Spinal Cord General Topography And Internal Structure Flashcards
Spinal cord begins
And extends
superiorly at foramen magnum
caudally in the vertebral canal
Spinal cord is
Elongated, approximately cylindirical part of CNS
Spinal cord terminates
inferiorly between L1 – 2 (adult)
Terminates at the upper border of L3
Spinal cord is longer in
males than females about 45cm
Enlargements
• Cervical (C3–T2 segments)
Spinal nn. forming the brachial plexus
• Lumbosacral (L1–S3 segments)
Spinal nn. forming the lumbosacral plexus
plexus
Network of nerves or vessels in the body
Enlargements of spinal cord
are in in segments like c8 is caused by
intumescentia
A spinal cord has …. segment
31
A spinal cord segment is
Region of spinal cord associated with the emergence of a pair of nn
It Provides the attachment of the rootlets of a pair of spinal nn
Each spinal nerve is connected to the spinal cord by
posterior and anterior roots :
• The posterior root contains the processes of sensory neurons carryin information to the CNS
• The anterior root contains motor nerve fibers, which carry signals away from the CNS
the cell bodies of the sensory neurons are
clustered in a spinal ganglion at the distal end of the posterior root, usually in the intervertebral foramen
the cell bodies of the primary motor neurons are
in anterior regions of the spinal cord
31 pairs spinal nerves
8 pairs in cervical region 12 pairs in thoracic region 5 pairs in lumbar region 5 pairs in sacral region 1 pair in coccygeal region
Spinal nerve is divided into
Dorsal ramus
Ventral ramus
Epineurium (surface of ganglion)
external connective-tissue sheath of a nerve trunk.
Major somatic plexuses formed from the anterior rami of spinal nerves are:
CERVICAL (C1 to C4), BRACHIAL (C5 to T1), LUMBAR (L1 to L4), SACRAL (L4 to S4), COCCYGEAL (S5 to Co) plexuses
Except for spinal nerve T1, the anterior rami of thoracic spinal nerves
remain independent and do not participate in plexuses
Conus medullaris
Spinal cord narrowing beginning from the inferior limit of lumbosacral enlargement
termination of spinal cord
Meninges of spinal cord are Continuation of
meninges of brain
Meninges
3 membranes that line the skull and vertebral canal
Dura mater spinalis
Arachnoidea mater spinalis
Pia mater spinalis
Dura mater and arachnoidea mater terminates (closes) at
Pia mater terminates (closes) at
S2 level
inferior limit of spinal cord
Denticulate ligament
Two flattened bands of piamater
that attach to the spinal duramater comprising 21 pairs of tooth-shaped extensions Anchores spinal cord to vertebral canal
Filum terminale
filament of connective tissue (about 20 cm) descends from apex of conus medullaris beginning from After the closure of pia mater.
Filum terminale internum:
upper 15 cm, surrounded by extensions of dural and arachnoid meninges, reaches caudal border of S2 vertebra
Filum terminale externum (lig. coccygeum)
Final 5 cm, fuses with investing dura mater, descends to dorsum of 1st coccygeal vertebral segment
External features of spinal cord
- Anterior median fissure
- Posterior median sulcus
- Anterolateral sulcus
- Posterolateral sulcus
- Posterior intermediate septum
Posterior root; enters spinal cord from
posterolateral sulcus, brings sensory information from periphery
Anterior root; leaves spinal cord from
anterolateral sulcus
• Fila radicularia (rootlets);
the fibres forming the anterior and posterior roots
Spinal nerve: Formed in …. and are ….. pairs
intervertebral foramen
31 pairs
Spinal nerves contain what fibers
GSE, GSA, GVE, GVA fibres
The first cervical nerve (C1) location
atlas – occipital bone
The first cervical nerve (C1) is called
suboccipital n.