The sternum is superficial to the heart.

Proximal Nearer to the trunk of the body. The shoulder is proximal to the elbow.

Distal Furthest from the trunk of the body.

The elbow is distal to the shoulder.

Regions

The body is split up into two main areas, the axial and appendicular regions. The axial region refers to the head, vertebral column and trunk, and the appendicular region refers to the pelvic girdles and the upper and lower limbs. Each area is further divided into descriptive regions.

Axial regions Description (pertaining to) Cephalic HeadFrontal Forehead Facial Face Occipital Back of the head Orbital Eye cavity Buccal Cheek Thoracic Chest Sternal Sternum Umbilical Navel (belly button) Inguinal Groin Pubic Mons pubis (pubic bone) Genital Reproductive organs Perineal Perineum

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Dorsum BackVertebral Spinal column Cervical Neck Thoracic Middle of the back Lumbar Lower back Sacral SacrumAppendicular regions Description (pertaining to)Upper limb Pectoral Chest Clavicular ClaviclesAcromial Acromion of the shoulder Scapular Scapula Interscapular Between the two scapulae Axillary Armpit Brachial Arm Antebrachial Forearm Cubital Elbow Carpal Wrist Digits Fingers Pollicis Thumb Palmar Palm of the hand Lower Limb Gluteal Buttocks Coxal Hip Femoral Thigh Patellar Front of the knee Popliteal Back of the kneeCrural Leg Tarsal Ankle Calcaneal Heel Pedal Foot

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Plantar Sole of the foot

REGIONS OF THE BODY

Body cavities

There are two main cavities within the body, the ventral and the dorsal cavities.

The dorsal body cavity is at the back of the body and is the smaller of the two cavities. It can be further divided into the upper and lower portions, the cranial cavity and the vertebral canal respectively.

The ventral body cavity is at the front of the body and is the larger of the two cavities. It can be further divided into three cavities, the thoracic cavity, abdominal cavity and pelvic cavity. The thoracic and abdominal cavities are divided by the diaphragm and the abdominal and pelvic cavities are continuous with each other.

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Name Description Boundaries Contain

Dorsal cavity

Small cavity at the back of the body.

Cranial cavity Upper portion. Bounded by the skull. Brain and meninges.

Vertebral canal Lower portion.

Bounded by the vertebral column, intervertebral discs and surrounding ligaments.

Spinal cord, spinal nerve roots.

Ventral cavity

Large cavity at the front of the body.

   

Thoracic cavity

Large cavity above the diaphragm.

It is bound laterally by the ribs (covered by costal pleura) and the diaphragm inferiorly (covered by diaphragmatic pleura)

Heart, lungs, trachea, oesophagus, large blood vessels and nerves.

Abdominal cavity

Large cavity below the diaphragm.

It is bound superiorly by the diaphragm, laterally by the body wall, and inferiorly by the pelvic cavity.

Gastrointestinal tract, spleen, kidneys and adrenal glands.

Pelvic cavity

Small cavity below the brim of the pelvis.

It is bounded superiorly by the abdominal cavity, posteriorly by the sacrum, and laterally by the pelvis

Urinary bladder, genitals, sigmoid colon and rectum.

Quadrants and regions of the abdomen

The abdomen can be divided by two lines into 4 quadrants or by 4 lines into 9 regions. The two lines that divide the abdomen into quadrants form a cross, the centre of which is positioned over the umbilicus (belly button). These quadrants are often used to indicate the location of pain.

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Quadrant Name Contains

Right upper quadrant

Liver, gallbladder, right kidney, duodenum, a portion of the ascending and transverse colons and the small intestine.

Left upper quadrant

Stomach, spleen, left kidney, pancreas, a portion of the descending and transverse colons and the small intestine.

Right lower quadrant

Appendix, caecum, a potion of the ascending colon and the small intestine.

Left lower quadrant

A portion of the descending and transverse colons and the small intestine.

QUADRANTS OF THE ABDOMEN

There are two vertical lines and two horizontal lines that divide the abdomen into a grid. The vertical lines also known as lateral lines are positioned using the middle of each clavicle as a reference. The upper horizontal line (also known as the transpyloric or subcostal line) is positioned at the level of the pylorus of the stomach close to the subcostal margin of the ribs. The lower horizontal line (also known as

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transtubercular line) is positioned at the level of the anterior superior iliac spines of the coxal (hip) bone.

Region Name Right hypochondriac region Left hypochondriac regionEpigastric region Right lateral region Left lateral region Umbilical region Right inguinal region Hypogastric (pubic) region Left inguinal region

REGIONS OF THE ABDOMEN

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SKELETAL TISSUE

The skeleton is a strong but bendable framework composed of 206 bones and their associated cartilages, connected by ligaments and muscles. It has 4 functions;

1. To support and protect the soft organs. 2. To give muscles somewhere to attach and something to pull

against. 3. To manufacture blood cells. 4. To provide storage for phosphorus and calcium.

Bone development

Osteoblasts are cells that convert soluble calcium chloride into insoluble calcium phosphate forming the basis of bone. This process is called ossification of which there are two types, intramembranous and intracartilaginous ossification. Intramembranous ossification occurs in the skull bones and is when the osteoblasts replace connective tissue with calcium phosphate.  Intracartilaginous ossification occurs in the majority of the skeleton and is when the osteoblasts replace hyaline cartilage with calcium phosphate.   

