ANAT2003 Regional Anatomy: Body Cavities

• ANAT2003 is a Regional Anatomy Unit
• The course covers the thorax, abdomen, pelvis, head, and neck
• The first half of the semester focuses on the thorax, abdomen, and pelvis regions
• The second half of the semester focuses on the head and neck regions
• The course will investigate bones, joints and ligaments, muscles, viscera, and neurovasculature for each region
• Lab 1 provides orientation to the trunk

Body Cavities

• Ventral body cavities include thoracic and abdominopelvic cavities
• Dorsal body cavities include cranial and spinal cavities
• The Thoracic Cavity contains the Mediastinum, Superior and Inferior portions, and Pulmonary Cavities: Right and Left
• The Abdominopelvic cavity contains Abdominal and Pelvic regions

Body Membranes

• The Cranial and Spinal Cavities contain meninges
• The Thoracic Cavity contains pleura around the lungs and pericardium around the heart
• The Abdominopelvic Cavity contains peritoneum

Joint Types

• Fibrous joints are immovable
• If long fibers are present in fibrous joints, they may allow movement
• Cartilaginous joints are slightly movable
• Synovial joints are highly or freely movable
• The range of motion (ROM) in synovial joints depends on the articular shapes or subtype of the synovial joint

Fibrous Joints

• Fibrous joints are mostly immovable and referred to as synarthroses
• Sutures, gomphoses, and syndesmosis are examples of fibrous joints

Cartilaginous Joints

• Cartilaginous joints are slightly movable and referred to as amphiarthroses
• Primary cartilaginous joints contain bone-hyaline cartilage-bone structures
• Secondary cartilaginous joints contain bone-hyaline cartilage-fibrocartilage-hyaline cartilage-bone structures

Synovial Joints

• Synovial joints are freely movable and referred to as diarthroses
• The structure of synovial joints are bone-hyaline cartilage-SPACE-hyaline cartilage-bone
• The range of movement depends on the articular bone shapes
• Some joints contain articular discs
• Hilton's Law: The nerve supplying a joint supplies prime movers and skin covering their distal attachments

Synovial Joint Types

• Nonaxial joints permit gliding or sliding movements
• Uniaxial joints permit flexion and extension only, or rotation
• Biaxial joints permit flexion and extension, abduction and adduction, and circumduction
• Multiaxial joints permit movement on several axes
• Examples of joints: Atlanto-axial (pivot joint), Elbow (hinge joint), Carpometacarpal (saddle joint), Metacarpophalangeal (condyloid joint), and Hip joint (ball and socket)

Torso/Trunk

• Main part of the body contains the chest, abdomen, pelvis, and back including the body's organs and backbone
• The torso/trunk extends the neck and limbs
• Three main segments: thoracic, abdominopelvic, and perineum
• The musculoskeletal framework including vertebral column, ribs, and hip bones is joined by multiple articulations and supported by muscles
• Cavities like thoracic and abdominopelvic contain viscera

Typical Vertebra Features

• Vertebral body
• Pedicle
• Vertebral arch
• Lamina
• Inferior articular surface
• Superior articular surface
• Transverse processes
• Spinous process

Typical Vertebrae

• Cervical vertebrae (n=7; typical = C3-C6)
• They have small bodies
• Large vertebral foramen
• Short bifid spinous process
• Transverse foramina in transverse processes
• Articular processes/facets oriented close to horizontal plane
• C1 & C2 are atypical vertebra
• Thoracic vertebrae (n=12)
• They have heart shaped bodies
• Small vertebral foramen
• Costal facets (for ribs) – on body & transverse processes
• Long spinous process slopes downwards
• Articular processes oriented vertically, facets in coronal plane
• Lumbar vertebrae (n=5)
• They have large kidney shaped bodies
• Large triangular vertebral foramen
• Quadrate spinous process oriented horizontally
• Articular processes oriented vertically, facets close to sagittal plane

Thoracic Vertebrae

• T2-T10 are thoracic vertebrae
• They feature superior and inferior costal facets and costal facets on transverse processes

Typical Ribs

• Typical ribs are ribs 3-9
• 'Costo' = rib; 'chondro' = cartilage
• The parts of the rib: the angle, tubercle (for costotransverse joints), outer surface, articular facet, neck, inner surface, costal groove

Ribs

• Rib 2 is flat, but longer than rib 1
• Ribs 11-12 do not have tubercles for the transverse process
• Rib 1 has grooves for the subclavian artery and vein, and a tubercle for the scalenus anterior

Sternum

• Suprasternal notch = jugular notch
• Manubriosternal joint is a symphysis that ossifies with age
• A horizontal plane passing through the manubriosternal joint is the transverse thoracic plane
• The Xiphisternal joint is a primary cartilaginous joint ossifies with age
• True ribs (1-7) articulate with the sternum directly
• False ribs (8-10) do not articulate with the sternum directly
• Floating ribs (11-12) do not articulate with the sternum

