This document provides information on the anatomy of the abdomen, including the lumbar spine, vertebrae, muscles of the anterior and posterior abdominal walls, and joints of the lumbar region. It describes the key features of the lumbar vertebrae and distinctive characteristics of L5. It also details the layers of the anterior abdominal wall, flat and vertical muscles, and posterior muscles including the psoas major, quadratus lumborum and diaphragm. Applied concepts like sacralization and lumbarization are also mentioned.

1. Dr. EIMAN SUMAYYAH
DPT, MSPT NEUROLOGY(KMU)
OSTEOLOGY OF ABDOMEN

2.  The lumbar spine is the third region of the
vertebral column, located in the lower
back between the thoracic and sacral
vertebral segments.
 It is made up of five distinct vertebrae,
which are the largest of the vertebral
column. This supports the lumbar spine in
its main function as a weight bearing
structure
LUMBAR VERTEBRAE

3.  Although the lumbar vertebrae lack some of the more
distinctive features of other vertebrae, there are several
characteristics that help to distinguish them.
 The VERTEBRAL BODIES are large and kidney-shaped. They
are deeper anteriorly than posteriorly, producing the
lumbosacral angle (the angle between the long axis of the
lumbar region and that of the sacrum). The vertebral foramen
is triangular in shape.
CHARACTERISTIC FEATURES

4.  Other features of a typical lumbar vertebrae:
 Transverse processes are long and slender.
 Articular processes have nearly vertical facets.
 Spinous processes are short and broad.
 Accessory processes can be found on the posterior aspect of
the base of each transverse process. They act as sites of
attachment for deep back muscles.
 Mammillary processes can be found on the posterior surface
of each superior articular process. They act as sites of
attachment for deep back muscles.

6.  The fifth lumbar vertebrae, L5, has some distinctive
characteristics of its own. It has a notably large vertebral
body and transverse processes as it carries the weight of the
entire upper body.
ATYPICAL VETEBRAE

7.  Between vertebral bodies – adjacent vertebral bodies are
joined by intervertebral discs, made of fibrocartilage. This is a
type of cartilaginous joint, known as a symphysis.
 Between vertebral arches – formed by the articulation of
superior and inferior articular processes from adjacent
vertebrae. It is a synovial type joint.
JOINTS

8.  The joints of the lumbar vertebrae are supported by several ligaments.
They can be divided into two groups; those present throughout the
vertebral column, and those unique to the lumbar spine.
 Present throughout Vertebral Column
 Anterior and posterior longitudinal ligaments: Long ligaments that run
the length of the vertebral column, covering the vertebral bodies and
intervertebral discs.
 Ligamentum flavum: Connects the laminae of adjacent vertebrae.
 Interspinous ligament: Connects the spinous processes of adjacent
vertebrae.
 Supraspinous ligament: Connects the tips of adjacent spinous
processes.
LIGAMENTS

10.  Unique to Lumbar Spine
 The lumbosacral joint (between L5 and S1 vertebrae) is
strengthened by the iliolumbar ligaments. These are fan-
like ligaments radiating from the transverse processes of the
L5 vertebra to the ilia of the pelvis

11.  SACRALIZATION
 LAMBARIZATION
 LUMBAR STENOSIS
 DISC BULGE
 LUMBAR LORDOSIS
APPLIED ANATOMY

12. Dr. EIMAN SUMAYYAH
DPT, MSPT NEUROLOGY(KMU)
MYOLOGY OF ABDOMEN

13.  The anterolateral abdominal wall consists of four main layers
(external to internal); skin, superficial fascia, muscles and
associated fascia, and parietal peritoneum.
ANTERIOR ABDOMINAL WALL

14.  The superficial fascia consists of fatty connective tissue. The
composition of this layer depends on its location:
 Above the umbilicus – a single sheet of connective tissue. It is
continuous with the superficial fascia in other regions of the
body.
 Below the umbilicus – divided into two layers; the fatty
superficial layer (Camper’s fascia) and the membranous deep
layer (Scarpa’s fascia).
 The superficial vessels and nerves run between these two
layers of fascia.
SUPERFICIAL FASCIA

16.  The muscles of the anterolateral abdominal wall can be
divided into two main groups:
 Flat muscles – three flat muscles, situated laterally on either
side of the abdomen.
 Vertical muscles – two vertical muscles, situated near the
mid-line of the body.
MUSCLES OF THE ABDOMINAL WALL

17.  There are three flat muscles located laterally in the
abdominal wall, stacked upon one another. Their fibres run in
differing directions and cross each other – strengthening the
wall, and decreasing the risk of herniation.
 In the anteromedial aspect of the abdominal wall, each flat
muscle forms an aponeurosis (a broad, flat tendon), which
covers the vertical rectus abdominis muscle. The aponeuroses
of all the flat muscles become entwined in the midline,
forming the linea alba (a fibrous structure that extends from
the xiphoid process of the sternum to the pubic symphysis).
FLAT MUSCLES

18.  The external oblique is the largest and most superficial flat
muscle in the abdominal wall. Its fibres run inferomedially.
 Attachments: Originates from ribs 5-12, and inserts into the
iliac crest and pubic tubercle.
 Functions: Contralateral rotation of the torso.
 Innervation: Thoracoabdominal nerves (T7-T11) and subcostal
nerve (T12).
EXTERNAL OBLIQUE