Name Ossification method Location Intramembranous ossification

Connective tissue is replaced by calcium. Skull bones.

Intracartilaginous ossification

Hyaline cartilage is replaced by calcium.

Most other bones.

There are also cells called osteoclasts that function to absorb calcium phosphate.  They work with the osetoblasts to remodel bone durng growth and throughout life. For example, in a long bone the osteoblasts originate in the tough outer covering of the cartilage called the periosteum and secrete bone onto the outer surface; simultaneously the osteoclasts remove bone from the inner surface, to create the medullary cavity and to prevent the bone becoming too thick and heavy.

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Clinical Considerations

Osteoporosis

When too much bone tissue is absorbed by the osteoclasts the bone becomes weakened and more likely to fracture. It is often common in women after the menopause and is known as osteoporosis.

Bone growth and repair

Calcium, phosphorus and vitamins C and D are essential to bone growth. Major phases of bone growth occur before birth, as a child grows and when recovering from injury or bone disease. The effects of these nutrients are summarised in the table below;

Nutrient Role in bone development

Foods it is found in; Deficiency causes

Calcium Needed to form calcium phosphate.

Milk, eggs, green vegetables.

Rickets in children and osteomalacia in adults (soft bones).

Phosphorous Needed to form calcium phosphate.

Meat, fish, egg yolks.

Rickets in children and osteomalacia in adults (soft bones).

Vitamin CPlays a part in laying down connective tissue.

Fresh fruit (particularly citrus fruit), green vegetables, tomatoes, potatoes.

Bone and cartilage are deficient in collagen, scurvy (ulceration and haemorrhage throughout the body).

Vitamin D

Allows calcium and phosphate to be absorbed into the intestine.

Animal fat, fish oils, can be converted from ergosterol by UV-rays from the sun on the skin.

Rickets in children and osteomalacia in adults (soft bones).

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Exercise also affects bone growth and repair as it increases blood supply to muscles and bones, stimulating growth. Muscles pulling on a bone will also affect the shape of a bone.

Types of bone tissue

There are two types of bone tissue, compact and spongy;

Compact bone forms the outer surface of bones and consists of Harversian systems.  Harversian systems are formed by tiny concentric plates of bone called lamellae which surround Harversian canals like the rings of a tree trunk.  Each canal contains blood vessels, nerves and lymphatic vessels.  In compact bone the lamellae and Haversian systems are packed closely together with only small spaces between the lamellae to house osteocytes and between each Harversian system for lymph.

Spongy bone fills the substance of bone and also consists of Haversian systems.  Spongy bone differs from compact bone in that the Harversian canals are larger and there are larger gaps between the lamellae. The spaces this creates are filled with red and yellow bone marrow, which is a mixture of fat and red blood cells. The spaces also help to reduce the weight of the bone.

Types of bone

Bones can be classified in terms of their shape and have been divided into four categories; long, flat, irregular and short bones.

Long bones

Long bones such as the femur and phalanges have a long shaft with two extremities; their main differences are associated with size. The shaft has an outer layer of compact bone with a hollow cavity called the medullary canal that contains yellow bone marrow for fat storage. Long bones are covered in periosteum and receive a rich blood supply.

Ossification

Long bones develop from three areas; the first to ossify is the shaft and is called the diaphysis. There are then two secondary ossification centres at either end of the shaft called epiphyses, which develop after birth. From each centre of ossification, bone tissue gradually spreads through the

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cartilage until they meet. There remains a layer of epiphyseal cartilage between the diaphysis and the epiphyses that allows the shaft to continue growing until the age of 18 - 25. At this time the epiphyseal cartilage will ossify and the bone will stop growing.

Flat bones

Flat bones are plates formed by two layers of compact bone held together by spongy bone. Examples include the squamous bones of the skull, the scapula and the sternum. They are smooth and flat to protect delicate organs and provide attachment for muscles.

Irregular bones

Irregular bones are a mass of spongy bone surrounded by compact bone. Examples include vertebrae, middle ear bones and the sphenoid bone of the skull.

Short bones

Short bones are roughly cube-like and are approximately equal in all dimensions. Examples include the carpal and tarsal bones.

Surface irregularities

Bones display certain types of irregularities that are identified in the table below;

Name

Articular (joint surfaces)

Non-articular (for muscle attachments)

Projection

Depression Description Example

Head Articular - Projectio

n - Spherical or disc-like end to a bone

Femur: head

Condyle Articular - Projectio

n - Rounded but oval

Femur: medial condyle

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Fossa Articular - - Depressi

onShallow depression

Humerus: coronoid fossa

Process - Non-articular

Projection -

Rough projection for muscle/ligament attachment

Radius: styloid process

Spine - Non-articular

Projection - Pointed rough

projection Scapula: spine

Tuberosity - Non-

articularProjection - Broad rough

projection

Tibia: tibial tuberosity

Trochanter - Non-

articularProjection - Large rough

projection

Femur: greater trochanter

Tubercle - Non-articular

Projection - Small rough

projection

Humerus: lesser tubercle

Crest - Non-articular

Projection - Long narrow

projection

Hip bone: iliac crest

Fossa - Non-articular - Depressi

on Notch

Hip bone: iliac crest

Groove - Non-articular

- Depression

Long narrow depression

Tibia: groove for tibialis posterio

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r tendon

Foramen - Non-articular - Depressi

on Hole

Occipital bone: foramen magnum

Sinus - Non-articular - Depressi

onCavity within the bone

Frontal bone: frontal sinus

APPENDICULAR SKELETON

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The appendicular skeleton is formed by the pectoral girdle and upper limb, and the pelvic girdle and lower limb, which are described below.