Trunk Articulations

• Primary cartilaginous joints: sternocostal and costochondral
• Secondary cartilaginous joints: manubriosternal, intervertebral, lumbosacral, sacroccocygeal, and the pubic symphysis
• Synovial joints: sternocostal, xiphisternal, interchondral, costotransverse, costovertebral
• There are also combined synovial and fibrous joints like the sacroiliac

Joints of Thoracic Wall

• Intervertebral joints contain Adjacent Vertebral Bodies bound together by IV Disc, which supports the anterior and posterior longitudinal ligaments
• Movements are limited to small degrees of rotation
• Costovertebral joints contains the head of each rib with the superior demi or costal of the vertebral body or the same number, and the inferior demi- or costal facet of the vertebral body
• Costotransverse joints contains tubercle of the rib with the transverse process of vertebra of same number, supports the costotransverse, lateral and superior costotransverse ligaments
• No movement normally occurs at the costochondral joint; costal cartilage provides flexibility
• 1st sternocostal or primary cartilaginous joint (synchondrosis), where there is articulation of 1st costal cartilage with the manubrium of the sternum
• 2nd- 7th sternocostal or synovial plane joint, where there ist articulation of the 2nd- 7th pairs of Costal cartilages with the sternum

Costovertebral & Costotransverse Joints

• Costovertebral Joints Participants in joint; of head of rib; Body of vertebra; superior to rib in the Intervertebral disc. Head of rib (crest); Body of vertebra, of same number; as rib.
• The Costotransverse Joint contains the Transverse process; of vertebra, of the same number as rib 7 is attached to the tubercle of rib with an Axis, of rib rotation
• Rib 7 articulates with the following vertebral structures; the body of ___ superior; vertebra and the body of ___ same vertebra and transverse process of ___same vertebrae.

Costovertebral j (j of head of the rib)

• Costal facet on vertebra + facet on rib head = plane synovial j
• Ribs 2-10: between 2 adjacent vertebral bodies
• Intra-articular ligament (a) joins crest of rib with intervertebral disc; divides joint cavity into 2 parts
• Atypical ribs (1, 11, 12) have one joint cavity
• Radiate (triradiate) ligaments (b) are upper, lower, and middle

Costotransverse j (j of rib tubercles)

• Synovial joints are present between the facet on rib tubercle + vertebrae
• This is supported by costotransverse ligaments

Rib Articulation

• Note: rib 1 forms primary cartilaginous j with the manubrium and is not very movable
• Upper ribs (2-7) rotate about an axis that runs longitudinally through the neck of the rib
• Lower ribs (8-10) glide

Movement of Thoracic Wall

• Upper limb elevation increases the AP dimension of the thorax (pump-handle mechanism)
• Lower limb elevation increases TV (bucket-handle)

Thorax/Thoracic Cage

• The superior part of the trunk makes up the Thorax/Thoracic Cage region
• It consists of an anterior sternum, costal cartilages, posterior thoracic vertebrae and IVD, and lateral pairs of ribs and their rib cartilage
• The chest region consists of two openings which make up the Superior (thoracic aperture) & Inferior (articulation of each rib with vertebral column)

Upper Thoracic Aperture

• Articulation w/ thoracic vertebral column w/ the upper 7 ribs ( the "True ribs)
• In the absence of the vertebral column, the upper 7 ribs ( true ribs) do not properly meet
• Ribs are considered "False ribs" (ribs (8,9,10)) the intercostal joints in coordination with the ribs articulate them
• The floating ribs do not articulate with the upper true ribs and they articulate with the Anterior ends of ribs' costal cartilages as if they "float".

Thoracic Cage

• Thoracic Cage = truncated cone:
• The narrow upper end called "thoracic inlet" has a continuous line with the neck's spinal cord
• Has a spinal cord & a neck which each a separated from the fascia
• Broad lower end = thoracic outlet, separated into 2: a transverse thoracic or a "diaphragm"

Thoracic Inlet (bony)

• Gateway to the root of the neck through the Superior thoracic aperture
• The thoracic inlet is located anterior to the superior surface of T1 vertebra, medial to the cartilage of first costal cartilage and the first rib itself

Muscular Diaphragm on Brachial Plexus Route

• Anterior: the superior border on the manubrium sterni
• Posterior: anterior spinal surface of the upper T1 vertebra
• Lateral position: Medial border connecting & linking the first rib to the first cartilage
• The arteries are positioned in a manner "downward and slightly forward" with The aorta's Manubrium sterni and is located between the level linking T3 vertebrae.
• The arteries/diaphragm is prone to injury around the thoracic inlet making a "brachial plexus arche"

Diaphragm and Muscle Function

• It is a truncated cone formation
• It's structure has*:

1. The root of the neck (narrow to wide)

• The origin = thoracic inlet
• Separation occurs partially from Fascia
• The distal end separates via the "thoracic diaphragm".
• Inferior thoracic aperture is enclosed to separate muscle segments via "thoracic & abdominal" sections.