19.  The internal oblique lies deep to the external oblique. It is
smaller and thinner in structure, with its fibres running
superomedially (perpendicular to the fibres of the external
oblique).
 Attachments: Originates from the inguinal ligament, iliac
crest and lumbodorsal fascia, and inserts into ribs 10-12.
 Functions: Bilateral contraction compresses the abdomen,
while unilateral contraction ipsilaterally rotates the torso.
 Innervation: Thoracoabdominal nerves (T6-T11), subcostal
nerve (T12) and branches of the lumbar plexus.
INTERNAL OBLIQUE

21.  The transversus abdominis is the deepest of the flat muscles,
with transversely running fibres. Deep to this muscle is a well-
formed layer of fascia, known as the transversalis fascia.
 Attachments: Originates from the inguinal ligament, costal
cartilages 7-12, the iliac crest and thoracolumbar fascia.
Inserts into the conjoint tendon, xiphoid process, linea alba
and the pubic crest.
 Functions: Compression of abdominal contents.
 Innervation: Thoracoabdominal nerves (T6-T11), subcostal
nerve (T12) and branches of the lumbar plexus.
TRANSVERSUS ABDOMINIS

22.  There are two vertical muscles located in the midline of the
anterolateral abdominal wall – the rectus abdominis and
pyramidalis.
VERTICAL MUSCLES

23.  The rectus abdominis is long, paired muscle, found either side of the
midline in the abdominal wall. It is split into two by the linea alba. The
lateral border of the two muscles create a surface marking, known as
the linea semilunaris.
 At several places, the muscle is intersected by fibrous strips, known as
tendinous intersections. The tendinous intersections and the linea alba
give rise to the ‘six pack’ seen in individuals with a well-developed
rectus abdominis.
 Attachments: Originates from the crest of the pubis, before inserting
into the xiphoid process of the sternum and the costal cartilage of ribs
5-7.
 Functions: As well as assisting the flat muscles in compressing the
abdominal viscera, the rectus abdominis also stabilises the pelvis
during walking, and depresses the ribs.
 Innervation: Thoracoabdominal nerves (T7-T11).
RECTUS ABDOMINIS

24.  This is a small triangular muscle, found superficially to the
rectus abdominis. It is located inferiorly, with its base on the
pubis bone, and the apex of the triangle attached to the linea
alba.
 Attachments: Originates from the pubic crest and pubic
symphysis before inserting into the linea alba.
 Functions: It acts to tense the linea alba.
 Innervation: Subcostal nerve (T12).
PYRAMIDALIS

25.  There are five muscles in the posterior abdominal wall: the
iliacus, psoas major, psoas minor, quadratus lumborum and
the diaphragm.
POSTERIOR ABDOMINAL MUSCLES

26.  The quadratus lumborum of the posterior abdominal wall. Fig 1.0
– The quadratus lumborum of the posterior abdominal wall.
 The quadratus lumborum muscle is located laterally in the
posterior abdominal wall. It is a thick muscular sheet which is
quadrilateral in shape. The muscle is positioned superficially to
the psoas major.
 Attachments: It originates from the iliac crest and iliolumbar
ligament. The fibres travel superomedially, inserting onto the
transverse processes of L1 – L4 and the inferior border of the
12th rib.
 Actions: Extension and lateral flexion of the vertebral column. It
also fixes the 12th rib during inspiration, so that the contraction
of diaphragm is not wasted.
 Innervation: Anterior rami of T12- L4 nerves.
QUADRATUS LUMBORUM

28.  The psoas major is located near the midline of the posterior
abdominal wall, immediately lateral to the lumbar vertebrae.
 Attachments: Originates from the transverse processes and
vertebral bodies of T12 – L5. It then moves inferiorly and
laterally, running deep to the inguinal ligament, and attaching
to the lesser trochanter of the femur.
 Actions: Flexion of the thigh at the hip and lateral flexion of
the vertebral column.
 Innervation: Anterior rami of L1 – L3 nerves.
PSOAS MAJOR

29.  The psoas minor muscle is only present in 60% of the
population. It is located anterior to the psoas major.
 Attachments: Originates from the vertebral bodies of T12 and
L1 and attaches to a ridge on the superior ramus of the pubic
bone, known as the pectineal line.
 Actions: Flexion of the vertebral column.
 Innervation: Anterior rami of the L1 spinal nerve.
PSOAS MINOR

30.  The iliacus muscle is a fan-shaped muscle that is situated
inferiorly on the posterior abdominal wall. It combines with
the psoas major to form the iliopsoas – the major flexor of
the thigh.
 Attachments: Originates from surface of the iliac fossa and
anterior inferior iliac spine. Its fibres combine with the tendon
of the psoas major, inserting into the lesser trochanter of the
femur.
 Actions: Flexion of the thigh at the hip joint.
 Innervation: Femoral nerve (L2 – L4).
ILIACUS

32.  Diaphragm
 The posterior aspect of the diaphragm is considered to be part
of the posterior abdominal wall. It is described in detail here.

33.  PSOAS SIGN
APPLIED ANATOMY