Pectoral girdle

The pectoral girdle refers to the bones that attach the upper limb to the thorax, and is made up of the scapula and clavicle.

Bone Name

No. of Bones Description Important Landmarks

Scapula 2

A large, flat, triangular bone that lies on the back of the trunk over the 2nd to 7th ribs.

It has a concave costal (front) surface known as the subscapular fossa.

It has a convex dorsal (back) surface which is split into the supraspinous fossa and infraspinatus fossa by the spinous process.

It has superior, medial and lateral borders.

Glenoid cavity - a shallow socket, which articulates with the head of the humerus to form the shoulder joint.

Acromion - a large lateral projection which articulates with the clavicle.

Coracoid - a large anterior projection that provides attachment for muscles.

Spinous process - a ridge of bone on the back of the scapula.

Clavicle 2

The clavicle is an S-shaped bone which extends almost horizontally to connect the upper limb (appendicular skeleton) to the trunk (axial skeleton).

Sternal end - enlarged medial end which articulates with the manubrium of the sternum and the first costal cartilage.

Acromial end - enlarged flattened lateral end which articulates with the acromion.

Upper limb

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The upper limb includes the shoulder, arm, forearm, wrist, hand and fingers and is attached to the axial skeleton via the pectoral girdle.

Arm and forearm

Bone Name

No. of Bones Description Important Landmarks

Humerus 2 The humerus is a long thick bone which forms the upper arm and provides attachment for the arm muscles.

It consists of an articular head above (proximally) which articulates with the scapula to form the shoulder joint and two articular condyles below (distally) which articulate with the radius and ulna to form the elbow joint.

The head and condyles are united by a long thick shaft.

Head - forms one third of a sphere that articulates with the glenoid cavity of the scapula.

Anatomical neck - a pinched section that joins the head to the greater and lesser tubercles.

Greater and lesser tubercles - large projections that provide attachment for the rotator cuff muscles.

Surgical neck - junction between the tubercles and the shaft; a common site for fractures.

Intertubercular groove - located anteriorly between the tubercles, it holds the tendon of biceps brachii.

Shaft - long and thick. Deltoid tuberosity - a

prominent roughened area about half way down the shaft for the attachment of the deltoid muscle.

Radial groove - A shallow groove found obliquely around the back and side of the shaft, it carries the radial nerve.

Capitulum - lateral of the two distal condyles, it

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articulates with the radius. Trochlea - medial of the two

distal condyles, it articulates with the ulna.

Coronoid fossa - an anterior fossa above the trochlea for the coronoid process of the ulna.

Radial fossae - an anterior fossa above the capitulum, for the head of the radius.

Olecranon fossa - a large posterior fossa for the olecranon of the ulna.

Medial and lateral epicondyles - found either side of the condyles and are easily felt through the skin.

Radius 2 The radius is a long bone situated on the lateral side side of the forearm.

Together with the ulna, it provides attachment for the forearm muscles.

It consists of an articular head above, which articulates with the humerus and ulna to form the elbow joint, and an articular surface below, which articulates with the carpal bones to form the wrist.

Its lower end rotates around the ulna, whose position is

Head - the cylindrical upper end is convex to articulate with the capitulum of the humerus, the circular circumference articulates with the ulna at the radial notch.

Radial (bicipital) tuberosity - a rounded projection on the medial side of the upper shaft; it provides attachment for biceps brachii.

Shaft - triangular in cross section.

Interosseous border - the raised medial border forms a sharp crest for the attachment of the interosseous membrane.

Ulnar notch - a depression on the medial aspect of the

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fixed, to supinate and pronate the forearm and hand.

expanded lower end; it articulates with the ulna.

Styloid process - a palpable projection from the lateral expanded lower end.

Ulna 2

The ulna is a long bone situated on the medial side of the forearm.

Together with the radius, they provide attachment for the forearm muscles.

It consists of a large trochlear surface above, which articulates with the humerus to form the elbow joint, and a small head below, which articulates with the radius to form the radioulnar joint

Its lower end is fixed allowing the radius to rotate around the ulna, whose position is fixed, to supinate and pronate the forearm and hand.

Trochlear notch - a large saddle shaped notch on its upper end; it articulates with the trochlea of the humerus.

Coronoid process - the anterior raised projection of the trochlear notch.

Olecranon - an elongation found proximally on the posterior surface the ulna.

Radial notch - lateral to the trochlear notch, it articulates with the radial head.

Head - the lower expanded end of the ulna.

Styloid process - a palpable medial projection which rotates around the ulna during forearm rotation.