4 Boundaries of the Trunk (bone)

• Bone is from the Xiphisternal joint
• vertebral column = Body of 12th thoracic vertebra'
• Costal margin is positioned along with 11-12 rib segments.
• "thoraco-abdominal" (the diaphragm is the Inferior component)
• The dome allows for an inferior thoracic and creates an abdominal barrier
• Domed portions made from flat muscle for respiration
• Muscle from the thoracic origin connect into the muscle cord
• The insertion point of the muscular fibre

Muscle attachments and origin

Muscular attachments on diaphragmatic fibre & tissue around two domes The right dome is situated over the right side

3 origins and attachments

1. Connective cords- attached the medial centre of the body & lumbar(L1-L3) section
2. Medial attachments=L1-L3 vertebral segments & cord, anterior longitudinals (linking)
3. 1st section is attached to the aorta & spinal cord.
4. The upper part from (L1)
5. Second connective tissue or "tendinous arche" linking the aorta with a similar tissue and spinal surface (L2)
6. Connective arche tissue connecting the "quadratus lumborum arc" to the spinal cord (L2).
7. The connecting point, linked to the coastal (rib) and ( L2-rib 12) joints. Sternal section, along the rear spinal location to the "xiphoid process", linking it to the spinal cord.

Diaphragm (2)

• 2 crura: The Right Crus (RC) is bigger than the Left Crus (LC)
• 3 parts: sternal, costal, vertebral (lumbar)
• 5 ligaments include: 1 x median; 2 x medial; 2 x lateral Innervation: phrenic nerve (C3-C5)

Caval vs. Oesophagal openings

There are 3 sections: Caval, Esophageal & Aortic with respective vertebrae

1. Spinal cord linking to all 3
2. From the upper to distal sections are inter linked
3. Inferior and transverse positioning is required
4. Distal portions are (linked and parallel)
5. Transverse arteries function as a unit
6. Transverse arteries support celiac segments
7. Vein and nerves: Connective vein and vessels

Spinal Cord Vertebrae Connections for Breathing

• The diaphragm assists when the (spinal cord vertebrae) functions
• The diaphragm is in the the vertebrae's peripheral sides and the centre of the body

Muscles and Support

• Breathing muscles have the phrenic cord linked back to the "centre cord" sections
• Spinal cord sections ( C3 -C5) are in the rear vertebrae or peripheral rib area

Breathing Function

• This main function of the "diaphragm" assists with cord and muscle support for inhalation
• The secondary function increases spinal support allowing weight distribution.

Wall Muscle (intrinsic and extrinsic):

• Upper Limb Muscle: posterior with the superior border & chest(UL) muscle and anterolateral back muscle.

Lower Limb muscle

• tv.p. area, the vertebrae attaches from rib 1, or is adjacent & linking to the middle scalene position which is
• tv.p vertebrae and attaches to L1, or is adjacent & linked to the posterior scalene cord.

Intercostal sections of the rib

1: Attaches via the Transverse portions from (T7-11)

• Distal ribs sections which lie in between rib joints from ( 2 - 6).
• Muscular segments are separated in the anterior side of the rib
• Dorsal segments transverse anteriorly

Diaphragm in relation to the Lungs

• (the upper sections) external attachment helps movement;
• Muscle placement is anteriorly;
• The mid-section has the outer layer;
• The dorsal attachment has the inner location;
• The diaphragm in the spinal column runs with muscle covering and functions a protection from fluid.

Intercostal Space Location

The external cord and fluid placement The arteries are found in the"thoracic aorta" or the heart muscle The bundle of "intercostal" or vein bundles

Three Muscle layers and Attachments via the Upper Limbs

• outer most muscle that is "horizontal" across the body assists via the outer placement & helps elevate ribs
• The middle muscle placement has anterior and posterior sections.
• Middle Placement
• The most muscle supports upper joints on sides
• Elevates joints to hold ribs.
• The distal muscles (the bottom most layer) connect the inner rib locations.

The Mediastinum location for the Lungs

• Three key components form lung structure:

1. pulmonary (right) or peripheral sections.
2. peripheral left lung
3. spinal cord with the mediastinum location.

Three areas of the spinal cord

• Anterior border
• Rear segments/posterior with middle support
• The main muscle has 2 sections: -superior -inferior