Wrist and hand

Bone Name No. of Bones Description Important Landmarks

Carpal bones

16 The 8 carpal bones on each side form the

They are positioned in two rows, the proximal

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wrist. They articulate

above with the radius at the radiocarpal joint.

They articulate with each other at the intercarpal joints.

They articulate below with the metatarsals at the carpometacarpal joints.

row articulate with the radius and ulna and include the;

o Scaphoid , lunate, triquetral and pisiform.

The distal row articulate with the metacarpal bones and include the;

o Trapezium , trapezoid, capitate and hamate.

Scaphoid tuberosity - a bump that can be felt at the base of the thumb, just distal to the distal wrist crease.

Metacarpal bones

10 5 miniature long bones in each hand form the structure of the palm.

The 1st metacarpal lies laterally, providing a base for the thumb; the 5th metacarpal lies medially, forming a base for the little finger.

Proximally they articulate with the carpal bones at the carpometacarpal joints.

Distally they articulate with the proximal phalanges at the

Base - the expanded concave proximal ends that articulate with the carpal bones.

Shaft (body) - short. Head - the condylar

distal ends that articulate with the bases of the proximal phalanges.

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metacarpophalangeal joints.

Phalanges 28

14 miniature long bones that form the fingers, and articulate with each other at the interphalangeal joints.

 

Proximal Phalanges 5

They consist of a base, shaft and head.

They articulate proximally at their bases with the heads of the metacarpal bones and distally at their heads with the bases of the intermediate phalanges.

Base - the proximal, expanded, concave articular end.

Shaft (body) - short, joining the base with the head.

Head - rounded distal articular end.

Intermediate Phalanges 4

They consist of a base, shaft and head.

They articulate proximally at their bases with the heads of the metacarpal bones and distally at their heads with the bases of the intermediate phalanges.

Base - the proximal, expanded, concave articular end.

Shaft (body) - short, joining the base with the head.

Head - rounded distal articular end,

Distal Phalanges

5 They consist of a base, shaft and head.

They articulate proximally at their bases with the heads of the metacarpal bones and distally at

Base - the proximal expanded concave articular end.

Shaft (body) - short, joining the base with the head.

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their heads with the bases of the intermediate phalanges.

Head - distal non-articular end.

Pelvic girdle

The pelvic girdle connects the lower limbs to the trunk and refers to the two hip bones as well as the sacrum. The hip bones articulate with each other in front at the symphysis pubis (pubic symphysis) and with the sacrum behind at the sacroiliac joints.

Bone Name No. of Bones Description Important Landmarks

Hip bone (os coxa or innominate bone)

2 A large irregular shaped bone made up by the fusion of three bones;

o Ilium o Ischium o Pubis

The ilium forms the largest part of the hip bone; it forms two-fifths of the acetabulum and is expanded superiorly to form the fan-shaped ala.

The ischium forms the lower posterior part of the hip bone.

The pubis is the front part of the pelvis which articulates with the opposite bone at the symphysis pubis.

The two hip bones from each side articulate anteriorly at the

lliac crest - superior border of the ilium; it gives attachment to the abdominal muscles.

Anterior and posterior superior iliac spines - terminal projections at the front and back of the iliac crest.

Ischial tuberosity - a large roughened tuberosity on the posterior surface of the ischium; it provides attachment for the hamstrings.

Acetabulum - a cup shaped fossa on the external surface of the hip bone; it articulates with the femoral head.

Body of pubis - a flattened body.

Superior and inferior

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symphysis pubis, and posteriorly with the sacrum to form the pelvic girdle.

pubic rami - articulate with the ilium and ischium.

The obturator foramen - an opening in the front of the pelvis formed by the pubis and the ischium.

LATERAL ASPECT OF THE RIGHT HIP BONE

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MEDIAL ASPECT OF THE RIGHT HIP BONE

The pelvis refers to the articulated hip bones and sacrum. The pelvis is divided into greater and lesser parts by a plane through the pelvic brim. The pelvic brim is bounded by the arcuate lines anteriorly and laterally, and by the sacral promontory posteriorly. The greater, or false pelvis is above the pelvic brim and forms the lower part of the abdominal cavity. The lesser, or true, pelvis is below the pelvic brim.

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BOUNDARIES OF THE ABDOMEN AND PELVIS

In the female, the lesser pelvis forms the birth canal; and is described in terms of its inlet, cavity and outlet The pelvic brim forms the inlet.

The male and female pelvis differ slightly in size and shape. The male pelvis tends to be heavier, with the pelvic inlet being more heart-shaped. The female pelvis tends to be lighter, longer and thinner, with a circular pelvic inlet.

Male Pelvis Female Pelvis Heavier. Lighter and thinner. Heart shaped pelvic inlet. Round or oval shaped pelvic inlet. Prominent muscle and ligament attachments.

Less prominent muscle and ligament attachments.

Subpubic angle is less than 90 degrees.

Subpubic angle is greater than 90 degrees.

Longer narrower pelvic cavity. Shorter wider pelvic cavity.

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THE MALE AND FEMALE PELVIS

Lower limb

The lower limb includes the hip, thigh, leg, ankle and toes and is attached to the axial skeleton via the pelvic girdle.

Thigh and leg

Bone No. of Bones Description Important Landmarks

Femur 2 The bone of the thigh and the longest bone in the body.

It consists of a head above, which articulates with the hip bone to form the hip joint, and two large condyles below, which articulate

Head - nearly spherical with a smooth articular surface for articulation with the acetabulum of the hip bone.

Fovea - a pit in the medial aspect of the femoral head that gives attachment to the ligament of the head of femur (ligamentum teres).

Neck - constricted area below the head.

Lesser and greater trochanters - expanded tuberosities from the

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with the tibia and patella to form the knee joint.

neck which provide attachment for muscles.

Lateral and medial condyles - two large articular prominences at the distal end of the shaft; they articulate with the tibial condyles.

Intercondylar fossa - a deep notch separating the medial and lateral condyles posteriorly.

HIP JOINT

Bone No. of Bones Description Important Landmarks

Patella 2 The patella, the largest sesamoid bone in the body.

It is embedded in the tendon of quadriceps femoris, and is located anterior to the knee-joint.

Its outline is somewhat in the shape of an inverted triangle.

It is separated from the femur by the suprapatellar

Base - situated superiorly, it gives attachment to the quadriceps muscles.

Apex - is pointed and directed inferiorly.

Posterior surface - is covered with articular cartilage with facets for articulation with the medial and lateral femoral condyles.

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bursa.

Tibia 2

The tibia is the larger and medial of the two bones of the leg.

It consists of two expanded extremities joined by a shaft.

Tibial plateau - the upper surface of the proximal end of the tibia.

Medial and lateral condyles - two prominent masses which articulate with the femur.

Tibial tuberosity - a large tuberosity found on the front of the upper end of the tibia which gives attachment to the patellar ligament.

Shaft - long and approximately triangular in cross section.

Anterior border - found on the front of the tibial shaft, it is commonly referred to as the shin and is easily palpable.

Lateral border - found on the lateral side of the tibial shaft, it gives attachment to the interosseous membrane.

Distal surface - articulates with the talus at the ankle joint.

Medial malleolus - a thick process formed by the distal expanded medial end of the tibia; it is easily palpable.

Fibula 2

The fibula is the lateral and more slender of the two bones of the leg.

Head - the expanded proximal end which articulates with the lateral condyle of the tibia.

Lateral malleolus - the distal expanded and somewhat flattened end which articulates with the talus

Shaft- elongated and slender it passes between the proximal and distal ends.

Medial crest - a slender medial ridge that gives attachment to the interosseous membrane.

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Foot and ankle

Bone Name

No. of Bones Description Important Landmarks

Tarsal bones 14

There are 7 tarsal bones that make up the posterior part of each foot.

 

Talus - the second largest tarsal bone it forms the summit of the foot.

Calcaneus - it is the largest tarsal bone and forms the heel.

Navicular - sits in between the talus and the cuneiforms bones.

Medial cuneiform - wedge shaped bone, lies between the talus and 1st metacarpal bone.

Intermediate cuneiform - wedge shaped bone, lies between the talus and 2nd metacarpal bone.

Lateral cuneiform - wedge shaped bone, lies between the talus and 3rd metacarpal bone.

Cuboid - lateral to the cuneiforms and in between the 4th and 5th metatarsal bones and the calcaneus.

Metatarsal bones 10

5 miniature long bones in each foot.

The 1st metatarsal lies laterally, providing a base for the big toe; the 5th metatarsal lies medially, forming a base for the little toe.

Base - the expanded proximal end.

Shaft (body) - short. Head - is the condylar

distal end.

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Phalanges 28

The phalanges are miniature long bones which form the toes.

There are 14 phalanges in each foot;

o 5 proximal phalanges.

o 4 intermediate phalanges.

o 5 distal phalanges.

Base - the expanded concave proximal end.

Shaft (body) - short. Head - the condylar distal

end that articulates with the base of the proximal phalanx.

Clinical Considerations

Osteoporosis

In a patient with osteoporosis their bone mineral density (BMD) is lower than normal, which makes their bones weak and brittle, and much more susceptible to fractures.

In a normal person bone is continuously remodelled; old bone is absorbed and new bone is laid down. In young people bone is laid down at a quicker rate than it is absorbed and so our bone mass increases. This cumulates in people having a peak bone mass in the years between their mid 20s and 30s. After this age the rate at which bone is absorbed becomes slightly quicker than it is laid down. This cumulates in the gradual lose of bone density with age.

Factors such as low intake of dietary calcium and vitamin D, a sedentary life style, a drop in oestrogen levels due to the menopause, alcoholism and smoking, can all accelerate this process.

Preventing osteoporosis is the best way to treat it, this includes a diet rich in calcium and vitamin D and regular exercise.

Fractures

A fracture is another name for a broken bone and usually occurs due to trauma. If the fracture does not penetrate the skin then it is referred to as a

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closed fracture. If the fractured bone penetrates through the skin then it is referred as an open or compound fracture and is more serious because the wound can allow infection into the area.

Fractures have many classifications; a few of them are listed below.

Classification of fractures Description

Complete The bone has broken into two pieces

Transverse Fracture is at right angles to the bones shaft (long axis)

Spiral The bone has been twisted apart

Greenstick Fracture occurs on one side of the bone only, like when you bend a greenstick.

Comminuted Three or more fragments Stress Small cracks (hair line) on the surface of the bones

If a broken bone is moved, additional damage can be caused to the fracture as well as to the surrounding structures. The movement of the fracture must therefore be controlled 'immobilized'. This is often achieved with a splint or a cast, but more serious fractures may need surgical intervention to re-align the bones and internal or external fixation (plates, wire, screws and rods) to hold the bones in position until they have knitted together.

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AXIAL SKELETON

The axial skeleton forms the central axis of the body. It is made up of the skull, the vertebral column, the ribs and the sternum.

Skull

The bones of the skull can be divided into two categories, those that form the vault or cranium and enclose the brain, and those which form the framework of the face.

Cranial bones

There are 8 cranial bones which form a case to protect and contain the brain;

Bone No. of Bones Description Important Landmarks

Frontal bone 1

The frontal bone is a single convex bone extending from the orbits to the coronal suture behind.

It forms the forehead and the roof of the orbits.

Frontal eminences - smooth elevated prominences above the eyebrows.

Supra-orbital margins - are two ridges which lie beneath each eyebrow.

Orbital plates - two horizontal plates that form the roofs of the orbits.

Frontal sinuses - are air filled cavities, lined with a mucous membrane and that lie within the frontal bone above and behind the superciliary arches.

Parietal bones

2 The two parietal bones form the bulk of the vault of the skull behind the frontal bone.

Grooves for meningeal vessels - the concave internal surface of the parietal bone shows grooves related to the meningeal vessels.

Groove for the superior sagittal sinus - a groove present along the internal surface of the sagittal

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Each bone is quadrilateral in shape and articulates with the frontal, occipital, temporal and sphenoid bones as well as with each other.

 

margin.

Occipital bone 1

The occipital bone forms the back and base of the skull.

It is divided into squamous, lateral and basilar parts.

External occipital protuberance - an external pronounced lump on the back of the head.

Foramen magnum - a large, ovoid opening in the floor of the posterior cranial fossa.

Occipital condyles - located on the either side of the foramen magnum on the lateral parts of the occipital bone they articulate inferiorly with the atlas at the atlanto-occipital joints.

Temporal bone

2 Each temporal bone contributes to the base and to the lower lateral aspect of the skull.

It is divided into squamous, petrous, mastoid and tympanic parts.

The squamous part is thin,

Zygomatic process - an arched process that projects from the lower part of the squamous part to articulate with the zygomatic bone.

Mastoid process - a large prominence located immediately behind the external acoustic meatus; it gives attachment to the sternocleidomastoid muscle.

External acoustic meatus - the opening into the temporal bone

Styloid process - is an elongated, narrow projection of bone which

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translucent and forms the anterior and upper part of the bone.

The petrous part is the solid, wedge of bone that forms most of the posterior and inferior portions of the temporal bone.

The mastoid part of the temporal bone lies below the squamous part and behind the tympanic part.

The tympanic part of the temporal bone surrounds the external auditory meatus.

passes downwards and forwards from the base of the tympanic part.

Ethmoid bone

1 The ethmoid is a single mid line bone which forms parts of the nasal septum, medial wall of the orbital cavity and the roof and lateral wall of the

Cribriform plate - a thin plate of bone that forms a large part of the nasal roof. It is perforated with holes (olfactory foramina), which transmit the olfactory nerves from the nose to the olfactory bulbs.

Perpendicular plate - a thin, mid line quadrilateral plate of bone, which descends vertically from the cribriform plate to form the superior part of the nasal septum.

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nose.

Ethmoidal labyrinths - a network of air cells which lie under the cribriform plate.

Superior nasal concha - upper, thin scroll-like plate of bone that hangs down from the medial surfaces of the ethmoidal labyrinth.

Middle nasal concha - lower, thin scroll-like plate of bone that hangs down from the medial surfaces of the ethmoidal labyrinth.

Sphenoid bone 1

This single bone is found in the base of the skull and is often described as being ‘butterfly-shaped’ as it consists of a central body and three paired processes.

Greater wings - two strong processes of bone, which arise from the sides of the body.

Lesser wings - are two thin triangular plates, which arise from the upper and anterior parts of the body.

Pituitary (hypophysial) fossa - a deep pit in the body, which houses the pituitary gland.

There are usually two air sinuses within the body of the sphenoid bone which communicate with the nasal cavity.

Optic canals - two holes located where the lesser wing attaches to the body; they transmit the optic nerves.

Superior orbital fissures - a large fissure between the greater and lesser wings at the back of the orbit. It transports important nerves and vessels into the orbit.

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SKULL VIEWED FROM THE SIDE

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SKULL CUT VIEWED FROM ABOVE

Clinical Considerations

SinusitisThe frontal sinuses within the frontal bone of the cranium are lined by mucous membrane and may become infected, causing sinusitis.

Facial bones

These 14 bones do not contribute to the cranial cavity, but form the structure of the face;

Bone Number of bones Description Important Landmarks

Maxilla 2 The paired maxillary bones support the teeth of the upper jaw

Alveolar process - extends inferiorly from the body of the maxilla and supports the teeth within bony sockets.

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and contribute to much of the skeleton of the upper face.

Zygomatic process - projects laterally from the body and articulates with the zygomatic bone.

Palatine process - extends horizontally to form most of the hard palate.

Maxillary sinuses - are the largest of the paranasal sinuses and are situated in the bodies of the maxillary bones. It communicates with the nasal cavity through the maxillary hiatus.

Zygomatic bones 2

The two zygomatic bones form the skeleton of the cheeks and the inferior and lateral walls of the orbit.

Frontal process - forms outer margin of the orbit by articulating with the zygomatic process of the frontal bone.

Temporal process - forms the prominent zygomatic arch by articulating with the zygomatic process of the temporal bone.

Mandible 1 The mandible is the only movable bone in the skull.

It consists of a horizontal, horseshoe-shaped body and two vertical rami.

Body - an arch that forms the main bulk of the mandible.

Alveolar ridge - forms the superior margin of the body of the mandible and houses the lower teeth.

Rami - these are the flat vertical projects that ascend from the obtuse angle of the body.

Coronoid - found on the top of the ramus it lies anteriorly and serves as an attachment

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point for temporalis. Condylar processes - found

on the top of the ramus it lies posteriorly and articulates with the temporal bone at the temporomandibular joint (TMJ).

Palatine bones 2

The palatine bone forms part of the hard palate, the floor and lateral wall of the nasal cavity and the floor of the orbit.

Horizontal plate - forms the posterior portion of the hard palate.

Perpendicular plate - the medial surface forms the lateral wall of the nasal cavity and articulates with the inferior nasal concha.

Orbital process - projecting from the perpendicular plate it forms the posterior part of the orbital floor.

Hyoid bone

1 The horseshoe-shaped hyoid bone is situated in the upper part of the front of the neck, at the level of C3.

It does not articulate with any bones but is maintained in position by the muscles, ligaments and membranes attaching to it.

It gives attachment to the

Body - the curved medial portion of the bone.

Lesser cornu - two small superior projections from the junction between the body and the greater cornu.

Greater cornu - two backward projections from the body.

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tongue muscles.

Inferior nasal conchae

2

The inferior nasal conchae are curved plates of bone attached to the lateral wall of the nasal cavity covered in mucous membrane.

There are also superior and middle conchae but they are part of the ethmoid bone.

It has medial and lateral surfaces.

Superior border - attaches the bone to the lateral wall of the nasal cavity.

Inferior border - thick and curved inwards, it lies free within the nasal cavity.

Lacrimal bones 2

The paired lacrimal bones are small, thin and rectangular, and each lie in the anterior part of the medial wall of the orbit.

They house the lacrimal sac which collects tears from the eyes via the nasolacrimal duct and empties them into the nasal cavity.

Lacrimal fossa - a depression that houses the lacrimal sac.

Nasal bones

2 The two nasal bones form the upper part of the

Superior border - articulates with the frontal bone.

Inferior border - is

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bridge of the nose.

continuous with the lateral nasal cartilage.

Vomer 1

The vomer is a flat bone which forms the lower part of the septum of the nose.

Alae - a wing like projection which articulates with the sphenoid bone.

Anteriorly it articulates with the septal cartilage.

SKULL VIEWED FROM THE FRONT

Trunk

The trunk includes the thorax and abdomen and is supported by the thoracic cage and vertebral column.

Thoracic cage

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Bone Number of bones Description Important Landmarks

Sternum 1

The sternum is a flat bone forming the middle part of the anterior thoracic wall.

It is constituted from three bones; the manubrium sterni, body and xiphoid process.

o Manubrium - a triangular portion on top of the body.

o Body - the largest part of the sternum.

o Xiphoid process - is the narrow irregular shaped inferior end of the sternum.

Suprasternal notch - a large indentation in the superior border of the manubrium.

Articular fossae for clavicles - two indents found either side of the suprasternal notch for articulation with the clavicles.

Articular facets for the 1st costal cartilages - shallow depressions either side of the manubrium for articulation with the 1st costal cartilage.

Sternal angle - the junction between the manubrium and the sternal body.

Facets for the costal cartilages - indents found on the lateral borders of the body for articulation with the 2nd - 7th costal cartilages.

Ribs 24 The ribs are 12 paired bones which form the curved walls of the thorax.

The first 7 ribs are termed 'true ribs' and join the sternum directly via costal cartilages.

Head - slightly expanded, it is found at the back of the rib and has two articular facets for articulation with the corresponding thoracic vertebrae.

Shaft - the longest part of the rib, it is thin and

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The 8th to 10th pairs of ribs are joined to the sternum via the cartilage of the rib above and so termed 'false ribs'.

The lowest 2 ribs are unconnected to the sternum and termed 'free-floating'.

All the ribs are connected behind to the vertebral column.

flat with a curved convex external surface.

Tubercle - located at the angle of the rib at the junction between the neck and the shaft, it has an articular part for articulation with the transverse process of the corresponding thoracic vertebrae.

Vertebral column

The vertebral column forms the axis of the trunk and is formed by 31 firmly connected irregular bones. It allows minimal movement and encases and protects the spinal cord. The vertebral column displays a series of normal curvatures when viewed from the side (in the sagittal plane); the cervical, thoracic, lumbar and pelvic curves. The cervical curve is convex forwards, the thoracic curve is concave forwards, the lumbar is convex forwards and the pelvic curve is concave forwards and downwards.

The thoracic and pelvic curves are primary curves and are present at birth; the cervical and lumbar curves are secondary curves and develop after birth. The cervical curve develops when the child is able to hold its head up and the lumbar curve when they begin to walk.

The curves give the vertebral column strength when in the upright position by distributing the weight evening and acting as a shock absorber.

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NORMAL CURVES OF THE VERTEBRAL COLUMN

Clinical Considerations

Abnormal curves of the spine

The overall alignment of the spine can be altered in many conditions; degenerative, congenital or traumatic and can be severe enough to result in an abnormal curvature of the spine. Abnormal curves are described as below and their severity is measured using Cobb's Measurement Method.

All vertebrae possess similar main features, but the size and shape of them change depending on their position along the vertebral column. The vertebral body is the most anterior and largest structure of each vertebra, with the exception of the first cervical vertebra which does not have a body. Each body is separated from the bodies of adjacent vertebra by a fibrous intervertebral disc. Behind the body is a hole, the vertebral canal (foramen) for the passage of the spinal cord and meninges. Projecting posteriorly from the vertebral body are two stout pedicles, which together with the laminae and spinous process form the vertebral arch posteriorly. Between the pedicles of adjacent vertebrae are openings called intervertebral foramen; they allow the exit of the spinal nerves from the vertebral canal. The two laminae are broad, flat structures which emerge

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posteriorly from each pedicle; they join in the mid line to form a posterior projection, the spinous process. The transverse processes project laterally from the sides of the vertebrae at the junctions between the laminae and the pedicles. The superior articular facets project superiorly and the inferior articular facets project inferiorly from the junctions between the laminae and the pedicles. They articulate with the articular facets of the adjacent vertebrae.

Bone Number of bones Description Important Landmarks

Cervical vertebrae

7 The cervical vertebrae form the neck.

The 1st (atlas) and 2nd (axis) cervical vertebrae are specialised to allow the head to rotate on the neck.

The atlas does not have a body; it is a ring of bone that articulates with the occipital bone of the cranium.

The body of the axis has an upward projection

Vertebral foramen - large and triangular.

Body - small and broad the bodies are separated from each other by the cervical intervertebral discs; except between the 1st and 2nd vertebrae where there is no disc.

Spinous process - short bifid processes.

Transverse processes - short with a transverse foramen for the passage of the vertebral arteries.

Superior articular facets - they point postero-superiorly to articulate with the inferior facets of the vertebra above.

Inferior articular facets - they point antero-inferiorly to articulate with the superior facets of the vertebra below.

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(dens) which the atlas rotates around.

Thoracic vertebrae 12

The thoracic vertebrae form the vertebral column of the thorax.

The 12 bones articulate with the 12 ribs.

Vertebral foramen - small and round.

Body - heart-shaped, they are separated from each other by the fibrous thoracic intervertebral discs.

Spinous processes - long and thin.

Transverse processes - large and club-like.

Superior articular facets - they point postero-superiorly to articulate with the inferior facets of the vertebra above.

Inferior articular facets - they point antero-inferiorly to articulate with the superior facets of the vertebra below.

Lumbar vertebra

5 The lumbar vertebrae are the largest vertebrae as they are designed to support the weight of the body.

Vertebral foramen - triangular. Body - large and kidney-shaped,

they are separated from each other by the fibrous lumbar intervertebral discs.

Spinous process - quadrangular. Transverse process - long and

thin. Superior articular facets - they

point medially and slightly posteriorly to articulate with the inferior facets of the vertebra above.

Inferior articular facets - they point laterally and slightly

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anteriorly to articulate with the superior facets of the vertebra below.

Sacrum 5

The 5 sacral vertebrae fuse to each other to form the large triangular sacrum.

It is concave anteriorly.

It articulates laterally with the hip bones.

Sacral canal - triangular it is the vertebral canal of the sacrum and contains the cauda equina and the lower dural sac.

Body - the bodies are fused together to form the ventral and dorsal surfaces of the sacrum.

Sacral promontory - the upper border of the upper end of the 1st sacral vertebral body.

Ventral and dorsal sacral foramina - 4 holes on the front and 4 holes on the back of the sacrum which communicate with the vertebral canal and transmit the sacral spinal nerves.

Median sacral crest - an irregular raised ridge on the back of the sacrum; it represents the fused spinous processes of the sacrum.

Alae (lateral parts) - wide above and narrower below, they represent the fused transverse processes and pedicles of the sacrum.

Sacral hiatus - an inverted U-shaped opening in the posterior wall of the sacral canal.

Coccygeal vertebrae

3-5 The 3-5 coccygeal vertebrae fuse to each other to form the

Cornu - two processes that project from the sides of the 1st coccygeal vertebra to articulate with the sacrum above.

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coccyx.

A TYPICAL CERVICAL, THORACIC , AND LUMBAR VERTEBRA VIEWED FROM ABOVE

Curvature Description Scoliosis Side-to-side (lateral) curvatures.

Kyphosis Hunchback curve (forward bend) commonly found in the thoracic or thoracolumbar regions.

Lordosis Excessive inward curve of the spine, commonly found in the lumbar region.